OT - Geothermal Heat issue...?

"Kenneth" <[email protected]> wrote in message
news:[email protected]...
>
> Howdy,
>
> This is way OT...(again), but:
>
> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?
>
>

The fellow you are talking to may not be able to tell you!
One point to consider is you can "stress" the ground by pulling a bunch of
heat out of it at one time. If you leave an area colder, then bump it up
5-10 degrees the heat pump will run longer than normal and pull an abnormal
amount of heat from the ground. Once the ground gets too cold, the
equipment does not as efficiently also. Same with air conditioning, but then
you are putting heat into the ground.Generally with heat pumps they are
slower to heat up the home than say gas or electric, so the equipment runs
longer to get to the occupied temps.
I am with your heating contractor, leave the temperature constant, unless
you have an area of the home you can close off and leave cold for many days.
I would not bother to set back the temperature once or twice a day like you
might with electric or gas heat. If you want to save money, wear a sweater,
and turn the temps down a couple degrees.
Greg

"Kenneth" wrote:


> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?


In a nutshell, thermal inertia.

Once the system is balanced, it requires minimum energy to maintain
the balance.

Change the set point to a lower level, remain there for a while, then
return to the higher level requires a lot of thermal work.

Heat intensive industries such as steel, refineries, etc, run 24/7 for
just this reason.

Lew

"Kenneth" <[email protected]> wrote in message
news:[email protected]...
>
>
> Though, indeed, the efficiency of the system decreases as
> the temperature of the well goes down, could that loss of
> efficiency compensate for the significant savings we would
> have if we were to drop the temp of our house by, say, 10
> degrees for 8 or 10 hours each day?
>
> My intuition tells me that it would not.
>
> What do you think?
>
> Thanks,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

I don't think you will see significant savings setting back the temps. Also
consider the time it takes to recover after a 10 degree setback. It is very
possible that equipment may run longer to recover the temps than it would to
just maintain a "normal" occupied temp, more possible when you consider the
stress it may put on the well.
Again, I would set the temps and leave them at one set point, unless the
home is not occupied for days.
Can I ask where you may be located?
Greg

"Kenneth" wrote:

> I don't deny it... I just don't understand it:
<snip>

OK, let's try a different way.

Moving thermal energy from place to place is at best a very
inefficient process.

You pay to move energy(heat) into the building, but not all the energy
is used due to efficiency losses.

Then you turn down the thermostat and move energy from the building to
a colder source, but again, efficiency losses come into play.

Then you turn the thermostat back up, and you need to move energy back
into the building, again with efficiency losses.

System efficiencies are the problem.

Other examples where efficiency bites you.

1) Wet cell batteries.

For every 100 ampere-hours you consume out of a wet cell battery, you
must replace 125 ampere-hours.

Batteries are convenient, not efficient.

2) A big ball.

It takes a lot of energy to get a big ball rolling.

Once it is up to speed, to keep it rolling, all that is needed is to
replace the frictional losses.

If you let the ball slow down, it takes a bunch of energy to bring the
ball back up to speed.

Maybe these are poor analogies, but it's late, and I'm lazy tonight.

I'd refer you to one of my old thermo text books, but it's easier to
run a field test than wade thru one of those books.

I'd keep my sticky fingers off the thermostat.

Lew

In article <[email protected]>,
Kenneth <[email protected]> wrote:
>On Mon, 26 Nov 2007 16:44:48 -0800, "Lew Hodgett"
><[email protected]> wrote:
>>
>>In a nutshell, thermal inertia.
>>
>>Once the system is balanced, it requires minimum energy to maintain
>>the balance.
>>
>>Change the set point to a lower level, remain there for a while, then
>>return to the higher level requires a lot of thermal work.
>>
>>Heat intensive industries such as steel, refineries, etc, run 24/7 for
>>just this reason.
>>
>>Lew
>>
>
>Hi Lew,
>
>I don't deny it... I just don't understand it:
>
>(Though there may be parallels to industrial applications,
>I'll stick with home heating for my example.)
>
>For a given outside and inside temperature, the house loses
>a constant amount of heat per hour, and that amount must be
>replaced if we are to keep the internal temperature
>constant.
>
>If the internal temperature of the house is allowed to drop,
>two things happen. First, there is the direct energy savings
>because it takes fewer BTUs to keep the house at the lower
>temp;

_THOSE_ BTUs are just 'deferred spending'. you spend exactly
that amount to raise the temp back to the original setting.

> but perhaps less obviously, the rate of heat loss to
>the outside environment is decreased. (Because the greater
>the temperature differential, the more rapid the rate of
>equalization.)

That is the -totality- of the energy savings -- the lowered losses.
from the reduced temperature.
>
>So, for the eight hours or so that the interior temperature
>was lowered, there are savings for two reasons: We are
>providing less heat to the house, and we are losing less per
>hour of what heat we do supply.

FALSE. you are double-counting the same saving there.

to maintain any system 'at equilibrium', all you do is replace
the losses. if you are maintaining a lower equilibrium point,
the 'savings' are exactly equal to the difference in the losses
at the two equilibrium points.

>When we decide to go back to the original interior
>temperature, at every stage (prior to reaching that temp)
>the hourly rate of heat loss is something less than it would
>be when we reach the desired internal temperature.
>
>Now, of course, heating up the house those 10 degrees will
>take a bushel of BTUs, but (unless I am way off here) that
>would have to be fewer than those saved.
>
>I well understand that the efficiency of the system goes
>down as the well cools, but it seems to me that the
>diminished efficiency, though regrettable, is more than
>balanced by the savings at the lower temperatures.

authoritative answer: "it depends".

1) _how_much_ lower are the building thermal losses for the temperature
reduction employed?
2) _how_much_ less efficient is the heat plant as the -rate- of draw
increases?

Depending on the _quantitative_ answers to those two questions the
'savings' can 'net' to either a positive or negative result.

The exact answers to both questions will be specific to a particular
installation.

Getting an answer by 'science' is -very- messy. It's much simpler to
use the 'experimentalist' approach and simply 'measure' what actually
happens.

The building loss rates are relatively easy -- measure the required heat
input at both equilibrium points. It _is_ reasonable to assume that the
delta on the loss rates is the same for both temperature rising and falling,
so the cool-down, and warm-up phases effectively cancel each other.

The changing 'efficiency' of the heat plant is harder. You really need
to have a running monitor on the well-water temperature for that. (with
that you can tell 'when' things have 'recovered' from the excessive
consumption to raise the building back to the higher level.

Failing instrumentation on the water temperature, one can use outside
air temperatures as a -rough- basis for comparison. (it helps greatly if
you have historical power usage data [at stable inside temperature operation]
that you can correlate with 'heating degree days' for various periods)

If you have the above-mentioned historical data, you'll see that 'cost of
operation' goes up as the heat demand increases. both in absolute terms
and on a per unit basis.

Now, run the system for a while in 'set-back' mode. Total the 'heating
degree days', and the cost. See where that 'per unit' cost falls relative
to the same degree-days for stable temperature operation.

NOTE: this is all figuring 'cost' on the basis of "how cold it is outside"
-not- on a "per BTU of heat added" basis, so you have a direct comparison
of the 'efficiency' of the methods, and can reasonably predict what, if any,
the overall savings will be.


Heat pumps are, by their nature, less efficient, the larger the temperature
differential between the 'external' and 'internal' sides. And that efficiency
does degrade significantly with relatively small increases in that
differential.

Things will depend 'a whole lot' on the thermal conductivity of the external
heat reservoir, and how fast stuff in the vicinity of the 'radiator' there
recovers to equilibrium after a draw-down.

W/o extensive geological testing, that's hard to quantify.

I _would_ tend to believe that the designers/installers *DO* know what
they're talking about when they recommend stable (and not 'set back')
operation, counter-intuitive though it may seem.

In article <[email protected]>,
Kenneth <[email protected]> wrote:
>On Tue, 27 Nov 2007 18:07:39 -0000,
>[email protected] (Robert Bonomi) wrote:
>
>
>Hi Robert,
>
>I thank you for your detailed response...
>
>Perhaps I am not understanding what you have written, but
>allow me to ask something further.
>
>Please see my comments inline below:
>
>
>I wrote:
>>>If the internal temperature of the house is allowed to drop,
>>>two things happen. First, there is the direct energy savings
>>>because it takes fewer BTUs to keep the house at the lower
>>>temp;
>
>You responded:
>>_THOSE_ BTUs are just 'deferred spending'. you spend exactly
>>that amount to raise the temp back to the original setting.
>
>I wrote:
>>> but perhaps less obviously, the rate of heat loss to
>>>the outside environment is decreased. (Because the greater
>>>the temperature differential, the more rapid the rate of
>>>equalization.)
>>
>You responded:
>>That is the -totality- of the energy savings -- the lowered losses.
>>from the reduced temperature.
>>>
>
>In my attempt to understand this...
>
>Suppose I lowered the temperature of the house 10 degrees,
>but not merely overnight. Instead, I left them lower for a
>month.
>
>Would I not have very significant savings for that month?

Relative to what you would have 'spent' at the 10degree higher
temperature yes.

>If so, would not the reasons for those savings apply as well
>to my overnight lowering of the house's internal temperature
>(though with decreased benefit because of the diminished
>duration)?

Yes and no. <grin>

There are three intervals to consider.
1) while the temperature is falling from 'X' to 'X-10',
2) while the temperature is stable at 'X-10',
3) while the temperature is rising from 'X-10' to 'X'.

As the house cools from 'X' to 'X-10', you aren't providing any heat input
at that time. *THAT* 'savings', is cancelled by the 'extra' energy you
have to put back into the building the next day, to raise the temperature
from 'X-10' back to 'X'. For complicated reasons, it usually takes a little
more energy to go from 'X-10' to 'X' than was 'saved' by letting things
fall from 'X' to 'X-10'. This differential is usually fairly minor, however
it can be magnified if the -rates- at which the temperature falls and rises
are different.

The heat input required to maintain the house at a constant "X" is exactly
the heat losses being radiated by the house to the exterior.

The heat input required to maintain the house at a constant "X-10" is exactly
the heat losses being radiated by the house to the exterior.

In both cases the rate of loss is a function of (a) the temperature
differential, _and_ the quality of the insulation.

The point is, however, that the difference in heat input is exactly the
difference in thermal losses, at a constant temperature. You cannot count
a savings for less heat input, -and- a savings for lower thermal losses.

In article <[email protected]>, DanG <[email protected]> wrote:
>We are running multiple schools on ground source heat pumps. Each
>building has a single loop with individual Trane heat pumps
>running in each classroom tapped onto that loop. There is NO
>auxiliary heat. There are NO heat strips. Our Energy Czar
>believes in night set backs and holding temperatures at minimums
>until someone gripes. The systems are computerized to central
>control and the units can only be changed from the central
>location other than a small allowance at the thermostats.
>
>Each building, or even portions of buildings, have different
>thermal mass/draft and air leakage issues/poor glazing/etc that
>each requires its own start up time. Some take 2 hours, some
>almost 4 hours if they have been allowed to get too far out of
>design or conditions are extreme. The water loop is circulated
>full time through the well field, but the compressors at each heat
>pump function by thermostat. The buildings have become so much
>easier to control that we continue to install these systems as
>money permits. The buildings are so much more stable that we tend
>to ignore old fashioned insulation/draft/weatherstrip conditions -
>perhaps we will get back to them as energy costs continue to
>spiral.
>
>Our HVAC technicians would prefer just letting the systems run
>full time and maintain a steady temperature, especially when
>equipment is new just to run it through its paces while under
>warranty. The Energy Czar tends to win. I will try to remember
>to ask tomorrow about the whys.

A 'medium-insulated' school building full of people doesn't need _any_
additional heat source until the outside temperature gets below about
-20F.

Look up how much heat an 'at rest' human body gives off, and multiply by
the 25-30 bodies preset in the average classroom.

Getting the heat _out_ of the building is the issue.

At 'above zero' temperatures, it's _common_ to be venting hot air outside
and pulling in cold outside air for 'make-up'.

Not infrequently, the chillers will be running, in addition.

Robert Bonomi wrote:

... snip
>>Our HVAC technicians would prefer just letting the systems run
>>full time and maintain a steady temperature, especially when
>>equipment is new just to run it through its paces while under
>>warranty. The Energy Czar tends to win. I will try to remember
>>to ask tomorrow about the whys.
>
> A 'medium-insulated' school building full of people doesn't need _any_
> additional heat source until the outside temperature gets below about
> -20F.
>
> Look up how much heat an 'at rest' human body gives off, and multiply by
> the 25-30 bodies preset in the average classroom.
>

From EDEE 101 (or Physics 112), we were told that the average human body
is equivalent to 100 watt light bulb as far as heat output. Depending upon
age, kids in a school would most likely be considerably less.


> Getting the heat _out_ of the building is the issue.
>
> At 'above zero' temperatures, it's _common_ to be venting hot air outside
> and pulling in cold outside air for 'make-up'.
>
> Not infrequently, the chillers will be running, in addition.

--
If you're going to be dumb, you better be tough

In article <[email protected]>,
Mark & Juanita <[email protected]> wrote:
>Robert Bonomi wrote:
>
>... snip
>>>Our HVAC technicians would prefer just letting the systems run
>>>full time and maintain a steady temperature, especially when
>>>equipment is new just to run it through its paces while under
>>>warranty. The Energy Czar tends to win. I will try to remember
>>>to ask tomorrow about the whys.
>>
>> A 'medium-insulated' school building full of people doesn't need _any_
>> additional heat source until the outside temperature gets below about
>> -20F.
>>
>> Look up how much heat an 'at rest' human body gives off, and multiply by
>> the 25-30 bodies preset in the average classroom.
>>
>
> From EDEE 101 (or Physics 112), we were told that the average human body
>is equivalent to 100 watt light bulb as far as heat output.

That's a bit on the low side -- about right for sleeping. 'resting' is more
in the 110-120 range. Circa 125 is frequently used for estimating purposes.

Call it 12,000 BTU/hr per room, plus another few thousand for the lighting.

Scale up by a factor of 4, for equivalent footage to a medium house,
and you've got the equivalent of an 80% efficient 150,000 BTU/hr furnace
running at a _50%_ duty cycle.

> Depending upon
>age, kids in a school would most likely be considerably less.

Surprisingly small differences. lower elementary ages are about 75-80% of
adult.

>> Getting the heat _out_ of the building is the issue.
>>
>> At 'above zero' temperatures, it's _common_ to be venting hot air outside
>> and pulling in cold outside air for 'make-up'.
>>
>> Not infrequently, the chillers will be running, in addition.

In article <[email protected]>,
Han <[email protected]> wrote:
>Mark & Juanita <[email protected]> wrote in
>news:[email protected]:
>
>> From EDEE 101 (or Physics 112), we were told that the average human
>> body
>> is equivalent to 100 watt light bulb as far as heat output. Depending
>> upon age, kids in a school would most likely be considerably less.
>>
>
>You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.

Depending on activity level, you can _triple_ (or somewhat more) the base
number, which is in the 100-140 watt range.

A 250 watt kid is -not- all that extreme! <grin>

In article <[email protected]>,
Han <[email protected]> wrote:
>[email protected] (Robert Bonomi) wrote in
>news:[email protected]:
>
>> In article <[email protected]>,
>> Han <[email protected]> wrote:
>>>Mark & Juanita <[email protected]> wrote in
>>>news:[email protected]:
>>>
>>>> From EDEE 101 (or Physics 112), we were told that the average
>>>> human body
>>>> is equivalent to 100 watt light bulb as far as heat output.
>>>> Depending upon age, kids in a school would most likely be
>>>> considerably less.
>>>>
>>>
>>>You haven't seen my 11 year-old granddaughter - 250 Watt is more like
>>>it.
>>
>> Depending on activity level, you can _triple_ (or somewhat more) the
>> base number, which is in the 100-140 watt range.
>>
>> A 250 watt kid is -not- all that extreme! <grin>
>>
>Also, I think that heat dissipation would be equivalent to body surfacce
>area, which would make skinny kids radiate more (proportionally) than
>chunky ones ...

While you might think so, reality is somewhat counter-intuitive. :)
Total heat output is relatively -independant- of surface area. Less skin
just means more output per unit area.

Han wrote:

> Mark & Juanita <[email protected]> wrote in
> news:[email protected]:
>
>> From EDEE 101 (or Physics 112), we were told that the average human
>> body
>> is equivalent to 100 watt light bulb as far as heat output. Depending
>> upon age, kids in a school would most likely be considerably less.
>>
>
> You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.
>

You know, I know exactly what you are saying -- our son has been like that
also.


--
If you're going to be dumb, you better be tough

On Dec 8, 6:57 pm, Doug Winterburn <[email protected]> wrote:
> Kenneth wrote:
>
> > Hello to all (again),
>
> > Well, I am the OP on this "Will I save if I use a thermostat
> > setback on my geothermal system" thread, and I believe that
> > I now have an answer:
>
> > Part of the hassle I faced in experimenting with this was
> > that for some reason, I kept thinking only of my house. We
> > have a number of electrical appliances there that are used
> > (essentially) randomly, and their use would certainly throw
> > off any comparisons that I could make over a relatively
> > short period of time.
>
> > I commented on that to my wife, and she said "So do the
> > experiment in the barn." (She did not actually say "So do
> > the experiment in the barn, you idiot", but that is what I
> > heard.)
>
> > Our office-barn is heated with exactly the same system as is
> > our house (water to air geo with no backup resistance heat)
> > and there is no variability of electrical consumption other
> > than the heating system for most of each day.
>
> > So, with that information, I did a very simple experiment. I
> > have run it only for six days but, as you will see, the
> > pattern seems quite clear:
>
> > I set the programmable thermostat to drop the "call heat"
> > temperature by 10 degrees F for 12 hours on alternating
> > nights.
>
> > Each morning, at the same time, I read the barn's electric
> > meter.
>
> > Finally, I got the degree days, and wind speed, from a
> > weather service site.
>
> > With that, I could calculate the ratio of KWH to Degree Day.
> > I have also included in the table below the reported max
> > wind speed for the day.
>
> > KWH/DD WS
>
> > Day 1: 1.2 (setback) 14
>
> > Day 2: 1.6 (no setback) 17
>
> > Day 3: 1.0 (setback) 8
>
> > Day 4: 1.3 (no setback) 0
>
> > Day 5: 1.0 (setback) 12
>
> > Day 6: 1.2 (no setback) 3
>
> > So, on the days with setback, the mean KWH/DD was 1.06. On
> > the days with no setback, that mean was 1.36.
>
> > The resulting savings are approximately 22%.
>
> > I do remain baffled by the reasons the geothermal folks
> > (installers, designers, sellers) seem to be consistent in
> > suggesting that such setbacks are not of value.
>
> > All the best,
>
> I'm wondering if your savings aren't as great as you think. The reason
> is that on a setback day, you have zero electrical usage as the house
> coasts down to the setback temp. The next day's usage gets nailed with
> the recovery time usage. Perhaps week long vs day long alternating
> periods might mitigate some of this effect?

So long as he reads the meter after his house i swarmed up,
it doesn't matter. But it should be well after it has warmed up
as lingering cold spots away from the thermostat will have the
effect you suggest. It would be better to read the meter at the
same time every night, right before the setback.


--

FF

On Dec 2, 7:56 pm, Fred the Red Shirt <[email protected]> wrote:
> On Dec 2, 6:18 pm, dpb <[email protected]> wrote:
>
>
>
> > Fred the Red Shirt wrote:
>
> ...
>
> > Whatever "caveats" were suggested to counteract that would have to be
> > extreme, indeed...
>
> If he's talking bout a new engine them maybe removing the radiator

Er, I meant removing the 'thermostat'.

There is little doubt that removing the radiator will cause the engine
to
overheat...

--

FF

On Sat, 01 Dec 2007 15:11:19 GMT, chuckb <[email protected]>
wrote:

>Kenneth wrote:
>
>> On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
>> <[email protected]> wrote:
>>
>>
>>>Now that has a few good answers. I would not have thought about the
>>>freezing closed loops.
>>
>>
>> Howdy,
>>
>> Any responsibly designed system protects against such
>> freezing...
>>
>> All the best,
>
>
>but on the other hand:
>
>from your OP
>"The folks who designed the heating system say that with
>these systems, it is best to leave the set temp unchanged."
>
>any system that is operated outside it's design criteria risks failure!
>
>good luck with yours!
>
>chuck b:-)

Hi Chuck,

It would seem that I have not communicated clearly...

Indeed, the design folks tell me not to use any setback, but
they seem unable to tell me "why." Their lack of a
meaningful explanation was the cause of my original question
about the setback issue.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
<[email protected]> wrote:

>Now that has a few good answers. I would not have thought about the
>freezing closed loops.

Howdy,

Any responsibly designed system protects against such
freezing...

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Sat, 08 Dec 2007 10:00:24 -0600, dpb <[email protected]>
wrote:

>Kenneth wrote:
>> On Sat, 08 Dec 2007 09:22:52 -0600, dpb <[email protected]>
>> wrote:
>>
>>> Kenneth wrote:
>>> ...
>>>
>>>> So, on the days with setback, the mean KWH/DD was 1.06. On
>>>> the days with no setback, that mean was 1.36.
>>>>
>>>> The resulting savings are approximately 22%.
>>>>
>>>> I do remain baffled by the reasons the geothermal folks
>>>> (installers, designers, sellers) seem to be consistent in
>>>> suggesting that such setbacks are not of value.
>>> As at least one other poster noted, they're concerned w/ other factors
>>> that aren't applicable in your case (primarily dominated by the use of
>>> resistance electric heat in many/most systems)...
>>>
>>> There are others including the potential freezeup, etc., that are
>>> possible but imo they're mostly cya kinds of responses. Did you try the
>>> Water Furnace people directly or contact the Okla State or some of the
>>> other resources for other input?
>>
>> Howdy,
>>
>> The CYA analysis makes sense to me, but as you probably
>> know, there is no real "freeze up" danger at all. These
>> systems simply turn themselves off is the incoming water is
>> too cold.
>
>The problem I've normally seen is on the once-through water exchange
>systems (which is also what I think I recall being mentioned in one of
>the earlier postings of a problem--whether it was yours or another I
>don't recall) is the freezeup of the outlet when systems aren't running.
> My opinion remains as I noted there is that if that's a problem for a
>given system, it will be so whether there's a setback or not unless the
>system is so undersized as to run continuously; hence my assessment of
>that as a response as being in the "CYA" category.
>
>> Also, as you may know "Water Furnace" is a brand name. Our
>> equipment is ClimateMaster.
>
>Yes, I had thought that was who you had said earlier...I don't know
>ClimateMaster; had a Water Furnace system earlier and was pretty
>impressed w/ their factory rep service/technical support.
>
>> I have communicated about all this at some length with the
>> ClimateMaster folks, with the geo folks from my electric
>> utility, and with the installer of the equipment. They all
>> have said "no setback" is best.
>
>I think again all of those folks are addressing the general case still
>rather than the specifics of a given installation and are still using
>the answer that is easiest for them. It would be interesting if could
>get to one of the actual research facilities that might address a
>specific system rather than the general consumer response. If you were
>still interested in pursuing it from that standpoint I'd again suggest
>ORNL, TVA R&D (not power) or OSU might be more likely to answer a real
>question.

Hi again,

For me there are two (essentially unrelated) issues:

First, I am concerned with my system(s) and whatever savings
I might realize with the setbacks.

Second, I am a curious sort, and often enjoy understanding
this sort of thing.

Right now, my energies are focused on #1, and with my very
simple experiment, I do believe I have my answer.

#2 will have to wait a bit!

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

dpb wrote:

> chuckb wrote:
>
>> Kenneth wrote:
>>
>>> On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
>>> <[email protected]> wrote:
>>>
>>>
>>>> Now that has a few good answers. I would not have thought about the
>>>> freezing closed loops.
>>>
>>>
>>>
>>> Howdy,
>>>
>>> Any responsibly designed system protects against such
>>> freezing...
>>>
>>> All the best,
>>
>>
>>
>> but on the other hand:
>>
>> from your OP
>> "The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged."
>>
>> any system that is operated outside it's design criteria risks failure!
>
> ..
>
> A few degrees lower is "outside the design" for a residential hvac
> system? I still think there's been no rational basis for the
> proscription given unless, as Ken says, there's a problem--and if
> there's a problem, I think there will be a problem irrespective of the
> setback.
>
> --


you seem to be reading things that i didn't say or if i did i certainly
did not mean to.. oh well, have a good day!

chuck b:-)

Robatoy wrote:
> On Nov 27, 9:01 am, dpb <[email protected]> wrote:
>> Robatoy wrote:
>>> On Nov 26, 7:07 pm, Kenneth <[email protected]> wrote:
>>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>> <[email protected]> wrote:
>>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
>>>>>> Howdy,
>>>>>> This is way OT...(again), but:
>>>>>> We heat and cool our home geothermally (water to air
>>>>>> system.)
>>>>>> We would, of course, like to decrease our costs further if
>>>>>> we can, and so have explored the benefits of setting our
>>>>>> thermostat lower at those times when the house (or parts of
>>>>>> it) are not occupied.
>>>>>> The folks who designed the heating system say that with
>>>>>> these systems, it is best to leave the set temp unchanged.
>>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>>> smoke starts to come out of the phone. In essence, they say
>>>>>> that it is "best" but seem unable to say why.
>>>>>> Might any of you know what would be best in this regard ,
>>>>>> and particularly whether the issue of thermostat setback is
>>>>>> actually any different for geothermal systems?
>>>>>> Sincere thanks,
>>>>>> --
>>>>>> Kenneth

The phone smoke may merely be the designers attempting to discourage you
from messing with their system. As far as designers are concerned, the
system is perfect, and any user adjustment may break it, resulting in
warranty service, on their nickel. Designers and installers are like
that.

--
David J. Starr

Blog: www.newsnorthwoods.blogspot.com

On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
> Howdy,
>
> This is way OT...(again), but:
>
> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?
>
> Sincere thanks,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

Cycling a building in and out of extremes will bring into play the
building's phase.
The lower extremes may force the auxiliary heating to start up (maybe
electric?).
It might be cheaper to keep things at a low wick rather than replacing
lost heat with expensive heat.

Just a hunch.

Kenneth wrote:
>
>
> Hello to all (again),
>
> Well, I am the OP on this "Will I save if I use a thermostat
> setback on my geothermal system" thread, and I believe that
> I now have an answer:
>
> Part of the hassle I faced in experimenting with this was
> that for some reason, I kept thinking only of my house. We
> have a number of electrical appliances there that are used
> (essentially) randomly, and their use would certainly throw
> off any comparisons that I could make over a relatively
> short period of time.
>
> I commented on that to my wife, and she said "So do the
> experiment in the barn." (She did not actually say "So do
> the experiment in the barn, you idiot", but that is what I
> heard.)
>
> Our office-barn is heated with exactly the same system as is
> our house (water to air geo with no backup resistance heat)
> and there is no variability of electrical consumption other
> than the heating system for most of each day.
>
> So, with that information, I did a very simple experiment. I
> have run it only for six days but, as you will see, the
> pattern seems quite clear:
>
> I set the programmable thermostat to drop the "call heat"
> temperature by 10 degrees F for 12 hours on alternating
> nights.
>
> Each morning, at the same time, I read the barn's electric
> meter.
>
> Finally, I got the degree days, and wind speed, from a
> weather service site.
>
> With that, I could calculate the ratio of KWH to Degree Day.
> I have also included in the table below the reported max
> wind speed for the day.
>
>
> KWH/DD WS
>
> Day 1: 1.2 (setback) 14
>
> Day 2: 1.6 (no setback) 17
>
> Day 3: 1.0 (setback) 8
>
> Day 4: 1.3 (no setback) 0
>
> Day 5: 1.0 (setback) 12
>
> Day 6: 1.2 (no setback) 3
>
>
> So, on the days with setback, the mean KWH/DD was 1.06. On
> the days with no setback, that mean was 1.36.
>
> The resulting savings are approximately 22%.
>
> I do remain baffled by the reasons the geothermal folks
> (installers, designers, sellers) seem to be consistent in
> suggesting that such setbacks are not of value.
>
> All the best,

What was the recovery time after the setback days?

On Dec 2, 6:18 pm, dpb <[email protected]> wrote:
> Fred the Red Shirt wrote:
>
>
>
> > On Nov 27, 7:26 am, Robatoy <[email protected]> wrote:
> >> ...
>
> >> I was going to try to equate this with the reason why when you
> >> increase the waterflow through your car's radiator by taking out the
> >> thermostat, your engine will overheat. The water HAS to spend time in
> >> the rad to be able to give up its heat. So the thermostat slows down
> >> the waterflow. Conventional thinking would suggest that by increasing
> >> the waterflow, it should cool better. (There are a few caveats in
> >> there too, so everybody keep their shirts on.)
>
> > That is the first I ever heard of that.
>
> > The higher the flow rate the higher the Reynolds number and
> > therefor the higher the convective heat-transfer coefficient.
> > You may get less heat transferred per gram of water flowing
> > through the radiator, but not in inverse proportion to the
> > rate at which grams of water flow through. IOW you might
> > get only 75% of the heat loss per gram of water but will
> > have twice as many grams of water flowing through.
>
> Yes, it's simply wrong in general. If one didn't get additional cooling
> capacity when the thermostat opened as compared to when it is closed,
> there would be insufficient cooling capacity to prevent overheating at
> almost any operating condition.
>
> Whatever "caveats" were suggested to counteract that would have to be
> extreme, indeed...

If he's talking bout a new engine them maybe removing the radiator
could confuse the computer and really screw things up--but since
normal operation is for the thermostat to open when the water gets
hot--how COULD it overheat by leaving ti open? Once it gets hot, it
would open anyways.

Sound's like an old wive's) mechanic's tale.

--

FF

On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
<[email protected]> wrote:

>
>What was the recovery time after the setback days?

Hi Doug,

I don't know with certainty, but I do know it to be less
than an hour.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Tue, 27 Nov 2007 13:43:34 -0500, Kenneth
<[email protected]> wrote:

>On Tue, 27 Nov 2007 18:07:39 -0000,
>[email protected] (Robert Bonomi) wrote:
>
>
>Hi Robert,
>
>I thank you for your detailed response...
>
>Perhaps I am not understanding what you have written, but
>allow me to ask something further.
>
>Please see my comments inline below:
>
>
>I wrote:
>>>If the internal temperature of the house is allowed to drop,
>>>two things happen. First, there is the direct energy savings
>>>because it takes fewer BTUs to keep the house at the lower
>>>temp;
>
>You responded:
>>_THOSE_ BTUs are just 'deferred spending'. you spend exactly
>>that amount to raise the temp back to the original setting.
>
>I wrote:
>>> but perhaps less obviously, the rate of heat loss to
>>>the outside environment is decreased. (Because the greater
>>>the temperature differential, the more rapid the rate of
>>>equalization.)
>>
>You responded:
>>That is the -totality- of the energy savings -- the lowered losses.
>>from the reduced temperature.
>>>
>
>In my attempt to understand this...
>
>Suppose I lowered the temperature of the house 10 degrees,
>but not merely overnight. Instead, I left them lower for a
>month.
>
>Would I not have very significant savings for that month?
>
>If so, would not the reasons for those savings apply as well
>to my overnight lowering of the house's internal temperature
>(though with decreased benefit because of the diminished
>duration)?
>
>Thanks again,


Why do you need a second electric meter to excrement with? You can
read your own meter every day at the same time. As long as you record
when you are drying clothes or other significant electricity burning
events you should be able to test for no hardware costs.

Are you torturing the group by not doing your own meter reading and
reporting back?

On Mon, 26 Nov 2007 22:59:57 -0500, Jim Behning
<[email protected]> wrote:

>
>The neighbor down the road has a couple of geothermal units that they
>zoned for the main part of the house they lived in and another zone
>and unit for the extra bedrooms. They claimed power bills less than my
>house even though their house was much bigger. Makes me mad enough to
>finish insulating the concrete walls in my conditioned basement.

Hey, don't feel bad about that...

Someone I work with used exactly the same equipment to heat
a home about the size of ours, and her costs are about half
of ours...

Though she is only a few miles away, she is served by a
different power company.

Her's has a dual-rate policy. Mine, does not.

As a result, she pays slightly more than half of what I pay.

'Feels great...

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Nov 27, 9:01 am, dpb <[email protected]> wrote:
> Robatoy wrote:
> > On Nov 26, 7:07 pm, Kenneth <[email protected]> wrote:
> >> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>
> >> <[email protected]> wrote:
> >>> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
> >>>> Howdy,
> >>>> This is way OT...(again), but:
> >>>> We heat and cool our home geothermally (water to air
> >>>> system.)
> >>>> We would, of course, like to decrease our costs further if
> >>>> we can, and so have explored the benefits of setting our
> >>>> thermostat lower at those times when the house (or parts of
> >>>> it) are not occupied.
> >>>> The folks who designed the heating system say that with
> >>>> these systems, it is best to leave the set temp unchanged.
> >>>> Of course, I have asked "why", but when I do, it seems that
> >>>> smoke starts to come out of the phone. In essence, they say
> >>>> that it is "best" but seem unable to say why.
> >>>> Might any of you know what would be best in this regard ,
> >>>> and particularly whether the issue of thermostat setback is
> >>>> actually any different for geothermal systems?
> >>>> Sincere thanks,
> >>>> --
> >>>> Kenneth
> >>>> If you email... Please remove the "SPAMLESS."
> >>> Cycling a building in and out of extremes will bring into play the
> >>> building's phase.
> >>> The lower extremes may force the auxiliary heating to start up (maybe
> >>> electric?).
> >>> It might be cheaper to keep things at a low wick rather than replacing
> >>> lost heat with expensive heat.
> >>> Just a hunch.
> >> Howdy,
>
> >> There is no auxiliary heat...
>
> >> So, whatever heat energy lost by the house is replaced by
> >> the heat energy extracted (at some cost of electricity) from
> >> the well water.
>
> >> My reasoning was that keeping the house warm when empty
> >> would have greater cost than keeping it cool when empty
> >> (that part seems obvious) and heating it up to comfort would
> >> take less energy than that which would be lost were it kept
> >> warm continuously.
>
> >> What am I missing?
> >> --
> >> Kenneth
>
> >> If you email... Please remove the "SPAMLESS."
>
> > It keeps coming back to the building's phase. It doesn't cycle at the
> > same speed your internal temperature does.
> > As you turn down the thermostat, the building's stored heat is given
> > up, some to the interior, but some to the exterior (loss).
> > To reheat the building's interior, the heat is not only heating the
> > interior, but also the building's mass.
> > So, when you turn down the thermostat, you need to later replace the
> > heat you lose. Once the building is up to temperature, you just
> > overcome the building's heat loss...like Lew's Ball.
>
> ...
>
> No, you don't need to "replace" the heat you lost for the period the
> setpoint was lower -- that's the gain.
>
> --

Only if you decide to keep the building's mass at that temperature.
If you want to restore the temperature of the model, you also have to
re-heat the container.

On Nov 26, 7:07 pm, Kenneth <[email protected]> wrote:
> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>
>
>
> <[email protected]> wrote:
> >On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
> >> Howdy,
>
> >> This is way OT...(again), but:
>
> >> We heat and cool our home geothermally (water to air
> >> system.)
>
> >> We would, of course, like to decrease our costs further if
> >> we can, and so have explored the benefits of setting our
> >> thermostat lower at those times when the house (or parts of
> >> it) are not occupied.
>
> >> The folks who designed the heating system say that with
> >> these systems, it is best to leave the set temp unchanged.
>
> >> Of course, I have asked "why", but when I do, it seems that
> >> smoke starts to come out of the phone. In essence, they say
> >> that it is "best" but seem unable to say why.
>
> >> Might any of you know what would be best in this regard ,
> >> and particularly whether the issue of thermostat setback is
> >> actually any different for geothermal systems?
>
> >> Sincere thanks,
> >> --
> >> Kenneth
>
> >> If you email... Please remove the "SPAMLESS."
>
> >Cycling a building in and out of extremes will bring into play the
> >building's phase.
> >The lower extremes may force the auxiliary heating to start up (maybe
> >electric?).
> >It might be cheaper to keep things at a low wick rather than replacing
> >lost heat with expensive heat.
>
> >Just a hunch.
>
> Howdy,
>
> There is no auxiliary heat...
>
> So, whatever heat energy lost by the house is replaced by
> the heat energy extracted (at some cost of electricity) from
> the well water.
>
> My reasoning was that keeping the house warm when empty
> would have greater cost than keeping it cool when empty
> (that part seems obvious) and heating it up to comfort would
> take less energy than that which would be lost were it kept
> warm continuously.
>
> What am I missing?
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

It keeps coming back to the building's phase. It doesn't cycle at the
same speed your internal temperature does.
As you turn down the thermostat, the building's stored heat is given
up, some to the interior, but some to the exterior (loss).
To reheat the building's interior, the heat is not only heating the
interior, but also the building's mass.
So, when you turn down the thermostat, you need to later replace the
heat you lose. Once the building is up to temperature, you just
overcome the building's heat loss...like Lew's Ball.

I was going to try to equate this with the reason why when you
increase the waterflow through your car's radiator by taking out the
thermostat, your engine will overheat. The water HAS to spend time in
the rad to be able to give up its heat. So the thermostat slows down
the waterflow. Conventional thinking would suggest that by increasing
the waterflow, it should cool better. (There are a few caveats in
there too, so everybody keep their shirts on.)

On Nov 26, 11:48 pm, Kenneth <[email protected]>
wrote:
> Howdy,
>
> This is way OT...(again), but:
>
> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?
>


The rate at which your house loses heat to the environment
depends in an almost linear fashion on the temperature difference
between your house and the outside environment.

So as your house cools, the rate at which it loses heat will
decrease. Keeping the house at the higher temperature means
it will constantly lose heat at that higher rate, and all of that heat
lost must be mad eup to maintain the temperature. If you let
it cool down and heat it back up the 'stored' heat that is lost
to the environment while cooling is exactly equal to the extra
heat needed to heat it back up. But the heat loss to the enviornment
is less the whol time during which the house is cooler than
normal.

Ergo, it ALWAY will use less heat to let it cool down and
heat it back up than to maintain it at the higher temperature.

What comes into play is the cost of pumping that heat into
your house at the higher rate for the short period of time
during which it heats back up. If that is down with auxillary
electric resistance heat that MAY cost more or use more
energy overall than just keeping it warm.

The presumption that you have an auxiliary heating system
may be part of the reason why you get advice to the
contrary. Another concern may be that cycling the
temperature may result in persistent cold spots or
condensation problems that could lead to overall
dissatisfaction with the system.

But mostly I doubt you have ever spoken on the
phone with anyone who actually studied heat
transfer phenomenon or even took a physics course
ever.

The other possibility suggested is that extracting heat
too fast from the groundwater could create a pool
of cooled water underground with a resultant lower
efficiency of heat extraction. That would depend
largely on the groundwater environment and how
extensive the heat exchange area is underground.

I doubt that a definitive general answer can be given
regarding that last concern. It would be highly dependent
on the specific situation.

--

FF

On Nov 27, 12:44 am, "Lew Hodgett" <[email protected]> wrote:
> "Kenneth" wrote:
> > We heat and cool our home geothermally (water to air
> > system.)
>
> > We would, of course, like to decrease our costs further if
> > we can, and so have explored the benefits of setting our
> > thermostat lower at those times when the house (or parts of
> > it) are not occupied.
>
> > The folks who designed the heating system say that with
> > these systems, it is best to leave the set temp unchanged.
>
> > Of course, I have asked "why", but when I do, it seems that
> > smoke starts to come out of the phone. In essence, they say
> > that it is "best" but seem unable to say why.
>
> > Might any of you know what would be best in this regard ,
> > and particularly whether the issue of thermostat setback is
> > actually any different for geothermal systems?
>
> In a nutshell, thermal inertia.
>
> Once the system is balanced, it requires minimum energy to maintain
> the balance.
>
> Change the set point to a lower level, remain there for a while, then
> return to the higher level requires a lot of thermal work.
>
> Heat intensive industries such as steel, refineries, etc, run 24/7 for
> just this reason.
>

No, the reason is that it costs them money to keep it warm and it also
costs them money to warm it up , but they can produce a product while
it is warm and not while it is warming up.

It is not how much they are spending on energy, it is their return on
that investment--less than zero (due to other operating costs)
while warming up, and greater than zero (hopefully) when at operating
temperature.

There are other considerations such as thermal stresses during warm-up
and cooling down.

--

FF

Because you have no control over the systems ability to "produce" more or
less. It's out put is a relative constant.
If you request more out of the system you pay more through an external
source.


"Kenneth" <[email protected]> wrote in message
news:[email protected]...
>
> Howdy,
>
> This is way OT...(again), but:
>
> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?
>
> Sincere thanks,
> --
> Kenneth
>
> If you email... Please remove the "SPAMLESS."

Robert, as you said, bodies and lights make a huge load on a
building. Our Energy Czar (EC) lets the buildings get cold enough
that they typically require a morning warm up before the occupant
load takes over. We have one 2 pipe school that requires a full
conversion to either heat or cool that can be quite troublesome on
those moderate days. We turn all chillers off and dump the
cooling towers as we head into the freezing months. The buildings
can usually be tempered by outside air. The geothermal schools
eliminate this problem and allow partial usage of buildings for
special events and summer school type needs.

I did ask about the setback issues. We had one series of heat
pumps whose open/close valves did not have stops installed. These
machines have a sensor that says if the water is too cold it
prevents the unit from running rather than make ice - this issue
was rectified by installing stops that never allow the valves to
completely close which keeps the water circulating back to the
loop. We now install all systems to run the well field pumps
continuously as we have one that turns off the circulating pumps
if there is no demand anywhere on the system which can allow some
of the loop to reach that same "don't run" temperature. Believe
it or not, the pumps have shut down several times because the
building is that stable. As Robert says, lights and people can
keep a large building quite warm or too warm when the rest of us
need heat. We do continue to have a problem with people wanting
cooling on warm afternoons turning the thermostat down to the
bottom at 55°: the computer limits the units so the 55 never
happens, but the units also don't come up on morning warm-up,
though the rooms seem to recover quickly if the rest of the
building is satisfied. He swears emphatically that no matter what
system is used, intense run time in the mornings uses less energy
than the start/stop cycle of leaving the system at temperature
around the clock. They have put in-line monitors with recording
capability on units set up each way on highly similar usage, run
them for a week, then reversed the study for another week on the
same units. Setback with a substantial run time to recover uses
less energy than maintaining the temperature during non critical
times. The setback needs to be able to protect critical needs as
in not freezing water lines or baking cookies in the attic.


______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
[email protected]



"Robert Bonomi" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, DanG
> <[email protected]> wrote:
>>We are running multiple schools on ground source heat pumps.
>>Each
>>building has a single loop with individual Trane heat pumps
>>running in each classroom tapped onto that loop. There is NO
>>auxiliary heat. There are NO heat strips. Our Energy Czar
>>believes in night set backs and holding temperatures at minimums
>>until someone gripes. The systems are computerized to central
>>control and the units can only be changed from the central
>>location other than a small allowance at the thermostats.
>>
>>Each building, or even portions of buildings, have different
>>thermal mass/draft and air leakage issues/poor glazing/etc that
>>each requires its own start up time. Some take 2 hours, some
>>almost 4 hours if they have been allowed to get too far out of
>>design or conditions are extreme. The water loop is circulated
>>full time through the well field, but the compressors at each
>>heat
>>pump function by thermostat. The buildings have become so much
>>easier to control that we continue to install these systems as
>>money permits. The buildings are so much more stable that we
>>tend
>>to ignore old fashioned insulation/draft/weatherstrip
>>conditions -
>>perhaps we will get back to them as energy costs continue to
>>spiral.
>>
>>Our HVAC technicians would prefer just letting the systems run
>>full time and maintain a steady temperature, especially when
>>equipment is new just to run it through its paces while under
>>warranty. The Energy Czar tends to win. I will try to remember
>>to ask tomorrow about the whys.
>
> A 'medium-insulated' school building full of people doesn't need
> _any_
> additional heat source until the outside temperature gets below
> about
> -20F.
>
> Look up how much heat an 'at rest' human body gives off, and
> multiply by
> the 25-30 bodies preset in the average classroom.
>
> Getting the heat _out_ of the building is the issue.
>
> At 'above zero' temperatures, it's _common_ to be venting hot
> air outside
> and pulling in cold outside air for 'make-up'.
>
> Not infrequently, the chillers will be running, in addition.
>
>

Mark & Juanita <[email protected]> wrote in
news:[email protected]:

> From EDEE 101 (or Physics 112), we were told that the average human
> body
> is equivalent to 100 watt light bulb as far as heat output. Depending
> upon age, kids in a school would most likely be considerably less.
>

You haven't seen my 11 year-old granddaughter - 250 Watt is more like it.

--
Best regards
Han
email address is invalid

[email protected] (Robert Bonomi) wrote in
news:[email protected]:

> In article <[email protected]>,
> Han <[email protected]> wrote:
>>Mark & Juanita <[email protected]> wrote in
>>news:[email protected]:
>>
>>> From EDEE 101 (or Physics 112), we were told that the average
>>> human body
>>> is equivalent to 100 watt light bulb as far as heat output.
>>> Depending upon age, kids in a school would most likely be
>>> considerably less.
>>>
>>
>>You haven't seen my 11 year-old granddaughter - 250 Watt is more like
>>it.
>
> Depending on activity level, you can _triple_ (or somewhat more) the
> base number, which is in the 100-140 watt range.
>
> A 250 watt kid is -not- all that extreme! <grin>
>
Also, I think that heat dissipation would be equivalent to body surfacce
area, which would make skinny kids radiate more (proportionally) than
chunky ones ...

<grin>

--
Best regards
Han
email address is invalid

We are running multiple schools on ground source heat pumps. Each
building has a single loop with individual Trane heat pumps
running in each classroom tapped onto that loop. There is NO
auxiliary heat. There are NO heat strips. Our Energy Czar
believes in night set backs and holding temperatures at minimums
until someone gripes. The systems are computerized to central
control and the units can only be changed from the central
location other than a small allowance at the thermostats.

Each building, or even portions of buildings, have different
thermal mass/draft and air leakage issues/poor glazing/etc that
each requires its own start up time. Some take 2 hours, some
almost 4 hours if they have been allowed to get too far out of
design or conditions are extreme. The water loop is circulated
full time through the well field, but the compressors at each heat
pump function by thermostat. The buildings have become so much
easier to control that we continue to install these systems as
money permits. The buildings are so much more stable that we tend
to ignore old fashioned insulation/draft/weatherstrip conditions -
perhaps we will get back to them as energy costs continue to
spiral.

Our HVAC technicians would prefer just letting the systems run
full time and maintain a steady temperature, especially when
equipment is new just to run it through its paces while under
warranty. The Energy Czar tends to win. I will try to remember
to ask tomorrow about the whys.

Each well field happens to have hit multiple water tables, so each
field is way under capacity as they are originally designed on the
assumption of no significant water zones and rely on ground
contact through the custom gel only. We have two sites without
well fields that run the loop through a cooling tower (no chiller)
and small redundant boilers with plate frame exchangers. These
were the first 2 sites when too many folks were afraid of the
ground source. Who knows on a 20 to 50 year cycle, but right now
groundsource is far and away the most efficient, cleanest, lowest
maintenance system out there. We're not walking, we're running!

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
[email protected]



"J. Clarke" <[email protected]> wrote in message
news:[email protected]...
> Kenneth wrote:
>> On Tue, 27 Nov 2007 11:31:32 -0500, "J. Clarke"
>> <[email protected]> wrote:
>>
>>>> But the time at lower setpoint more than compensates for the
>>>> differential loss. It's well-established in general that a
>>>> setback
>>>> lowers overall heating costs in general. It would take
>>>> unusual
>>>> circumstances for that to not be so.
>>>
>>> It's not something one should just assume. Especially with
>>> alternative energy.
>>
>> Hi John,
>>
>> Might you know of some reasons that the general principle of
>> savings through setbacks would not apply to my geothermal
>> source...?
>>
>> As I have said before here, I certainly do not (know enough
>> to) disagree, but I have no understanding of why that should
>> be true.
>>
>> Sincere thanks,
>
> I don't know enough details of your setup or the structure to be
> able
> to run the numbers. The main objection I'm seeing is that it's
> likely
> to cause the resistance elements in the heat pump to kick in but
> you
> say that you don't have any, but there might be something else
> unique
> to your situation.
>
> --
> --
> --John
> to email, dial "usenet" and validate
> (was jclarke at eye bee em dot net)
>
>

On Tue, 27 Nov 2007 01:36:07 GMT, Larry Kraus
<[email protected]> wrote:

>
>>There is no auxiliary heat...
>
>You might want to verify that..

Hello again,

Other than repeating it, and assuring you that I know what I
am talking about in this regard, there is little more I can
do.

When we installed the system, we discussed this issue at
length with our contractor, the designer is the system, and
the system's installation folks.

Based upon their input, we opted for a design with capacity
sufficient to eliminate the necessity for any auxiliary
system. In fact, there is a box in the air handler that
would allow for the installation of such a resistance heat
supply, but it is empty.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Tue, 27 Nov 2007 07:59:03 -0600, dpb <[email protected]>
wrote:

>The thing to do is to add an exterior thermocouple to the aux heat
>control so the aux heat doesn't come on unless exterior temperature is
>at some preset temp. This can eliminate the mostly gratuitous usage.

Hi,

As I described just above your comment, we do not have
auxiliary heat at all.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Nov 27, 7:26 am, Robatoy <[email protected]> wrote:
>
> ...
>
> I was going to try to equate this with the reason why when you
> increase the waterflow through your car's radiator by taking out the
> thermostat, your engine will overheat. The water HAS to spend time in
> the rad to be able to give up its heat. So the thermostat slows down
> the waterflow. Conventional thinking would suggest that by increasing
> the waterflow, it should cool better. (There are a few caveats in
> there too, so everybody keep their shirts on.)

That is the first I ever heard of that.

The higher the flow rate the higher the Reynolds number and
therefor the higher the convective heat-transfer coefficient.
You may get less heat transferred per gram of water flowing
through the radiator, but not in inverse proportion to the
rate at which grams of water flow through. IOW you might
get only 75% of the heat loss per gram of water but will
have twice as many grams of water flowing through.

--

FF

Kenneth wrote:

>
> Howdy,
>
> This is way OT...(again), but:
>
> We heat and cool our home geothermally (water to air
> system.)
>
> We would, of course, like to decrease our costs further if
> we can, and so have explored the benefits of setting our
> thermostat lower at those times when the house (or parts of
> it) are not occupied.
>
> The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged.
>
> Of course, I have asked "why", but when I do, it seems that
> smoke starts to come out of the phone. In essence, they say
> that it is "best" but seem unable to say why.
>
> Might any of you know what would be best in this regard ,
> and particularly whether the issue of thermostat setback is
> actually any different for geothermal systems?
>
> Sincere thanks,


hi all!

i sent this email to Alliant Energy Geothermal
===============
there is a discussion underway with this as topic: -
We heat and cool our home geothermally (water to air system.) We
would, of course, like to decrease our costs further if we can, and so
have explored the benefits of setting our thermostat lower at those
times when the house (or parts of it) are not occupied. The folks who
designed the heating system say that with these systems, it is best to
leave the set temp unchanged. Of course, I have asked "why", but when I
do, it seems that smoke starts to come out of the phone. In essence,
they say that it is "best" but seem unable to say why. Might any of you
know what would be best in this regard , and particularly whether the
issue of thermostat setback is actually any different for geothermal
systems?
could you help me understand the issues involved? thanks in advance
for any input! chuck b:-)
==============
and i got this reply
-----------------------

Dear Chuck,

Set-up of a Geo system temperature during the cooling time of year
should allow a Geo system to recover the cooling and dehumidify as
quickly and more efficiently than other air sourced cooling systems.

Set-back is not typically recommended during the heating time of year
due to 1) a slower recovery time for heating, 2) the potential for the
back up electric elements kicking in to boost the reheating rate but, at
an added electric expense to you, 3) dependent on if you use a straight
well water open loop or only a minimal to non freeze protected closed
loop fluid, the lack of normal flows may allow for a potential for a
loop to freeze up and 4) many people who own set-back thermostats are
easily confused by the instructions for operating them and re-setting them.

All of these can cause contractor callbacks, they hate callbacks.

We do have a few of our regional Geo system owners who do a slight
setback for heating at maybe 2 to 4 degrees F maximum for 4 to 6 hours
but, all must realize the potential results.

During AC season and the daytime hours of unoccupied homes, they might
also do set up to minimize On Peak energy charges when they choose Time
of Use electric rate options.

I hope this helps. Thanks for the inquiry.

Leo

From: Alliant Energy Geothermal Web Forms
[mailto:[email protected]]
Sent: Wednesday, November 28, 2007 9:29 PM
To: Geothermal
Cc: Webmaster
Subject: Alliant Energy Geothermal -- Contact Us Form



chuck b:-)

On Tue, 27 Nov 2007 14:09:49 GMT, "Leon"
<[email protected]> wrote:


>
>"Kenneth" <[email protected]> wrote in message
>news:[email protected]...
>>
>> Howdy,
>>
>> This is way OT...(again), but:
>>
>> We heat and cool our home geothermally (water to air
>> system.)
>>
>> We would, of course, like to decrease our costs further if
>> we can, and so have explored the benefits of setting our
>> thermostat lower at those times when the house (or parts of
>> it) are not occupied.
>>
>> The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged.
>>
>> Of course, I have asked "why", but when I do, it seems that
>> smoke starts to come out of the phone. In essence, they say
>> that it is "best" but seem unable to say why.
>>
>> Might any of you know what would be best in this regard ,
>> and particularly whether the issue of thermostat setback is
>> actually any different for geothermal systems?
>>
>> Sincere thanks,
>> --
>> Kenneth
>>
>> If you email... Please remove the "SPAMLESS."
>

>Because you have no control over the systems ability to "produce" more or
>less. It's out put is a relative constant.
>If you request more out of the system you pay more through an external
>source.
>

Hi Leon,

Yes, its output is constant, but does that lead to the
conclusion that we would, or would not save with a setback?

Thanks,
--
Kenneth

If you email... Please remove the "SPAMLESS."

In article <[email protected]>,
Kenneth <[email protected]> wrote:

> On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
> <[email protected]> wrote:
>
> >
> >What was the recovery time after the setback days?
>
> Hi Doug,
>
> I don't know with certainty, but I do know it to be less
> than an hour.
>
> All the best,

Please be careful on high wind load, very cold days - I would suggest
that if you know that the next day is going to be that way you not do
the setback.

I have had Geothermal for more than 20 years, in the early winter and in
the spring, set back saves a lot of money, but from about the middle of
December to the End of February here in Michigan, we do not do a
setback, since the secondary electric elements cost way more than the
savings.

I am looking at adding solar thermal heating the south wall of the house
next summer to further reduce the winter heating bill. I have 60 feet of
southern facing wall that is in direct sunlight almost all of the day.
That should give me a good thermal boost on even partly cloudy days.

Doug

On Sat, 08 Dec 2007 09:22:52 -0600, dpb <[email protected]>
wrote:

>Kenneth wrote:
>...
>
>> So, on the days with setback, the mean KWH/DD was 1.06. On
>> the days with no setback, that mean was 1.36.
>>
>> The resulting savings are approximately 22%.
>>
>> I do remain baffled by the reasons the geothermal folks
>> (installers, designers, sellers) seem to be consistent in
>> suggesting that such setbacks are not of value.
>
>As at least one other poster noted, they're concerned w/ other factors
>that aren't applicable in your case (primarily dominated by the use of
>resistance electric heat in many/most systems)...
>
>There are others including the potential freezeup, etc., that are
>possible but imo they're mostly cya kinds of responses. Did you try the
>Water Furnace people directly or contact the Okla State or some of the
>other resources for other input?

Howdy,

The CYA analysis makes sense to me, but as you probably
know, there is no real "freeze up" danger at all. These
systems simply turn themselves off is the incoming water is
too cold.

Also, as you may know "Water Furnace" is a brand name. Our
equipment is ClimateMaster.

I have communicated about all this at some length with the
ClimateMaster folks, with the geo folks from my electric
utility, and with the installer of the equipment. They all
have said "no setback" is best.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Wed, 28 Nov 2007 09:46:22 -0500, Kenneth
<[email protected]> wrote:

>On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
><[email protected]> wrote:
>
>>
>>Why do you need a second electric meter to excrement with? You can
>>read your own meter every day at the same time. As long as you record
>>when you are drying clothes or other significant electricity burning
>>events you should be able to test for no hardware costs.
>>
>>Are you torturing the group by not doing your own meter reading and
>>reporting back?
>
>Hi Jim,
>
>I am lost...
>
>How would reading my meter at the same time every day tell
>me my heat-related energy consumption?
>
>Thanks,
Day zero meter reads 1480
Day one with no thermostat changes reads 1520
Day two no thermostat change 1570
day 3 no thermostat change 1620
Day 4 after thermostat rollback 1680
day 5 with thermostat rollback 1740
day6 with thermostat rollback 1800
day 7 no thermostat change 1850
day 8 thermostat rollback 1910
day 9 thermostat rollback 1970
day 10 no thermostat change 2020

and so on. Just read the meter every day at the same time. Do the
math. Do it over enough days to factor out clothes dryers and baking
festivals. If there is indeed any significant energy saving to be had
by thermostat rollback it will show up with a month of measuring.
Especially if you do rollback every other night.

That said I think when I feel rich I will buy
http://www.theenergydetective.com/store or one of these with the split
core
http://eyomenergy.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=EES&Category_Code=ES

On Mon, 26 Nov 2007 18:51:12 -0600, dpb <[email protected]>
wrote:

>
>Would be interested in the capacity of the well, amount of exchange
>tubing, etc., to support the system you have as a comparison. They
>wanted to punch two or three holes here for deep ground loop, but at
>$1500/ea, that gets terribly pricy quickly. Would have to have a second
>well to go that route, but I'd think it could be only one although it
>would not suit me to have it be a once-through in an arid area.

Hi again,

Trusting my memory here...

Our well was designed for the 9 ton capacity. It is 460'
deep, and is 8" in diameter. It has a sleeve for just under
400'.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Robatoy wrote:
> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
>> Howdy,
>>
>> This is way OT...(again), but:
>>
>> We heat and cool our home geothermally (water to air
>> system.)
>>
>> We would, of course, like to decrease our costs further if
>> we can, and so have explored the benefits of setting our
>> thermostat lower at those times when the house (or parts of
>> it) are not occupied.
>>
>> The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged.
>>
>> Of course, I have asked "why", but when I do, it seems that
>> smoke starts to come out of the phone. In essence, they say
>> that it is "best" but seem unable to say why.
>>
>> Might any of you know what would be best in this regard ,
>> and particularly whether the issue of thermostat setback is
>> actually any different for geothermal systems?
>>
>> Sincere thanks,
>> --
>> Kenneth
>>
>> If you email... Please remove the "SPAMLESS."
>
> Cycling a building in and out of extremes will bring into play the
> building's phase.
> The lower extremes may force the auxiliary heating to start up (maybe
> electric?).
> It might be cheaper to keep things at a low wick rather than replacing
> lost heat with expensive heat.

The need for the aux heat should be minimal at most for an
adequately-sized geothermal system. Some t-stats may demand it if the
temperature differential from setpoint gets too large, though, so it
should be ensured the rampup doesn't force that.

In general, the same rules apply -- a setback at night, for example,
will result in a lower average temperature so the effect is still there.

As a side note, had a ground-loop geothermal system in TN and liked it a
bunch. Am considering it for a replacement here...

--

Kenneth wrote:
> On Mon, 26 Nov 2007 17:58:20 -0600, dpb <[email protected]>
> wrote:
>
>> Robatoy wrote:
>>> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
>>>> Howdy,
>>>>
>>>> This is way OT...(again), but:
>>>>
>>>> We heat and cool our home geothermally (water to air
>>>> system.)
>>>>
>>>> We would, of course, like to decrease our costs further if
>>>> we can, and so have explored the benefits of setting our
>>>> thermostat lower at those times when the house (or parts of
>>>> it) are not occupied.
>>>>
>>>> The folks who designed the heating system say that with
>>>> these systems, it is best to leave the set temp unchanged.
>>>>
>>>> Of course, I have asked "why", but when I do, it seems that
>>>> smoke starts to come out of the phone. In essence, they say
>>>> that it is "best" but seem unable to say why.
>>>>
>>>> Might any of you know what would be best in this regard ,
>>>> and particularly whether the issue of thermostat setback is
>>>> actually any different for geothermal systems?
>>>>
>>>> Sincere thanks,
>>>> --
>>>> Kenneth
>>>>
>>>> If you email... Please remove the "SPAMLESS."
>>> Cycling a building in and out of extremes will bring into play the
>>> building's phase.
>>> The lower extremes may force the auxiliary heating to start up (maybe
>>> electric?).
>>> It might be cheaper to keep things at a low wick rather than replacing
>>> lost heat with expensive heat.
>> The need for the aux heat should be minimal at most for an
>> adequately-sized geothermal system. Some t-stats may demand it if the
>> temperature differential from setpoint gets too large, though, so it
>> should be ensured the rampup doesn't force that.
>>
>> In general, the same rules apply -- a setback at night, for example,
>> will result in a lower average temperature so the effect is still there.
>>
>> As a side note, had a ground-loop geothermal system in TN and liked it a
>> bunch. Am considering it for a replacement here...
>
> Hello again,
>
> Your reasoning is similar to mine...
>
> We do not have any auxiliary source of heat: Our (9 ton
> rated) heat pumps are more than sufficient to do the deed
> even at 20 below.
>
> For the life of me, I can't understand why the folks who
> design the system say it is best (that is, less costly) to
> keep the temp constant.
>
> One possibility that I have thought of:
>
> The cooler the water in the well, the lower the efficiency
> of (and thus, the higher the costs of running) the system.
>
> Suppose that each night, we allow the temp of the house to
> drop, say, 10 degrees F.
>
> Then, in the morning, lots of energy would have to be
> extracted from the well in order to rapidly bring the house
> up those ten degrees.
>
> That would (obviously) cool the well, thus decreasing the
> efficiency of the system, until the house warmed up. As a
> result, the costs per BTU would go up during that period of
> (relatively rapidly) re-heating the house.
>
> Assuming that reasoning to be correct, the issue boils down
> to whether the cost of that loss of efficiency is greater or
> less than the savings to be had with the lower overnight
> temperatures.

All depends on the capacity of the well and how the loop is configured.
Unless the well is stagnant and of marginal size and the exchanger is
closed loop, I would expect that to be a minimal problem. If the well
weren't a well but a closed tank, maybe, but that's unlikely to be a
realistic model. Would have to know more to do a real
calculation/estimate, but I think it's not likely such a big issue.

I have been told by one installer here that owing to our very dry
climate there's an issue w/ ground loops and heat transfer. I've not
yet delved into it in sufficient detail to decide whether I think that's
hokum or not -- this guy hasn't yet actually installed a system, he's
just going on what somebody else has told him.

Would be interested in the capacity of the well, amount of exchange
tubing, etc., to support the system you have as a comparison. They
wanted to punch two or three holes here for deep ground loop, but at
$1500/ea, that gets terribly pricy quickly. Would have to have a second
well to go that route, but I'd think it could be only one although it
would not suit me to have it be a once-through in an arid area.

--

Larry Kraus wrote:
> Kenneth <[email protected]> wrote:
>
>> Howdy,
>>
>> There is no auxiliary heat...
>
> You might want to verify that...
>
> Our WaterFurnace heat pump maintains temperature very well when it
> drops to below zero here in central Ohio. But if you raise the
> thermostat by more than two degrees at a time, the auxiliary heat
> coils in the "furnace" do kick on, and the electric meter spins like
> crazy until the house temp is back within two degrees of the set temp.
> In our case, the "auxiliary" heat is for quick temperature changes.
>
> This is different than our old house with an air-to-air heat pump,
> where the auxiliary heat came into play whenever the outside air was
> too cold for the pump to generate sufficient heat. Fairly often, in
> other words, since air-to-air pumps lose efficiency as the temp drops.
>
> To use a setback thermostat, we would need one that raised the
> temperature only two degrees at a time and/or would need to disconnect
> the internal resistance coils. We are satisfied with a fixed
> temperature of 69, and heating bills that are a third the size of
> friends who have gas heat and homes that a half the size of ours.

The thing to do is to add an exterior thermocouple to the aux heat
control so the aux heat doesn't come on unless exterior temperature is
at some preset temp. This can eliminate the mostly gratuitous usage.

What we did for the Water Furnace unit we had. (Unfortunately, I had
completely forgotten doing so and when we had moved and the new buyer's
inspection showed up the elements didn't work, I was gone and we ended
up w/ a service call to re-enable them to close the sale. :( ).

Anyway, there was also a setting on the thermostat that overrode the
"high" heat setting that could be used as well. Seems like that
thermostat was an option over the base one that came w/ the unit,
however. It had a setback option built in this worked with iirc,
whereas the other was a simple setpoint t-stat. This is quite a while
back now, memory's getting dim on precise detail.

I agree the units are well worth the initial extra installation cost,
particularly if don't have relatively cheap gas available...

--


--

Robatoy wrote:
> On Nov 26, 7:07 pm, Kenneth <[email protected]> wrote:
>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>
>>
>>
>> <[email protected]> wrote:
>>> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
>>>> Howdy,
>>>> This is way OT...(again), but:
>>>> We heat and cool our home geothermally (water to air
>>>> system.)
>>>> We would, of course, like to decrease our costs further if
>>>> we can, and so have explored the benefits of setting our
>>>> thermostat lower at those times when the house (or parts of
>>>> it) are not occupied.
>>>> The folks who designed the heating system say that with
>>>> these systems, it is best to leave the set temp unchanged.
>>>> Of course, I have asked "why", but when I do, it seems that
>>>> smoke starts to come out of the phone. In essence, they say
>>>> that it is "best" but seem unable to say why.
>>>> Might any of you know what would be best in this regard ,
>>>> and particularly whether the issue of thermostat setback is
>>>> actually any different for geothermal systems?
>>>> Sincere thanks,
>>>> --
>>>> Kenneth
>>>> If you email... Please remove the "SPAMLESS."
>>> Cycling a building in and out of extremes will bring into play the
>>> building's phase.
>>> The lower extremes may force the auxiliary heating to start up (maybe
>>> electric?).
>>> It might be cheaper to keep things at a low wick rather than replacing
>>> lost heat with expensive heat.
>>> Just a hunch.
>> Howdy,
>>
>> There is no auxiliary heat...
>>
>> So, whatever heat energy lost by the house is replaced by
>> the heat energy extracted (at some cost of electricity) from
>> the well water.
>>
>> My reasoning was that keeping the house warm when empty
>> would have greater cost than keeping it cool when empty
>> (that part seems obvious) and heating it up to comfort would
>> take less energy than that which would be lost were it kept
>> warm continuously.
>>
>> What am I missing?
>> --
>> Kenneth
>>
>> If you email... Please remove the "SPAMLESS."
>
> It keeps coming back to the building's phase. It doesn't cycle at the
> same speed your internal temperature does.
> As you turn down the thermostat, the building's stored heat is given
> up, some to the interior, but some to the exterior (loss).
> To reheat the building's interior, the heat is not only heating the
> interior, but also the building's mass.
> So, when you turn down the thermostat, you need to later replace the
> heat you lose. Once the building is up to temperature, you just
> overcome the building's heat loss...like Lew's Ball.
...

No, you don't need to "replace" the heat you lost for the period the
setpoint was lower -- that's the gain.

--

Robatoy wrote:
> On Nov 27, 9:01 am, dpb <[email protected]> wrote:
>> Robatoy wrote:
>>> On Nov 26, 7:07 pm, Kenneth <[email protected]> wrote:
>>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>> <[email protected]> wrote:
>>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]> wrote:
>>>>>> Howdy,
>>>>>> This is way OT...(again), but:
>>>>>> We heat and cool our home geothermally (water to air
>>>>>> system.)
>>>>>> We would, of course, like to decrease our costs further if
>>>>>> we can, and so have explored the benefits of setting our
>>>>>> thermostat lower at those times when the house (or parts of
>>>>>> it) are not occupied.
>>>>>> The folks who designed the heating system say that with
>>>>>> these systems, it is best to leave the set temp unchanged.
>>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>>> smoke starts to come out of the phone. In essence, they say
>>>>>> that it is "best" but seem unable to say why.
>>>>>> Might any of you know what would be best in this regard ,
>>>>>> and particularly whether the issue of thermostat setback is
>>>>>> actually any different for geothermal systems?
>>>>>> Sincere thanks,
>>>>>> --
>>>>>> Kenneth
>>>>>> If you email... Please remove the "SPAMLESS."
>>>>> Cycling a building in and out of extremes will bring into play the
>>>>> building's phase.
>>>>> The lower extremes may force the auxiliary heating to start up (maybe
>>>>> electric?).
>>>>> It might be cheaper to keep things at a low wick rather than replacing
>>>>> lost heat with expensive heat.
>>>>> Just a hunch.
>>>> Howdy,
>>>> There is no auxiliary heat...
>>>> So, whatever heat energy lost by the house is replaced by
>>>> the heat energy extracted (at some cost of electricity) from
>>>> the well water.
>>>> My reasoning was that keeping the house warm when empty
>>>> would have greater cost than keeping it cool when empty
>>>> (that part seems obvious) and heating it up to comfort would
>>>> take less energy than that which would be lost were it kept
>>>> warm continuously.
>>>> What am I missing?
>>>> --
>>>> Kenneth
>>>> If you email... Please remove the "SPAMLESS."
>>> It keeps coming back to the building's phase. It doesn't cycle at the
>>> same speed your internal temperature does.
>>> As you turn down the thermostat, the building's stored heat is given
>>> up, some to the interior, but some to the exterior (loss).
>>> To reheat the building's interior, the heat is not only heating the
>>> interior, but also the building's mass.
>>> So, when you turn down the thermostat, you need to later replace the
>>> heat you lose. Once the building is up to temperature, you just
>>> overcome the building's heat loss...like Lew's Ball.
>> ...
>>
>> No, you don't need to "replace" the heat you lost for the period the
>> setpoint was lower -- that's the gain.
>>
>> --
>
> Only if you decide to keep the building's mass at that temperature.
> If you want to restore the temperature of the model, you also have to
> re-heat the container.

But the time at lower setpoint more than compensates for the
differential loss. It's well-established in general that a setback
lowers overall heating costs in general. It would take unusual
circumstances for that to not be so.

--

Leon wrote:
> Because you have no control over the systems ability to "produce" more or
> less. It's out put is a relative constant.

Water Furnace uses avariable speed (or at least two-speed) units so
there is some control.

> If you request more out of the system you pay more through an external
> source.

Beyond high-speed, correct, but that can also be controlled as to
whether it is used or not in a couple of different ways.

It's possible (probable?) the initial installation didn't not take
advantage of any of those options and the installer isn't clever enough
to recognize/implement them, but there are alternatives for most of the
issues.

When/if the unit does "max out" w/ the ground source, then the only
choice is an aux heat output, but OP has indicated they chose not to use
one anyway owing to having sized the unit(s) at a quite high output.

So, my conclusion is still that it would be very unusual set of
circumstances in this case if the setback would not reduce overall usage.



>
> "Kenneth" <[email protected]> wrote in message
> news:[email protected]...
>> Howdy,
>>
>> This is way OT...(again), but:
>>
>> We heat and cool our home geothermally (water to air
>> system.)
>>
>> We would, of course, like to decrease our costs further if
>> we can, and so have explored the benefits of setting our
>> thermostat lower at those times when the house (or parts of
>> it) are not occupied.
>>
>> The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged.
>>
>> Of course, I have asked "why", but when I do, it seems that
>> smoke starts to come out of the phone. In essence, they say
>> that it is "best" but seem unable to say why.
>>
>> Might any of you know what would be best in this regard ,
>> and particularly whether the issue of thermostat setback is
>> actually any different for geothermal systems?
>>
>> Sincere thanks,
>> --
>> Kenneth
>>
>> If you email... Please remove the "SPAMLESS."
>
>

dpb wrote:
> Robatoy wrote:
>> On Nov 26, 7:07 pm, Kenneth <[email protected]>
>> wrote:
>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>
>>>
>>>
>>> <[email protected]> wrote:
>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]>
>>>> wrote:
>>>>> Howdy,
>>>>> This is way OT...(again), but:
>>>>> We heat and cool our home geothermally (water to air
>>>>> system.)
>>>>> We would, of course, like to decrease our costs further if
>>>>> we can, and so have explored the benefits of setting our
>>>>> thermostat lower at those times when the house (or parts of
>>>>> it) are not occupied.
>>>>> The folks who designed the heating system say that with
>>>>> these systems, it is best to leave the set temp unchanged.
>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>> smoke starts to come out of the phone. In essence, they say
>>>>> that it is "best" but seem unable to say why.
>>>>> Might any of you know what would be best in this regard ,
>>>>> and particularly whether the issue of thermostat setback is
>>>>> actually any different for geothermal systems?
>>>>> Sincere thanks,
>>>>> --
>>>>> Kenneth
>>>>> If you email... Please remove the "SPAMLESS."
>>>> Cycling a building in and out of extremes will bring into play
>>>> the
>>>> building's phase.
>>>> The lower extremes may force the auxiliary heating to start up
>>>> (maybe electric?).
>>>> It might be cheaper to keep things at a low wick rather than
>>>> replacing lost heat with expensive heat.
>>>> Just a hunch.
>>> Howdy,
>>>
>>> There is no auxiliary heat...
>>>
>>> So, whatever heat energy lost by the house is replaced by
>>> the heat energy extracted (at some cost of electricity) from
>>> the well water.
>>>
>>> My reasoning was that keeping the house warm when empty
>>> would have greater cost than keeping it cool when empty
>>> (that part seems obvious) and heating it up to comfort would
>>> take less energy than that which would be lost were it kept
>>> warm continuously.
>>>
>>> What am I missing?
>>> --
>>> Kenneth
>>>
>>> If you email... Please remove the "SPAMLESS."
>>
>> It keeps coming back to the building's phase. It doesn't cycle at
>> the
>> same speed your internal temperature does.
>> As you turn down the thermostat, the building's stored heat is
>> given
>> up, some to the interior, but some to the exterior (loss).
>> To reheat the building's interior, the heat is not only heating the
>> interior, but also the building's mass.
>> So, when you turn down the thermostat, you need to later replace
>> the
>> heat you lose. Once the building is up to temperature, you just
>> overcome the building's heat loss...like Lew's Ball.
> ...
>
> No, you don't need to "replace" the heat you lost for the period the
> setpoint was lower -- that's the gain.

If the structure had no thermal mass then that would be the case. But
it does have thermal mass and changing the temperature of that thermal
mass requires the addition or removal of heat.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

J. Clarke wrote:
> dpb wrote:
>> Robatoy wrote:
>>> On Nov 26, 7:07 pm, Kenneth <[email protected]>
>>> wrote:
>>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>>
>>>>
>>>>
>>>> <[email protected]> wrote:
>>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]>
>>>>> wrote:
>>>>>> Howdy,
>>>>>> This is way OT...(again), but:
>>>>>> We heat and cool our home geothermally (water to air
>>>>>> system.)
>>>>>> We would, of course, like to decrease our costs further if
>>>>>> we can, and so have explored the benefits of setting our
>>>>>> thermostat lower at those times when the house (or parts of
>>>>>> it) are not occupied.
>>>>>> The folks who designed the heating system say that with
>>>>>> these systems, it is best to leave the set temp unchanged.
>>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>>> smoke starts to come out of the phone. In essence, they say
>>>>>> that it is "best" but seem unable to say why.
>>>>>> Might any of you know what would be best in this regard ,
>>>>>> and particularly whether the issue of thermostat setback is
>>>>>> actually any different for geothermal systems?
>>>>>> Sincere thanks,
>>>>>> --
>>>>>> Kenneth
>>>>>> If you email... Please remove the "SPAMLESS."
>>>>> Cycling a building in and out of extremes will bring into play
>>>>> the
>>>>> building's phase.
>>>>> The lower extremes may force the auxiliary heating to start up
>>>>> (maybe electric?).
>>>>> It might be cheaper to keep things at a low wick rather than
>>>>> replacing lost heat with expensive heat.
>>>>> Just a hunch.
>>>> Howdy,
>>>>
>>>> There is no auxiliary heat...
>>>>
>>>> So, whatever heat energy lost by the house is replaced by
>>>> the heat energy extracted (at some cost of electricity) from
>>>> the well water.
>>>>
>>>> My reasoning was that keeping the house warm when empty
>>>> would have greater cost than keeping it cool when empty
>>>> (that part seems obvious) and heating it up to comfort would
>>>> take less energy than that which would be lost were it kept
>>>> warm continuously.
>>>>
>>>> What am I missing?
>>>> --
>>>> Kenneth
>>>>
>>>> If you email... Please remove the "SPAMLESS."
>>> It keeps coming back to the building's phase. It doesn't cycle at
>>> the
>>> same speed your internal temperature does.
>>> As you turn down the thermostat, the building's stored heat is
>>> given
>>> up, some to the interior, but some to the exterior (loss).
>>> To reheat the building's interior, the heat is not only heating the
>>> interior, but also the building's mass.
>>> So, when you turn down the thermostat, you need to later replace
>>> the
>>> heat you lose. Once the building is up to temperature, you just
>>> overcome the building's heat loss...like Lew's Ball.
>> ...
>>
>> No, you don't need to "replace" the heat you lost for the period the
>> setpoint was lower -- that's the gain.
>
> If the structure had no thermal mass then that would be the case. But
> it does have thermal mass and changing the temperature of that thermal
> mass requires the addition or removal of heat.

But the time integral is still less...

--

dpb wrote:
> J. Clarke wrote:
>> dpb wrote:
>>> Robatoy wrote:
>>>> On Nov 26, 7:07 pm, Kenneth <[email protected]>
>>>> wrote:
>>>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>>>
>>>>>
>>>>>
>>>>> <[email protected]> wrote:
>>>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]>
>>>>>> wrote:
>>>>>>> Howdy,
>>>>>>> This is way OT...(again), but:
>>>>>>> We heat and cool our home geothermally (water to air
>>>>>>> system.)
>>>>>>> We would, of course, like to decrease our costs further if
>>>>>>> we can, and so have explored the benefits of setting our
>>>>>>> thermostat lower at those times when the house (or parts of
>>>>>>> it) are not occupied.
>>>>>>> The folks who designed the heating system say that with
>>>>>>> these systems, it is best to leave the set temp unchanged.
>>>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>>>> smoke starts to come out of the phone. In essence, they say
>>>>>>> that it is "best" but seem unable to say why.
>>>>>>> Might any of you know what would be best in this regard ,
>>>>>>> and particularly whether the issue of thermostat setback is
>>>>>>> actually any different for geothermal systems?
>>>>>>> Sincere thanks,
>>>>>>> --
>>>>>>> Kenneth
>>>>>>> If you email... Please remove the "SPAMLESS."
>>>>>> Cycling a building in and out of extremes will bring into play
>>>>>> the
>>>>>> building's phase.
>>>>>> The lower extremes may force the auxiliary heating to start up
>>>>>> (maybe electric?).
>>>>>> It might be cheaper to keep things at a low wick rather than
>>>>>> replacing lost heat with expensive heat.
>>>>>> Just a hunch.
>>>>> Howdy,
>>>>>
>>>>> There is no auxiliary heat...
>>>>>
>>>>> So, whatever heat energy lost by the house is replaced by
>>>>> the heat energy extracted (at some cost of electricity) from
>>>>> the well water.
>>>>>
>>>>> My reasoning was that keeping the house warm when empty
>>>>> would have greater cost than keeping it cool when empty
>>>>> (that part seems obvious) and heating it up to comfort would
>>>>> take less energy than that which would be lost were it kept
>>>>> warm continuously.
>>>>>
>>>>> What am I missing?
>>>>> --
>>>>> Kenneth
>>>>>
>>>>> If you email... Please remove the "SPAMLESS."
>>>> It keeps coming back to the building's phase. It doesn't cycle at
>>>> the
>>>> same speed your internal temperature does.
>>>> As you turn down the thermostat, the building's stored heat is
>>>> given
>>>> up, some to the interior, but some to the exterior (loss).
>>>> To reheat the building's interior, the heat is not only heating
>>>> the
>>>> interior, but also the building's mass.
>>>> So, when you turn down the thermostat, you need to later replace
>>>> the
>>>> heat you lose. Once the building is up to temperature, you just
>>>> overcome the building's heat loss...like Lew's Ball.
>>> ...
>>>
>>> No, you don't need to "replace" the heat you lost for the period
>>> the
>>> setpoint was lower -- that's the gain.
>>
>> If the structure had no thermal mass then that would be the case.
>> But it does have thermal mass and changing the temperature of that
>> thermal mass requires the addition or removal of heat.
>
> But the time integral is still less...

Or not as the case may be.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

dpb wrote:
> Robatoy wrote:
>> On Nov 27, 9:01 am, dpb <[email protected]> wrote:
>>> Robatoy wrote:
>>>> On Nov 26, 7:07 pm, Kenneth <[email protected]>
>>>> wrote:
>>>>> On Mon, 26 Nov 2007 15:55:03 -0800 (PST), Robatoy
>>>>> <[email protected]> wrote:
>>>>>> On Nov 26, 6:48 pm, Kenneth <[email protected]>
>>>>>> wrote:
>>>>>>> Howdy,
>>>>>>> This is way OT...(again), but:
>>>>>>> We heat and cool our home geothermally (water to air
>>>>>>> system.)
>>>>>>> We would, of course, like to decrease our costs further if
>>>>>>> we can, and so have explored the benefits of setting our
>>>>>>> thermostat lower at those times when the house (or parts of
>>>>>>> it) are not occupied.
>>>>>>> The folks who designed the heating system say that with
>>>>>>> these systems, it is best to leave the set temp unchanged.
>>>>>>> Of course, I have asked "why", but when I do, it seems that
>>>>>>> smoke starts to come out of the phone. In essence, they say
>>>>>>> that it is "best" but seem unable to say why.
>>>>>>> Might any of you know what would be best in this regard ,
>>>>>>> and particularly whether the issue of thermostat setback is
>>>>>>> actually any different for geothermal systems?
>>>>>>> Sincere thanks,
>>>>>>> --
>>>>>>> Kenneth
>>>>>>> If you email... Please remove the "SPAMLESS."
>>>>>> Cycling a building in and out of extremes will bring into play
>>>>>> the building's phase.
>>>>>> The lower extremes may force the auxiliary heating to start up
>>>>>> (maybe electric?).
>>>>>> It might be cheaper to keep things at a low wick rather than
>>>>>> replacing lost heat with expensive heat.
>>>>>> Just a hunch.
>>>>> Howdy,
>>>>> There is no auxiliary heat...
>>>>> So, whatever heat energy lost by the house is replaced by
>>>>> the heat energy extracted (at some cost of electricity) from
>>>>> the well water.
>>>>> My reasoning was that keeping the house warm when empty
>>>>> would have greater cost than keeping it cool when empty
>>>>> (that part seems obvious) and heating it up to comfort would
>>>>> take less energy than that which would be lost were it kept
>>>>> warm continuously.
>>>>> What am I missing?
>>>>> --
>>>>> Kenneth
>>>>> If you email... Please remove the "SPAMLESS."
>>>> It keeps coming back to the building's phase. It doesn't cycle at
>>>> the same speed your internal temperature does.
>>>> As you turn down the thermostat, the building's stored heat is
>>>> given up, some to the interior, but some to the exterior (loss).
>>>> To reheat the building's interior, the heat is not only heating
>>>> the
>>>> interior, but also the building's mass.
>>>> So, when you turn down the thermostat, you need to later replace
>>>> the heat you lose. Once the building is up to temperature, you
>>>> just
>>>> overcome the building's heat loss...like Lew's Ball.
>>> ...
>>>
>>> No, you don't need to "replace" the heat you lost for the period
>>> the
>>> setpoint was lower -- that's the gain.
>>>
>>> --
>>
>> Only if you decide to keep the building's mass at that temperature.
>> If you want to restore the temperature of the model, you also have
>> to
>> re-heat the container.
>
> But the time at lower setpoint more than compensates for the
> differential loss. It's well-established in general that a setback
> lowers overall heating costs in general. It would take unusual
> circumstances for that to not be so.

It's not something one should just assume. Especially with
alternative energy.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Kenneth wrote:
> On Tue, 27 Nov 2007 07:59:03 -0600, dpb <[email protected]>
> wrote:
>
>> The thing to do is to add an exterior thermocouple to the aux heat
>> control so the aux heat doesn't come on unless exterior temperature is
>> at some preset temp. This can eliminate the mostly gratuitous usage.
>
> Hi,
>
> As I described just above your comment, we do not have
> auxiliary heat at all.

I was responding to the guy who does, not you...

-

Kenneth wrote:
> On Tue, 27 Nov 2007 11:31:32 -0500, "J. Clarke"
> <[email protected]> wrote:
>
>>> But the time at lower setpoint more than compensates for the
>>> differential loss. It's well-established in general that a setback
>>> lowers overall heating costs in general. It would take unusual
>>> circumstances for that to not be so.
>> It's not something one should just assume. Especially with
>> alternative energy.
>
> Hi John,
>
> Might you know of some reasons that the general principle of
> savings through setbacks would not apply to my geothermal
> source...?
>
> As I have said before here, I certainly do not (know enough
> to) disagree, but I have no understanding of why that should
> be true.

I don't think it is, in general, any different unless one of the
conditions outlined previously were to be true for a given installation.

I've not looked recently, but when we were looking into it initially,
Oklahoma State was the leading research university on geothermal. I'm
sure there are many others with useful information that a google would
uncover as well. The other place that had a wealth of geothermal
information online back then was also TVA (tva.gov). I would also
expect the EIA and DOE energy conservation web sites to be potentially
useful as well. You might try Water Furnace directly rather than the
local distributor/installer to see what they say -- I found them to be
quite knowledgeable with their evaluation/sizing software packages. It
wouldn't surprise me at all but what they could actually make that a
part of their analysis for your particular system -- of course, being as
it is already installed, they might not want to run another gratis...

--

Kenneth wrote:
> On Tue, 27 Nov 2007 14:09:49 GMT, "Leon"
> <[email protected]> wrote:
>
>
>> "Kenneth" <[email protected]> wrote in message
>> news:[email protected]...
>>> Howdy,
>>>
>>> This is way OT...(again), but:
>>>
>>> We heat and cool our home geothermally (water to air
>>> system.)
>>>
>>> We would, of course, like to decrease our costs further if
>>> we can, and so have explored the benefits of setting our
>>> thermostat lower at those times when the house (or parts of
>>> it) are not occupied.
>>>
>>> The folks who designed the heating system say that with
>>> these systems, it is best to leave the set temp unchanged.
>>>
>>> Of course, I have asked "why", but when I do, it seems that
>>> smoke starts to come out of the phone. In essence, they say
>>> that it is "best" but seem unable to say why.
>>>
>>> Might any of you know what would be best in this regard ,
>>> and particularly whether the issue of thermostat setback is
>>> actually any different for geothermal systems?
>>>
>>> Sincere thanks,
>>> --
>>> Kenneth
>>>
>>> If you email... Please remove the "SPAMLESS."
>
>> Because you have no control over the systems ability to "produce" more or
>> less. It's out put is a relative constant.
>> If you request more out of the system you pay more through an external
>> source.
>>
>
> Hi Leon,
>
> Yes, its output is constant, but does that lead to the
> conclusion that we would, or would not save with a setback?

Are you sure it is constant--at least I was unaware that W-F used
single-speed units--they weren't when we did ours anyway, but that's
been quite a while ago.

Even if so, it does not lead to the conclusion. The savings of a
setback depend on the integral of the the demand over the time
period--if the average demand is lower, then the input required is lower
for a similar set of external conditions.

The only kicker in the mix is whether there really would be such a
significant loss in efficiency owing to the heat source "drawdown" that
the overall system efficiency drops sufficiently to cause more energy to
be used than is saved. I have an extremely difficult time believing
that to be at all likely.

See my other response for some suggested places to look for some more
definitive research and sources.

--

Kenneth wrote:
> On Tue, 27 Nov 2007 11:31:32 -0500, "J. Clarke"
> <[email protected]> wrote:
>
>>> But the time at lower setpoint more than compensates for the
>>> differential loss. It's well-established in general that a
>>> setback
>>> lowers overall heating costs in general. It would take unusual
>>> circumstances for that to not be so.
>>
>> It's not something one should just assume. Especially with
>> alternative energy.
>
> Hi John,
>
> Might you know of some reasons that the general principle of
> savings through setbacks would not apply to my geothermal
> source...?
>
> As I have said before here, I certainly do not (know enough
> to) disagree, but I have no understanding of why that should
> be true.
>
> Sincere thanks,

I don't know enough details of your setup or the structure to be able
to run the numbers. The main objection I'm seeing is that it's likely
to cause the resistance elements in the heat pump to kick in but you
say that you don't have any, but there might be something else unique
to your situation.

--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Jim Behning wrote:
> On Wed, 28 Nov 2007 18:56:46 -0500, Jim Behning
> <[email protected]> wrote:
>
>> On Wed, 28 Nov 2007 09:46:22 -0500, Kenneth
>> <[email protected]> wrote:
>>
>>> On Tue, 27 Nov 2007 18:56:19 -0500, Jim Behning
>>> <[email protected]> wrote:
>>>
>>>>
>>>> Why do you need a second electric meter to excrement with? You
>>>> can
>>>> read your own meter every day at the same time. As long as you
>>>> record when you are drying clothes or other significant
>>>> electricity burning events you should be able to test for no
>>>> hardware costs.
>>>>
>>>> Are you torturing the group by not doing your own meter reading
>>>> and
>>>> reporting back?
>>>
>>> Hi Jim,
>>>
>>> I am lost...
>>>
>>> How would reading my meter at the same time every day tell
>>> me my heat-related energy consumption?
>>>
>>> Thanks,
>> Day zero meter reads 1480
>> Day one with no thermostat changes reads 1520
>> Day two no thermostat change 1570
>> day 3 no thermostat change 1620
>> Day 4 after thermostat rollback 1680
>> day 5 with thermostat rollback 1740
>> day6 with thermostat rollback 1800
>> day 7 no thermostat change 1850
>> day 8 thermostat rollback 1910
>> day 9 thermostat rollback 1970
>> day 10 no thermostat change 2020
>>
>> and so on. Just read the meter every day at the same time. Do the
>> math. Do it over enough days to factor out clothes dryers and
>> baking
>> festivals. If there is indeed any significant energy saving to be
>> had
>> by thermostat rollback it will show up with a month of measuring.
>> Especially if you do rollback every other night.
>>
>> That said I think when I feel rich I will buy
>> http://www.theenergydetective.com/store or one of these with the
>> split core
>> http://eyomenergy.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=EES&Category_Code=ES
>
> You are not measuring how much you spend on heating, you are
> measuring
> much less or more you are spending by trying different thermostat
> strategies. You also need to note wind, sunshine and outside temp.
> My
> heat does not run on a 50 degree day with sun and little to no wind.

Just for some perspective, last week the temperature here was 60
degrees, which melted the snow that had come down a couple of days
previously.
--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

Kenneth wrote:

[...asking about setback and subject...]

Don't know if you gave up or got an answer but I mentioned the OSU site
earlier. Being bored, I went and found it -- here's the current link.
Didn't find a specific answer in the faq's, but they have a couple of
contact ways you can get to them.

http://www.igshpa.okstate.edu/index.htm


hth...

--

Kenneth wrote:
> On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
> <[email protected]> wrote:
>
>> Now that has a few good answers. I would not have thought about the
>> freezing closed loops.
...
> Any responsibly designed system protects against such
> freezing...

...

My thinking precisely. The response basically is a bunch of
weasel-words. The upshot basically is if the aux heat issue is taken
care of properly and one doesn't mind the recovery time, setback will
save. For a reasonable source capacity, our experience was that while
the outlet temperatures aren't equivalent to gas, they're sufficiently
high the air feels "warm enough" circulating as opposed to the and as
compared to air-air heat pump that felt cool...

If there's freeze-up w/ a few degrees setback so the unit runs a little
less at night, there's going to be freeze up on other days as well...

--

chuckb wrote:
> Kenneth wrote:
>
>> On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
>> <[email protected]> wrote:
>>
>>
>>> Now that has a few good answers. I would not have thought about the
>>> freezing closed loops.
>>
>>
>> Howdy,
>>
>> Any responsibly designed system protects against such
>> freezing...
>>
>> All the best,
>
>
> but on the other hand:
>
> from your OP
> "The folks who designed the heating system say that with
> these systems, it is best to leave the set temp unchanged."
>
> any system that is operated outside it's design criteria risks failure!
..

A few degrees lower is "outside the design" for a residential hvac
system? I still think there's been no rational basis for the
proscription given unless, as Ken says, there's a problem--and if
there's a problem, I think there will be a problem irrespective of the
setback.

--

chuckb wrote:
> dpb wrote:
>
>> chuckb wrote:
>>
>>> Kenneth wrote:
>>>
>>>> On Fri, 30 Nov 2007 22:21:13 -0500, Jim Behning
>>>> <[email protected]> wrote:
>>>>
>>>>
>>>>> Now that has a few good answers. I would not have thought about the
>>>>> freezing closed loops.
>>>>
>>>>
>>>>
>>>> Howdy,
>>>>
>>>> Any responsibly designed system protects against such
>>>> freezing...
>>>>
>>>> All the best,
>>>
>>>
>>>
>>> but on the other hand:
>>>
>>> from your OP
>>> "The folks who designed the heating system say that with
>>> these systems, it is best to leave the set temp unchanged."
>>>
>>> any system that is operated outside it's design criteria risks failure!
>>
>> ..
>>
>> A few degrees lower is "outside the design" for a residential hvac
>> system? I still think there's been no rational basis for the
>> proscription given unless, as Ken says, there's a problem--and if
>> there's a problem, I think there will be a problem irrespective of the
>> setback.
>>
...
> you seem to be reading things that i didn't say or if i did i certainly
> did not mean to.. oh well, have a good day!

Well, what _did_ you mean, then???

--

Fred the Red Shirt wrote:
> On Nov 27, 7:26 am, Robatoy <[email protected]> wrote:
>> ...
>>
>> I was going to try to equate this with the reason why when you
>> increase the waterflow through your car's radiator by taking out the
>> thermostat, your engine will overheat. The water HAS to spend time in
>> the rad to be able to give up its heat. So the thermostat slows down
>> the waterflow. Conventional thinking would suggest that by increasing
>> the waterflow, it should cool better. (There are a few caveats in
>> there too, so everybody keep their shirts on.)
>
> That is the first I ever heard of that.
>
> The higher the flow rate the higher the Reynolds number and
> therefor the higher the convective heat-transfer coefficient.
> You may get less heat transferred per gram of water flowing
> through the radiator, but not in inverse proportion to the
> rate at which grams of water flow through. IOW you might
> get only 75% of the heat loss per gram of water but will
> have twice as many grams of water flowing through.

Yes, it's simply wrong in general. If one didn't get additional cooling
capacity when the thermostat opened as compared to when it is closed,
there would be insufficient cooling capacity to prevent overheating at
almost any operating condition.

Whatever "caveats" were suggested to counteract that would have to be
extreme, indeed...

--

Kenneth wrote:
...

> So, on the days with setback, the mean KWH/DD was 1.06. On
> the days with no setback, that mean was 1.36.
>
> The resulting savings are approximately 22%.
>
> I do remain baffled by the reasons the geothermal folks
> (installers, designers, sellers) seem to be consistent in
> suggesting that such setbacks are not of value.

As at least one other poster noted, they're concerned w/ other factors
that aren't applicable in your case (primarily dominated by the use of
resistance electric heat in many/most systems)...

There are others including the potential freezeup, etc., that are
possible but imo they're mostly cya kinds of responses. Did you try the
Water Furnace people directly or contact the Okla State or some of the
other resources for other input?

--

Kenneth wrote:
> On Sat, 08 Dec 2007 09:22:52 -0600, dpb <[email protected]>
> wrote:
>
>> Kenneth wrote:
>> ...
>>
>>> So, on the days with setback, the mean KWH/DD was 1.06. On
>>> the days with no setback, that mean was 1.36.
>>>
>>> The resulting savings are approximately 22%.
>>>
>>> I do remain baffled by the reasons the geothermal folks
>>> (installers, designers, sellers) seem to be consistent in
>>> suggesting that such setbacks are not of value.
>> As at least one other poster noted, they're concerned w/ other factors
>> that aren't applicable in your case (primarily dominated by the use of
>> resistance electric heat in many/most systems)...
>>
>> There are others including the potential freezeup, etc., that are
>> possible but imo they're mostly cya kinds of responses. Did you try the
>> Water Furnace people directly or contact the Okla State or some of the
>> other resources for other input?
>
> Howdy,
>
> The CYA analysis makes sense to me, but as you probably
> know, there is no real "freeze up" danger at all. These
> systems simply turn themselves off is the incoming water is
> too cold.

The problem I've normally seen is on the once-through water exchange
systems (which is also what I think I recall being mentioned in one of
the earlier postings of a problem--whether it was yours or another I
don't recall) is the freezeup of the outlet when systems aren't running.
My opinion remains as I noted there is that if that's a problem for a
given system, it will be so whether there's a setback or not unless the
system is so undersized as to run continuously; hence my assessment of
that as a response as being in the "CYA" category.

> Also, as you may know "Water Furnace" is a brand name. Our
> equipment is ClimateMaster.

Yes, I had thought that was who you had said earlier...I don't know
ClimateMaster; had a Water Furnace system earlier and was pretty
impressed w/ their factory rep service/technical support.

> I have communicated about all this at some length with the
> ClimateMaster folks, with the geo folks from my electric
> utility, and with the installer of the equipment. They all
> have said "no setback" is best.

I think again all of those folks are addressing the general case still
rather than the specifics of a given installation and are still using
the answer that is easiest for them. It would be interesting if could
get to one of the actual research facilities that might address a
specific system rather than the general consumer response. If you were
still interested in pursuing it from that standpoint I'd again suggest
ORNL, TVA R&D (not power) or OSU might be more likely to answer a real
question.

--

Kenneth wrote:
...

> First, I am concerned with my system(s) and whatever savings
> I might realize with the setbacks.
>
> Second, I am a curious sort, and often enjoy understanding
> this sort of thing.
>
> Right now, my energies are focused on #1, and with my very
> simple experiment, I do believe I have my answer.
>
> #2 will have to wait a bit!

The answer to the first is clear -- a lower setpoint is less total
integrated demand as compared to no setback so unless there are
mitigating factors such as the higher-rate aux heat (that you don't
have), then a setback will invariably be less input.

The other issues are also system-specific but the design issues have
been dealt with by the various research groups. I never had a
convenient water source so didn't pursue the logistics of them that much.

--

Doug Winterburn wrote:
> Kenneth wrote:
>>
>> Hello to all (again),
>>
>> Well, I am the OP on this "Will I save if I use a thermostat
>> setback on my geothermal system" thread, and I believe that
>> I now have an answer:
>>
>> Part of the hassle I faced in experimenting with this was
>> that for some reason, I kept thinking only of my house. We
>> have a number of electrical appliances there that are used
>> (essentially) randomly, and their use would certainly throw
>> off any comparisons that I could make over a relatively
>> short period of time.
>>
>> I commented on that to my wife, and she said "So do the
>> experiment in the barn." (She did not actually say "So do
>> the experiment in the barn, you idiot", but that is what I
>> heard.)
>>
>> Our office-barn is heated with exactly the same system as is
>> our house (water to air geo with no backup resistance heat)
>> and there is no variability of electrical consumption other
>> than the heating system for most of each day.
>>
>> So, with that information, I did a very simple experiment. I
>> have run it only for six days but, as you will see, the
>> pattern seems quite clear:
>>
>> I set the programmable thermostat to drop the "call heat"
>> temperature by 10 degrees F for 12 hours on alternating
>> nights.
>>
>> Each morning, at the same time, I read the barn's electric
>> meter.
>>
>> Finally, I got the degree days, and wind speed, from a
>> weather service site.
>>
>> With that, I could calculate the ratio of KWH to Degree Day.
>> I have also included in the table below the reported max
>> wind speed for the day.
>>
>>
>> KWH/DD WS
>>
>> Day 1: 1.2 (setback) 14
>>
>> Day 2: 1.6 (no setback) 17
>>
>> Day 3: 1.0 (setback) 8
>>
>> Day 4: 1.3 (no setback) 0
>>
>> Day 5: 1.0 (setback) 12
>> Day 6: 1.2 (no setback) 3
>>
>> So, on the days with setback, the mean KWH/DD was 1.06. On
>> the days with no setback, that mean was 1.36.
>>
>> The resulting savings are approximately 22%.
>>
>> I do remain baffled by the reasons the geothermal folks
>> (installers, designers, sellers) seem to be consistent in
>> suggesting that such setbacks are not of value.
>>
>> All the best,
>
> I'm wondering if your savings aren't as great as you think. The reason
> is that on a setback day, you have zero electrical usage as the house
> coasts down to the setback temp. The next day's usage gets nailed with
> the recovery time usage. Perhaps week long vs day long alternating
> periods might mitigate some of this effect?

That's an effect if compares only one to the other. The point is,
however, that the time integral demand over the days w/ setback is lower
than without. Over a period of time when the average daily temp and
wind differences average out, the net will still be less with less
demand as a simple heat balance will show.

The better overall test would indeed, be to run for a longer period of
time at each operating mode and then compensate for the correlating
variables. Of course, the ideal test would be to hold the environment
fixed... :)

--

Doug Houseman wrote:
> In article <[email protected]>,
> Kenneth <[email protected]> wrote:
>
>> On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
>> <[email protected]> wrote:
>>
>>> What was the recovery time after the setback days?
>> Hi Doug,
>>
>> I don't know with certainty, but I do know it to be less
>> than an hour.
>>
>> All the best,
>
> Please be careful on high wind load, very cold days - I would suggest
> that if you know that the next day is going to be that way you not do
> the setback.
>
> I have had Geothermal for more than 20 years, in the early winter and in
> the spring, set back saves a lot of money, but from about the middle of
> December to the End of February here in Michigan, we do not do a
> setback, since the secondary electric elements cost way more than the
> savings.
...

OP has stated a zillion times already he has no aux heating and the unit
is sized to handle it w/o. So the aux heat is not an issue for him...

--

On Fri, 30 Nov 2007 20:56:41 GMT, chuckb <[email protected]> wrote:

>Kenneth wrote:
>
>>
>> Howdy,
>>
>> This is way OT...(again), but:
>>
>> We heat and cool our home geothermally (water to air
>> system.)
>>
>> We would, of course, like to decrease our costs further if
>> we can, and so have explored the benefits of setting our
>> thermostat lower at those times when the house (or parts of
>> it) are not occupied.
>>
>> The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged.
>>
>> Of course, I have asked "why", but when I do, it seems that
>> smoke starts to come out of the phone. In essence, they say
>> that it is "best" but seem unable to say why.
>>
>> Might any of you know what would be best in this regard ,
>> and particularly whether the issue of thermostat setback is
>> actually any different for geothermal systems?
>>
>> Sincere thanks,
>
>
>hi all!
>
>i sent this email to Alliant Energy Geothermal
>===============
>there is a discussion underway with this as topic: -
> We heat and cool our home geothermally (water to air system.) We
>would, of course, like to decrease our costs further if we can, and so
>have explored the benefits of setting our thermostat lower at those
>times when the house (or parts of it) are not occupied. The folks who
>designed the heating system say that with these systems, it is best to
>leave the set temp unchanged. Of course, I have asked "why", but when I
>do, it seems that smoke starts to come out of the phone. In essence,
>they say that it is "best" but seem unable to say why. Might any of you
>know what would be best in this regard , and particularly whether the
>issue of thermostat setback is actually any different for geothermal
>systems?
> could you help me understand the issues involved? thanks in advance
>for any input! chuck b:-)
> ==============
>and i got this reply
>-----------------------
>
>Dear Chuck,
>
>Set-up of a Geo system temperature during the cooling time of year
>should allow a Geo system to recover the cooling and dehumidify as
>quickly and more efficiently than other air sourced cooling systems.
>
>Set-back is not typically recommended during the heating time of year
>due to 1) a slower recovery time for heating, 2) the potential for the
>back up electric elements kicking in to boost the reheating rate but, at
>an added electric expense to you, 3) dependent on if you use a straight
>well water open loop or only a minimal to non freeze protected closed
>loop fluid, the lack of normal flows may allow for a potential for a
>loop to freeze up and 4) many people who own set-back thermostats are
>easily confused by the instructions for operating them and re-setting them.
>
> All of these can cause contractor callbacks, they hate callbacks.
>
>We do have a few of our regional Geo system owners who do a slight
>setback for heating at maybe 2 to 4 degrees F maximum for 4 to 6 hours
>but, all must realize the potential results.
>
>During AC season and the daytime hours of unoccupied homes, they might
>also do set up to minimize On Peak energy charges when they choose Time
>of Use electric rate options.
>
>I hope this helps. Thanks for the inquiry.
>
>Leo
>
>From: Alliant Energy Geothermal Web Forms
>[mailto:[email protected]]
>Sent: Wednesday, November 28, 2007 9:29 PM
>To: Geothermal
>Cc: Webmaster
>Subject: Alliant Energy Geothermal -- Contact Us Form
>
>
>
>chuck b:-)
Now that has a few good answers. I would not have thought about the
freezing closed loops.

On Sat, 08 Dec 2007 16:35:50 -0500, Doug Houseman
<[email protected]> wrote:

>In article <[email protected]>,
> Kenneth <[email protected]> wrote:
>
>> On Sat, 08 Dec 2007 11:48:34 -0700, Doug Winterburn
>> <[email protected]> wrote:
>>
>> >
>> >What was the recovery time after the setback days?
>>
>> Hi Doug,
>>
>> I don't know with certainty, but I do know it to be less
>> than an hour.
>>
>> All the best,
>
>Please be careful on high wind load, very cold days - I would suggest
>that if you know that the next day is going to be that way you not do
>the setback.
>
>I have had Geothermal for more than 20 years, in the early winter and in
>the spring, set back saves a lot of money, but from about the middle of
>December to the End of February here in Michigan, we do not do a
>setback, since the secondary electric elements cost way more than the
>savings.
>
>I am looking at adding solar thermal heating the south wall of the house
>next summer to further reduce the winter heating bill. I have 60 feet of
>southern facing wall that is in direct sunlight almost all of the day.
>That should give me a good thermal boost on even partly cloudy days.
>
>Doug

Hi Doug,

Your offer good thoughts for the general geo situation, but
we do not have resistance auxiliary heat in either of our
two buildings. Our systems were designed for 20 year cold
days.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

"Robatoy" wrote
>
> I was going to try to equate this with the reason why when you
> increase the waterflow through your car's radiator by taking out the
> thermostat, your engine will overheat. The water HAS to spend time in
> the rad to be able to give up its heat. So the thermostat slows down
> the waterflow. Conventional thinking would suggest that by increasing
> the waterflow, it should cool better. (There are a few caveats in
> there too, so everybody keep their shirts on.)

I had an old volvo that had a thermostat that would die on a regular basis.
So I just ran without the thermostat. The problem with this particular
configuration is that it took over twenty minutes for it to heat up. And
until it heated up, you had no heat, defrosters and the engine did not run
well.

But volvo engineers had a unique solution. They had a window shade type
device located in front of the radiator. You pulled a chain under the dash
to pull the shade up over the radiator and it heated up quick! This model
also had a baby bottle warmer under the dash as well.

On Sun, 2 Dec 2007 09:55:59 -0800 (PST), Fred the Red Shirt
<[email protected]> wrote:

>On Nov 26, 11:48 pm, Kenneth <[email protected]>
>wrote:
>> Howdy,
>>
>> This is way OT...(again), but:
>>
>> We heat and cool our home geothermally (water to air
>> system.)
>>
>> We would, of course, like to decrease our costs further if
>> we can, and so have explored the benefits of setting our
>> thermostat lower at those times when the house (or parts of
>> it) are not occupied.
>>
>> The folks who designed the heating system say that with
>> these systems, it is best to leave the set temp unchanged.
>>
>> Of course, I have asked "why", but when I do, it seems that
>> smoke starts to come out of the phone. In essence, they say
>> that it is "best" but seem unable to say why.
>>
>> Might any of you know what would be best in this regard ,
>> and particularly whether the issue of thermostat setback is
>> actually any different for geothermal systems?
>>
>
>
>The rate at which your house loses heat to the environment
>depends in an almost linear fashion on the temperature difference
>between your house and the outside environment.
>
>So as your house cools, the rate at which it loses heat will
>decrease. Keeping the house at the higher temperature means
>it will constantly lose heat at that higher rate, and all of that heat
>lost must be mad eup to maintain the temperature. If you let
>it cool down and heat it back up the 'stored' heat that is lost
>to the environment while cooling is exactly equal to the extra
>heat needed to heat it back up. But the heat loss to the enviornment
>is less the whol time during which the house is cooler than
>normal.
>
>Ergo, it ALWAY will use less heat to let it cool down and
>heat it back up than to maintain it at the higher temperature.
>
>What comes into play is the cost of pumping that heat into
>your house at the higher rate for the short period of time
>during which it heats back up. If that is down with auxillary
>electric resistance heat that MAY cost more or use more
>energy overall than just keeping it warm.
>
>The presumption that you have an auxiliary heating system
>may be part of the reason why you get advice to the
>contrary. Another concern may be that cycling the
>temperature may result in persistent cold spots or
>condensation problems that could lead to overall
>dissatisfaction with the system.
>
>But mostly I doubt you have ever spoken on the
>phone with anyone who actually studied heat
>transfer phenomenon or even took a physics course
>ever.
>
>The other possibility suggested is that extracting heat
>too fast from the groundwater could create a pool
>of cooled water underground with a resultant lower
>efficiency of heat extraction. That would depend
>largely on the groundwater environment and how
>extensive the heat exchange area is underground.
>
>I doubt that a definitive general answer can be given
>regarding that last concern. It would be highly dependent
>on the specific situation.

Hello to all (again),

Well, I am the OP on this "Will I save if I use a thermostat
setback on my geothermal system" thread, and I believe that
I now have an answer:

Part of the hassle I faced in experimenting with this was
that for some reason, I kept thinking only of my house. We
have a number of electrical appliances there that are used
(essentially) randomly, and their use would certainly throw
off any comparisons that I could make over a relatively
short period of time.

I commented on that to my wife, and she said "So do the
experiment in the barn." (She did not actually say "So do
the experiment in the barn, you idiot", but that is what I
heard.)

Our office-barn is heated with exactly the same system as is
our house (water to air geo with no backup resistance heat)
and there is no variability of electrical consumption other
than the heating system for most of each day.

So, with that information, I did a very simple experiment. I
have run it only for six days but, as you will see, the
pattern seems quite clear:

I set the programmable thermostat to drop the "call heat"
temperature by 10 degrees F for 12 hours on alternating
nights.

Each morning, at the same time, I read the barn's electric
meter.

Finally, I got the degree days, and wind speed, from a
weather service site.

With that, I could calculate the ratio of KWH to Degree Day.
I have also included in the table below the reported max
wind speed for the day.


KWH/DD WS

Day 1: 1.2 (setback) 14

Day 2: 1.6 (no setback) 17

Day 3: 1.0 (setback) 8

Day 4: 1.3 (no setback) 0

Day 5: 1.0 (setback) 12

Day 6: 1.2 (no setback) 3


So, on the days with setback, the mean KWH/DD was 1.06. On
the days with no setback, that mean was 1.36.

The resulting savings are approximately 22%.

I do remain baffled by the reasons the geothermal folks
(installers, designers, sellers) seem to be consistent in
suggesting that such setbacks are not of value.

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Tue, 27 Nov 2007 18:07:39 -0000,
[email protected] (Robert Bonomi) wrote:


Hi Robert,

I thank you for your detailed response...

Perhaps I am not understanding what you have written, but
allow me to ask something further.

Please see my comments inline below:


I wrote:
>>If the internal temperature of the house is allowed to drop,
>>two things happen. First, there is the direct energy savings
>>because it takes fewer BTUs to keep the house at the lower
>>temp;

You responded:
>_THOSE_ BTUs are just 'deferred spending'. you spend exactly
>that amount to raise the temp back to the original setting.

I wrote:
>> but perhaps less obviously, the rate of heat loss to
>>the outside environment is decreased. (Because the greater
>>the temperature differential, the more rapid the rate of
>>equalization.)
>
You responded:
>That is the -totality- of the energy savings -- the lowered losses.
>from the reduced temperature.
>>

In my attempt to understand this...

Suppose I lowered the temperature of the house 10 degrees,
but not merely overnight. Instead, I left them lower for a
month.

Would I not have very significant savings for that month?

If so, would not the reasons for those savings apply as well
to my overnight lowering of the house's internal temperature
(though with decreased benefit because of the diminished
duration)?

Thanks again,
--
Kenneth

If you email... Please remove the "SPAMLESS."