This may sound like an obvious question to some of you, but if a
furnace-type blower is overly restricted, so has a higher pressure drop than
it is designed for, what would you expect to happen to the blower motor?
Eventually fail from over-heating?
Just finishing up a shop-built air cleaner/outfeed table/downdraft table
(based on a design by charlie b - thanks), and with it running on low, my
manometer readings show almost twice the pressure drop that a typical
furnace is designed for.
I'm pretty sure the blower is over-sized for this application. Even on low
speed, it moves a lot of air. But there's no reason to change it now; it
works. I'll use it unless and until the motor does fail.
Just curious whether I might expect it to run for a long time. Or.......
expect to see smoke coming out of it anytime.
Thanks
A centrifugal type pump blower/compressor (as opposed to positive
displacement) uses less horsepower as you restrict air flow. As an
example, a dust collector uses the least amount of horsepower when you
block it completely. Cooling the motor does not depend on whether air
is flowing through the blower.
Think of it as your particular blower is "loafing".
Bob
"Keith Carlson" <[email protected]> wrote in message
news:S_yTd.1930$r55.537@attbi_s52...
> This may sound like an obvious question to some of you, but if a
> furnace-type blower is overly restricted, so has a higher pressure drop
> than it is designed for, what would you expect to happen to the blower
> motor? Eventually fail from over-heating?
>
>
Depends on how much the air flow is reduced. If you are still moving a fair
amount of air you probably will be ok. I would run it and get a feel of how
hot is gets.
A typical furnace blower trying to move restricted air will over amp, and
over heat. How long will it run? It is any body's guess.
Greg
If the unit is an "air over" design (motor is inside the airflow) it
might overheat from lack of air movement. Blowers that place the
motor outside of the airflow don't have this problem - but then their
motors have to have better heat dissipation in the first place so they
are typically more expensive.
"Greg O" <[email protected]> wrote in message
news:[email protected]...
>
> "Keith Carlson" <[email protected]> wrote in message
> news:S_yTd.1930$r55.537@attbi_s52...
>> This may sound like an obvious question to some of you, but if a
>> furnace-type blower is overly restricted, so has a higher pressure drop
>> than it is designed for, what would you expect to happen to the blower
>> motor? Eventually fail from over-heating?
>>
>>
>
> Depends on how much the air flow is reduced. If you are still moving a
> fair amount of air you probably will be ok. I would run it and get a feel
> of how hot is gets.
> A typical furnace blower trying to move restricted air will over amp, and
> over heat. How long will it run? It is any body's guess.
> Greg
>
Hmm... if it's just "loafing", that would be great. On the low speed, I
measured 2.4 amps current draw. Not sure what is typical for something like
a 1400cfm furnace blower, but that doesn't sound too bad.
Definitely will be running it. No reason to actually do anything about it
unless it does break, and then it would probably be replaced by a lower-cfm
unit if I can scrounge one.