A small electric motor (1/4hp?) drives the blower which ventilates and
pressurizes the hallways in our small apartment block. The blower
draws too much cold air into the building during the winter. It would
be far too costly to install a heater to warm the air as it's drawn in
from the outdoors.
If a small variable-speed or multi-speed electric motor is available,
we were thinking that we could manually adjust the airflow to suit
outdoor air temperatures by increasing or decreasing the speed of the
Can anyone provide any practical feedback on this idea, or offer other
suggestions on how we might be able to alter the airflow from time to
Thanks in advance,
I really appreciate your helpfulness, but I think that restricting
incoming air would be like putting your hand over the end of a vacuum
cleaner hose while it's running, and restricting outgoing air would be
like putting your hand over the exhaust port of a running vacuum
cleaner -- the motor would probably burn out.
Any other suggestions?
Okay. I am not quite sure how the heating system in your apartment
I live in a bungalow where there are separate outside fresh air intake
ducts for the gas furnace combustion air and another one for the room
air. If I restrict the intake duct for the room air, all the motor
fan will do is the circulate the in-house air more often. It will
never overload the motor because there is no possibility of the leaky
(inside house) air ducts ever developing a differential pressure to
Throttling of the flow through centrifugal impellers (pumps and blowers) is
quite common. It actually relieves the load on the motor since the product
of volume times velocity which represents the total work delivered by the
motor is reduced.
firstname.lastname@example.org (go fish) wrote in message
If this system is running as described, it's a bad system for most of
the climates in the US, regardless of the blower speed. All you're
doing is blowing cold air into the building, which is precisely what
buildings go to great lengths to avoid. To do this correctly, the
system should have a heat exchanger, which minimizes the heat loss.
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