Daughter's 18 year old house air exchanger failed. It's in her
basement, hung from the main floor joists above. Found the single 115
volt one-twelfth HP motor that is mounted vertically and turns two
impellers, one for incoming air, one for exhaust air, not turning.
Reaching in it was just possible to push the impeller around by hand;
but very stiffly indeed.
The motor runs continuously. Although there is a local AC switch that
turns off the whole air exchanger unit, also a low voltage remote
control from a humidistat mounted in main floor hallway of the house.
The motor is mounted between two black plastic housings. The upper
encloses a squirrel cage exhaust air impeller, about six inches in
diameter, the lower a similar one for incoming air. Have marked to
make sure they go back in correct places, otherwise they will run
The motor frame is mounted within in the fresh interior air section
flow of the unit
Apart from the motor and a few other parts, the 'heart' of the unit is
the heat exchanger. A square unit where fresh incoming air is drawn
through narrow chambers while stale house air is drawn past on the
opposite side of the chambers exchanging some of it's warmth.
Have disassembled unit and extracted the motor; and finally, by
repeated oiling and turning manually and gentle tapping of the shaft
got the motor to run apparently smoothly. Left it running on the bench
for an hour or two.
BUT although running smoothly it's getting very hot. Could burn one's
The motor is marked 40 degrees C. Ambient. Forty Celsius is about 112
degrees F. Which is about the temp. of hot water at a 'low heat' hot
water heater setting (although Depts. of Health often ask for 160F for
safe dish washing!).
Intend to run motor again tomorrow and to simulate actual operation by
arranging a slight air flow across it and try to measure motor temp.
BTW. The motor is also marked 'Lubricate every y six months with
SAE20! It appears that the motor MAY have been oiled once only in it's
18 years of service! (Son in law apparently not the most mechanically
minded or 'do it yourself' inclined!).
Could anyone knowledgeable of this type of unit help by commenting on
the high temperature? Does it indicate motor has
failed; .................. come to think will measure the current draw
(motor unloaded by spinning impellers). Have both a cheap clamp on and
ability to measure AC current with a Fluke. 1/12th HP should be a bit
above half an amp?
Advice and comment welcomed. Not a stranger to this type of repair but
am puzzled by the high temperature of the motor which apart from its
now freed up bearings otherwise seems to be in excellent condition.
There is no sign of burnt windings, or any smell of anything unusual.
Maybe it did suffer damage while being left switched on but not
rotating, possibly for several weeks? Or longer! But at approx. 60+
The overall air exchanger unit is seemingly manufacture-