Air exchanger motor runs hot.


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 backwards!
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 hand!
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. while running.
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+ watts??????
The overall air exchanger unit is seemingly manufacture- discontinued.
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Sealed bearings sould have been used in a unit like that, it doesnt say much for the quality built into that unit.
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First, I think it's a good idea to flush out the old oil with brake cleaner, or something like that. Then oil generously with the non detergent oil.
The air flow through the air handler is likely what cools the motor. Bench testing is not the natural environment for that species of motor.
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detergent oil.
The air flow through the air handler is likely what cools the motor. Bench testing is not the natural environment for that species of motor.
-- Christopher A. Young Learn more about Jesus www.lds.org
Good advice...now if you could ONLY STOP top-posting...it would be a better place!
bob
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Buy a new motor. The best way to check is to put an amprobe on it and see the current draw and check the rpm. It may be running smooth right now, but the bearings are just about shot after 18 years and no lubrication so the motor is probably drawing much more current than normal.
Check www.grainger.com for a replacement. You can also take it to a local motor shop to be checked out. Most small motors are disposable and cheaper t replace than to repair, but no harm in asking.
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And this time make sure the bearings are sealed
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terry wrote:

When I was a lad, an old fart told me that if you can't hold your hand on a motor for ten seconds, the motor's running too hot.
In your case, the motor wouldn't even turn without some fiddling. I'd say replace it. The cost of a 1/12th HP motor isn't worth the aggravation.
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HeyBub wrote:

Motor can run hot either overloaded or underloaded. It runs at top efficiency with full rated load.
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On Sat, 15 May 2010 23:43:10 -0700, terry wrote:

Replace it, what were you seeking a miracle?
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In typed:

First, how hot is "hot"? Second, that type of motor would run hot if it were free-wheeling without a load. Put it back into its natural environment and it'll probably run normally. It might be time to start looking for a replacement; very often that type of wear will continue to happen until it crashes. You might get years more service from it, or just a few days; no way to tell for sure. I suspect your chances of getting a payback for your effort are good though.
HTH,
Twayne`
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terry wrote:

Just for peace of mind, son't wate time on it. It saw it's better days. Replace it. You have a choice of ball bearing or sleeve shaft. If noise is not a concern I'd go for bearing.
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About to have another go at it: Thanks for all the advice .................... Just to answer some points raised .................. 1) No signs of burning or overheat smell. 2) Bench running without either of the two impellers attached is not normal and there is no airflow across the motor as there would be within the unit. 3) Will test amp. draw and make provision to also do that if/when re- installed. 4) Looks like got two choices .......... a) Replace it anyway, perhaps not easy except by special order (within Canada preferably) because cross border customs, security and unnecessary brokerage fees as a result, is now making it a very slow process. We are still looking for some auto ignition parts shipped out of USA on March 21st.!!!!! Whereas illegal guns and drugs get smuggled in every day from south of that border! It would do international trade a lot of good and allow both the US and Can. economies to recover a lot quicker if some of that nonsense were done away with! b) Do some more testing and since the motor has already run some 3 plus hours, hot, cos I dozed off until about 2.30 AM and left it running longer than intended; put it back together. Knowing how to and that I can replace motor before end of summer by disassembling the unit, now that all the rusty and deteriorated screws and connection have been attended to and replaced. After 18 years of sucking in damp air and blowing out stale house air!
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You cant expexct anyone to ever oil that motor again, its to much of a pain in the ass to get at and do, put it back and order a new one, maybe if you order some guns and drugs with it, it will come tuesday.
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terry wrote:

Electricmotorwarehouse in Mich. won't let you down if you order from them. They predo all the paper work for cross border shipping. One payment covers all including choice of your courier. They just deliver the item to your door.
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terry wrote:

Motors have an "ambient" temperature rating and a "rise" rating. A 1/3 HP motor might have ratings of 25C ambient and 40C rise - running temp of 65C = 150F.
Providing air flow over the motor would reduce the temperature, but adding the impellers and pushing air would raise the temp - for a 1/12 HP motor maybe not much.
Having the motor not rotating would increase the temperature which deteriorates the insulation faster. In general, insulation deteriorates twice as fast at 10C higher and half as fast at 10C lower. (Four times as fast at 20C higher....)
If it were my house, I would make sure the motor was operating freely, which you have probably done, and reinstall it. Check it once in a while and keep it oiled.
--
bud--

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My GE Profile dishwasher worked just fine on Saturday. When I tried to run it on Sunday, the display read "2h" instead of the number of minutes remaining in the cycle. It clearly has power, but it doesn't do anything. I checked some online sites and found others who described this "error code", but no solutions. I followed the directions in the manual to "reset" by both using the reset button and by turning off the breaker for 30 seconds (I left it off for 10 minutes) and then tried again. Same thing.
The GE.com site is useless, since the "error codes" they provide don't list "2h", and none of the DIY repair sites that I've found list that code. Neither does the manual. So...anyone have experience with this or know of a good DIY site? Thanks in advance for any info.
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Start by not hijacking another thread.
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wrote:

Umm, I posted it as a new thread. It posted in other places and even other forums. I don't know why.
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Is there normally air flow around the motor that is not flowing on a bench set-up?
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