Home furnace motor vibration

[Bob OH]

This problem concerns my home furnace. There was a squeaking noise coming from the motor.
A repair company said the bearings were bad and the motor needs replacing. After they installed
a new motor the vibration and noise was 10 times worse. When I complained they said I need a new furnace.
I can't believe that. When I bring a new company in to look at the noise problem, can a vibration
problem be fixed instead of installing a new furnace?

 

[3DDave]

Anything can be fixed. First one needs to understand what is broken. I would not first suspect bearings as a primary cause of vibration. I would see if the fan is balanced and that the motor shaft is straight. I would also look to see if the motor mounts are still soft. They might be stiff, but should not be rock-hard and you can compare to other mounts. They are cheap enough to buy new ones just for the diagnositic and keep them on hand.

You can check the fan for bent or missing blades and for any uneven accumulation of dirt and dust; cleaning the entire fan is fine. You can also check to see if the hub is solidly attached to the fan - I've had one fatigue loose and it makes a lot of racket.

The motor should have leads long enough to operate outside the furnace - a qualified tech should do this to confirm if the motor and fan are the source of vibration. Some just chuck parts at the problem.

 

[miningman]

When was this unit manufactured?? If this were me , Id be evaluating the merits and economics of replacing the entire unit as recommended by your tech.

 

[Strong]

If fan is driven by a V-belt, then check sheave/pulley alignment, loose sheave on fan shaft, and belt tension.
Other possibilities for vibration:
Fan bearing fault
Fan rotor position on shaft shifter and is rubbing on housing
Balance weight came off fan wheel
Noise/vibrations may be from oil burner motor or pump

If the furnace in not too old or you cannot afford to replace it, then get a tech/engineer that can do a proper diagnosis. Talk to your sound/vibration specialist at your plant. I could inspect and test it if you lived nearby.

Walt

 

[Bob OH]

Thanks for the replies!
Its not a new furnace but I feel there shouldn't be this vibration problem after getting a new motor.
I'm a retired mechanical engineer, so I feel I can evaluate these kinds of problems.
Maybe I'll check it out myself but would rather have a company that I can trust look at it.

 

[EnergyProfessional]

First, fire that company. No technician should replace a part, and then it is worse and they just leave and take your money. You didn't hire them to create more vibrations.
Obviously either they installed it wrong, or the motor wasn't the cause of the vibrations to begin with.

Everything vibrating can be fixed by a knowledgeable technician. vibration that weren't there before means something came lose, or wore out. Impossible for the internet to tell. If a new furnace makes sense depends on age, condition, efficiency etc.

 

[LittleInch]

Maybe they put in a bigger motor?

Air draft fan or water pump?

What vibrates?

This is a information free post so no one can help you I'm afraid as we can't see what you can see, feel, experience.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MintJulep]

Direct drive or belt drive?

Perhaps they knocked a balance weight off the fan while working.

 

[Bob OH]

I didn't watch him work.....but.....he was banging on something for maybe 5 minutes.
The fan is direct drive. When I questioned all the hammering, he said that he was just trying to get
a "collar" off the motor shaft....but he said he didn't bend anything(?)
I went back to the company, told them the worker did a lousy job and to replace the other parts attached to
the motor. They said OK.
After a few months of calls, I gave up. I don't want this company to touch my furnace.
I'm just trying to figure out the next step. I will eventually call someone else but I have zero confidence in choosing
a repairman.

 

[miningman]

Hate to state the obvious but if the OP is not adequately confident to repair this himself , with the liklihood of temperatures dropping soon , he needs to replace the entire furnace. He hasnt provided anywhere near enough info to troubleshhot this on line

 

[LittleInch]

Well that helps a bit.

Sounds like the fan shaft was bigger than the new motor shaft and he was trying to get the old collar off to re use it, but couldn't.

So maybe he just put the fan on in an eccentric manner hence the extra vibration.

Look at the motor and fan and see if you can remove it to have a look. If you can't get another repair company to look at it. Just watch him this time....

Even then you might need a new boiler (furnace)!


Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[MintJulep]

A new blower/motor for a residential furnace is $300 max.

If your can find a direct OEM replacement, maybe 30 minutes to install.

Longer if you need to fiddle to make the mounting work.