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-   -   furance blower loud noise just started (http://www.diychatroom.com/f17/furance-blower-loud-noise-just-started-120439/)

Tom Gramc 10-17-2011 09:46 PM

furance blower loud noise just started
 
My furnace is 6 years and old and always was very quiet. In the past 2 months, the blower got very loud and vibrates. If I take it out of the furnance, it runs very quiet on the floor. When I cover half the exhuast area with a board, I can recreate the loud noise and vibration. This occurs at all speeds, low, med or high. My observation is that when the blower has to work hard, it starts to vibrate and make a loud sound.

Is it my blower motor, the fan or do I have a restricted air way? I did all obvious thing, removed the filter, opened all the ducts, cleans the ducts and fan blades etc. It is not obvious to me what I should do next.

JJboy 10-17-2011 09:52 PM

PSC or ECM motor?

Tom Gramc 10-17-2011 09:58 PM

Bryant 350MAV system
3/4 HP Motor
14.6A
120VAC

Doc Holliday 10-17-2011 10:51 PM

http://www.gogeisel.com/geiselonline..._355MAV_OM.pdf

Does not say what the blower is. Any fault codes?

Tom Gramc 10-17-2011 10:55 PM

no fault codes. The unit is working, just very loud. THe motor is a PSC motor

Doc Holliday 10-17-2011 10:56 PM

Sitting here behind my computer I'm going to have to put my money on the bearings on the blower motor are wearing out.

JJboy 10-17-2011 11:03 PM

Yeap, sounds like bearings

Tom Gramc 10-17-2011 11:03 PM

The motor date code is Dec 2004. It is coming up on 7 years, it run both AC and Heat year round. Does that sound like the typical life of a blower motor? If so, it would be worth the shot to replace it if it is near the end of life anyhow.

Tom Gramc 10-17-2011 11:11 PM

The sound only occurs when in the unit or loaded down. Quiet when running on the floor. ALso, it is not a high pitch screaching sound like bearings. It is more like the fan metal is rubbing on something. Do you still think it could be bearings? Just wanted to bounce that off you before a shop for a motor. Any suggestions motor purchase sites?

Doc Holliday 10-17-2011 11:16 PM

Quote:

Originally Posted by Tom Gramc (Post 751030)
The motor date code is Dec 2004. It is coming up on 7 years, it run both AC and Heat year round. Does that sound like the typical life of a blower motor? If so, it would be worth the shot to replace it if it is near the end of life anyhow.

Certainly. And since you have a 90% condensing furnace you can always uprgrade that single stage psc motor to an ecm and get quite a bit more efficiency out of it.

http://www.youtube.com/watch?v=8argdl3MU3E

Doc Holliday 10-17-2011 11:21 PM

Quote:

Originally Posted by Tom Gramc (Post 751036)
The sound only occurs when in the unit or loaded down. Quiet when running on the floor. ALso, it is not a high pitch screaching sound like bearings. It is more like the fan metal is rubbing on something. Do you still think it could be bearings? Just wanted to bounce that off you before a shop for a motor. Any suggestions motor purchase sites?


Is there a loose screw, possibly causing the housing to vibrate or are there any marks internally on the blower motor housing reminiscent of the blower wheel rubbing on it?

Is there possibly a blade on the wheel broken and hitting the housing, scraping it? A loose weight perhaps, such as on your vehicles rim for tire balancing?

Does the shaft of the motor move in and out at all?

Tom Gramc 10-17-2011 11:31 PM

I looked for marks and scratches and could not find any. ( I did not take the housing completely apart, only what I could see) The shaft does not move up or down, but does move in and out a bit ( maybe a 1/8 inch) when I spin the fan with no power, it spins very free and quiet and coast for a few minutes.

Doc Holliday 10-17-2011 11:39 PM

Quote:

Originally Posted by Tom Gramc (Post 751050)
I looked for marks and scratches and could not find any. ( I did not take the housing completely apart, only what I could see) The shaft does not move up or down, but does move in and out a bit ( maybe a 1/8 inch) when I spin the fan with no power, it spins very free and quiet and coast for a few minutes.


Bearings are going bad, the shaft should not move in and out at all. In blower motor shaft movement that 1/8th of an inch might as well be a mile.

In time, shortly I'd have to assume, you will hear the high pitch squealing and scratching an irritating metal on metal of the point of no return bad bearings. What you hear now is just the beginning.

But on the bright side, if you watched that vid I'd be pretty excited if I were in your shoes as now's your chance to really have an awesome, evergy efficient furnace. Granted those motors are not cheap compared to psc but you'll make a return on your investment through your noticabley lowered electrical bill.

Tom Gramc 10-17-2011 11:42 PM

OK, you convinced me. I watched the video, and it does make good sense. I will look into this more tomorrow. Getting late, thank you for your help exchanging ideas.
:)

Doc Holliday 10-17-2011 11:49 PM

You're welcome. Let us know what you decide and how it works out for you.


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