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Loud buzzing sound from furnace

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  • Dec 18th, 2015 7:35 pm
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[OP]
Member
Nov 4, 2007
427 posts
35 upvotes

Loud buzzing sound from furnace

I've got an odd buzzing sound coming from our furnace. The sound is constant, not just when the fan is on, it only goes away if I flip the power switch.

The furnace is a 3 year old Keep Rite.

Anyone have any idea what might be causing this?
20 replies
Member
User avatar
Dec 1, 2010
281 posts
195 upvotes
Windsor
Ensure the cover(s) isn't loose. Could be draft inducer motor or fan.
Best call a HVAC to inspect; you wouldn't want to cause further damage.
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
I'll check that, but doesn't sound like a vibration noise. Best way to describe it is to call it electrical noise.

I called my AC installer and they suggested it may be a transformer causing this.
Deal Addict
Dec 17, 2007
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Alliston, ON
It could be the 24v transformer or one of the internal power supplies
Deal Fanatic
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Mar 20, 2009
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Vancouver
^ This. Many furnaces use 24vdc power for their controls, and they have a 110vac/24vdc transformer mounted next to the furnace to provide power. Like any transformer it can buzz at the 60Hz powerline frequency if anything is loose.
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
Ok so sounds like this may just be something loose rather than a bad transformer? Also, could this be caused by a power fluctuation in the house?
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Mar 20, 2009
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Vancouver
Nah, transformer buzz is common. It's the strong magnetic field oscillating back and forth at 60Hz. If anything is loose, including internal wire coils, it'll make noise. It makes more noise whenever it draws more current, because the magnetic field strength increases with the current.
Deal Addict
Dec 19, 2009
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JamesA1 wrote: ^ This. Many furnaces use 24vdc power for their controls, and they have a 110vac/24vdc transformer mounted next to the furnace to provide power. Like any transformer it can buzz at the 60Hz powerline frequency if anything is loose.
The transformer reduces it down to 24 volts AC ... not 24 volts DC
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
Ok is the transformer something I can replace on my own or should I get an hvac guy in?
Deal Addict
Dec 19, 2009
4713 posts
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Transformers are usually fairly easy to replace if you have a little sense with electricity. It may not even be necessary to change it as the buzzing doesn't mean it's actually failing as most normally buzz. Might not even be the transformer as it could be one of the relays instead.
Could possible use an insulated screwdriver and place it against the casing of the transformer or relay to see it the buzzing stops or if you feel a good vibration while it's operating to isolate which part it may be but lots of them buzz naturally.
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
The buzz is fairly loud and can be heard throughout the house from the vents.

My AC installer is quoting $160 plus parts if not covered by warranty. $80 to process the warranty plus $80 to replace the parts.

Is this reasonable, or should I look elsewhere?
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Mar 8, 2002
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Ottawa
Are you sure the buzz isn't coming from the gas valve solenoid?
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
Ok, I was able to open up the furnace and pull out the transformer. The buzz is definitely coming from it. Problem is I can't find the exact same model transformer. Can it be substituted with something else?

By the looks of it, they range in price from $20 - $50. So why would I spend $80 to go through warranty if I can just substitute with something else?
Deal Addict
Dec 19, 2009
4713 posts
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arctics wrote: Ok, I was able to open up the furnace and pull out the transformer. The buzz is definitely coming from it. Problem is I can't find the exact same model transformer. Can it be substituted with something else?

By the looks of it, they range in price from $20 - $50. So why would I spend $80 to go through warranty if I can just substitute with something else?
Yes other makes can be substituted, depends on the VA of the transformer. Give us the make and model number (a pic is usually nice) and someone will help you with a substitute.
Deal Addict
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Aug 4, 2010
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Thunder Bay
arctics wrote: Ok, I was able to open up the furnace and pull out the transformer. The buzz is definitely coming from it. Problem is I can't find the exact same model transformer. Can it be substituted with something else?

By the looks of it, they range in price from $20 - $50. So why would I spend $80 to go through warranty if I can just substitute with something else?
Peace of mind that it's working right? For $30 extra, why not have a trained pro ensure that a) that actually is a problem, and b) ensure the proper replacement part is in place. If you install it wrong, or put in a wrong part, you've potentially caused hundreds in other repairs.
Deal Addict
Dec 17, 2007
2619 posts
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Alliston, ON
all you need is a 24VAC 40VA transformer. Its a simple swap, just make sure you shut the power to your furnace off

24vac Transformer
Deal Fanatic
Jul 4, 2004
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Time to go to Amre supply, http://www.amresupply.com/
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Deal Addict
Mar 23, 2006
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I am a bit confused, $80 to process warranty ?

My personal opinion is call for a maintenance cleaning/tune up and get them to include the transformer replacement at a reduced cost.
Hopefully you can watch what they do and learn some techniques which you can comfortably do on your own in the future.
[OP]
Member
Nov 4, 2007
427 posts
35 upvotes
$80 processing fee he said was to cover the time to call in the warranty claim, plus pick up the parts and send back the old parts.

I like that idea, arrange it as part of a maintenance cleaning. My thought is just that the part seems so simple to replace, so why not take care of it on my own.

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