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  1. #1

    Is electrical humming / buzzing in furnace normal?

    I just got a carrier furnace installed yesterday. I notice that when the furnace is off (thermostat not prompting for either heat or fan), there is still a moderate buzzing/humming noise. If I switch off the electricity, of course the noise goes out.

    I called the installer, and he said that this is just the electrical noise which is present in all systems.... I do not need to worry about it. While the noise is not loud (especially after I close the furnace room door), I still am a little unconvinced that it is normal. Does your furnace make this slight noise in the off cycle as well?

    Thanks!

  2. #2
    Join Date
    Feb 2004
    Posts
    451
    did you have a humidifier installed with the furnace?
    Before you criticize someone, walk a mile in their shoes...that way you are a mile from them and have their shoes

  3. #3
    Join Date
    Nov 2006
    Location
    Oregon
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    853
    It's probably the low voltage control transformer. These things can be quite noisy. The one in my air handler is covered with an metal box and the reasonant frequency must be such that it amplifies the normal hum.. A first I thought there was some major problem inside.

    I just modified the metal cover by stiffening it to dampen the amplification. Get the installation tech out there and they can probably do something similar.

  4. #4
    Join Date
    Dec 2007
    Location
    Afton, VA / Khorat, Thailand
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    2,469
    As long as power is supplied to the unit, the 24v transformer is still energized and will hum a bit. Some more than others...
    Tough times don't last...Tough people do.

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  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
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    6,841
    Call your installation company back and tell them the noise is not normal and is unacceptable. Yes, you can get noise from transformers, relays, contactors, etc. Pro's hear those things all the time and tend to get desensitized to them. But in fact, they should not normally make noise. Yes, AC current 'vibrates' but I've got at least 12 AC wound transformers and/or relays in my heating/cooling system and I do NOT have any noise from any of them and if I did, I'd change out the offending item to make it quiet. Noise is not normal for these devices, IMO.
    If YOU want change, YOU have to first change.

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  6. #6
    Join Date
    Dec 2007
    Location
    Ohio
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    2,876
    Quote Originally Posted by skippedover View Post
    Call your installation company back and tell them the noise is not normal and is unacceptable. Yes, you can get noise from transformers, relays, contactors, etc. Pro's hear those things all the time and tend to get desensitized to them. But in fact, they should not normally make noise. Yes, AC current 'vibrates' but I've got at least 12 AC wound transformers and/or relays in my heating/cooling system and I do NOT have any noise from any of them and if I did, I'd change out the offending item to make it quiet. Noise is not normal for these devices, IMO.
    Got to agree with this one! I put 5 to 6 furnaces in a week, they make absolutley NO noise when there is no call. Have your install company come out and make it right.
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  7. #7
    Join Date
    Aug 2007
    Posts
    7
    I totally agree with having it checked, and I agree it is most likely transformer hum which does happen...BUT IS SOMETHING YOU SHOULDN'T HAVE TO LIVE WITH...All that may be required is tightening the mounting screws of the transformer but either way the installing contractor should take a look at it.

  8. #8
    Join Date
    Jan 2008
    Posts
    2,127
    A moderate hum to one person is inaudible to the next, and intolerable to another. Transformers do produce a "slight" hum. Some more than others.

  9. #9
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,660
    It's the transformer. Have them install a piece of rubber between the transformer and whatever it is mounted too. Probably blower housing.

  10. #10
    Yes, I have an AprilAire 500M humidifier fitted in there.

    Thanks everybody for the responses. Now the challenge is to convince the contractor that noise is not acceptable. When I talked to him initially, he is just making me sound as if I'm too fussy.

    Quote Originally Posted by hetrola View Post
    did you have a humidifier installed with the furnace?

  11. #11
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,660
    Sounds like you picked or got the wrong company. Good luck.

  12. #12
    Join Date
    Nov 2007
    Location
    Washington State (on the Peninsula)
    Posts
    80
    I have changed out noisy transformer without any argument at all at no charge at all if I just installed the system less than a year ago. It would be covered by the warranty. If the customer don't like it ... make it right!

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