switching transformer hum normal?

Discussion in 'HVAC' started by mstar, Dec 18, 2010.

  1. Dec 18, 2010 #1

    mstar

    mstar

    mstar

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    I have an older furnance with a Honeywell RA 89a 1074 switching transformer that has a loud hum at times at other times a low hum
    When I hear the loud hum the system still works and if I turn off the power switch and turn it back on , the hum changes most the time.
    It will usually get quieter. Sometimes tapping the box will change it.

    The loud hum is more frequent but not consistant. It is hard to tell if the transformer or relay is humming

    Does this loud hum mean the unit should be replaced? Are there any servicable parts or do you replace the entire unit.


    Thanks.
     
  2. Dec 18, 2010 #2

    paul52446m

    paul52446m

    paul52446m

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    We normally replace the hole control. But a person can replace just a transformer.
    All transformer will hum. A lot of times you can be 6' away and hear them. If they are in a control box they can get a vibration going which will sound loader. This does not mean that you have to replace it. Later Paul
     
  3. Dec 18, 2010 #3

    mstar

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    Thanks. since I have two db levels of hum I would say one is abnormal.
    I am assuming you are saying these can go a long time with a loud hum and still work.
    Still it is annoying to hear it through the floor in the basement late at night


    And why does flipping the power on and off temporarily fix the louder hum?
     
  4. Dec 18, 2010 #4

    paul52446m

    paul52446m

    paul52446m

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    And why does flipping the power on and off temporarily fix the louder hum?
    Don't know?? I could try to BS you but i won't. Later Paul
     

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