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  1. #1
    Join Date
    Dec 2014
    Posts
    21
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    New noise when air exchanger comes on

    I had a 5 ton HVAC put in 3 months ago. The outside air exchanger is outside of the downstairs living area. It was very quiet at first.

    Recently it has started making a loud "clunk" sound right as the unit comes on. Is this something that I need to have looked at and can it be adjusted?

  2. #2
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    3,021
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    Start with checking your air filter, if putting in a new one doesn't solve the noise issue then it's time to call the installer. A "clunk" could be anything from nothing to worry about to something mechanically coming apart that you would want resolved as soon as possible.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  3. #3
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    24,376
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    That’s a lot of capacity. How often does it start per hour?

  4. #4
    Join Date
    Dec 2014
    Posts
    21
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    Thread Starter
    Quote Originally Posted by firecontrol View Post
    Start with checking your air filter, if putting in a new one doesn't solve the noise issue then it's time to call the installer. A "clunk" could be anything from nothing to worry about to something mechanically coming apart that you would want resolved as soon as possible.
    The air filter is fine, check it pretty often. The unit was very quiet when they installed it.

    The unit is 5-ton downflow. According to Trane, they have a drain kit to modify the unit for the downflow application when it is 5-ton. They didn't have the kit when the unit was installed 3 months ago so they had to order it.

    So when the kit came in, they came out, disconnected everything, installed the kit which involved putting some gaskets and deflectors around the drain pan and a 'bib' or cover over the blower then hooked everything back up and evacuated and pressurized the system. But they had to take the coil and blower out and disconnect all lines to install the drain kit.

    After they were here for the drain kit is when the noise started. Can't say exactly when it started though. Being as the outside unit is outside my living room, the noise is unwelcome. I told them about it but they said it is probably nothing and that the units sometimes make the noises.

    I didn't know if something they could have done or not done when they put the drain kit in could be causing the noise since they had to disconnect all the lines and re-do the system when they were finished.

  5. #5
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    9,621
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    It could be the contactor pulling in, they can be loud, especially the larger ones. Cooler temps can cause the unit to shift which makes the noise more noticeable and less noticeable when warmer.

  6. #6
    Join Date
    Dec 2014
    Posts
    21
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    Thread Starter
    Quote Originally Posted by BNME8EZ View Post
    It could be the contactor pulling in, they can be loud, especially the larger ones. Cooler temps can cause the unit to shift which makes the noise more noticeable and less noticeable when warmer.
    Thanks, yes, it's right when the unit kicks on that it has the noise. So the contactor could be the culprit. Is there a way to quiet such a thing? Being right outside my living room window I would like to get it as silent as when they first installed the unit in July.

  7. #7
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    9,621
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    Hard to say, noise is hard to predict. A good tech may be able to track it down and come up with a solution or it may just have to do with temperature (expansion/contraction) affect on the equipment. Since it is new the installer should cover it as many good contractors handle labor the first year.

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