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Thread: HVAC vibrating line (lines) in the wall

  1. #1
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    HVAC vibrating line (lines) in the wall

    Hi
    I am living in 4 story condominium, top 4th floor. Moved in during winter, the noise was not there, when, most likely, all heat pumps were working (it was crispy cold for California.
    Now comes Summer, everyone started using ACs and now I have rattling noise in my wall. My AC is off, have good natural ventilation, plus fans, plus top floor makes a difference....
    I remember having similar problems in my previous residence (also top third floor), much simpler and cheaper place. Over there I caught the problem (similar rattling noise) during initial moving in and my HVAC pro changed insulation on my neighbors' roof coolant lines and added coils to the old rooftop coolant lines. I ate the price tag as I was the only one suffering. Similar problem of rattling noise in my old place was almost completely remedied.

    Now similar problem in the new condo, more posh, more expensive. I really don't want to spend my money fixing someone else HVAC rattling noise. Called HOA technical supervisor and he said that noise can be due to missing coolant drain line traps.

    So what can it be? Missing HVAC drain line traps or rooftop coolant lines bad insulation etc? Or something else?

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  2. #2
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    That kinda sounds like a dry trap trying to fill with water. It also sounds like a pvc pipe rattling against something. Hard to say. You will need someone to investigate it for you. It may be a simple fix, or it may take some extra care to locate and solve. Noise issues can be some of the hardest to track down depending on how it transfers.

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  4. #3
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    Quote Originally Posted by BNME8EZ View Post
    sounds like a dry trap ... sounds like a pvc pipe rattling against something
    Does any previous solutions from my first condo make any sense (insulating rooftop lines and adding coils to them)?
    It is definitely from working AC (mine is off), so it is a pipe connecting rooftop unit with blower in condo.

  5. #4
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    Quote Originally Posted by kisianik View Post
    Does any previous solutions from my first condo make any sense (insulating rooftop lines and adding coils to them)?
    It is definitely from working AC (mine is off), so it is a pipe connecting rooftop unit with blower in condo.
    Not sure what you mean by this.

    I agree it sounds more like a dry trap then vibration.

    Try running just the blower and see if it makes the noise.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  6. #5
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    Quote Originally Posted by pacnw View Post
    it sounds more like a dry trap then vibration.

    Try running just the blower and see if it makes the noise.
    Thanks, it is getting there.

    One more time to recap my problem and suggestions here.

    Vibrating pipes are from my neighbors unit or units, who lives below me, so I can not just experiment on how to run things, BUT, as I stated in OP, during winter, when it was very cold by our standards, I am sure everyone were using their ACs for heating (using blowers only) - the noise was not there! The noise appeared when everyone started using ACs for cooling! So it is dry trap after all.

    Now, can someone direct me to the basic knowledge site so I can understand the dry trap situation, and how to fix it? Is this job is expensive, I have no clue what is this, yet.

    Thank you for all your help.

  7. #6
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    Here is my setup



    So my setup is missing condensation line P-trap, would this potentially create problems for me? What kinds?
    If my, below me, neighbors have the same setup as me (missing P trap), could this potentially create this noise? And if they have P trap, but it is dry, this will create this noise, did I get it correctly?

  8. #7
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    Your drain line is in the suction side of the blower so it pulls air into the drain line and the water can’t drain until it builds up enough weight to overcome the suction.

    A trap should be put in the line so water fills the trap which blocks the suction so the water just drains.

    When the trap is dry/partially filled you get a noise like a straw at the bottom of a malt.

    I don’t see a trap so it may be under the floor or something.

    Since your unit is not running you may be hearing the noise from a different unit through your drain line. (Speculation)

  9. #8
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    I don’t see a P-trap at the air handler, but that doesn’t mean there’s not one downstream! Your tech needs to look.

  10. #9
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    Thank you all for helping me to understand my issues.
    I have found P trap, I do have it, got HOA come and clean the drainage line and install a cap over drain line vent. Apparently second floor AC doesn't have a P trap and HOA is planning to have it "appear" there, will HOA install it or the owner, unclear, but it planned to happen very soon. Hopefully al those actions will make this sound to disappear.

    Appreciate everyone's suggestions.

  11. #10
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    Quote Originally Posted by kisianik View Post
    Thank you all for helping me to understand my issues.
    I have found P trap, I do have it, got HOA come and clean the drainage line and install a cap over drain line vent. Apparently second floor AC doesn't have a P trap and HOA is planning to have it "appear" there, will HOA install it or the owner, unclear, but it planned to happen very soon. Hopefully al those actions will make this sound to disappear.

    Appreciate everyone's suggestions.
    If this is after the trap DON'T DO THAT!!!!!!!
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  12. #11
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    Quote Originally Posted by pacnw View Post
    If this is after the trap DON'T DO THAT!!!!!!!
    Can you please explain why not in simple terms. I tried to figure it out myself, but still struggling to understand the purpose of T (did I got abbreviation correctly).

    Here is my setup direction of condensate flow.

    Below is where my unit is, RED ARROWS show condensate flow direction.



    Inside, from the unit



    Next going down to other side, into return air space



    Close up, you can see P trap and T air vent



    Last step before connecting to the general drain line




    Right now weather permits me not to run AC yet. T air vent is loosely capped (easy to uncap holding by gravity) to minimize the noise (at least is what HOA tech told me will happened). HOA is planning to install missing P trap on the second floor (thinking that it is the main source of drain pipe rattling noise).
    HOA said that capped T air vent should minimize the noise while they are installing missing P trap.
    While my AC is not running can I keep T capped?

    Once I decide to run my AC it is really easy to get to T vent and uncap it, as it is a temporary solution (capping). Do I thinking properly?

    I need to understand the purpose of T air vent - if I uncap it and noise come back meaning that HOA did not install missing P trap, or there is something else. Because HOA will say that they capped my T and it should stay or there is nothing they can do to stop the noise (the worst case scenario in our arguments).

    Please help.
    I was in construction (but heavy structures, concrete, office buildings and similar) about 30 years ago, so I understand diagrams and other basics.

  13. #12
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    That filter is plugged!

    That is not a proper trap.

    Have the static pressure measured and get a trap sized to handle the high static!

  14. #13
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    Quote Originally Posted by pecmsg View Post
    That filter is plugged!

    That is not a proper trap.

    Have the static pressure measured and get a trap sized to handle the high static!
    I am not doing any HVAC repairs right now, will keep this advice for the future, thanks. I did not use AC yet this summer, maybe a month per year use.

    The original question was about the noise. So far noise is gone, but I don't know yet if second floor got P trap installed. One day at a time.

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