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  1. #1
    Join Date
    Mar 2009
    Posts
    214

    I could use a little lineset education- which is gas/liquid and insulation?

    I am trying to track a resonance issue and need to know a little more about the linesets. I have two lines, one large 5/8 and one small 3/8. The 5/8 is wrapped in foam, the 3/8 is bare copper. Is it normal for the smaller line to be bare and is it the liquid line or the gas? Thanks

  2. #2
    Join Date
    Feb 2008
    Location
    Massachusetts
    Posts
    701
    The 5/8 is vapor and should be insulated, the 3/8 liquid doesn't have to be.

  3. #3
    Join Date
    Feb 2011
    Location
    North East Ohio
    Posts
    772
    typically if you are having noise issues, it is a tight spot where the line enters the house. Or possibly it is fastened tooo tightly to the structure. When I install a new line set I strap the suction line (big) to the structure and use wire ties (zip ties) to connect the liquid line to it. You may want to call a professional in to remedy the situation for you. Good luck

  4. #4
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,014
    Lemme guess, you just had a new 410a system installed?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  5. #5
    Join Date
    Mar 2009
    Posts
    214
    Hell yes, please tell me you know what the problem is. I cannot believe my fellow Americans are satisfied with going from quiet operation to hearing their a/c. Who would care how quiet a variable speed a/h is, if all you hear is a pulsating drone. There has got to be a solution. I'd even run a new lineset up the exterior if necessary. But, I have a neighbor in the complex, who has the same system and ran the lineset up the exterior and he still has the drone in one room on the second floor. I live on the second floor and I have the drone.
    My gas line has rubber insulation and the liquid line is zip tied to it in the attic, I am not sure about what they did in the wall. I really want to solve this. I will speak with my downstairs neighbor. I am afraid of what it might sound like down there.
    So, how did you guess I now have 410-a?

  6. #6
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,014
    Quote Originally Posted by clydesdale View Post
    Hell yes, please tell me you know what the problem is. I cannot believe my fellow Americans are satisfied with going from quiet operation to hearing their a/c. Who would care how quiet a variable speed a/h is, if all you hear is a pulsating drone. There has got to be a solution. I'd even run a new lineset up the exterior if necessary. But, I have a neighbor in the complex, who has the same system and ran the lineset up the exterior and he still has the drone in one room on the second floor. I live on the second floor and I have the drone.
    My gas line has rubber insulation and the liquid line is zip tied to it in the attic, I am not sure about what they did in the wall. I really want to solve this. I will speak with my downstairs neighbor. I am afraid of what it might sound like down there.
    So, how did you guess I now have 410-a?
    I'll guess one more, and say you have a heat pump.

    410A heat pumps create a loud vibrational noise during normal operation, especially on the big, insulated line.

    As a general rule of thumb, a new lineset installed on a 410 heat pump system should be "suspended" using non-metallic hangers. I use a product that is essentially lawn chair webbing.
    When the connecting copper is physically clamped, or positively attached to the structure, you get vibration transfering throughout the building.

    It sounds like they had to keep the existing copper, due to your home being a condo. Unfortunetly, the lineset may just be an is what it is kind of thing.

    If possible, I would suggest running new copper lines.

    One thing to remember, is that the company who installed this system did nothing wrong by using 410a as the refrigerant, instead of r-22. Although you might not have had the noise issue, long term the 410a with a new lineset is a much better investment, than using a r-22 unit (that has refrigerant being phased out, costing x5 more for a repair in the future).
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  7. #7
    Join Date
    Mar 2009
    Posts
    214
    Yep, it is a Trane XL15i 2 ton HP. The lines are secured in the attic, and I do not remember that being that way. I have no access to the vertical run in the sheetrock. I wonder if I release the line in the attic, if it will help the noise in the wall? There is no resonance sound in the attic, but there also is no sheetrock.

    The only thing that concerns me with the idea of a new lineset is that I have a neighbor that has the same HP , installed by the same company. He got a whole new lineset and it runs up the exterior and he says he has the same pulsating resonance on the second floor, right where the line set runs up the exterior. That perplexes me.

    BTW, will the sound be better when in cooling mode.

  8. #8
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,014
    Quote Originally Posted by clydesdale View Post
    Yep, it is a Trane XL15i 2 ton HP. The lines are secured in the attic, and I do not remember that being that way. I have no access to the vertical run in the sheetrock. I wonder if I release the line in the attic, if it will help the noise in the wall? There is no resonance sound in the attic, but there also is no sheetrock.

    The only thing that concerns me with the idea of a new lineset is that I have a neighbor that has the same HP , installed by the same company. He got a whole new lineset and it runs up the exterior and he says he has the same pulsating resonance on the second floor, right where the line set runs up the exterior. That perplexes me.

    BTW, will the sound be better when in cooling mode.
    It may help with the noise, but at the same time if you're not extremely carefull, you could kink (squash) the copper.

    The reason your neighboor probably has the issue, is they clamped it to the exterior wall. Clamps = transmission = unhappy people. They should used some type of vibration isolator between the lineset and the exterior wall.

    While I can't say for certain if it would be better in cooling mode, every system I've seen would tell me it will be better in cooling mode.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  9. #9
    Join Date
    Mar 2009
    Posts
    214
    The problem is that in the wall it is hidden by my sheetrock. But, I would even consider running a new lineset on the exterior if it was a guaranteed fix. There has got to be a way to diagnose the issue. It is going to be 45 and sunny today. My indoor temp will likely be 69 or so. Can I switch this over to cooling or will it not like that with 45 degree outdoor temps? Thanks.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,929
    hvacmike85, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

    You can find the rules for posting and qualifications here.




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  11. #11
    Join Date
    Mar 2009
    Posts
    214
    HVACVEGAS, I put the HP in cooling mode and for the first 10 seconds the sound was deeper and worse. But, after that, it was absolutely better than in heating. So, what is the verdict? Sound like a lineset issue? The sound is coming right from the wall where the lineset is. Why is it better in cooling and was today a true test or is it too cold outside to really know. It was only 40 degrees outside when I put on a/c. But, it was quieter.

  12. #12
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    iti is not the type of refrigerant used it is the scroll compressor that is making the noise
    running a new lineset may help but first i would ask your contractor to rehang it so the small liquid line isnt against the wood or touching where it enters the wall

    your older unit was most liklely a recip compressor and didnt resonate like a scroll does
    isolation pads under the outside unit may also help a lot have had ocasion where the trane plastic base vibrates causing the same problem

    best to do this imho before replacing the lines and finding out you have the same problem

  13. #13
    Join Date
    Mar 2009
    Posts
    214
    Does the Trane unit use a scroll compressor? ON EDIT: never mind, looked that up and it does.

    The unit does have rubber isolators under it now. Unfortunately, they did not help.

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