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  1. #1
    Join Date
    Jul 2013
    Posts
    12

    Leaking line set: can leak's sound vibrations travel through copper?

    Hi all,

    Low pressure line will not hold pressure during nitrogen tests. It leaks down immediately. A distinct hissing noise can be heard in the HVAC equipment closet when nitrogen valve is opened. It sure sounds like the leak's gotta be there, but Tech cannot find a leak in the line up to the ceiling. He suspects leak might be just above ceiling in attic. After tech left, I crawled (army-man style as we have vaulted ceilings) into the attic and spotted what looked like a roofing nail going into the line, but it is a good 15 feet horizontally away from the furnace closet. Can the sound vibrations from a hiss travel through the copper and give the impression the leak is in the closet when it isn't? Roof was redone two years ago, and no A/C since. I can't get close to the nail to inspect due to ductwork and low clearance.

    I'd prefer to have the line set repaired, otherwise we have to run a new one up the side of the house. Equipment is 19 years old, so a new system may be in the near future (if not imminent). I'm already into this for 2 hours of labor. Don't want to put good money toward bad. Existing system is R22 and will need 7lbs.

    Thanks for any advice!

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    67,755
    A hissing noise can be heard from a long distance a way. Too bad you didn't investigate this when the roof was redone. could have had the roofer's insurance pay for it.
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  3. #3
    Join Date
    Dec 2008
    Location
    Ontario Canada
    Posts
    537
    Ya, sometimes leak noises can be deceiving. That noise can really bounce around in a funny way in a little mechanical room. you may very well have found it, or more likely, you have found 1 of several leaks.

    The new higher efficent R410A condensing units really should have a new line set installed anyways, if your already considering a new system, this may be the time

  4. #4
    Join Date
    Jul 2010
    Location
    nebraska
    Posts
    1,629
    If you can't get close enough to the nail because it's too tight do you really want a guy trying to fix it with a torch up there? Don't put much money in it. Sitting with a hole for 2 years means there is air and moisture in the system. The compressor might be short lived.

  5. #5
    Join Date
    Jul 2013
    Posts
    12
    Quote Originally Posted by beenthere View Post
    ...Too bad you didn't investigate this when the roof was redone ...
    No kidding! First time I've had a roof done, and I live in San Diego where the need for A/C is not often. Didn't even dawn on me this could happen or to check. After the first year, I did call the roofer to diplomatically "get his thoughts" on the matter. His response was he doesn't use nails long enough to puncture anything, and if something was punctured it means the line set installation wasn't to code (he said line sets needed to be 2 or more inches from the roof decking)--in other words--not his fault.

    Thanks for your comments.

  6. #6
    Join Date
    Jul 2013
    Posts
    12
    Quote Originally Posted by LKJoel View Post
    ...The new higher efficent R410A condensing units really should have a new line set installed anyways, if your already considering a new system, this may be the time
    Yeah, I've read about the recommendation to use a new line set. I've read they have rifling inside and even though the r22 can be flushed, it's safer to go new. Now, that's what I read--don't know whether to believe all that.

    It's possible I can run a new line set into the garage across my garage ceiling and up through the floor of the equipment closet (closet ison second story). I really don't want a line set on the outside of the house, even with a cap.

    Thanks for taking the time to reply.

  7. #7
    Join Date
    Jul 2013
    Posts
    12
    Quote Originally Posted by martyinlincoln View Post
    ... do you really want a guy trying to fix it with a torch up there? ....
    Well it turns out this area may be accessible from the ceiling of a closet. I'm handy enough to open up the sheet rock and repair it when it's done, but I'm sure I'd be in for another 2-3 hours of labor by the time all is said and done. What I've paid for so far was totally worth it to me--I just had to know one way or the other whether it was the line set. Now it's knowing when to say enough is enough.

    Thanks for your reply

  8. #8
    Join Date
    Mar 2009
    Location
    Mount Holly, NC
    Posts
    3,023
    Quote Originally Posted by lgutkows View Post
    Yeah, I've read about the recommendation to use a new line set. I've read they have rifling inside and even though the r22 can be flushed, it's safer to go new. Now, that's what I read--don't know whether to believe all that.

    It's possible I can run a new line set into the garage across my garage ceiling and up through the floor of the equipment closet (closet ison second story). I really don't want a line set on the outside of the house, even with a cap.

    Thanks for taking the time to reply.
    I don't think any linesets have rifling inside them, the equipment tubing has, but not the lines between the equipment.

    blowing out is safer than flushing, unless the original system was burned out. new is better in many ways, the most important is that ALL traces of moisture are easier to remove with a new lineset that's clean and empty.
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  9. #9
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,926
    19 year old equipment, lineset has a hole in it.

    I'd say new lineset, new equipment.

    Any amount of money you put toward this system is money in the hole.
    If it was newer equipment, I would say go for it though.
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  10. #10
    Join Date
    Jul 2013
    Posts
    12
    Quote Originally Posted by hvacvegas View Post
    19 year old equipment, lineset has a hole in it. I'd say new lineset, new equipment...
    Yeah, I think that's where I'm heading. Appreciate your thoughts.

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