Page 1 of 2 12 LastLast
Results 1 to 13 of 14
  1. #1
    Join Date
    May 2007
    Posts
    20

    Compressor hum through lineset in heat mode

    Good morning. I had a Trane 13 SEER variable speed air handler installed earlier this year. The existing heat pump was used, which is a Unitary Products (?) unit rated at 10 SEER. Unit works great for air conditioning.

    However, when we started using the heat I noticed a hum coming from the air handler. I narrowed it down to the suction line, so I had the contractor come back out and confirm. He heard the same noise, but unfortunately he left telling me there was nothing they can do (after claiming their main guy knows everything and if he don't know nobody knows). So, I got upset.

    Since then, the noise has gotten progressively worse. Seems like the noise is related to the temperature outside (louder when colder). I want to call them back out here, but before I do I wanted to get some advice on this problem.

    I have looked at past posts and saw other people having the same problem. The contractor did try moving linesets some, but he only checked pressures and temperature and gave up there. He didn't say anything about installing a muffler. To no surprise, he tried upselling me on a new compressor unit, but the unit I have outside is only 5 years old.

    Most of the sound is eminating from the downstairs return duct, so I imagine the open space might be amplifying the sound. Is there anything I can do to try and fix this?

    Would appreciate any help.

    Mike

  2. #2
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    Quote Originally Posted by mike2007 View Post
    Since then, the noise has gotten progressively worse. Seems like the noise is related to the temperature outside (louder when colder). I want to call them back out here, but before I do I wanted to get some advice on this problem.

    Most of the sound is eminating from the downstairs return duct, so I imagine the open space might be amplifying the sound. Is there anything I can do to try and fix this?
    Mine actually gets better as it gets colder. Makes me think that at colder temperatures, more refrigerant is flowing.

    Did they replace the coil as well as the air handler? Did you have any other work done over the last year (refrigerant add/removal, etc)?

    When they replaced the air handler, they might have moved the lines a bit and now the lines are in contact with your return ducts. That would certainly cause the noise to be transmitted throughout.

  3. #3
    Join Date
    Nov 2006
    Location
    SC
    Posts
    930
    Isolation and insulation for the lineset.
    Isolation: S turns or a loop at both ends of the lineset will help greatly in damping vibration noise. Make sure the lineset is not strapped tightly or laying against wood or metal. They both can act as a sounding board and amplify the noise.
    Insulation: almost but not quite the same. Make sure the black foam insulation has no rips, tears, or bare spots. Direct contact of the copper line to either wood or metal will set up the same sounding board effect.

  4. #4
    Join Date
    Oct 2002
    Location
    Florida Panhandle
    Posts
    4,550
    I'm a bit lost here, did you have an electric airhandler installed, or is this a furnace. If they installed a 13 seer airhandler on a old 10 seer heatpump condensing unit, then you have a mismatch unless he can show you its an aproved match.

    Just for your information, having a proper match on a heatpump is a must. Since a heatpump reverses its flow in heatmode, the coil inside now becomes the condensing coil, and the condenser outside becomes the evaporator. If its not a match, what generaly happens, its charged in cool mode in the summer and then when you get in heat mode its no longer charged correctly, and the pressures are out of range.

    If this is a variable speed furnace, with the existing coil and condenser, and it didnt make the noice before, he needs to recheck it. As someone else mentioned it could be as simple as lines vibrating against something, or could be incorrectly charged or an improper setup on the variable speed fan system.

    Roy
    "The perfect Totalitarian State is one where the political bosses, and their army of managers, control a population of slaves, who do not have to be coerced, because they love their servitude"

  5. #5
    Join Date
    Jun 2007
    Location
    Metro St. Louis
    Posts
    181
    Quote Originally Posted by gevans View Post
    Isolation and insulation for the lineset.
    Isolation: S turns or a loop at both ends of the lineset will help greatly in damping vibration noise. Make sure the lineset is not strapped tightly or laying against wood or metal. They both can act as a sounding board and amplify the noise.
    Insulation: almost but not quite the same. Make sure the black foam insulation has no rips, tears, or bare spots. Direct contact of the copper line to either wood or metal will set up the same sounding board effect.
    Is this vibration caused by the compressor itself (not having an outdoor coil to dampen the vibration before entering house), or is it due to the metering devices and associated check valves?

  6. #6
    Join Date
    Jan 2004
    Posts
    29
    Quote Originally Posted by gevans View Post
    Isolation and insulation for the lineset.
    Isolation: S turns or a loop at both ends of the lineset will help greatly in damping vibration noise. .

    Funny you should mention that!! i just had a new system installed yesterday by a very reputable company .. when they were taking the old line old, they had a hard time becasue of the loop at the air handler end of the line. The installer was telling me he has no idea why they put a loop! Now i know, wish i could go back and tell him ..

    Is this suppose to be common lnowledge and basic?

    When i touch the lines, i feel a very strong vibration which i don't recall with the old units .. is the vibration in lines a problem?

  7. #7
    Join Date
    May 2007
    Posts
    20
    Quote Originally Posted by Waterloo View Post
    Did they replace the coil as well as the air handler? Did you have any other work done over the last year (refrigerant add/removal, etc)?
    The airhandler is new with coil.

    When they replaced the air handler, they might have moved the lines a bit and now the lines are in contact with your return ducts. That would certainly cause the noise to be transmitted throughout.
    The line is insulated, but now that I look at it they clamped the line to the return box. Where the line goes through the wall to the garage the line insulation is also right up against the box. Perhaps that could be a source..?

  8. #8
    Join Date
    May 2007
    Posts
    20
    Quote Originally Posted by gevans View Post
    Isolation and insulation for the lineset.
    Isolation: S turns or a loop at both ends of the lineset will help greatly in damping vibration noise. Make sure the lineset is not strapped tightly or laying against wood or metal. They both can act as a sounding board and amplify the noise.
    Insulation: almost but not quite the same. Make sure the black foam insulation has no rips, tears, or bare spots. Direct contact of the copper line to either wood or metal will set up the same sounding board effect.
    I'll check this out. A previous posted mentioned something similar. Thanks.

  9. #9
    Join Date
    May 2007
    Posts
    20
    Quote Originally Posted by royc View Post
    I'm a bit lost here, did you have an electric airhandler installed, or is this a furnace. If they installed a 13 seer airhandler on a old 10 seer heatpump condensing unit, then you have a mismatch unless he can show you its an aproved match.

    Just for your information, having a proper match on a heatpump is a must. Since a heatpump reverses its flow in heatmode, the coil inside now becomes the condensing coil, and the condenser outside becomes the evaporator. If its not a match, what generaly happens, its charged in cool mode in the summer and then when you get in heat mode its no longer charged correctly, and the pressures are out of range.

    If this is a variable speed furnace, with the existing coil and condenser, and it didnt make the noice before, he needs to recheck it. As someone else mentioned it could be as simple as lines vibrating against something, or could be incorrectly charged or an improper setup on the variable speed fan system.

    Roy
    The contractor said it wouldn't be a problem. I had the same concern, but they didn't forewarn me of any issues down the road.

    This is an electric air handler with heat packs.

    How would I know if the system is an "approved" match?

    Thanks.

  10. #10
    Join Date
    May 2007
    Posts
    20
    I checked the lineset going through the house into the air handler and it is not touching anything that would cause a vibration. Before I call the contractor back, is it possible for them to install some sort of line filter to dampen the noise? What else could it be if the line is isolated? The heat pump is pretty noisy outside, but with my old comfortmaker unit (~ 25 years old before it was replaced) noise was never a problem in the house. Could this unit be operating at a higher pressure, thus causing the problem? Sorry for the novice questions.. just would like to understand before the contractor comes back.


    Thanks.

  11. #11
    Join Date
    Apr 2004
    Posts
    7,680
    It's not a match, so now you know. Your new indoor coil is likely larger (volume, not nessesarily size) than the one that would have been matched with that outdoor unit. Actually, you can post the model numbers of all the indoor coil, the indoor air handler, and the outdoor unit and someone here can tell you but honestly, 10 SEER systems were rarely, if ever, rated with 13 SEER coils and if they were, it was a previous 13 SEER coil, not the current one.

    Trane, just like any other mfg offers a level of performance but once a system is mismatched, you and your contractor are on your own. As the coined term "Frankensystem" implies, only Dr Frankenstien (the guy that invented the mismatch) can make it work but he gets no support from anyone else.

    Improper charging, non condensibles, flash gas, all can make the noises worse, but you really cannot address any of those until the system is matched.

  12. #12
    Join Date
    Sep 2007
    Location
    wash dc metro area
    Posts
    78

    attenuator will help

    It's always a dangerous road to travel when you mismatch equipment. Having said that , there are millions of mismatched systems out there providing comfort every day. I dont sell mismatched systems anymore but most hvac contractors service them quite often.
    Ask your contractor to put a vapor line Attenuator in a VERTICAL position on the lineset outside, I garandamtee that this will greatly reduce the noise. I have not used one lately and they may be a little hard to find. Carrier was selling a lot of attenuators in the early 90's when their version of Scroll compressors came out. I think the ones we used were made by parker controls and were available in 3/4 ,7/8 and inch+1/8.

  13. #13
    Join Date
    May 2007
    Posts
    20
    Quote Originally Posted by docholiday View Post
    It's not a match, so now you know. Your new indoor coil is likely larger (volume, not nessesarily size) than the one that would have been matched with that outdoor unit. Actually, you can post the model numbers of all the indoor coil, the indoor air handler, and the outdoor unit and someone here can tell you but honestly, 10 SEER systems were rarely, if ever, rated with 13 SEER coils and if they were, it was a previous 13 SEER coil, not the current one.
    The model number of the outside unit is: BRHS0301BD. It's a Unitary Products unit ~ 5 years old.

    The air handler inside is a Trane var. speed model: 2TEE3F31A1000A.

    Trane, just like any other mfg offers a level of performance but once a system is mismatched, you and your contractor are on your own. As the coined term "Frankensystem" implies, only Dr Frankenstien (the guy that invented the mismatch) can make it work but he gets no support from anyone else.

    Improper charging, non condensibles, flash gas, all can make the noises worse, but you really cannot address any of those until the system is matched.
    Is the best option here to spend the extra $$ and get the heat pump matched? Unfortunately budget was a problem back when I had the air handler installed. But the contractor didn't stress the importance of matching the system.

    This isn't the first problem I had with the system. They also had to install a hard-start kit because the compressor was experiencing mechanical lock: http://hvac-talk.com/vbb/showthread.php?t=139783.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event