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  1. #1

    Question

    I have two newer Carrier A/C units, both 38TDB, (one is an 024 and the larger unit is an 036) and the larger unit is very loud when it is on "high". The smaller unit, 024 is nice and quiet as promised in both high and low but the larger unit is so loud you can hear it in the house.

    Carrier replaced the large unit last Spring becasue Carrier agreed that it was too loud. However, the new replacement unit is just as loud as the first.

    Has anyone else had problems with too much noise from these new Carrier units?

  2. #2
    Join Date
    May 2006
    Location
    Las Vegas,Nevada
    Posts
    339
    If you contacted Carrier before because your contractor wouldn't do it,you'll probably be doing it again.Some compressors run at different db levels but, if they replaced it due to excessive noise, there's definitly a problem that they need to be aware of.

  3. #3
    Originally posted by monicacox
    I have two newer Carrier A/C units, both 38TDB, (one is an 024 and the larger unit is an 036) and the larger unit is very loud when it is on "high". The smaller unit, 024 is nice and quiet as promised in both high and low but the larger unit is so loud you can hear it in the house.

    Carrier replaced the large unit last Spring becasue Carrier agreed that it was too loud. However, the new replacement unit is just as loud as the first.

    Has anyone else had problems with too much noise from these new Carrier units?
    The problem is unlikely to be the unit itself. Chances are, there's a problem with the install (incorrect adjustments, too little clearance, etc.) making it noisy. Exactly what does it sound like? That might give a hint about the actual problem.

    If nothing else, put soundproofing material in the wall next to the condenser!

  4. #4

    reply to smngmu

    First time on a forum of any kind so hope I am replying correctly!

    I have an excellent HVAC contractor which I have used for years. They contacted Carrier last time and will be there when Carrier's residential rep. comes out. Everyone agrees that the unit is loud but no one knows why.

    The sound is a very loud hum.

    The fan and fan motor were replaced on the original unit, to no avail so the first unit was replaced... this unit is described in the literature as sounding as loud as a dishwasher or refrigerator (7.2 BELS) but is much louder. The smaller unit of the same type (Model 38TDB) in the same location is very quiet.

  5. #5
    To Star 882

    The sound is a very loud hum.

    The HVAC contractor has looked over the installation, (experienced repair person checked installer's work). And, there is nothing obviously wrong. They do say something about "harmonics" but don't have a solution.

    This unit is on a plastic pad, on a cement pad in my yard next to our brick house. The site is in a corner where the garage is slightly narrower than the house creating space for the A/C units without having them stick out from the building.

  6. #6

    Re: reply to smngmu

    Originally posted by monicacox
    First time on a forum of any kind so hope I am replying correctly!

    I have an excellent HVAC contractor which I have used for years. They contacted Carrier last time and will be there when Carrier's residential rep. comes out. Everyone agrees that the unit is loud but no one knows why.

    The sound is a very loud hum.
    Exactly where is it coming from?

  7. #7
    Join Date
    Jan 2005
    Posts
    123
    Try having your contractor put a sound blanket on the compressor, the unit on cork or rubber 2 inch pads, and a vibration elimanator on the discharge line. That's only if it's the unit itself. But I have heard a lot of large hums coming from the compressor contactor because of too small gauge wiring and low voltage to the outside unit.
    It's better to have people think you're an idiot, than to open your mouth and prove them right.

  8. #8
    Join Date
    Aug 2005
    Posts
    93
    I have the 36 unit.

    I had an old Bryant unit and it was noisy, definitely could hear it from inside the house.

    I think Carrier (and some pros) overstate the quietness of the infinity system. The brochure I got from Carrier listed a sound rating of 69dBA and then used a chart showing it as quiet as your refrigerator - or a small table top fan. Well the 69 dBA is okay – but don’t try to compare it to my newer refrigerator!

    When my unit was finally operating properly I was disappointed about the noise. It is quieter than my old AC unit for sure – but it not super quiet. I can tell it is running outside my bedroom window(low hum). Again - it is less noisey than the old AC unit I had - and I am happy about that - but it is still very noticable.

    I spent some time investigating the noise issue. I got hold of a sound meter and some literature (ARI 275-97) which is used by the HVAC industry to discuss sound ratings of outdoor units – and how that noise rating given in brochures is affected by differrent placements (next to a wall, under an overhang, distance, etc.... )

    Sure enough my Infinity unit metered out at 69dbA, but consumers should not think this is whisper quiet – or you won’t know it's on if it is outside your bedroom window - it is merely quiet(er) for an outdoor AC unit.

    [Edited by bertrand on 06-20-2006 at 10:26 AM]

  9. #9
    Join Date
    Mar 2006
    Posts
    92
    Bertrand, I just had the new 2006 version (24ANA7) of the 38TDB036 installed and I can tell you it is WHISPER QUIET! My neighbor has a carrier 3 ton unit and it is so loud that I can hear there unit from iside my house.

    You can't hear the 24ANA7-36 from inside the house, the installer who did it normally installs trane, when he fired this unit up he couldn't believe how quiet it was. Not sure what technology they're using this year but it works.

  10. #10
    Join Date
    Aug 2005
    Posts
    93
    The sound rating per ARI standards has not changed on the 2006 models vs 2005 as far as I can tell - it is still in the 69 to 70dbA rating.








  11. #11
    The hum sound seems to come from the top or center of the unit. At first it was thought that it was the fan but the fan and motor were replaced and the sound is still there.

  12. #12
    Join Date
    Mar 2006
    Location
    tex
    Posts
    477
    have the tech disconnect the fan for a minute, see if it stops , also when the fan is off the compressor will load up some , and you will be able to see the difference, then disconnect the compressor and see if it stops . i have many 38YDB out and most all are very quite. the contactors can make a loud noise like bbk stated

  13. #13
    Join Date
    Apr 2004
    Posts
    7,680
    Are the refrigerant lines installed within the specs on the installation instructions? (What size, how long, how much vertical seperation?) Refrigerant returning to the compressor in liquid form can cause the compressor to be noisy, too little (high superheat) will also cause noisy refrigerant. Airflow configurations for the indoor unit can have an effect on refrigerant flow outside. The unit needs to be 12" minimum from the home and 24" from the other unit.

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