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  1. #1
    Join Date
    May 2006
    Posts
    27
    A customer (possibly an escaped mental patient) doesn't think his newly installed compressor has the mounting bolts correctly torqued ??????
    Other than being SNUG, has anyone ever heard of a "correct torqueness? (not me)
    Carrier 10 seer 38CKC (regular residential condenser)

    He's an engineer & asks 2-300 useless questions a year!
    Thanks

  2. #2
    Join Date
    Dec 2005
    Posts
    783
    Most of the bolts on tin can compressors are self limiting shoulder type. They will not let the rubber mount get to tight by the nature of the bolt. The bolts do nothing but prevent the compressor from flying out of the unit when his wife hits it with her car. LOL

  3. #3
    Join Date
    Dec 2005
    Location
    Cleveland, OH
    Posts
    2,212
    Technically, there is a recommended torque setting for the mounting bolts which varies by manufacturer. Most bolts now have a stop on them that "sets" the torque for you so you can't crank it gorilla tight.

    Depending on the brand of compressor, you can call the wholesaler and get the torque setting. To be honest, I can't ever recall someone using a torque wrench on a resi unit. I have seen it done on large commercial units where torque was actually important.

    Good? Bad? I'm the guy with the gun.

  4. #4
    Not very critical for small units. A tight fit should do just fine.

    Maybe he's thinks that bolts in smaller units have to be tighthened using proper torque as commercial ones.

    Commercial ones will specify the torque values depending on gasket type, flange rating, flange size, and thread lubricant used.

    Not practical for small units.

  5. #5
    Join Date
    May 2006
    Location
    Warren, MI
    Posts
    910
    Originally posted by dougfamous
    Technically, there is a recommended torque setting for the mounting bolts which varies by manufacturer. Most bolts now have a stop on them that "sets" the torque for you so you can't crank it gorilla tight.

    Depending on the brand of compressor, you can call the wholesaler and get the torque setting. To be honest, I can't ever recall someone using a torque wrench on a resi unit. I have seen it done on large commercial units where torque was actually important.

    I'm a machine repairman in the auto industry and have never seen a torque sensing bolt or ever heard of one. That's not saying that there isn't but on a compressor mount, I doubt it. You may have a shoulder bolt like was mentioned used with a rubber cushion like a shock mount, so you don't want squeeze too much on it. Any fastner can be broken if enough torque is put on it. Removing broken bolts is interesting at times!
    Bill

  6. #6
    Join Date
    Dec 2005
    Posts
    783
    Actually the small compressors have a metal sleeve that fits down in the rubber motor mount hole. Once the washers on the bolt hits the metal you got it tight enough.

  7. #7
    Join Date
    May 2006
    Location
    Warren, MI
    Posts
    910
    Originally posted by hvac1000
    Actually the small compressors have a metal sleeve that fits down in the rubber motor mount hole. Once the washers on the bolt hits the metal you got it tight enough.
    That's just like using a shoulder or stripper bolt. Sometimes a concave spring washer is used also to provide some tension.
    Bill

  8. #8
    Join Date
    Jan 2006
    Posts
    1,120
    I always put em back about handtight so when it needs changed again its easier.
    There are three signs of old age.
    The first is your loss of memory,
    the other two I forget.


  9. #9
    Join Date
    Jan 2002
    Posts
    125
    Get the guy a manual and let him tell you.lol
    Don't love them o'll timers......we don't have the time they had in the day to do tasks. Some bolts need to be torqued and some don't......this one don't!
    Do it right the 1st. time!

  10. #10
    Join Date
    Dec 2005
    Posts
    783
    All compressors have mounting legs and grommets where the mounting bolts secure them firmly to the base of the condensing unit. This keeps them floating on the rubber of the grommets for quiet operation and also will prevent them from moving within the condenser and damaging anything else.

    Compressors used in air-conditioning and heat pump systems are typically mounted to an associated base plate through a vibration isolating mounting assembly. A typical vibration isolating mounting assembly includes elastomeric grommets disposed at the base of the compressor. These elastomeric grommets may act as feet for the compressor, maintaining the compressor above the base plate. The grommets support the weight of the compressor from its bottom and are spaced to prevent tipping. Further, the grommets vibrationally and acoustically isolate the compressor from the base plate. In such a mounting arrangement, resonance frequencies of the compressor may be inherently high and may tend to fall within the proximity of the compressor speed, thereby causing vibration and noise problems.

    Compressor mounting must be selected by application, with special consideration given to sound reduction and tubing reliability.

  11. #11
    Join Date
    Dec 2005
    Posts
    20
    I don't know if there is a torque requirement for the compressor mounting bolts, but if there is, I imagine it would exist to prevent under-torqued bolts from becoming loose due to vibration or over-torqued bolts from being stripped out or broken.

  12. #12
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    On a sorta-related note, what is "finger tight" anyway? You see a lot of torque specifications that basically say "1/8 turn past finger tight" or something like that. Thing is, my "finger tight" can be a good 1/2 to 1 turn less than the "finger tight" of some other people. That's a pretty wide range..

    And as for self-limiting torque bolts.. I thought that was what nylon bolts were for? When it shatters, that was too tight, try again..

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