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  1. #1
    Gene South's Avatar
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    Default Size matching of evaporator and condenser

    During a recent inspection of a 1980's home that had a new HVAC system installed, I noticed the new condenser was labled as 3.5 tons and the new evaporator was labled as 4 tons. Both were Lennox units and the condenser was configured as a heat pump. The system appear to be functoning fine. Do any of you see this often when the evaporator and condenser are not size-matched? I am not even sure this is a problem or not, that is why I am asking.

    PS, I know some might say this goes beyond the scope of a general inspection, etc, etc, however I am still curious about it.

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  2. #2
    Rod Butler's Avatar
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    Default Re: Size matching of evaporator and condenser

    Gene, I may be a little old school but that used to be routine when selecting AC equipment. Slightly over sizing the evaporator gave a bit better performance, a way to bridge the gap in equipment sizes.

    Of course if it were the other way around you would have a problem with freezing the coil.

    How were you able to determine the size of the coil?


  3. #3
    Bob Spermo's Avatar
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    Default Re: Size matching of evaporator and condenser

    Probably OK for the coil to be a 1/2 ton larger. However, I would be very careful about commenting on compatability between the condenser and the evaporator coil unless I had researched what the manuafacturers' said. The only way to assure compatability in by using the manuafcaturers' data sheets.


  4. #4
    Vern Heiler's Avatar
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    Default Re: Size matching of evaporator and condenser

    Gene, as others have said, it is not uncommon to have size difference but needs to be acceptable configuration by mfg. specs.

    When referring to a heat-pump, it is better to use "indoor unit" and "outdoor unit" as they are both condenser and evaporator.

    The beatings will continue until morale has improved. mgt.

  5. #5
    Gene South's Avatar
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    Default Re: Size matching of evaporator and condenser

    Hi Rob, Vern, and Bob. Thanks for the good input and it is consistent with what I guessed. I do understand that on a heat pump system the term condenser and evaporator can be used for either unit, but I did not put that in the post because I figured everyone would know what I meant and I wanted to stay "on-topic". You know on this forum,.... at any moment,.... a topic can spin off into another whole discussion about heat pumps or some other topic. HA. But to clarify your questions, the "indoor" unit was 4 ton and the outside unit was 3.5 ton. I decoded the model number to make that determination, to the best of my humble ability.

    Gene


  6. #6
    David Bell's Avatar
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    Default Re: Size matching of evaporator and condenser

    Larger evap coils are often the only way to reach intended SEER ratings. It is recommended by every manufacturer I have dealt with so far because it keeps thier equipment efficiencies where the government wants to see them.

    Last edited by David Bell; 10-30-2011 at 05:52 PM.
    Common sense seems to be less common.

  7. #7
    Bill Hetner's Avatar
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    Default Re: Size matching of evaporator and condenser

    is there any postings at the site as to who did the install? you could call them or ask some hvac installers in the area what they think too. they would know more about it, also it might have been a case of what they had in stock and wanted to move out too. what matters most is does it work and does it work good enought to do the job right for the house.


  8. #8
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    Default Re: Size matching of evaporator and condenser

    David's answer matches what I was told when I purchased new equipment for my home. Better SEER and better dehumidification.

    "the relentless pursuit of perfection"

  9. #9
    Sal Castro's Avatar
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    Default Re: Size matching of evaporator and condenser

    A problem we recently found was a builder/contractor who tried to mix a new R-417a condenser and an older R-22 air handler. That needs to be monitored as well.


  10. #10
    David Bell's Avatar
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    Default Re: Size matching of evaporator and condenser

    Quote Originally Posted by Sal Castro View Post
    A problem we recently found was a builder/contractor who tried to mix a new R-417a condenser and an older R-22 air handler. That needs to be monitored as well.
    Most 410-A units can be interchanged with r-22 coils with a txv change. A flush of the system is required to remove any oil that is not compatible.

    Common sense seems to be less common.

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