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  1. #1
    Join Date
    Jun 2007
    Posts
    72

    New 10SEER condenser with existing 8SEER Coil?

    Any problem installing new 10SEER 5 ton condenser with existing 8SEER Evap coil? Thanks.

  2. #2
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,841

    10 SEER? From Where?

    I can't imagine anyone having a new 10-SEER unit still in inventory. What I can tell you is that if it's an AC only unit, it will work but the SEER rating actually achieved will probably somewhere in the 8.5 area. A new evap coil is highly recommended. However if the unit is a heat pump, I wouldn't do it without replacing the indoor coil. An R-22 heat pump with an undersized coil will blow the high side pressure up over 500 PSIG when you switch to heating and the internal pressure valve will open in the compressor. Simply put it probably won't work on a heat pump.

  3. #3
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Add a txv. It should dehumidify well. Seer rating is tossed out the window, but if you're in an area with inexpensive electric and a cooler climate, why not use it. This isn't saying I don't prefer a new matched system.....
    If everything was always done "by the book"....the book would never change.

  4. #4
    Join Date
    Jun 2007
    Posts
    72
    Why add TXV? Thanks

  5. #5
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Quote Originally Posted by vrocrider View Post
    Why add TXV? Thanks

    With a mis-matched system, this controls the system's superheat, and adjusts according to the load on the coil, running more effeciently while preventing floodback to your compressor(slugging).
    If everything was always done "by the book"....the book would never change.

  6. #6
    Join Date
    Jun 2007
    Posts
    72
    Thanks. This is installed at and outside the coil? Rough cost for part for 5T?

  7. #7
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Quote Originally Posted by vrocrider View Post
    Thanks. This is installed at and outside the coil? Rough cost for part for 5T?
    They can be installed inside the cabinet or outside the cabinet. Due to rules, can't help you with cost, your A/C man can tell you.
    If everything was always done "by the book"....the book would never change.

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