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  1. #1
    Join Date
    Oct 2005
    Posts
    96
    If a contractor is charging a heat pump in 40 degree weather is it true that he cannot get a sufficient charge on it to meet my summer high temp conditions? I know this was the case in the old compressors but wasn't sure if this was still the case. If I have a contractor install a heat pump in this weather do I need to have him come back and check the refrigerant charge when the temperature warms up?

  2. #2
    Join Date
    Apr 2004
    Posts
    7,680
    No, he can weigh it in. In other words he can calculate the amount of refrigerant needed and charge the system by the required weight.

  3. #3
    Join Date
    Oct 2005
    Posts
    96
    Is this true with either R-410 or R-22? I assume it doesn't matter? When you say weigh it in what does that mean?

  4. #4
    Join Date
    Mar 2004
    Location
    Grottoes VA
    Posts
    5,856
    Use a scale, calculate the requried oz.'s needed for system and open valve. Shut valve off when scale reaches required number.
    Karst means cave. So, I search for caves.

  5. #5
    Join Date
    Apr 2004
    Posts
    7,680
    Really, it depends on the unit, some units allow charging at lower temps. You really need to consult the unit charging procedures (which only apply to a properly installed system).

  6. #6
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    Yes you can weigh in a charge in cool weather, but you should always have it checked during a hot day for proper charge. The weight a manufacturor specs is for up to "15-25ft" lineset, so charge can be off a little with the weigh in method. Always best to use subcool/superheat per manu's specs in cool mode IMO.
    If everything was always done "by the book"....the book would never change.

  7. #7
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,963
    Heat pumps can also be adequetly charged in cold weather using the hot gas discharge method. It is a bit of a pain, but quite accurate.
    Government is a disease...
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  8. #8
    Originally posted by RoBoTeq
    Heat pumps can also be adequetly charged in cold weather using the hot gas discharge method. It is a bit of a pain, but quite accurate.
    Never even heard of such a method. Please enlighten me sir.

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