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  1. #1
    Join Date
    Mar 2004
    Location
    Missouri
    Posts
    10

    charging heat pump in heat mode

    hey all im fairly new into the industry and been seeking the answer to this question and have been unable to come up with it.

    What is the proper charge rules for a heat pump operating in heat mode? How do you go about charging in heat mode if the unit is low?
    -brian

  2. #2
    Join Date
    Sep 2004
    Location
    Portage
    Posts
    909
    Most will have the procedure on the control access panel.
    I don’t always drink beer, but when I do I prefer Dos-Equis. I am the most interesting man in the world. Stay thirsty my friends.

  3. #3
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,405
    There really is no correct answer for how to charge a heat pump in heat mode. In the panel they might have a "getcha close guide", but it won't be dead on. You will have to come back in the summer to get it perfect.
    "If you call that hard work, a koala’s life would look heroic."

    VETO PRO PAC, The Official Tool Bag of HVAC-Talk.com

    Testo... you guys rule!

  4. #4
    Join Date
    Jan 2008
    Location
    michigan
    Posts
    1,145

    Wink

    Ya wanna do it right? Recover, find and repair leak, evacuate, weigh in charge!

  5. #5
    Join Date
    Feb 2005
    Location
    Miami, Fl.
    Posts
    3,559
    And,

    Why is the OP asking this in an open forum, and not even a pro member? Didn't you read the rules of the site?

  6. #6
    Join Date
    Mar 2004
    Location
    Missouri
    Posts
    10

    i cant ask a question?

    I read the rules didnt seem to far off from the ability to seek advice in the forum from the rules i read.

    Quote Originally Posted by arpa View Post
    And,

    Why is the OP asking this in an open forum, and not even a pro member? Didn't you read the rules of the site?

  7. #7
    Join Date
    Feb 2005
    Location
    Miami, Fl.
    Posts
    3,559
    Quote Originally Posted by kc0ovt View Post
    I read the rules didnt seem to far off from the ability to seek advice in the forum from the rules i read.
    Hmm..

    Feel free to ask any question relating to HVAC, or other topics of general interest except DIY.

    2. Do-It-Yourselfers - not here.

    This site is for industry professionals and folks seeking HVAC/R advice and knowledge. Please do not ask for step by step instructions on purchasing, installing or repairing your own HVAC equipment, that is our job and our livelihood. We are generous, but not to a fault.

  8. #8
    Quote Originally Posted by amickracing View Post
    There really is no correct answer for how to charge a heat pump in heat mode. In the panel they might have a "getcha close guide", but it won't be dead on. You will have to come back in the summer to get it perfect.
    I think you have that backwards. A system can tolerate a over charge in cooling but it won't in heating. I would rather charge in the heating mode. I put a thermometer under the insulation and slowly add freon and watch the temp rise while also adhering to the charging chart on the unit. You better just about be dead on with these new high seer units with no accumulator.

  9. #9
    Join Date
    Feb 2005
    Location
    Miami, Fl.
    Posts
    3,559
    If you are in the industry, get your required number of posts and apply for the pro forum.

    In the pro tech forum, you won't even have to ask this question, as it is explained.

  10. #10
    Join Date
    Apr 2002
    Location
    Omaha, NE
    Posts
    1,561
    Quote Originally Posted by Johnny Law View Post
    .................................................. ...............................
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    You better just about be dead on with these new high seer units with no accumulator.
    I was under the impression that all heat pumps have accumulators. Which manufacturers are not designing one into their units?

  11. #11
    Quote Originally Posted by snewman24 View Post
    I was under the impression that all heat pumps have accumulators. Which manufacturers are not designing one into their units?
    For years some Lennox units didn't and may still don't and new Rheem units don't have them

  12. #12
    Join Date
    Apr 2004
    Posts
    7,680
    Accumulators were required when pistons are used. They were the last protection from sending liquid back to the compressor. With TXV's you control the superheat and will not be sending liquid back. With pistons, the mfg had to do something to protect compressors from overcharge. The vast majority of systems out there are overcharged and with a piston system, that means slugging. If a little is good, then a lot must be better attitude.

    Accumulators as we know also carry liabilities in oil return and rust. Since there is no real advantage to having one on a TXV system, why take on the liabilities?

    Accumulators were the sole reason you could not accurately charge a HP in the cold winter months because as a tech, you could not know how much liquid was sitting in the accumulator. It had nothing to do with charge balance. That is the role of a reciever or charge compensator. The accumulator is not a storage tank. Its a place for liquid to boil off before entering the compressor.

  13. #13
    Join Date
    May 2004
    Location
    Rapid City, SD
    Posts
    7,405
    Quote Originally Posted by Johnny Law View Post
    I think you have that backwards. A system can tolerate a over charge in cooling but it won't in heating. I would rather charge in the heating mode. I put a thermometer under the insulation and slowly add freon and watch the temp rise while also adhering to the charging chart on the unit. You better just about be dead on with these new high seer units with no accumulator.
    Every unit I've worked on has said on that paper to charge in cooling mode. I know you can charge it in heating mode, but I've never seen or heard of a 100% sure fire way to get it right on.... like you can in cooling.

    But, before this gets too in depth we should likely wait to finish this debate off in the pro forum vs here.
    "If you call that hard work, a koala’s life would look heroic."

    VETO PRO PAC, The Official Tool Bag of HVAC-Talk.com

    Testo... you guys rule!

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