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  1. #1
    Join Date
    Sep 2004
    Posts
    116
    I had a discussion recently w/ a tech. guy from a local supplier about charging new installs. We always weigh-in are charges (units comes w/ enough refrigerant for 15' of liquid line, over that ,add .6 oz. for every 1' of liquid line ) he liked the superheat/subcool methods. To me, weigh-ins are fool proof ( if ya got a accurate scale ), and faster. Why do s.h. or subcool when your startin fresh.any thoughts??

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,619
    I don't trust the factory to have the base charge right


  3. #3
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    Weighing in the charge is best for self-contained systems where you actually know the correct charge. Superheat and subcooling for all others.

  4. #4
    Join Date
    Oct 2004
    Posts
    3,400
    Also, if there is a flow issue, like wrong orifice, fan speeds, etc, you can catch it.

  5. #5
    Join Date
    Sep 2004
    Posts
    116
    Loonie,I can understand the factory charge being off. I think.
    bwal2,how does fan speed determine charge?? alot of are new units are variable speed, and TXV.

  6. #6
    Join Date
    Oct 2004
    Posts
    3,400
    Originally posted by hvac64
    Loonie,I can understand the factory charge being off. I think.
    bwal2,how does fan speed determine charge?? alot of are new units are variable speed, and TXV.
    And a lot of them are not.

    Would heat load have any bearing on charge?

    If you have inadequate airflow, superheat will be low, even with a perfect factory charge.

    That includes packaged units hooked up to a tiny filter grill.

    Without airflow, you don't have heat to evaporate your refrigerant.

  7. #7
    Join Date
    May 2004
    Location
    Austin, TX
    Posts
    1,744
    You normally weigh in charges on small appliances,
    and car/truck air conditioners. You have to weigh
    in charges when it is cold, no other way to reliably
    charge properly when cold. Split a/c systems are
    difficult to weigh in because you do not know how
    long the lineset is, and the data plate is seldom
    correct.

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