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  1. #1
    Join Date
    Dec 2004
    Location
    Pensacola, Florida
    Posts
    304
    I have a 20 year old Amana heat pump. The condensing unit is stamped with 84 oz of R22. The A/H is stamped with 42 oz of R22.

    Is the correct charge 84 + 42 = 126oz. + pipe length over 15 ft?

    Or is it 84 oz + pipe length over 15 feet?

    Torch Man

  2. #2
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,536
    does it have quick connects??i would think 84....what's your superheat,sub-cooling?then again you may be on right track....what are you adding per foot over 15 if you don't mind me asking....a 1/4 ounce?what tonnage is unit?

  3. #3
    Split systems are not factory charged, they are guessed at and usually on the low side for a short run of pipe. You need to charge it properly on start-up.

  4. #4
    Join Date
    Dec 2004
    Location
    Pensacola, Florida
    Posts
    304
    This a rental property that I just bought. The I/D coil is clogged with dust. I am planning to recover, cut out coil, foam, then replace and charge.

    The coil is so clogged I haven't bothered taking a superheat calculation yet. The unit does have quick connects, but it does NOT have valves so I have to recover. If I recover the refrigeant then I might as well charge by weight. I usually add .6 oz of freon for each foot of 3/8" liquid line over 15'.

    I don't ever remember seeing an A/H with the R22 charge stamped on it. Remember this is a 20 year old system. comments?

    Torch Man

  5. #5
    Sounds like were going to mismatch coils with condensers which is fine just forget what he tag says you need to know what type of metering device. If it is a TXV then charge by subcooling if it is a piston or fixed orifice then charge by superheat the old one may have been a cap tube, don't worry the new one won't be.I wouldn't try to calculate the efrigerant chatge by weight but after you get it charged correctly you can write the correct weight down for the next time or next person.

  6. #6
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,536
    mod.&ser. #'s..???what tonnage is it????how much air you moving....didn't they use to have pre-charged line-sets???there is a difference between 3-5 ton.....on new factory charged units.all's i can say is get to it....first put in the lesser of 2 amounts....take readings...if that don't get you where you need to be then you will know that it is the sum of the 2...slowly add more to it until you are where you think your readings should be...all the while weighing your charge.this unit is 20 years old....it would be hard to say.....without tonnage.

  7. #7
    Join Date
    Feb 2004
    Location
    southern illinois
    Posts
    5,536
    or you could weigh how much you recover..........that might give you idea.GOOD-LUCK...

  8. #8
    Join Date
    Sep 2002
    Location
    South Dakota
    Posts
    6,579


    We have the blind leading the blind here on this post as well as many other posts. When will you guys learn some applied theory and become real technicians?

    Go to the "For Your Interest" area on the main page and there you will find a series of articles on both the theory behind and the practical application of properly charging systems.


  9. #9
    Join Date
    Apr 2004
    Posts
    7,680
    Aww c'mon Norm, its obvious to me, I think the thingamajiggy needs to be circumvented by the whatchamacallit.

  10. #10
    Join Date
    Jan 2005
    Location
    daytona florida
    Posts
    76
    well i'd just like to say if you charge a system and your pressures sub-cooling superheat are at the correct numbers for the seer system you are working on you'll do just fine

  11. #11
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,790
    What brand is the unit.

    Mo Flo gave you a good answer.
    You just have to remmember that if you remove 30LBS. from a 2 ton system, with 25' line set, you had a gas and go tech servicing that unit, so don't put 30lbs. back in.

    Or you could start with the condensers 84ozs, and then adjust charge by superheat/or subcool as per your metering device.
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  12. #12
    Join Date
    Dec 2004
    Location
    Pensacola, Florida
    Posts
    304
    The system is an Amana, 2 ton heat pump with a 25' line.

    Torch Man

  13. #13
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,790
    Didn't know Amana used precharged line sets and coils back then.
    They were common on Thermopride, GE, and Trane units in the early 80s. Still see them on mobile home units.

    They kept techs from over charging new installs.

    Weigh what you recover as Mo Flo said, but you might want to start out with the condensers charge and the do your fine tuning as i said above.
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