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  1. #1
    gcroe Guest
    Hey Folks,

    I have a Goodman 13 SEER HP with a varible speed air handler,
    The evap has a TXV. During heat mode what is the best way to charge the system. Th mfg instructions recommend hot gas charging ( outdoor ambient + 124 deg) however it doesn't designate this method for TXV. On fixed bored I have always followed this procedure. (OA + 115) on 10 and 12 SEER. But just wondered if subcooling should be used with TXV? Thanks for the help. BTW the reason for the question is when charged under hot gas method the actual suction seemed quite low given a 44 degree OA. Maybe just had brain lock since it was Saturday and I was 275 miles from home trying to help a friend.

    Thank You for your help.
    Glen

    Edit: No email addreses in posts. Put it in your profile biography.

    [Edited by Mod01 on 01-08-2006 at 03:48 PM]

  2. #2
    Join Date
    Mar 2005
    Location
    Suppy NC
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    4,513
    hot gas will work with both
    you can also go 110 over on the suction line

  3. #3
    110 degrees + OAT @ the hot gas service valve

  4. #4
    Join Date
    May 2005
    Location
    Seabeck, WA
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    1,870
    Subcooling is the prefered method. 10-14 degrees.
    Live for yourself and ask no one to live for you.

  5. #5
    Join Date
    Nov 2002
    Location
    southwest virginia
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    150
    the txv is not in the circuit in heahing goodman m# CPLT or CPKT 13 SEER has flowrater in out door unit installation manuel states 126+ambiet 6in from comp discharg

  6. #6
    Join Date
    Nov 2002
    Location
    Boiling Springs, SC
    Posts
    130
    would it not be better to recover the charge, pull a vaccum then weigh the charge in?

  7. #7
    Join Date
    Nov 2000
    Location
    Upstate, SC
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    2,919
    Maybe, but depends on what you mean by better. The discharge line temp method will get you very close if you are careful about making your temp measurement and have a good set of gauges. The weight method will get you very close if you take the time to carefully measure the lineset and know exactly how to calculate the charge needed, but it takes longer and costs more to the customer. I would only go to the time and expense to pull the charge, evacuate, and weigh it back in on problem systems, but that is just me.

    Bobby

  8. #8
    Join Date
    Nov 2000
    Location
    Eastern PA
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    68,943
    Originally posted by inturmoil
    Subcooling is the prefered method. 10-14 degrees.
    Not in heat mode. Discharge temperature is the way to go.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  9. #9
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,943
    Originally posted by fixer
    would it not be better to recover the charge, pull a vaccum then weigh the charge in?
    This would be fine if you know exactly what the capacity of the indoor coil is and the exact line size and length and feel like pumping down the system and recharging it.

    But the best method is the discharge temperature method.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  10. #10
    Join Date
    Jan 2006
    Location
    Hamilton Ontario Canada
    Posts
    1,406
    I was out on a GSH14 heatpump today and the owners book on the last page had the hot gas method in detail. I just got home and checked the Goodman site and can't seem to find it. Does someone have that information that I can get a copy of.

  11. #11
    Join Date
    Jul 2007
    Location
    Virginia
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    5,515
    Quote Originally Posted by ptemko View Post
    Does someone have that information that I can get a copy of.
    Is this what you want? See Attachment Page 21
    Attached Images Attached Images
    Instead of learning the tricks of the trade, learn the trade.

  12. #12
    Join Date
    Jan 2006
    Location
    Hamilton Ontario Canada
    Posts
    1,406
    Thats even better than I wanted thanks for the file. Page 21 and 22 are just what I was looking for.

  13. #13
    Join Date
    Apr 2009
    Posts
    523
    Quote Originally Posted by RoBoTeq View Post
    Not in heat mode. Discharge temperature is the way to go.
    Basing this off Goodman or in general? Some manufactures have very specific subcooling specs in HEAT MODE. Lennox for example on the schematic list outdoor unit, indoor air handler or cooling (heat pump or dual fuel) once you match those it list the additional requirement to charge and subcooling in cooling AND heat modes...

    http://www.cooperheatingandcooling.c...stallation.pdf

    Page 19 is the chart you will find on the unit itself. Anyway +/-5 degree is more then the typical +/-1 degree with cooling subcooling value but I would still think it has to be more accurate then XXX + ambient = arewestillworkingwithr12 or whatever...

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