Page 1 of 3 123 LastLast
Results 1 to 13 of 32
  1. #1
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632
    Hello Again,

    I am just cornfused. Today I installed a home A/C unit and was performing subcooling and these are the numbers I got.

    Out @ Cond. 85 Dry
    In @ Return 55 Wet
    Suc line temp 64
    Lo 68 PSI
    High 190 PSI

    T-Stat reads 74

    We installed a 3 TON system in a 1080 sq/ft split ranch.
    ***Now B4 you jump, I am a lowly install "tech" who is installing someone elses guestimate. My shirt is of a different color***

    Now back to my cornfusion. I was with another chap who did the nitro, vac and charge. He leaves and I finish upstaris and go to check out the charge. According to my subcooling calculator it tells me to run away. Seriously, all that is in the little window is a "-" and the side note tells me not to charge as it will cause slugging. The return line 'beer can cold at the king pin. What does my measurements mean? Aside from the oversized unit, bad blagh blagh blagh.

    This also peaques curiousity as to how much cooling the house actually needs. So I B.S. the customer and measure the house, walls, windows, doors and orient the house for NSEW. This is what I came up with and let me know if I am close.

    Design TD Cooling 20 Degrees Heat 70 Degrees

    Windows 8732 BTU's 7552 BTU's
    Doors 2106 BTU's 2965 BTU's
    Walls 1860.1 BTU's 4797.1 BTU's
    Ceiling &
    Floors 446.4 BTU's 1051.2 BTU's
    InFiltration &
    Ventilation 168.96 BTU's 591.36 BTU's
    Internal/
    Duct Gain 3245.336 BTU's 1215.956 BTU's
    Laten 690 BTU's
    Relative Humidity 55 %

    Total 17248.796 BTU's / 1.4373997 Tons Heat 18172.616 BTU's

    My last question. Am I on the right track or am I just being to concerned? Also, if there is any more info that I can give you to help make a better informed decision, let me know.

    Ok. I forgot the walls. I plugged them in and now we are correct.

    [Edited by atufano on 04-19-2005 at 09:09 PM]

  2. #2
    Join Date
    Apr 2004
    Location
    Niantic, Illinois
    Posts
    545
    Do you have a TXV?

  3. #3
    Since when doesn't the walls have an affect on the load calc??????????

    Someone made a Boo Boo....

  4. #4
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632

    Sub-Cool

    Originally posted by berad
    Do you have a TXV?
    Nope.. That is why I did subcooling and not superheat. Unless I have them backwards.

  5. #5
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632

    Band-Aid

    Originally posted by jultzya
    Since when doesn't the walls have an affect on the load calc??????????

    Someone made a Boo Boo....
    Re-Check, I added the walls.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,171
    The LL temp can't be less then the outdoor temp, unless you have extreme flash, or a restriction, which has nothing to do with over sizing.

    And I'd like to know also, how the walls have no gain or loss.

    I want some of those magic walls.LOL...


    You use superheat for a fixed metering device, and subcool for a txv.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,513
    you need to do super heat with an orfice
    did you install the orfice that came with the condenser very important to match with the correct orfice

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,171
    I think your light on your heat, but you didn't post outdoor design temp, or insulation values.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Apr 2004
    Posts
    7,680
    Beenthere is right, it is impossible for your liquid line to be below outdoor ambient (cooling mode) unless you have a restriction in the condesner or liquid line prior to your measurement. Find the temperature drop.

    Hopefully the "wacky readings" didnt lead you to a load calc.

  10. #10
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632
    Originally posted by tinknocker service tech
    you need to do super heat with an orfice
    did you install the orfice that came with the condenser very important to match with the correct orfice
    They gave us a 'matched' set for con and evap. So we are using the factory installed orifice.

  11. #11
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632
    Originally posted by beenthere
    I think your light on your heat, but you didn't post outdoor design temp, or insulation values.
    Don't know anything about out door design temp, and the program didn't ask. As for the insulation value,

    The walls are R-13, 3 1/2 and the floors and ceiling is R-19, 6".

  12. #12
    Join Date
    Jul 2004
    Location
    Poughkeepsie, Ny
    Posts
    632
    Originally posted by docholiday
    Beenthere is right, it is impossible for your liquid line to be below outdoor ambient (cooling mode) unless you have a restriction in the condesner or liquid line prior to your measurement. Find the temperature drop.

    Hopefully the "wacky readings" didnt lead you to a load calc.
    The reason that I am doing a load calc is for my own benefit. It wasn't done to begin with. I wanted to see how the 'years of experiance' compared to math. I don't understand about the liquid line being below the outdoor temp.

  13. #13
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,171
    You can't do the math, if you don't know how cold the outdoor design temp is, plus wind.

    Are you sure youo read 64, on the LL temp.
    The reading can't be right, if the OD is 85.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event