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  1. #27
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Hamons,

    Where are the supply grilles located??

    If in the floor also,you ahve an air flow problem,that's why the temp is 73 at returns and higher at the stat.Floor grilees need to have supply air felt at a minumum of 6' off the floor,IMHO.

  2. #28
    Join Date
    Jan 2005
    Posts
    159
    Quote:
    Outdoor temp: 90
    Indoor temp: 82
    drop accross coil: Not measured
    System running for 20min
    suction line: 75
    Liquid line: 150
    _______________________________
    These numbers sound odd, becuase I had *NO* a/c at all in the house for the entire summer, before it was installed. When they fired it up for the first time, it was boiling inside the house, and it was 90 outside. Isn't 150 on the liquid line a little low, given that it was 90 outside?

    Then, many days later, under normal cooling conditions, I measured the Delta, and the air was 75-76 entering the return, and ~61 coming out of the floor.


  3. #29
    Join Date
    Oct 2005
    Posts
    45
    Yes supplys and return are all floor mounted. Thats how almost every house here built -- pre 80's was built. I agree -- not ideal -- but will work.

    He did measure the floor space and said it was around 1400 ft2 and that 2.5 tons should be plenty big. Not atrue Manual J though I know. When I mentioned that he said they never do that except for commercial applications. I told him that if the TXV did not solve the problem i insisted a manual J be done.

    Current theory is that it is a bad TXV and they are going to come change that out on Wednesday. I'll keep you guys a breast.

    108 forecasted here for Sunday -- sheesh!


    No typo on numbers -- although I may have used wrong terminology. When he measured the temp of the right before it gets to the coil - -that was 73 when house is 77 - 81 depending on what room you are in.


  4. #30
    Join Date
    May 2006
    Posts
    230
    Originally posted by hamons
    He did measure the floor space and said it was around 1400 ft2 and that 2.5 tons should be plenty big. Not atrue Manual J though I know. When I mentioned that he said they never do that except for commercial applications. I told him that if the TXV did not solve the problem i insisted a manual J be done.
    They are guessing at the problem and guessing at the solution. Good luck.

  5. #31
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    House > 77° and return is 73°F.Part of the problem is the supply air from the floor grilles is not getting high enough in the room to "mix" properly .


    Look at it this way,if the floor air is 73 and the stat is say 77 then ,near the ceiling may be 81,if "mixed " properly the temperature would be 77°F ,floor to ceiling ,so to speak.

    We have seen this problem many times with this type of floor supply and return.The cause is lack of air flow.It could be on the wrong fan speed,something in the duct work they did,or they selected a model that doesn't have the fan capability that you duct system needs.

    hamons ,Did you check to see how high you can feel the supply air blowing??

    There may well be other problems ,but the temperature difference from the floor to the stat,is not correct and you'll have better comfort when it's corrected.

  6. #32
    Join Date
    Oct 2005
    Posts
    45
    Just to keep people abreast of situation.

    TXV was installed on wednesday 8am. He was done by 11:00 -- said he could get a 17 degree drop which was within mfg specs. Unit worked all day and never got to 75 degrees with 97 degree high. Yesterday was cool - 80's so no info therre.

    Today will be 90's so we'll see - I am tracking data.


  7. #33
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,580
    harmons

    Spend the $50 and do your own Manual “J”.
    (HVAC-CALC) above.
    It’s not that hard and will answer some of your questions.

  8. #34
    Join Date
    Mar 2006
    Location
    The South
    Posts
    2,189
    hamons

    I have followed your thread since initial post nearly three wks ago. Your dealer has had ample time to correct problem by now. But this dealer is being intellectually dishonest with himself and you. You have to decide if you are going to let dealer off the hook when you paid a premium price for a premium system and continue to suffer during AC season. Or are you going to stand your ground and make him do the right thing. You are clearly undersized and without more cooling output, you will continue to be uncomfortable. You should demand that dealer perform a load calculation and provide the written results to you. Also you should have this independently verified. Your situation is a real shame.

    IMO

  9. #35
    Join Date
    May 2006
    Posts
    230
    Originally posted by hamons
    This a/c is 1 ton smaller than my old 25+ year one I had before. They measured sq. footage of house and decided old one was too big for what I needed. They did not do a manual j or d
    This is the likely source of the problem.

    Why are you not insisting that they do a Manual J and D now?

  10. #36
    Join Date
    Oct 2005
    Posts
    45
    Ok -- when I inssited ona manual J they siad No One does those for residential. Since none of the estimates I had done last did one I didn't have much of a leg to stand on.

    I will be more insistent ehrn I call on Monday.

  11. #37
    Join Date
    May 2006
    Posts
    230
    Good. That is the ONLY WAY to know if your system is sized properly. If they give you some B.S. about other sizing methods (square feet, etc.) tell them you won't accept those since they aren't recognized by any HVAC industry association or local permitting agency.

    Once they do the Manual J then you should double-check it to make sure they used the right room sizes, window and door opening sizes, insulation, orientation, etc.

  12. #38
    Join Date
    Oct 2005
    Posts
    45
    As a final follow up to this old thread -- We are on our third summer now and we replaced the whole sytem this week witha new 3 ton unit.

    The company never would do a Manual J - but after replacign every part in the system -- they decided to trya bigger unit. Has not been hot enough yet to test it.

  13. #39
    Join Date
    Mar 2008
    Location
    mesa arizona
    Posts
    309

    Cool hey

    wow they upsize ur unit for a price or freeeeeeeeee

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