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  1. #1

    system working overtime?

    We recently purchased a new heat pump - a Carrier 2-ton performance series with a variable speed air handler. The expansion valve has already been replaced.

    We've noticed that the system outside doesn't seem to cycle off, that is the fan is always turning on the outside unit. Is this normal? How often should it cycle off?

    We've also noticed that when the outside temperature is 93 degrees, with the thermostat set at 72 degrees, that the system could not cool the house to under 76 degrees. I heard that we should only expect a system to cool the house to 20 degrees less than the outside temperature. Is this correct? Should we be concerned that our system is only getting our house 17 degrees cooler, or is that bit of difference considered negligible?

    Thanks,

    DougandLiz

  2. #2
    Join Date
    Dec 2007
    Location
    Ohio
    Posts
    2,875
    Did the contractor you bought this system from do a proper load calulation on your home to make sure that a 2 ton system is large enough?
    I need a new signature.....

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Was there an old unit,if so what size?


    If not did they measure your home,and do a load calculation ,like Man j from www.acca.org ?

  4. #4
    Join Date
    Jun 2008
    Location
    south central pa
    Posts
    133
    if you just had your txv replaced and its still not cooling adequatly you might want to find another contractor for a second opinion. let me guess the unit is fairly new?

  5. #5
    Join Date
    Mar 2008
    Location
    mesa arizona
    Posts
    309

    Wink hey

    good idea on load caluclations whats sq fttg of house may neeed a load calculation

  6. #6

    System working overtime?

    Thanks for the responses. This is a brand new system (3 weeks old). It replaced a 12 year old 2 ton Carrier comfort series which did an adequate job. We thought this was an upgrade. Other than the defective TVX (which was replaced), the failure to cycle off, and the inability to cool more then 17 degrees from the outside temperature it is also doing an adequate job. Our question is whether this unit should be operating more efficiently. If not what should our complaint be to the contractor. The contractor has a fairly good reputation and has generally been responsive (other than the time it takes to get back to us).

  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Sounds like an issue,call your contractor,and explain as you did here.

  8. #8
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,956
    Quote Originally Posted by DougandLiz View Post
    We recently purchased a new heat pump - a Carrier 2-ton performance series with a variable speed air handler. The expansion valve has already been replaced.

    We've noticed that the system outside doesn't seem to cycle off, that is the fan is always turning on the outside unit. Is this normal? How often should it cycle off?

    We've also noticed that when the outside temperature is 93 degrees, with the thermostat set at 72 degrees, that the system could not cool the house to under 76 degrees. I heard that we should only expect a system to cool the house to 20 degrees less than the outside temperature. Is this correct? Should we be concerned that our system is only getting our house 17 degrees cooler, or is that bit of difference considered negligible?
    Thanks, DougandLiz
    Actually a 50% RH, @ 76* should be very comfortable. Try setting it at 77* & see if it cycles when its 93. Maybe 93* is your areas' summer design, if so it's sized okay, ACCA (TVA) conditions, Tests @ 95*-OAT 75*-IDB 63*-IWB.

    However, if you want to find out what it is doing have the tech take these readings for your records.

    AC TROUBLE SHOOTING DATA
    SEER Rating ___
    Square Footage of home & major city near you __ ____

    Outdoor condenser’s DB discharge-air-temperature _____
    Out-Door temperature: ____
    Condenser air split _____


    Indoor Total-ESP/ accurate air flow in CFM: _________

    Suction line pres. _____tech
    Suction-Vapor line temperature: ______
    SST - Gage - Suction Saturated Temperature. ______
    Superheat ______

    Head pres. ______tech
    SCT - Gage - Saturated Condensing Temp _______
    LLT - Liquid line temperature: _______
    Subcooling: _______

    Return Air temp DB &, WB or %RH: ____________
    Supply Air temp DB &, WB or %RH: ____________

    You can fill in all but the pressures for us! You can reg up a wet bulb & use a small fan to aid the readings double check with a low cost %RH gage.

    My advice: get a low cost humidity gage at a local hardware store & see what the percentage-RH is in your home, I can cross-reference that to the wet bulb depression.

    Then, perhaps we can provide a ballpark opinion on how well the system is performing.

  9. #9
    Join Date
    Jun 2008
    Location
    south central pa
    Posts
    133
    if the unit is the same size as the old one and its not doing at least as good as the old system did then sizing isnt the issue. let me guess a couple things your unit is using R410a aka puron and your contractor might have told you that when the txv was bad that its and industry wide problem. well it kind of is but if its doing the samething with the new txv you should get a second opion theres a little more to the misnomer of inustry wide. your contractor should make a reference to both super heat and subcooling not just subcooling. if they dont find a new contractor. sorry but im not going to get more technical then that.

  10. #10
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    Just because the unit says 2 ton that dosn't mean it is getting 24,000 BTU out of it. It could be some way off of that depending on the coil matchup. Hense the need to do a load calculation on these jobs. The old unit may have put out 25,000 BTU or somthing like that so it was OK.

    How about a model and serial # of whats installed. Coil and outdoor unit.
    Its a good Life!

  11. #11
    Quote Originally Posted by m kilgore View Post
    Just because the unit says 2 ton that dosn't mean it is getting 24,000 BTU out of it. It could be some way off of that depending on the coil matchup. Hense the need to do a load calculation on these jobs. The old unit may have put out 25,000 BTU or somthing like that so it was OK.

    How about a model and serial # of whats installed. Coil and outdoor unit.
    HP is carrier 25HPA5
    Fan coil FV4BF

  12. #12
    Join Date
    Jan 2005
    Location
    Port Orange, Fl.
    Posts
    17

    Question system working overtime

    does the outside unit continue to run when the indoor unit stops ?

  13. #13
    Quote Originally Posted by hiflow View Post
    does the outside unit continue to run when the indoor unit stops ?
    We where told to keep the indoor fan running all the time. We did this with the old unit and it provides more of an even flow of air for the second floor. I have notice the outside unit cycle off but only when the outside tempeture is very close to the tempture set on the thermostate.

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