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  1. #1
    Join Date
    Feb 2008
    Posts
    12

    Hmm New Carrier Unit; Nothing but Problems

    We had a new central a/c-heat installed in Nov 07. Since then, i have called the company out numerous times because it doesn't seem to work correctly and they keep saying nothing is wrong. Our electric bill more than doubled. We are having to run the heat at 78 to get it warm. It is either to hot or to cold, it is never comfortable.

    I live in houston, texas and my house is 1,710 SF all electric. When i was getting quotes for this unit everyone said to get a 2.5 ton (that is also what was previously there) and not anything larger. That is what i thought i got so today i go to the carrier web site and put in the model number and it says it is a 3.5 ton. I call the company and they verified that it is a 3.5 ton. Could this be the cause of above problems?

    They are suppose to come out today after 3:00 again. If it could cause the problems should i insist that they change it? I am just so tired of dealing with these people and i am sure they are tired of dealing with me but i got a new energy efficient unit i darn sure didn't expect my electric bill to double.

  2. #2
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,153
    what is the model number? don't look at your paperwork. walk outside and look at the model number.
    Perhaps you should have read the instructions before calling.

  3. #3
    Join Date
    Feb 2008
    Location
    Kansas City, Kansas
    Posts
    476
    He's right. And if the unit is oversized its not cooling efficiently so it short cycles. it will cause problems with the power bill but it will also put a lot of wear and tear on the A/C. Post us up the Model number

  4. #4
    Join Date
    Feb 2008
    Posts
    12
    I am at work so i can't look. On the paper work is says A/H Model #FY4ANF042 and on Condensor #24ApA542. We haven't used a/c yet just the heat. i will check when i go home at 3 and see if it is the same model #.

    Thanks for the replies!

  5. #5
    Join Date
    Feb 2008
    Location
    Kansas City, Kansas
    Posts
    476
    FY4ANFO42...Carrier 3-1/2 ton air handler.
    24ApA542...Carrier 3-1/2 ton Condenser.

    Oversized systems will short cycle causing more usage. It raises your electrical bills from starting and stopping. It also causes more wear on the motors.

    This could have been a simple installer error.

    They need to replace it though.

  6. #6
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    24ApA542
    That is indeed the model number of a 3½ ton, Performance series cooling - only condenser.
    What you needed, being that your home is all electric, is a heat pump, the model number of which would look like 25APA.
    This space for rent.

  7. #7
    Join Date
    Feb 2007
    Location
    18951
    Posts
    1,593
    A lot of manufacturers print installation and home owner instructions for a whole series of units. When you get home, write down the model numbers and serial numbers of both the inside and outside units. Then look at your contract to see what that says. Then go from there.

  8. #8
    Join Date
    May 2007
    Location
    Naples, Fl
    Posts
    889
    Since this isn't a heatpump and he probably hasn't used the a/c yet the oversize issue doesn't apply. But maybe the system is heating and cooling at the same time.
    Last edited by adrianf; 02-28-2008 at 03:06 PM.

  9. #9
    Join Date
    Dec 2007
    Location
    Ohio
    Posts
    2,875
    Quote Originally Posted by adrianf View Post
    Since this isn't a heatpump and he hasn't used the a/c yet the oversize issue doesn't apply. But maybe the system is heating and cooling at the same time.
    Sounds like a good theory to me...I wonder why the HO didn't go with a heat pump in this all electric set up? Or.....maybe that's what was supposed to be installed and they put in a strait AC instead?? Either way, something sounds rather fishy!
    I need a new signature.....

  10. #10
    Join Date
    Jun 2007
    Location
    Piedmont Triad, NC
    Posts
    76
    I assume you had a central air unit in before they installed this one? They would have to remove the old unit first. Sounds like someone really screwed up. To make sure the unit was sized right from the start someone would have to do a load calculation for the house.

    Manual J residential load calculation, enables contractors to estimate heating and air conditioning loads more accurately. Using Manual J, a contractor calculates heat loss from the building through walls and ceilings and infiltration through windows, doors, and other penetrations as well as heat gain into the building from sunlight, people, lights and appliances, doors, walls, and windows and infiltration though wall penetrations. Design conditions for the area are also used as inputs into load calculations.

    Did you have the house built and was this done originally? Lots of contractors use the rule of thumb method. It varies with the contractors. Most use around 750 square feet per ton. Some go as low as 500 square feet per ton. Either way it is not the correct way to size a unit. At just over 1700 square feet it sounds like someone may have went with 500 square feet per ton.

  11. #11
    Join Date
    Jun 2003
    Location
    Hell Hole Swamp
    Posts
    4,180
    Maybe they took out a HP and just put in AC/Electric heat, that would double the power bill

    need the actual model numbers to confirm

  12. #12
    Join Date
    Jun 2007
    Location
    Piedmont Triad, NC
    Posts
    76
    All electric and you have not used the air conditioning? I don't understand how you could be having problems with the electric heat being over sized? Electric resistive heat has a COP = 1 no matter what size. That part of the unit should not matter as much. It should not have run the bill up that much.

  13. #13
    Join Date
    May 2006
    Location
    east central indiana
    Posts
    1,117
    Yeah, but disregard COP for a minute and consider this:
    Each typical resistive element draws about 20 Amps. At 230 Volts, if you have three elements, that's 13.8 kilowatts per hour.
    Now if you're using a heat pump, say it's drawing 9 Amps on the compressor and 1 amp on the ODF for a total of 10 Amps at 230 Volts. Now it's only consuming 2.3 kilowatts per hour.
    Now these are just numbers I pulled out of nowhere but that's about what you'd see. You're right, if they had electric resistance heat only, the bill shouldn't have doubled. But if they went from having a heat pump to not having a heat pump, you'd see a light bill shoot up like a rocket.
    This space for rent.

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