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  1. #1

    Just an uneducated consumer with a SEER 21 AC

    Our AC broke and my mother was really cranky in the hot humidity of VA. So she just wanted to get something into the house and get cool again. I sent her a ton of links to ACCA website, NATE certification website, and printed off the checklist for a manual J installation so that she could make sure the contractor was doing it right. But i dont know if he did a load calculation or not. He gave us a Carrier unit, 21 SEER that jumps from a 2 ton to a 3 ton depending on the work it needs to do to stay cool. Now that we have this super piece of equipment, what do i need to do to make sure that it is working as efficiently as possible? What about mini-duct air distribution? because i am sure we are losing a lot in old ductwork. Did we just waste a ton of money?

  2. #2
    Join Date
    Jun 2008
    Location
    Cincinnati, Ohio
    Posts
    2,171
    kspencer, was it just the a/c that was replaced, or did your contractor replace the furnace (air handler) as well?

    Did the contractor do a load calculation before the equipment was quoted?

    If the load was properly calculated, all you need to do is have an HVAC professional perform semi-annual preventative maintenance which will include checking airflow, refrigerant pressures, condenser coil cleaning (and evap coil if necessary), among 20 - 30 other items (depending on contractor). All you really need to do is change the filters regularly and set the thermostat to an appropriate setting (htg- 66 to 70 deg F., cooling 72-78 deg F.).
    Last edited by CincyHVAC; 06-26-2008 at 04:38 PM. Reason: adding information

  3. #3
    thanks...too bad i work all day so my mother was the one to deal with the contractors. yes it was just the ac, but i have not clue if they did a load calculation, and i dont think my mother does either. But it can change from a 2 ton to a 3 ton, so wouldnt that pretty much cover it? my house is probably 2,500 square ft...is it possible to have a system that is too good?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    66,786
    What size was you old A/C.
    It was just the A/C, did they replace the idoor section also.
    Contractor locator map

    How-to-apply-for-Professional

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

  5. #5
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    4,471
    Quote Originally Posted by kspencer View Post
    thanks...too bad i work all day so my mother was the one to deal with the contractors. yes it was just the ac, but i have not clue if they did a load calculation, and i dont think my mother does either. But it can change from a 2 ton to a 3 ton, so wouldnt that pretty much cover it? my house is probably 2,500 square ft...is it possible to have a system that is too good?
    A 21-SEER system is awful high.
    If you deal with high humidity, a lower EER & SEER might have been a better match for those conditions.

    How do you think it is doing?

    The ductwork & air handler's airflow are extremely important.

    TROUBLE SHOOTING DATA
    Age a unit & SEER Rating ________
    Square Footage of home & major city near you __________
    Out-Door temperature: _____________
    Outdoor condenser’s DB discharge-air-temperature _____
    In-Door temp DB and WB: ___________
    Total-ESP/ air flow in CFM: _____________
    Return air temp DB and, WB, or %RH: ____________
    Supply air temp DB and, WB, or %RH: ____________
    Which stage was it operating in with above data _______

    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.

    Just click the "Quote" button & fill in all the questions you can.

    Then, perhaps we can provide a ballpark opinion on what it is going on.

  6. #6
    Join Date
    Jun 2008
    Location
    Cincinnati, Ohio
    Posts
    2,171
    At 2500 square feet, I would be concerned about the system being too small and not about being too good. Double check the square footage of your home. I did a quick load calc. based on only square footage (not being able to see about windows, insulation, age of home for air infiltration purposes).

    beenthere also asked what size your old a/c was. It would help.

  7. #7
    Join Date
    May 2007
    Location
    DC Metro Area (MD)
    Posts
    3,350
    It's better if the indoor section is variable speed for that A/C... What's the indoor model number(s)?

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