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  1. #1
    Join Date
    May 2017
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    Is our new AC install underpowered?

    Hi all, first post here!

    We've just built a house and I wanted air conditioning installed, so this is my first experience with an air conditioner. My initial reactions were that it was not cooling as much as I expected and took a long time to do so. I wanted to get some professional opinions on whether I'm expecting too much or whether the system is inadequate.

    The house is brand new. 2600 square feet for the main floor (9 foot ceilings) plus upstairs(8 foot ceilings). We also have a developed basement (9 foot ceilings). It is a single furnace, with 3 zone controls one for each floor. There is a Heat Recovery Ventilator system as well.

    The temperature has been 24 degrees celsius outside today and i set the main floor controls to 18 degrees and upstairs to 18 degrees. I closed the blinds to keep the sun out in the day.

    So far from looking at the temperatures, the main floor managed to achieve 18 degrees but seemed to take many hours to achieve that. Upstairs never got below 20 degrees (starting off at 24 degrees)

    Timing wise it felt like over an hour to drop 1 degree. Upstairs seemed to struggle to get down to 20 and failed to go below.

    So a few questions:
    Should my upstairs temperature be expected to go below 20 degrees?
    Should I be running my HRV while running the AC?
    Is 1-2 hours too long to drop 1 degree celsius?
    Is my system running as expected?

    Many thanks!
    I can provide some more numbers/tests if the above are too wishy washy.

  2. #2
    Join Date
    Sep 2014
    NW Arkansas
    Post Likes
    Am I doing my math wrong or are you trying to cool you house to 65 degrees Fahrenheit?

    75 (24) at 50% relative humidity is what you can expect on a design day (one of the normal hottest day of the year).

    A few questions:
    1) Did you leave your a/c on all day or did you have it off then turned it on?

    2)what is the serial and model number of the outdoor unit

    3) does your house have a HERS (or equivalent) rating?

    4) how many square feet for the upstairs and basement?

    Sent from my SAMSUNG-SM-G891A using Tapatalk

  3. #3
    Join Date
    Jan 2004
    Post Likes
    68F for the upstairs, and 65F for the downstairs is a bit more then an A/C is suppose to do. When it reaches 78F/26C or better outside, try setting those zones to 22C/72F. And see if it does any better. If it doesn't then it may just not correctly charged. Many companies won't do a full A/C check on a new install in the winter. If that is when the home was completed.
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