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  1. #1
    Join Date
    Aug 2008
    Posts
    107

    Determining cooling hours

    I was looking at the hvacopcost website and it shows 2800 cooling hours. What parameters are they using to calculate cooling hours? Is this at a 75 degree temperature set point? Is there a site where I can find cooling hours for my area using different set points?

  2. #2
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,006
    This may be the closest to what you are looking for. - Darrell

    http://www.coloradoenergy.org/procor...g_load_hrs.htm

  3. #3
    Join Date
    Jun 2009
    Location
    Spicewood, Tx
    Posts
    35
    If you don't mind a few hrs work, you can make any data set you want from the nearest weather site. I did this yesterday for Central Texas, pulled hourly data from May, 2008 thru Sept., 2008. Then for more detailed info, I split the data into 5 degree intervals. There were a few missed observations, but out of 3544 total hours, 425 hrs < 71F, 736 hrs between 71 & 75F, 766 hrs between 76 & 80F, 530 hrs between 81 & 85F, 522 hrs between 86 & 90F, 431 hrs between 91 & 95F, 132 hrs between 96 & 100F and 2 hrs > 100F. By combining this info with both load calculations and system peformance at different ambient air temps, I may get a better understanding of operating cost and operating hours.

  4. #4
    Join Date
    Jun 2009
    Location
    Spicewood, Tx
    Posts
    35
    Quote Originally Posted by udarrell View Post
    This may be the closest to what you are looking for. - Darrell

    http://www.coloradoenergy.org/procor...g_load_hrs.htm
    That chart is pretty accurate, at least in my case. It shows between 1250 hrs and 1500 hrs of system operation. My data shows May thru Sept. a total of 3544 hrs with 2383 hrs above 75F. I calculate a 2.5T, 15 SEER system would run for 1397 hrs and use 3432 kW. A 3.0T, 16 SEER system running on 1st stage only would run for 1594 hrs but use only 2893 kW.

  5. #5
    Join Date
    Apr 2002
    Posts
    11,808
    If it wasn't for the fact that the sun is a big part of the cooling load, I would almost say that there would be merit in the 'cooling hours' based on temperature alone
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

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