Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 5 of 5

Thread: Some Pool Heater Math ... Is this correct?

  1. Back To Top    #1

    Join Date
    Feb 2015
    Location
    Dallas, TX
    Posts
    36

    Some Pool Heater Math ... Is this correct?

    So planning on getting a 400,000 BTU NG heater for a new build 15,000 - 15,500 gallon pool and was trying to do some cost estimates of running the heater. First my assumptions:
    • from some research it appears that 1 BTU will heat 1 pound of water 1 degree.
    • There are 8.34 pounds of water per gallon.
    • 400,000 BTU heater puts out 400,000 BTUs per hour
    • 1 CCF is roughly 102,500 BTU

    So for this pool and heater I can expect to raise the pool 400,000 / (15,500 * 8.34 ) = 3.09 degrees per hour of run time.

    My current cost for NG is $.19 per Ccf. so roughly 4 Ccf per hour to get 400,000 BTU or about 80 cents per hour of run time. Or if I want to think about it in cost per degree roughly 80 cents / 3.09 degrees = 25.85 cents per degree of temperature increase.

    Is my math correct? It seems like it will just cost me 26 cents and 20 minutes to raise my pool 1 degree.
    In Ground 17X29 90 ft perimeter; 3.5 to 5 depth; 15,000 gallons, Stonescapes Tropics Blue, Jandy stealth 1.5 HP 2 speed, Jandy 450 SQ cartridge, Jandy JXi 400K BTU NG, POLARIS 280 W/ HP booster pump, North Texas

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Location
    Tucson, AZ
    Posts
    37,389

    Re: Some Pool Heater Math ... Is this correct?

    Pretty close ... the heater will actually put less BTUs into the water and there are going to be losses to evaporation and the surroundings. So might be closer to use 80% of the heater output ... or 320k BTU. So maybe 2.5 degrees an hour. Even this might be optimistic.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  3. Back To Top    #3
    JasonLion's Avatar
    Join Date
    May 2007
    Location
    Silver Spring, MD
    Posts
    37,879

    Re: Some Pool Heater Math ... Is this correct?

    Most heaters are right around 80% efficient.

    Heat loss that needs to be made up by the heater varies depending on the difference between the unheated temperature and the actual temperature, as well as if you are using a solar cover or not. As the temperature difference goes up the heat loss that needs to be made up goes up.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  4. Back To Top    #4

    Join Date
    Jan 2011
    Location
    Richmond, Texas
    Posts
    594

    Re: Some Pool Heater Math ... Is this correct?

    I did the math a few years back and I was at 4 degrees per hour @ 4 dollars per hour. It really depends on if the sun is shinning and if it is windy.
    Approx 11K Gal. 10'X30' Semi free-form IG - 6 ' raised spa w/6 jets - 10' circle sun shelf with 1 bubbler - Waterfall - 3 / 1.5 HP pumps - Polaris 280 Cleaner - 3 Pentair Color LED Intellibrite Lights - Pentair 400K Master Temp - 2 Valve Actuators - 5 Fiberstar Mini Laminars - 1 Fiberstars 2004 Illuminator - 2 Skimmers - 6 Returns - Caribbean Blue Pebble Tech - 600+ sq ft kool decK - Auto Fill - 2 Boston Acoustics VOYA RK5 Outdoor Rock Speakers - 2 TIC Corporation TFS5CN 6.5-Inch 150-Watt Terra-Forms Rock Speakers - Apple Airport Express - 1 Awesome View.

  5. Back To Top    #5

    Join Date
    Feb 2015
    Location
    Dallas, TX
    Posts
    36

    Re: Some Pool Heater Math ... Is this correct?

    Thanks,

    So 4 degrees an hour for an 11K pool if I use the calcs for a 15.5 K pool at 80% efficiency I get 3.09 * 80% efficiency * 15.5/11 = 3.48 which doesn't seem too far off.

    So bottom line it looks like 400K BTU will use roughly 4 Ccf per hour and I can probably expect somewhere in the range of 2.5 degrees of increased temperature per hour depending on the efficiency of the system ( 2.5 at 80% )

    Thanks everyone!
    In Ground 17X29 90 ft perimeter; 3.5 to 5 depth; 15,000 gallons, Stonescapes Tropics Blue, Jandy stealth 1.5 HP 2 speed, Jandy 450 SQ cartridge, Jandy JXi 400K BTU NG, POLARIS 280 W/ HP booster pump, North Texas

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •