Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 3 of 3

Thread: Choosing correct heater size

  1. Back To Top    #1

    Join Date
    Oct 2014
    Location
    Rio Rancho, NM
    Posts
    114

    Choosing correct heater size

    How do you determine the proper size heater for swimming pool?
    I was suppose to get the 350K BTU heater that's no longer available.
    Pentair now offers 300K or 400K units.
    The cost is only ~$65, but PB already delivered 300K unit.
    I want to get some data on proper sizing of my 16'x40' FB pool, with all plumbing running with 2" PVC.
    I have a hard time figuring out the proper size.
    I know that any heater will eventually get my pool to temp, but what's the most economical?
    Is the right direction to go with 300K unit and run the heater/pump longer, or do I blast the 400K unit and run it that much shorter?
    Running gas is not a determining factor as we already have to redo the gas pressure to deliver either 300K or 400K to the pool.
    Viking fiberglass Island Breeze II (16'x40'x8'); Pentair pump/filter/heater/chlorinator; IntelliTouch with iX+3; Autelis.

  2. Back To Top    #2
    Richard320's Avatar
    Join Date
    Jan 2010
    Location
    San Dimas, CA (LA County)
    Posts
    18,768

    Re: Choosing correct heater size

    Heaters are BTU per hour. The size of the plumbing has little to do with it. (gas line excepted) A 400K BTU heater will raise the pool temperature 33% faster than a 300K BTU in a perfect world. In reality, it's probably faster than that. You lose a certain amount of heat to the air and the surrounding soil, and that's a function of time. Wait long enough, and the pool will cool down to the ambient temperature. So a pool that takes 8 hours to warm up will lose a lot more heat to the surroundings than a pool that takes 6 hours, everything else being the same. So it would likely be more like 9 hours versus 6 hours.

    All that is my way of saying, I'd go bigger. My pool is considerably smaller than yours, and I have a 400K heater. It might be warmer where you live, and a cover will help a lot, but faster is still better. If you're hosting a pool party, you don't want to be waiting around for the thing to heat. The cost to heat will be roughly the same - a BTU is a BTU, whether it's 100 for an hour or 10 for 10 hours.

    Estimating your pool at about 24000 gallons, that's roughly 192000 lbs of water. 192K/300K = 38 minutes per each degree rise. 400K lowers that to about 29 minutes. Say the water is a chilly 69 and you want it to a comfy 83. 9 hours running full tilt versus 6:45, excluding losses.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3

    Join Date
    Oct 2014
    Location
    Rio Rancho, NM
    Posts
    114

    Re: Choosing correct heater size

    Thank you Richard.
    That's a lot of help.

    I emailed my PB and he responded that he'll swap the 300K unit that was delivered for the 400K.

    I really like my PB.
    Viking fiberglass Island Breeze II (16'x40'x8'); Pentair pump/filter/heater/chlorinator; IntelliTouch with iX+3; Autelis.

Posting Permissions

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