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Thread: Heater heating pool very very slowly

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    Join Date
    Aug 2011
    Location
    Toronto
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    8

    Heater heating pool very very slowly

    We inherited a Hayward H250 natural gas heater with our pool and this season is the first time we're attempting to use it (first season with our pool as well). We've got a vinyl in-ground, about 18500 gallons. No solar cover. We ran the pump 24/7 while heating.

    We live in Toronto, Ontario and temperature ranged from 60 degrees at night to 77 during the day (ignoring humidity effects) the past couple days.

    I started heating the pool 8pm Friday and the water measured about 71 degrees using a floating digital thermometer that measures down about 4 inches. Fast forward 36 hours to Sunday 8am and the pool water now measures 82 degrees.

    That's 11 degrees in 36 hours. Seems way too low from what I've been reading.

    The heater does give some trouble starting. It's not the push button type, it fires electronically but it takes a few attempts to get going. Once it's going however it stays running. I don't think there are any adjustments I can make on the heater to vary it's output - it's either on or off if I understand it correctly.

    There is a bypass on the heater which is how I run it when not heating. When the water flows through the heater there is only a 1 PSI increase in the pressure so it doesn't look like the heat exchanger is clogged or anything.

    Any ideas?
    Tampa, FL - 13,500 gallon in-ground concrete pool, standard cartridge filter

  2. Back To Top    #2

    Re: Heater heating pool very very slowly

    60 degrees at night seems very cold for the heater to combat. For that matter, 77 isn't very warm. Are you covering the pool as it heats? When the heater is on, does the water feel warm as it enters the pool?
    POOL: Intex ultra new in 2014 (32 x 16 x 52) (seasonal; on concrete pad covered with 1.5" extruded or whatever foam insulation sheets - ugly, but comfy); added a through-wall skimmer; I add salt for feel. EQUIPMENT: Pentair SuperFlo pump (1HP, 2SPD); Pentair cartridge filter (200 sq. ft); Pentair MasterTemp natural gas heater (400,000 btu) Climate/Location: Eastern Nebraska

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    Join Date
    Aug 2011
    Location
    Toronto
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    Re: Heater heating pool very very slowly

    No, I'm not covering the pool at all. But even taking that into consideration isn't that a low heating rate? There wasn't much wind at all either. I read somewhere that someone used a couple circular above ground pool covers as a cheap solar cover for an IG pool. Maybe I can try that as an experiment.

    I measured the temperature at the skimmer and the return jets - there's about a 5 degree difference in the temperature.
    Tampa, FL - 13,500 gallon in-ground concrete pool, standard cartridge filter

  4. Back To Top    #4

    Re: Heater heating pool very very slowly

    Cool nights - no cover = good luck keeping up. I lose 2-3F per night with cover on if 60-65F out. I lose 10F+ without it on.

  5. Back To Top    #5
    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    37,879

    Re: Heater heating pool very very slowly

    How large is your pool heater? Pools require huge amounts of heat. Using a solar pool cover can improve the situation dramatically, but even with a solar cover it will take a while to heat the pool.
    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

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    TFP Guide

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    Jun 2012
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    western NY
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    1,557

    Re: Heater heating pool very very slowly

    That is a 250,000 BTU heater the 250,000 is the rated input. The output on these heaters is roughly 80% of input. Based on the volume of water in your pool you are trying to heat over 157,000 lbs of water. At an 80% efficiency rating you are at most getting 1.25 deg/hr temp change. This is assuming no heat loss due to evaporation and conduction. Add those two in and I would be surprised to see half that rate. Throw in the temperature differential of 20 deg at night and I am surprised you are getting the heat you have. A solar cover would be a big help in getting the water to warm up faster
    Unknown make 18' above ground (bought used in 1999) Sparco sand filter. Hayward 100,000 BTu heater. 2 speed pump

  7. Back To Top    #7

    Join Date
    Aug 2011
    Location
    Toronto
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    Re: Heater heating pool very very slowly

    Thanks for the feedback guys.

    Well alright, given the conditions and no cover, it seems the heater is performing as spec'ed. I'm definitely going to get a solar cover of one form or another. We got some hot days coming down the pipe so that should give us a break on the heating bill. It really is amazing how much heat a pool can suck up!
    Tampa, FL - 13,500 gallon in-ground concrete pool, standard cartridge filter

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