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Thread: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

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    Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    Just a quick question about upgrading to a 400 BTU Gas Heater vs. staying with the 250 or 300 BTU base models. Is it worth it time and efficiency wise to upgrade to the higher model. The cost differential isn't that much so that is not the worry for me. I'm more concerned with the gas usage - is 400 BTU model going to to make our gas bill significantly higher?

    Thanks so much!

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    Join Date
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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    A 400 will use more than a 300, sure. But, it wont run as long. The gas use vs. run time is fairly linear. If you do the 400, just make sure you have enough gas to the heater in terms of meter size, line size, and pressure. I assume you're on natural gas?
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    JasonLion's Avatar
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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    The total gas usage will be about the same, since the overall efficiency is about the same, the pool will just heat up more quickly.

    I'd go with the larger one unless it was much more expensive. Faster heating is really nice
    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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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    Thanks for the feedback1 We have natural gas on our street but we are going to have to have to dig a line back to our house for this heater, but based on the research that I've done that is a better option for us than going with the electric heat pump.

    The cost differential is $400, which doesn't seem too much considering the life of the pool and it is really appealing to be able to get in the spa much more quickly

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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    Heat pumps are great, but they typically only put out around 150K btu's.

    Do the math to insure you will be satisfied with the rise time.
    You my not be happy with time it will take to heat your pool.


    Uncle Dave
    20K Gallon Gunnite pool/900 Gallon in ground Spa/2HP WhisperflowSpa
    Pentair Master temp 400/Hayward Sand WZeobrite/Jandy RS-8 Aqualink/Jandy 2HP Epump
    12 - 4x10 Panels/Zodiac G3-T5 / BBB

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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    Quote Originally Posted by Davegvg
    Heat pumps are great, but they typically only put out around 150K btu's.

    Do the math to insure you will be satisfied with the rise time.
    You my not be happy with time it will take to heat your pool.


    Uncle Dave
    I dont think he's considering one.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Gas Heaters - 300 BTU vs. 400 BTU - which is better???

    With a spa you may prefer gas heat for faster heatup.

    Regardless of size if you are running a new gas line I would size it for the larger heater just in case you need it. I would go with the 400 also. I like mine.
    IG 24k plaster with overflow spa. Goldline PS-8 SWG. Tristar 0.75 HP filter pump, Polaris 280, large cartridge filter, 400k BTU NG Max-E-Therm HD, SR Smith Turbo Twister, Life Saver pool fence, ORP managed.

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