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Thread: Gas Heater size for a 24 foot round 54" height AGP

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    Gas Heater size for a 24 foot round 54" height AGP

    Anyone have a link for a good calculator to determine the Right size BTU for a Gas Heater?

    Thanks,
    Dan
    24' Round 54" Impulse Ovation AGP, 1.5 HP 2 Spd, 150 Sq Ft. Cartridge Filter, RayPak 130K BTU NG Heater, BBB in full effect!!
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    Mod Squad Bama Rambler's Avatar
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    Re: Gas Heater size for a 24 foot round 54" height AGP

    There are a few topics here that link a calculator, but the best pool heater sizing algorithm you can have is to get the largest one they make. 400k btu's is the norm that's recommended for a gas heater.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Gas Heater size for a 24 foot round 54" height AGP

    X2 to Bama's post. Bigger is better for pool heaters (and filters).

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by simicrintz
    X2 to Bama's post. Bigger is better for pool heaters (and filters).
    I disagree.

    1. A bigger heater costs more
    2. A bigger heater requires a larger gas supply which costs more
    3. A bigger heater may require a meter, or feeder to the meter to be replaced which will costs more.
    4. A bigger heater creates a lot more heat inside the firebox, which may or may not cause premature failure.

    Putting a 400K heater on a 24' round AGP is ill advised, unless you are trying to heat 90+ degrees in a cold climate year round.

    Most 24' pools use somewhere around a 125-200k heater.

    It really can vary by your climate, and temperature you want to maintain the pool.
    20X40 30,000 gallon gunite pool

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    FWIW, On that pool I'd use a heat pump if the power rates were reasonable.
    20X40 30,000 gallon gunite pool

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by racket

    Most 24' pools use somewhere around a 125-200k heater.

    .
    Well, yea thats pool industry dogma, sure. You'll find a lot of TFP doesnt follow industry dogma that may or may not be suspect.


    400,000 BTU heaters are worth the added expense. It's only upfront costs anyway. When you figure the line size/meter for NG or propane, its really the same stuff with any heater over 250k anyway. If you're running propane, it cost no more for a 400k as compared to 200k. Use a 2 stage regulator system and you use 1/2" pipe from the tank to the second regulator, then 3/4 " iron to the heater (have to figure distance of course). The cost difference between a 250 and 400 is minimal, really.
    Once its installed, the cost of running a 400k over a 200k is about the same since you run the 400k half the time.

    On the heat pump, depending on where you are located they can be pretty useless on the ends of the heating season. If you have NG, a gas heater is about as economical as a HP. Propane is a different animal. A HP definately saves you money over LP, but depending where you live it wont extend the swim season by much at all.
    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 Heater size for a 24 foot round 54" height AGP

    In seattle, heat pumps can start you in early April, and take you into late october. They are typically .40-.60% cheaper to operate than a nat gas heater (.09 KWH| $1.25 per therm NG).

    Most people in colder climates seem to heat from Memorial day-Labor day.

    "Well, yea thats pool industry dogma, sure. You'll find a lot of TFP doesnt follow industry dogma that may or may not be suspect."

    No that is properly sizing equipment for the task.
    20X40 30,000 gallon gunite pool

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by racket
    No that is properly sizing equipment for the task.
    I stand by what I said. A 400k heater is almost always the better buy to heat a pool.

    Maybe the HP works ok is Seattle, but in New England, New York, and really and where in the northeast, a HP is pretty useless in April, half of may, mopst of september and october for sure. It really doesnt mater how cheap they are to operate, if they wont put heat into the pool, they just spin the electric meter.
    Cost is also relative. What works in one area may not work in another. In California, NG heat will always beat a heat pump since electric rates can approach 40 cents whereas NG is a little over a buck a therm. I pay 15 cents for elctricty and, if i had it in my hood, NG is $1.05 a therm. For 100,000 BTU, my heat pump will cost around $1.00. Very much a wash.
    What you have to realize is that TFP members are from all over the world. When giving advice for heat, constuction techniques, etc, you really have to take into account location for what might work.
    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 Heater size for a 24 foot round 54" height AGP

    Electricity is very cheap in Cleveland, OH but the weather would be prohibitive to a heat pump
    I paid .114 per KWH last month alone
    Nat Gas is 6.60 per MCF with del charges last month it was 11.08 per MCF total charge

    Are these heaters on/off or do they work as a thermostat would?
    24' Round 54" Impulse Ovation AGP, 1.5 HP 2 Spd, 150 Sq Ft. Cartridge Filter, RayPak 130K BTU NG Heater, BBB in full effect!!
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    Re: Gas Heater size for a 24 foot round 54" height AGP

    I agree with bk. I have never sold anything smaller than a 400k heater, even on a spa only. Why wait any longer for something to heat up than you have to? You will use whatever gas is needed to heat to the temp you decide, so a smaller heater only prolongs the heating and uses gas for a longer period of time.

    Go 400k and be done. You'll be happy you did.

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by Red Shirt Ensign
    Electricity is very cheap in Cleveland, OH but the weather would be prohibitive to a heat pump
    I paid .114 per KWH last month alone
    Nat Gas is 6.60 per MCF with del charges last month it was 11.08 per MCF total charge

    Are these heaters on/off or do they work as a thermostat would?
    Ok, 1 therm is 100 cubic feet. So you pay about a $1.10 per therm.
    Lets do the math.
    It's a bit hard to figure since a heat pump puts out variable BTU's depending on ambient conditions. But for this example we can use 100,000 BTU.


    A Heat pump will cost ~ $0.70-80 per 100,000 BTU
    Natural gas ~ $1.10 per 100,000 BTU.
    A heat pump is about 30 cents cheaper. But in Cleveland, you wont get 100,000 BTU in April or sepatember, let alone october.

    An electronic heater has a thermostat you can set just like your house.
    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 Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by simicrintz
    I agree with bk. I have never sold anything smaller than a 400k heater, even on a spa only. Why wait any longer for something to heat up than you have to? You will use whatever gas is needed to heat to the temp you decide, so a smaller heater only prolongs the heating and uses gas for a longer period of time.

    Go 400k and be done. You'll be happy you did.
    +1
    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 Heater size for a 24 foot round 54" height AGP

    I agree with racket. A 400K on a 24' round is overkill. Ray-Pak's 133k unit will do just fine. Heat pumps on AGPs? They cost more than the pool did.

    Scott
    Owner of - PoolGuyNJ LLC
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    Re: Gas Heater size for a 24 foot round 54" height AGP

    133k? Scott, I could heat it faster with a match!

    Seriously? You would have no problem (I think) putting a 400k heater on a 600 gallon hot tub. But, you would put a 133k on a 10,000 gallon pool?

    For a 10 degree rise in temp, a 133k heater would take 6 hours. A 400k would take 2 hours.

    I know what i'd buy.
    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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    dmanb2b's Avatar
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    Re: Gas Heater size for a 24 foot round 54" height AGP

    IMO...(I know I'm not an industry guru) a 133k heater is too small for a 13K gal pool... AGP or IG. It would get the water heated up after a while, but we have all (Scott included) agreed and debated that it sure is nice to have those extra BTUs to get the water up to temp as quick as possible...even for a spa in the winter, let alone the entire pool. The main downside to a larger heater is space required on the pad, additional cost of the heater (not much...maybe $300) and running a larger gas line (if one has to be run anyway is the upgraded plumbing going to cost that much extra?) It's just like we advise everyone to upgrade their plumbing to 2+" vs 1.5" or oversize their filter...may not be popular opinion among pool stores, but I think between the 20k or so members on this board, someone would have by now proven those thoughts wrong.

    Anyhow, my opinion assumes a new install. If there is an existing line and it can't accomodate a 400k heater, then I'd say stick with a 250k.

    To OP, not to make your mind spin, but have you cosidered at least supplementing with Solar Heating?

    edit...this is from another NE perspective...maybe the 133k makes sense down south, but not where temps are know to drop into the 40's in late May/early sep.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by bk406
    Quote Originally Posted by Red Shirt Ensign
    Electricity is very cheap in Cleveland, OH but the weather would be prohibitive to a heat pump
    I paid .114 per KWH last month alone
    Nat Gas is 6.60 per MCF with del charges last month it was 11.08 per MCF total charge

    Are these heaters on/off or do they work as a thermostat would?
    Ok, 1 therm is 100 cubic feet. So you pay about a $1.10 per therm.
    Lets do the math.
    It's a bit hard to figure since a heat pump puts out variable BTU's depending on ambient conditions. But for this example we can use 100,000 BTU.


    A Heat pump will cost ~ $0.70-80 per 100,000 BTU
    Natural gas ~ $1.10 per 100,000 BTU.
    A heat pump is about 30 cents cheaper. But in Cleveland, you wont get 100,000 BTU in April or sepatember, let alone october.

    An electronic heater has a thermostat you can set just like your house.
    Are gas heaters 100% efficient?
    18k gal inground, everbrite finish, 505 sq ft; 1.5 hp two speed whisperflow; rheem 5100ti 100k btu heat pump; 3 sheer descent falls; DE filter; swg (cell out and using trichlor for now)

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    Quote Originally Posted by no-mas

    Are gas heaters 100% efficient?
    In one word, no. The new ones can approach 90% but more likely 85+. If you want to do a DETAILED analysis, you have to take it into consideration. The quick and dirty calculation with advertised BTU gets you close.
    One reason i never bother with it too much is because I usually am comparing it to a heat pump. With a heat pump, you rarely get the book BTU out of one, either. The BTU ratings and COP values are based on 80 degree air temp, and 80% humidity; hardly real world situations, especially when considering heating a pool in the early spring and fall months. For a 120,000 BTU heat pump, you might be hard pressed to get 80-90k out of it on a 55 degree, overcast, drizzly day. Thats basically 80% efficiency. Just my own observations having owned one for 3 years, I can say that in the months I really want heat, a heat pump might put out 85% of the rated COP.
    The harder a heat pump works the more amps it pulls to a point, but if it's 53 degrees and rainy, it's not very efficient at all but still uses 5-6 kW/hour, plus.

    You HP efficiency in April, may and october is probably really good being in florida, but for most of us, not so much.
    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 Heater size for a 24 foot round 54" height AGP

    [quote=no-mas]
    Quote Originally Posted by bk406
    Quote Originally Posted by "Red Shirt Ensign":1hlbbfjl
    Electricity is very cheap in Cleveland,


    Are gas heaters 100% efficient?
    [/quote:1hlbbfjl]

    who has a 90% plus heater besides jandy/zodiac?

    Who will spend $5k for 13%

    raypak = 80-82%
    Pentair = 84%
    lochinvar= 86%
    jandy other than hi-e 82%

    a combustion anaysis is the only way to prove the efficient of you unit.


    so the $4.40 only buys you ~326k btu


    so related
    20X40 30,000 gallon gunite pool

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    I don't know which brand of heat pump you own/Ed but we use 4.0 cop as a reference and it
    seems to correlate with our clients bill.
    20X40 30,000 gallon gunite pool

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    Re: Gas Heater size for a 24 foot round 54" height AGP

    I never said 90+. I said approach 90 and most are 85 and i meant to type +/-.
    I still stand by my original premise that:

    1) A NG heater, for a lot of the USA, is as cost efficient as a heat pump (and not near the frustration)
    2) Get the biggest heater you can afford.

    Quote Originally Posted by racket


    so the $4.40 only buys you ~326k btu
    Yep. But the difference is I know that I'm getting 326k worth of heat for my $4.40, even when the ambient air temp is 55 degrees. At 55 degrees, my electric meter still spins at ~6kw/hr for a $1.00 an hour. I might have to run it 6 hours to get 326k BTU. Now i've spent 6 bucks to do what $4.60 in gas would do. Thats my point with NG being about as efficient as a heat pump in a lot of applications. The only reason i have a heat pump is that i only have access to propane. If they ever put NG on my street, the heat pump's going on ebay!

    I'm not a heat pump basher, i like mine. But it's not a panacia like some pool dudes make it out to be.
    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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