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Can you use a tankless water heater to lets say Heat a small pool? only for a day!

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Mail4tommo
Mail4tommo Member Posts: 51
in Domestic Hot Water

Could a tankless water heater recirc the water in the pool? Its only used for a few hours once a month. So lets say it heated and filled the pool, could it keep that pool hot 86 degrees for less than 24 hours? If so this would be my best option for a project. Thanks in advance

Comments

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,703
    edited March 8

    Most pool heaters are tankless, so it depends what size you choose.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Mail4tommo
    Mail4tommo Member Posts: 51

    @Alan (California Radiant) Forbes Thanks, I'm not looking for a pool heater, I'm looking for an answer so I can make a decision based on the answer

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,703
    edited March 8

    My question is: What size tankless do you want to use. They have different sizes.

    I’ve seen Mikvah’s heated with tankless units, but I don’t remember BTU’s or gallons capacity.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • kcopp
    kcopp Member Posts: 4,665

    Should combine this into 1 post…

  • Mail4tommo
    Mail4tommo Member Posts: 51

    @Alan (California Radiant) Forbes I just need to know if they are capable of recirculating what it puts in. As if it heats up something let's say a tub for example can it keep that tub hot with a recirc pump

  • Jamie Hall
    Jamie Hall Member Posts: 27,279

    Depends entirely on the heat loss of the pool — but in general, I'd say yes. But it seems to me there is another very similar thread just now about a baptistry?

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jesmed1
    jesmed1 Member Posts: 1,455

    The pool heat loss should be less than 20,000 BTU/hr at 86 degree water temp and 68 degree indoor temp.

    Mail4tommo
  • Larry Weingarten
    Larry Weingarten Member Posts: 4,074

    Hi, I'd expect a very big pressure drop through a tankless heater, forcing you to use a bigger pump. Using a pool heater (which is designed for low pressure drop) with a pump sized for good flow through the existing piping seems the simplest approach. 🙂 Do you know what the gas supply piping is to the heater that leaked?

    Yours, Larry

  • PC7060
    PC7060 Member Posts: 1,790

    Wouldn't a pool require a heat exchanger to protect the boiler from chlorinated water?

    Larry Weingarten
  • hot_rod
    hot_rod Member Posts: 27,351

    This is just municipal water traht fills and dumps after every use? A typical gas fired WH would work and be the least $$.

    Of a tankless with a bypass, flow just enough4 gpm or so through the tankless, bypass the rest.

    Petty much any device with a flame or resistenance element willhgeat waer for a tub. It depends on how quickly you ant it, how long you want the equipment to last. I would say 10 year from a glass lined tank in that condition.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Intplm.
    Intplm. Member Posts: 2,998

    Yes…you can heat any size pool with the properly sized tankless.

  • Larry Weingarten
    Larry Weingarten Member Posts: 4,074
    edited 12:33AM

    Hi, You say a 6" vent cannot fit in your situation. Can a 5" vent fit. It seems a 5" vent can do up to 122,000 BTUs. What are the dimensions inside the chimney? Perhaps oval vent can work. 🤔. My goal here is to keep things simple. It usually costs less to do so, and is easier to manage than more complex stuff.

    Yours, Larry

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