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Commercial pool boiler sizing??

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tim smith
tim smith Member Posts: 2,752
I just looked at a commerical 50x100 pool at a country club here in Seattle. Someone had put in 2- 400mbh input pool heaters. This shows to be fairly undersized for outdoor pool in our climate. I calculate appx 1.0 -1.2 million btu output requirement for appx 1.2 degree per hr rise at low avg temp month heating requirement which they start heating appx mid to end may. Any others have some input? PS no pool cover at night which I have given them the 3rd degree for. Thanks in advance, Tim

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  • hr
    hr Member Posts: 6,106
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    Google pool heaters

    and you will find a bunch of online calculators. I think the DOE website has one also. The biggest variable is the recovery rate you want, or need. the faster you want to move the temperature the more horsepower required.

    Pools are a lot like snowmelts, energy hogs ;)

    Covers make a huge difference in the loads, but I understand their challanges with a commercial pool.

    What does solar look like in that area for some "boost"?

    hot rod

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  • hr
    hr Member Posts: 6,106
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    Heat pump pool heater

    maybe with your power cost this would pencil out better.

    hot rod

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  • Paul B._2
    Paul B._2 Member Posts: 62
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    Seasonal pool heating

    Hi Tim,

    You're right, those two 400 mbh heaters do sound a little small.

    Typically for pool heating you ignore the volume of the pool, (unless it's a spa) and you also ignore the heat up time as well. Once the pool is up to temperature the surface area poses the greatest heat loss. This number is generally greater than the btu input required to bring the pool up to temperature in the first place.

    As an example, this 5000 square foot pool operating at 82° with a mean outdoor air temp of 60° at night with a 3 mph wind would have a heat loss of 210 btu/sqft.

    This would require a heater output of 1,050,000 btu/hr. If you were to use a heater with an efficiency of 82% the heater input required would be 1,280,488 btu/hr.

    Considerably more than the existing 400mbh heaters can deliver.

    I would also urge them to put a pool cover in place. Without one, you will have to design for worst case, which could be considerably more than 210 btu/sqft.

    Sincerely,

    Paul Bock
    Laars Heating Systems
  • tim smith
    tim smith Member Posts: 2,752
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    Solar & or heat pump

    > and you will find a bunch of online calculators.

    > I think the DOE website has one also. The

    > biggest variable is the recovery rate you want,

    > or need. the faster you want to move the

    > temperature the more horsepower

    > required.

    >

    > Pools are a lot like snowmelts,

    > energy hogs ;)

    >

    > Covers make a huge difference

    > in the loads, but I understand their challanges

    > with a commercial pool.

    >

    > What does solar look

    > like in that area for some "boost"?

    >

    > hot

    > rod

    >

    > _A

    > HREF="http://www.heatinghelp.com/getListed.cfm?id=

    > 144&Step=30"_To Learn More About This

    > Professional, Click Here to Visit Their Ad in

    > "Find A Professional"_/A_



    Hotrod, Solar I think could be viable if they could find an area large enough and that would not bother the community members. A heat pump would be mighty large to handle even part of the load so I think that is out. Thanks for the reply. Tim
  • tim smith
    tim smith Member Posts: 2,752
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    Solar & or heat pump

    Hotrod, Solar I think could be viable if they could find an area large enough and that would not bother the community members. A heat pump would be mighty large to handle even part of the load so I think that is out. Thanks for the reply. Tim
  • tim smith
    tim smith Member Posts: 2,752
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    Reply to Paul

    Paul, thanks for the reply, pool cover is in next seasons budget, (not that they really need a budget in this area). I have urged them to do so, but not now they say. I think they need at least 1.2 to 1.5 million btu input to do the job properly and not lose temp on the abnormal 50+ avg temp days we sometimes see. The members do not like it when it gets belwo 82 in pool and generally they like 84. Thanks again, Tim
  • Paul B._2
    Paul B._2 Member Posts: 62
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    50° ambient air

    Hi Tim,

    you are in the right neighbor hood with your calculation. With 84° water, and a 50° ambient they would lose 375 btu/sqft. Now that cover really looks good.

    That pumps the required heater input up to 1,875,000 btu/hr. The 1.2 million you are coming up with would probably do the job most of the time for them.

    If local codes require an ANSI Z21.56 pool heater certification for direct heating of pools that would pretty much rule out the use of a condensing boiler to heat the pool directly. Listed pool heaters typically run 82% to 85% efficiency depending on the model.

    If local codes allow a Z21.13 boiler certification to be used for direct pool heating it would allow for a much broader choice of equipment. It may be worth asking the question at the local level.

    Sincerely,

    Paul B.
  • Tom Hopkins
    Tom Hopkins Member Posts: 554
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    HX

    Triangle Tube has an extensive line of pool heat exchangers that would allow you to use a condensing boiler. Of course you'd have to design for a large delta T across the boiler side for significant energy savings.
  • Eric S
    Eric S Member Posts: 1
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    Commercial Pool Boilers

    Tim,
    I have used several Lochinvar Copper-Fin II pool heaters in the past. Great heater and a thermal efficiency of 89% may allow you to reduce the btu input a bit compared to 82% heaters. Worth a look www.lochinvar.com give them a call, they will size the right heater for you as well. Best of luck with the project.
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