Geothermal for Swimming Pool?

Discussion in 'Swimming Pools and Hot Tubs' started by dwink2u, Sep 22, 2009.

  1. dwink2u

    dwink2u New Member

    Any thoughts on this? Are there units that are made to heat pools? Do you need a separate well or can you use one for the house? Haven't installed geothermal yet - just looking for answers.

  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    What do you want to do?

    Heat and cool the house or the pool?

    Either or both can be done.
  3. dwink2u

    dwink2u New Member

    Planning on having it installed for the house and would like to heat the pool also.
  4. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    Doable, expensive to install very inexpensive to operate. Closed loop can benefit from this double duty.
    Good Luck,
  5. dwink2u

    dwink2u New Member


    Thanks for all your info.! Can you expand on this? Yesterday they said it would take 3 add'l. (300 ft.) wells to install geo for pool. Does that sound right? And, would you use a pool heater specifically designed for geo? Haven't seen them anywhere - where would I look for pricing?

    Thanks again!!
  6. teetech

    teetech Member Forum Leader

    They make water to air heat pumps for pools.
  7. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I would use the

    Pool to cool the house. Move the heat from the house to the pool. I like passive use of thermal dynamics, but the guys that make electricity need to eat too.
  8. dwink2u

    dwink2u New Member


    Can you explain what you mean? I'm not in the "biz" so I don't understand all the terminology :) .

  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I just get waves of thought

    If you are hot and have a pool take the heat out of the house and put it in the pool. Warmer swimming. If you are cold I doubt you want in the pool, so take the heat out of the pool and put it in the house.

    I will type more if needed. I just think this stuff up, while trying to move BTUH.
  10. dwink2u

    dwink2u New Member

    Great concept but how would you do this? I read about a system that actually uses attic heat (water circulates thru the attic) - sounds kind of like what you're suggesting.

    Thanks again!
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I still read Mother Earth News,

    .....but that is not what I type about. Look up a few posts and see air to water heat pumps made for pools.

    There are water to water units that beet Energy-star by spades, so it is possible.
  12. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Re: I just get waves of thought

    I've thought about trying that here in Jax. An inground pool might have enough ground contact to support our mild heating season, and cooling the pool water in the off season might help inhibit bio fouling and / or reduce chemical usage. During the cooling season we'd have to watch for overheating the pool, but evaporative losses, evening convection and radiation might suffice. A high temperature-activated fountain might help as well.

    Just some thoughts I've had...
  13. dwink2u

    dwink2u New Member

    I just received the quote from the SolarAttic pool heater and installed it's $5,800 (+9.25% tax!)! That seems quite high for such an seemingly simple operation and installation. Anyone have any ideas as to what geothermal poolheating (or solar) would cost - inground w/approx. 40,000 gallons.
  14. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    The difference between

    a pool and a pond is concrete or vinyl and paint.
  15. ecosystem3

    ecosystem3 New Member

    Yes, you can take the waste heat out of the house and use it to heat the pool. The question is will it be cost effective to do so.

    It all depends on the amount of BTU's you're taking out of the house, the surface area of the pool, desired water temperature and average air temperature. The volume of water is taken into consideration when you wish to raise the current temperature.

    Back of the envelope calculation, a pool with a surface area of 800 square feet (20'x40'), average air temp of 70 degrees, and a desired water temp of 85 degrees would require about 60K BTU's just to maintain water temperature. If you wish to raise the temperature when the pool is opened in the springtime, for instance, it'll require greater BTU's. And this only happens when the air conditioner is on. If you don't need the AC, you're not heating the pool.

    Just my two cents
  16. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    IMO I'd go with an external roof mounted solar thermal panel system for heating pools long before I'd allow poolwater in my attic.

    As for heat pumps, I'd stick with conventional air source pool heat pumps. They are mass-produced, reasonably priced, effective, simple to install and operate at quite favorable COPs at air temperatures realistic for outdoor pool use.

    If your app is an indoor year-round pool needing heat all winter in a northern clime, that's a different matter and water-source geo might make more sense.
  17. dwink2u

    dwink2u New Member

    Thanks for input. And, pardon my ignorance :) but what is COP? What should I search for in looking for this type of unit (air source pool heat pump)? And, does it effectively heat the pool and efficiency in operation? Just don't want to spend $300-400/mo. to heat a pool!

    Thanks again!
  18. engineer

    engineer Well-Known Member Industry Professional Forum Leader


    COP refers to coefficient of performance, the ratio of heat out per unit of electricity consumed. Florida code requires COP >4.0 for heat pump pool heaters.

    The devil is in the details - COPs are calculated at differing conditions - there seems to be less standardization as there is with house HVAC systems. I do believe some are AHRI certified, so check there.

    I'm really not an expert, but I'd look for efficiency, quiet operation, and a reasonable warranty. Local pool contractors probably have favorite brands. A titanium heat exchanger may help the unit endure pool water longer.
  19. While I have not been in the geothermal industry as long as a lot of the other folks on this forum, some of the guys I work with have been doing geothermal for a long time, and the consensus seems to be that geothermal can be a cost effective way to heat an outdoor pool, but with a few caveats. Yes, it will require more loop (two extra 300' bores sounds reasonable), and the big one-it may take several weeks to raise the temperature of the pool to the desired temperature. Kicking it on a week before a spring pool party wouldn't be enough time, whereas a gas-fired heater could probably handle it (with a pool cover at night). Also, I don't think there are any tax incentives for geothermal pool heat. Heat pumps are great at producing hot water, but outdoor pools are really big loads.
  20. spence57

    spence57 New Member

    I just tried it myself. I have a 5 ton unit and I hooked it up to my 20,000 gallon 20 x 40 pool. It had cooled off to 61 degrees after our PA 40 to 75 degree fall weather. I kept a bubble cover on all except the steps the whole time. The Heat Pump raised the water temperature of I'd guess about 15 gallons/minute of water 10 degrees and I ran it about 3 days. It pumped from the bottom and the incoming water stayed at 61 for a day and then went up to about 64 after 72 hours. I guess that there was some kind of thermal gradient in the pool. I think I'd really have to be a daily swim lover to keep it up. I don't think I'd install a ground source heat pump just for the pool unless I would use it for 3 mos/year or more. If I had one anyway for the house it would make sense to use it if I could and didn't mind the electric bills. I'd guess that it would make a lot of sense for an indoor pool though. If you heated the pool and the pool heat heated the house then I'd guess it would be fairly cheap if your pool room were well insulated. Humidity would be a consideration.

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