Desert Geoexchange with Pools

Discussion in 'Swimming Pools and Hot Tubs' started by Marck, Sep 4, 2009.

  1. Marck

    Marck New Member

    Hi everyone.. I am an urban planner that works on numerous projects in desert climates and a common problem it the high heating costs of swimming pools and high cooling costs of the adacent buildings. I was wondering if anybody has developed a system which uses the building and pool to work together to extract the heat from the building to heat the pool which then cools the home? If so I would greatly appreciate contact info to discuss further. Most of the projects are in coastal regions such as Baja if that makes a diffrence.

  2. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    There are several factors that contribute to such a design. A building and pool load must first be calculated. Would the pools ever require cooling? Is water scarce (suggesting that we don't want to cause extra evaporation)? Wants one or the other has reached temp how do you plan to satisfy the other.
    Typically you would still employ ground loops or ASHP equipment.
    I know a ME in New Mexico who has been involved in the design of such a system. I'm not sure he could be much help without more information or a more specific question.
    Good Luck,
  3. Marck

    Marck New Member

    Historically the pools never need to be cooled and water is not a problem, each of the projects has its own desal plant which produces more than enough water. We also don't plan on this system being self sustainable. There would still be a pool heater and AC units on the home, we would just like to be able to reduce the electricty & propane loads. Currently each home is averaging $2,000 a month in utility bills, so every little bit helps out.
  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    Joe's right - gotta have load calcs. Pools that don't need cooling now may suddenly need it with the addition of heat from building AC.

    $2k / month for utilities...yikes! How big are these houses and what are units costs of electricity and propane?

    Certainly if there are long conincident periods of building cooling and pool heating then yes, the two should be able to be married with great gains in efficiency.

    That said, there are myriad details of controls, corrosive pool water, and coordination with conventional systems.
  5. Generally, cooling your house with pool water works. In fact, the WaterFurnace people having been studying it well in Nevada where high ground temps and poor drilling make earth loops difficult. The pool itself becomes heat sink in contact with the ground. The cooling energy is not all supported by evaporation.( or even primarily) I have been pushing this concept (with little success) in Houston , Texas but people are skeptical. I understand that this will extend your pool season a couple of months in the Spring and Fall, and raise pool temps by about 5 degrees in summer. if pool gets too warm, you can add an aerator fountain that should bring it down a few degrees. This application does qualify for the 30% tax rebate. By the way, another neat trick. Use a water to water geo unit to heat you spa or hot tub and cool the pool and the same time. As far a corrosion of your geo coils, pool water (even salt type) should not corrode your coils is the water flows bubble free.
  6. engineer

    engineer Well-Known Member Industry Professional Forum Leader


    Sounds like you've thought this through. My builder and I have tossed this idea around. His observation is that screen enclosures, a virtual necessity here in north Florida owing to bugs and debris, cause pools to lose out on solar gain.

    My concern about corrosion stems in part from the fact that several major pool heat pump mfgs stress their titanium heat exchangers as being corrosion resistant.

    I'd bet the fountain trick would work really well at night in the desert southwest where dewpoints are quite low.

    Heating a spa using pool water in a WW unit should give a COP of 8 or so, done right.
  7. teetech

    teetech Member Forum Leader

    Pool water can be very corrosive to a coax as low PH can be too. Most manufacturers have water quality guidelines and will not warranty a coax damaged by water quality. If the water gets inside the refrigeration system your unit will be toast. A secondary heat exchanger (stainless steel or equivalent) would be a wise choice.
  8. Marck

    Marck New Member

    Thanks for the replys. To answer some of the questions. The homes range from 3k-4k sq ft. and I am not sure what the unit costs are; however I know that the propane costs are extremely high. All of the units do/will have hot tubs, so I do like the idea of heating them also.
  9. Marck

    Marck New Member

  10. Low PH(acid) will corrode without air, but a pool (I think) is kept fairly neutral. (7.0) Salt or chemicals need air to reac. Thus said, plate exchanger is better, but adds cost to the installation. Another concept in hot climates, add a small inline cooling tower to absorb some heat load, and depend on pool temp for heat in winter. That is to say, if pool starts getting too warm (85 or more) the cooling tower can take the load off the pool in summer. There are closed loop evap coolers available for about $3000 for a 10 ton unit.
  11. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    I surfed that Blue EQ site. It seemed long on sizzle and short on steak - no hard data to wrap my mind around.
  12. Marck

    Marck New Member

    I was thinking the same thing. I have called them and they should be calling me back soon with some more information.
  13. Schono

    Schono New Member

    I agree that the BluEQ site is pretty fluffy. I spoke with a rep from "Air Conditioning by Jay" which is the HVAC company Shasta has been working in Phoenix. It sounds like they have a difference of opinion on the best design. AC by Jay is doing geothermal/pool installations, using a cooling tower to take some of the heat load off the pool in the summer, whereas it looks like the Shasta approach is an undergrond radiator and includes a spa "upper reservoir" (all the better for Shasta to sell more pools with spas, if nothing else!) I also spoke with a Shasta rep and they are not (yet) doing retrofits - only offering it with new pool installations. The comments from the AC by Jay rep indicate the installations that had been done using the Shasta design were not doing a good job at regulating the pool temperature in the summer. Take that with as much salt as your personal chlorinator requires!
  14. TedKidd

    TedKidd New Member

    Sounds like a solar opportunity.
  15. Chuy

    Chuy New Member

    I am trying to cool a 2500 ft^2 house, with R30 insulation all around (exterior walls are 8" thick) located in El Paso, TX with a 13,000 gallon pool that is set in the mountain. The mountain was literally cut out to build the pool so it acts like a heat sink. I am thinking of using a heat exchanger (5 ton) Aqua Systems efficient Liquid to Refrigerant Heat Exchangers unit after my compressor to boost my AC efficiency. Do you see any problems with this? What is the 30% tax rebate you are talking about? All I was going to do was put the exchanger between compressor and condensor and flow about 20gpm of pool water through it.

  16. The pool will probably not handle all your heating and cooling needs, but a good part. In summer it will try to get too warm, and you will need a small (not expensive) cooling tower to supplement heat discharge. In winter, you may need ground piping to supplement warmth that may exceed what you can extract from pool. Wilol still be less expensive than a full ground loop system, and will extend your swimming season some,and control your pool from overheating in summer (as some do even without geo). Make sure, as you indicate, to use a heat exchanger and not run pool water through the system. Check Global Industrial. You will need some controls , temp sensors, and valving to control flow and cooling tower. All this qualifies for the 30%. Careful trying to charge 30% of your pool install. Need a good accountant to advise you on that.

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