Heating swimming pool with geothermal

Discussion in 'General Discussions' started by Chad, Apr 23, 2019.

  1. Chad

    Chad New Member

    We live in southern Missouri. Our home is heated with geothermal (closed loop). We are in the process of replacing our main floor geothermal unit with a WaterFurnace series 7 unit. During this process, the possibility of heating our pool with geothermal came up.

    We have an approximate 16,000 gallon pool. Pool is currently unheated. If we decided to heat the pool, we'd probably extend the swimming season from beginning of May to end of September. Average highs and lows for May and September are 77/53 and 82/57. We'd probably heat the pool to 82 degrees.

    I've found it difficult to find information online re: heating a pool with geothermal. I would think the 2 best options would be 1) geothermal vs 2) air to water heat pump.

    If going geothermal route, I'd assume we'd be looking at purchasing another geothermal unit specifically for the pool. Does anyone have experience with this?

    Thanks in advance for the help.
  2. gsmith22

    gsmith22 Member

    I am by no means an expert here so please chime in if I got this wrong, but heat naturally wants to go from hot to cold (downhill). A heat pump (ground source or air source) can reverse that using the refrigeration cycle (ie it moves heat uphill from cold to hot). Unless your ground is on average hotter than the air between May and Sept, I would think an air source heat pump would be more efficient than a ground source heat pump to heat the pool. Heat the pool year round and the ground source probably makes more sense.

    It seems likely that the air will be warmer than your pool for most of the summer as well. This is the same scenario for a ground source heat pump used for air conditioning in the summer in northern climates (ground cooler than air in home). Heat is flowing downhill from hot (air) to cold (pool/ground) in both scenarios in the direction that it wants to go naturally making it very efficient to use an air source heat pump.
  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    get an air source heat pump for your pool. Aquacal is one of the recommended brands
  4. alx

    alx New Member

    we are in massachusetts and my neighbor heats their pool with air sourced heat pump.

    it is a disaster. she uses 2-3 megawatts per month to heat the pool to 78 and the darn thing is always below that and the pump is always running despite the pool having a thermal cover most of the time
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Are you referring to 2-3 mw/h/month? 3 MW/h divided by 720/months = 4.166 kw/h
    Possible, but obviously there appears to something wrong with the heat pump. Maybe a maintenance visit is in order.

    I am a geo guy who installs ASHPs for pools. Because as mentioned above, the air at the time when I heat my pool (May-Oct) is warmer than the ground, thus it is more efficient to heat the pool that way. Cheaper upfront too.
  6. alx

    alx New Member

    yes, i refer to 3-4 mw/h per month... at 25 cents per kwh it tends to get expensive.

    they have had many service calls (the family is really well off) to remedy the situation, but the consumption has remained very high. her pool is 25k gallon outdoor with a thermal cover.

    otherwise, i agree with the observation that you are better off using the 60-80 degree air temp instead of the 50-ish ground temp to heat a pool during the warm months. it is just that i have a single point of reference/ experience and it is not a good one at all..
    Last edited: Apr 24, 2019
  7. Chad

    Chad New Member

    Any other recommended brands? Want to see what options I have re: installers.

  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Pool heat pumps are not geo.

    2" pvc inlet piping, 2" pvc outlet piping, connect the power, set the pool temperature.......not rocket science
  9. Chad

    Chad New Member

    Ok. Will look into Aquacal. Will have to research differences between Heatwave and Tropical.

    One additional question:
    All pool equipment is located in a covered utility room (unconditioned) attached to the garage. This is ventilated to outdoors with 2 vents (as we have gas heater for spa). Installation of air to water heat pump would be easier if placed in this utility room. However, I assume efficiency would be better if we installed outdoors. Utility room has an exterior wall. Any idea of ballpark efficiency improvement if installed outdoors?

    Thanks for all the help!
  10. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    They are like an outdoor condenser for an a/C, they need to be outside and have air flow.
  11. alx

    alx New Member

    you really need 8 feet of clear space above and good air flow for those darn things to work well

Share This Page