Heating a pool with Geothermal

Discussion in 'General Discussions' started by Liquorman1, May 5, 2020.

  1. Liquorman1

    Liquorman1 New Member

    I’m in South Carolina, with a WF7 & 4 ~150ft bores.

    I’ve read Doc Jensen and others say that ASHP is cheaper and a better option because of ground temps vs air temps while attempting to heat a pool. I’m assuming this is because many of the Geo guys on here are up north with Much lower ground temps.

    My question: my Loop temps currently sit at 72 (never got above 75 last summer even in the south) and in the winter never got below 67 (my WF7 only ran 6 times the whole winter. Spray foam and having to run a separate dehumidifier cured having to run the Geo).

    In the shoulder seasons where I would want to heat my pool, I use absolutely no geo, and in any case, I assume it would help the loop field by taking heat from the ground just before and after I am adding heat from the geo due to cooling load. Would it make sense in my case to heat the pool using my existing loop field and an add on W-W unit or just go with the existing consensus and get an AquaCal ASHP for my pool?

    I also consider Upfront cost VS long term savings with either option. A Hayward Heat Pump (I would upgrade to an Aquacal) was quoted at $4500 installed, approximately how much would a W-W system cost?
  2. gsmith22

    gsmith22 Active Member Forum Leader

    Which temp is higher when you are planning on heating the pool - ground temp or air temp? Besides the fact that ASHP's cost less to install than a GSHP (even with looping already in place), you want to take heat from the highest temperature source to heat the pool for maximum efficiency. If your ground temp is roughly 70deg, I would think your air temp even in shoulder seasons has to be higher than that. From a macro point of view, ground temps (away from your loop piping) don't change and are roughly equivalent to the average yearly air temperature in your climate. Unless you plan to exclusively use a heat pump to heat the pool in January or February, I would have to think the ASHP wins in spring, summer, and fall. You want the highest temperature source because that limits the amount of compressor use so that you have energy running down hill (the way it wants to flow). Most heat pumps (and their refrigeration cycle) are needed to push heat uphill (a/c in the summer, your refrigerator, geo in the winter, heat pump water heater, etc.). If you can set up a situation to have energy run downhill, you are way ahead. Which is why ASHP are so efficient for pool heating because generally the air is hotter than the water when you are swimming.
  3. Deuce

    Deuce Member

    The Geo should have a much longer life (2x - 3x).
  4. gsmith22

    gsmith22 Active Member Forum Leader

    I'm not sure that is true - would love to hear feedback from an actual user in this manner. You would be circulating chlorine/salt water so I would assume that a cupro-nickle heat exchanger is needed. Longevity/maintenance is probably more akin to an open loop system. And even then I'm not sure its the correct comparison because ground water isn't chlorinated/salty. Plus, the unit I would think would be outside and not inside. Much of the touted longer life span is because of the interior/sheltered placement of most units. Look, I'm not saying there is never a situation where geo for pool makes sense, and I have run the various what ifs (we are getting a pool), but I quickly decided "no" on this option.
  5. Deuce

    Deuce Member

    Why couldn't it be inside?
  6. gsmith22

    gsmith22 Active Member Forum Leader

    i'm sure it could. but then you are running the pool plumbing inside the house. if its outside the house, you are bringing the loop piping back outside (or diverting to the pool before it goes inside). pool equipment is typically all grouped together outside. its really not the main issue and could probably be worked out if someone was hell bent on using geo for pool heating.
  7. rothmanproperties

    rothmanproperties New Member

  8. Air Locked

    Air Locked Member

    Not titanium??? I went with it for my spa project. I had good dealings with Bowman in the UK; it costs far less to phone them than you'd think.
  9. gsmith22

    gsmith22 Active Member Forum Leader

    no, titanium is correct. I was loosely following your other thread where folks who know better than me directed you in the correct manner. The primary point I was making above is that for the vast majority of pools (they are outdoor and swimming occurs in the summer), air source heat pumps make more sense both from an HVAC and economic standpoint. Indoor, year round heated pools are a different matter entirely but that is not what the original OP was asking about.
  10. Air Locked

    Air Locked Member

    Yes, my project is an edge case. It will be in an unheated solarium, except for the sun and losses from the spa. But it will be used year-round.

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