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  1. #1

    Heating pool with heat recovery unit for AC or Geothermal heat pump

    I have a question about transferring the heat from my house to my swimming pool when I am cooling my house.

    Some info about my house:
    Location: N. CA (San Jose, CA)
    Pool: In ground, 26,000 - 30,000 gal (20x40 feet), salt water
    House: Currently 1,800 square feet, single story, plan to expand to 2,300
    Current HVAC: Just forced air NG furnace, no A/C

    Plan: Install A/C or Heat pump, and use water from my pool
    I was planning to replace all the duct works and have traditional A/C installed, but want to investigate possibility of geothermal.

    Geothermal Question:
    Can I get by just using geothermal for cooling, that is installation of a geothermal open loop system using a swimming pool as the heat sink. My web searches show sporadic results, not much info I can find.
    I would like to install such a system if it is feasible.
    But will my pool get too hot? In my climate it might work, rarely do we get long heat waves.
    Due to the temperate weather, the pool seems like a good candidate for a heat sink. Also, it would aid in heating the pool.

    From what I have researched so far, I would want to install an open loop system, taking the water from my pool, then dumping it back in. Pool would get cooling effect from evaporation. Heating should not be a problem, as winters are quite mild, and I always have the gas furnace as backup.

    Has anyone done this? If so, how was the plumbing done? Tie into the pool plumbing with check valves so pool pump and geothermal pump do not affect each other? Or use pool pump for everything? Any advice or suggestion from someone that has experience with geothermal?

    Any recommendation for geothermal heat pump? I might need one with titanium heat exchanger due to salt water and chlorine.


    A/C question:
    Another option I found is to install traditional A/C and retrofit with a water cooled heat exchanger, using my pool water.
    I found this product that does this:
    http://www.hotspotenergy.com/pool-heater/

    This has a refrigerant to water heat exchanger, which seems the most efficient for an AC.

    My question for this product is if it will be reliable.
    This brochure shows more details:
    http://www.hotspotenergy.com/pool-he...r-brochure.pdf

    Basically, there is a controller that will switch the refrigerant from going to your normal A/C condenser to the heat exchanger using your pool water. This will heat your pool. If your pool gets too hot, it will switch back to using your condenser.

    Any issues with this setup?
    Anyone have any experience with something like this?

    Any advice?
    I plan to have everything professional installed. Since I will be purchasing a completely new cooling system, what do you think will work best?


    Thanks,

  2. #2
    Join Date
    Mar 2012
    Location
    West Chester, PA
    Posts
    511
    Not a geo expert at all but just some thougts...

    You can buy geo just for cooling but why would you? all that investment to only get half the benifit?

    open loop systems in general are undesiarable and require more maintenace
    open loop in a swimming pool is not going to happen

    there are options for using a desuper heater from the geosystem to preheat water for your pool. you would likely still require a pool heater but the desuperheater could preheat the water and reduce the load on the pool heater

    a water source heatpump/ac with special heat exchangers designed so endure the chemicaly treated pool water might be another option. as you mentioned but i don't think you could do a geo loop inside of your pool. Naval ships use units like this, designed to endure salt water. don't know if they make one for pool water..

    the last set up you mentioned is likely the most realistic and is in line with the desuperheating option i had metioned before. This type of work requires a very compitent geo contractor not just any geo guy will do a job like this.

    choose your contractor/engineer carefully

  3. #3
    Join Date
    Feb 2009
    Location
    Portland OR
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    1,851
    You can not run an open loop in a pool, the heat exchanger on a geothermal unit is not meant for this, typically when hooking geothermal up to a pool a titanium heat exchanger is used because of the corrosive properties of pool water.
    How much property do you have? I don't know many areas where there is acreage in San Jose, typically 1 acre or more is most cost effective for geothermal. If you want to heat the pool and cool the house you can always bury the closed loop system next to the pool, this way as your system rejects heat it heats the ground by the pool and during the winter(assuming the pool is not used) will pull heat from the ground around the pool. Even though you have minimal heating in San Jose a ground source heat pump is probably close to half the cost to operate vs your furnace.

    It will certainly be best to contact an IGSHPA certified installer in your area, check www.waterfurnace.com for their dealer locator as they provide excellent training for their dealers and remember, installation first, equipment brand name second.
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  4. #4
    Thanks everyone for the response.
    I don't have anywhere near an acre.
    There is not much room in my backyard for a horizontal ground loop, as it has mostly pool, concrete patio, and an out building. This is a track home in a suburban area, total lot size is about 8,000 sq. feet, which is a big lot for San Jose. But the house and front yard take up a big chunk of that.
    Putting the ground loop around my pool would be require demo of the concrete/stone patio, which I don't want to do as it would be costly to replace.
    I have not looked into vertical loops, but I understand drilling is expensive, but I guess I can check on that in this area.
    I have not heard of Water Furnace, but I just started looking into possibility of geothermal.
    So it looks like a geo with a desuperheater might work.
    But what if my pool gets too hot? Do they have systems with thermostatic control that can bypass desuperheater if my pool gets too hot?
    Do they make desuperheaters with titanium heat exchangers? I imagine this is what is in a Pool heat pump?

    Thanks again for your help,

  5. #5
    Join Date
    Mar 2012
    Location
    West Chester, PA
    Posts
    511
    In our area we do almost exclusively vertical loops. i don't know what the geological differences are in CA. it is roughly 100-150ft per ton of cooling. multiple vertical loops are often used and fit easily in less than an acre lot.

  6. #6
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    IT sounds like given your arear, your heating and cooling loads are minimal for the home, so the pool is descent size migh be large enough for a heat sink. However, couple problems come ot mind.

    1) you'll have to use a heat exchanger as mentioned above. Pool chmicals will eat throguh a copper coils in a heat pump in jsut a few months. SO you'll need a SS heat exchanger and a secodn circulation pump. NBD.

    2) THe pool water temps may be in the 70-80F range most of hte summer. This will need ot be taken into account when sizing. The heat pumps should operate fine at thsi temp, but you won't have near the efficeincy of a ground loop system, but it will still be more efficient than most air source.


    Howeve,r all that being said, unless you NEED to heat your pool, A ulttra high efficiency air source sytem will give you a better ROI, and need less maintenance and fewer things ot fail. With the system your looin at, you have 2 circulation pumps and a heat exchanger to maintain. In winter, you'll have ot cool off the pool ot heat the house, or use only the furnace. SO you're losing a lot of the benfit of a water surce system wince it will only be used for cooling. Plus in winter, the water temps will be cool enough that a HE furnace is probably more efficient overall and just as cheap to operate anyway.

  7. #7
    Join Date
    Feb 2009
    Location
    Portland OR
    Posts
    1,851
    Quote Originally Posted by ADillon View Post
    In our area we do almost exclusively vertical loops. i don't know what the geological differences are in CA. it is roughly 100-150ft per ton of cooling. multiple vertical loops are often used and fit easily in less than an acre lot.
    I wish I was in your area, we would do so much more geo! Vertical loops are maybe one out of every 25 systems here, drilling is $18-20 a foot plus mobilization and a few other charges
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  8. #8
    Join Date
    Mar 2012
    Location
    West Chester, PA
    Posts
    511
    it is usually around 3,000 dollars per 150ft well or 3000 dollars per ton, when it comes to the wells. this is of course just amn estimate and could vary drasticly depending on the situation and the well company and what they do for you. But yes i don't know that i have seen a single trench system in our area. I'm sure there are a few out there but most are verticle. Also i would agree with the above statement, that high effeciency air to air is often a better choice than geo.

  9. #9
    Join Date
    Mar 2012
    Location
    West Chester, PA
    Posts
    511
    trench or horizontal loops often require longer/larger loops and so they cost more money. Shallow trenches don't have the temp stability that a deep vertical wells do

  10. #10
    Well I stumbled on your post and I had to reply. Heating your pool with the heat from your home in the summer is something that we do a lot of. We also heat the home in the winter with the pool. I know other responses are from out of our area but we just completed another one last week. We are Doesn't matter who you are until you are a vetted Pro Member. Please read the site rules. Dad
    Last edited by Dad; 03-05-2013 at 07:11 PM.

  11. #11
    Join Date
    May 2004
    Posts
    11,859
    Quote Originally Posted by snichol View Post
    Well I stumbled on your post and I had to reply. Heating your pool with the heat from your home in the summer is something that we do a lot of. We also heat the home in the winter with the pool. I know other responses are from out of our area but we just completed another one last week. We are Doesn't matter who you are until you are a vetted Pro Member. Please read the site rules. Dad
    Not good.

    See the Rules link in my profile.

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