Using swimming pool as water source for heat pump AC? - Page 5
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  1. #53
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    2,298
    Quote Originally Posted by GoofBall View Post
    I assume your question is "what happens when you turn off the pool waterpump?"
    In my proposal the original condensor is still installed and ready for action - just flick on the power switch to the condensor fan, and you're back to the original old-fashioned low-efficiency setup.
    lol...you must work for or rep a geo company.

    The addition of a condenser fan does not make a AC unit low effeciency. Plenty of high seer air source units that are far cheaper to install and much more practical in some parts of the Country.

    It reminds me of the guys that push heat pumps in my neck of the woods when natuaral gas is practically given away.

  2. #54
    Join Date
    Aug 2012
    Location
    Upstate NY
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    3
    Old post but I thought I'd put some numbers to the question....

    Assume the hp is rejecting 3 tons of heat into a medium sized inground pool of 20,000 gallons.

    Heat into pool 36,000 btu/hr
    Specific heat of water 1 Btu/lbm-F
    Pool water volume 20,000 gal (167,000 lbs)

    =167,000 lbs / (36,000 btu/hr / 1 Btu/lbm-F)
    =4.63 hrs/F

    So for about every 4.6 hrs of run time on the heat pump, the pool water temp would increase 1 degree.

    This is assuming no other heat transfer to the air/ground/eveaporation/solar which there obviously will be. During the summer months I think it is safe to say that the pool temp would hit the 100F mark without much trouble after a couple of weeks. I live in upstate NY and even without the solar cover my inground pool maintains 80F+ during july and august (especially this summer). From a more practicle point of view, any pool warmer than 85 starts to feel like bathwater to me.

  3. #55
    Join Date
    Apr 2012
    Location
    Georgetown Delaware
    Posts
    197
    The whole concept is reffered to as a " geo battery " and all the math I have seen on operateing it, the pool/or burried tank is allways followed by how much btu replenishment of the battery in fresh water in and hot or cold water is needed opposed to hours of operation for the heat pump. The one that was built and works was a coil of copper pipe put into a tank that was fed continuously by a natural spring at a slow rate and then piped to waste in the nearby creek. It enjoys being a closed, open loop/ with continuous replenishment. I think the load was around 3 tons or so.
    Eric
    Eric Sackett
    weberwelldrilling.com
    Delta P= 8 ATA
    www.youtube.com/weberwelldrilling

  4. #56
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by BigBlock View Post
    Old post but I thought I'd put some numbers to the question....

    Assume the hp is rejecting 3 tons of heat into a medium sized inground pool of 20,000 gallons.

    Heat into pool 36,000 btu/hr
    Specific heat of water 1 Btu/lbm-F
    Pool water volume 20,000 gal (167,000 lbs)

    =167,000 lbs / (36,000 btu/hr / 1 Btu/lbm-F)
    =4.63 hrs/F

    So for about every 4.6 hrs of run time on the heat pump, the pool water temp would increase 1 degree.

    This is assuming no other heat transfer to the air/ground/eveaporation/solar which there obviously will be. During the summer months I think it is safe to say that the pool temp would hit the 100F mark without much trouble after a couple of weeks. I live in upstate NY and even without the solar cover my inground pool maintains 80F+ during july and august (especially this summer). From a more practicle point of view, any pool warmer than 85 starts to feel like bathwater to me.
    But it won't evaporation is pretty significant and the warmer the water is, the higher the evaporation rate. Plus it will reject more heat into the ground as well. But yes, it would raise the pool temp. 5-7F wouldn't suprise me. I don't think that's enough heat to hold much over 90F. But it might make the pool less enjoyable mid-summer.

  5. #57
    Join Date
    Jun 2012
    Location
    Louisville, KY
    Posts
    141
    To OP - Not to over-simplify, but wouldn't it cheaper and simpler - if you are just trying to cool a relatively small space for a couple hours at a time - to install a small ductless AC or, heck, even window units? I'm not a tech but this whole pool setup seems like overkill!!

  6. #58

    Waste Heat From House To Swimming Pool

    I built a system such as the one that is in question here and it is in its sixth year of operation. The WSHP is a Climate Master 5 ton that was designed/intended for geothermal application. The only water the WSHP has ever seen is the water from a 18x36x6 vinyl ig pool, location being Long Island,NY.

    I am a professional pool builder by trade, not HVAC. The system works flawlessly and is part of a pool system that creates more energy than it consumes. ( No this is not over-unity nonsense), but relies on the fact that the pool is idle for 5 months of the year.

    Should anyone need free advice on how to heat your pool for free, do not hesitate to contact me.

  7. #59
    Join Date
    Jun 2011
    Location
    Virginia Beach VA
    Posts
    43
    Quote Originally Posted by BigBlock View Post
    Old post but I thought I'd put some numbers to the question....

    Assume the hp is rejecting 3 tons of heat into a medium sized inground pool of 20,000 gallons.

    Heat into pool 36,000 btu/hr
    Specific heat of water 1 Btu/lbm-F
    Pool water volume 20,000 gal (167,000 lbs)

    =167,000 lbs / (36,000 btu/hr / 1 Btu/lbm-F)
    =4.63 hrs/F
    Actually, a 36000 BTU unit will have to reject at least 15000BTU per ton or total 45000BTU/h for 3 tons including superheat etc. So in a 8 hour day of running AC you would get somewhere around 360,000BTU, which is equal to about 7 of the extra large solar water heating panels from somewhere like aquatherm. That's enough to maintain heat in most pools. There are some products on the market that heat pools with air conditioners, not sure if they work with heat pumps. Google hotspot pool heater to see an example.

  8. #60
    Join Date
    Oct 2003
    Posts
    63
    Quote Originally Posted by GoofBall View Post
    Let's assume it gets as bad as some have suggested: Isn't it still more efficient to heat exchange with 100F water than with 80F air?
    The COP (efficiency) depends on the "lift" - the temperature difference between indoors and outdoors. If you want 75F indoors: 80F outdoors requires only 5R(Rankin) of lift. But 100F outdoors requires 25R of lift, with a corresponding drop in efficiency.
    This answer has been bugging me: If you have a perfectly efficient exchange with an 80F sink of course you prefer that to a 100F sink for cooling. But isn't a sink's thermal conductivity a factor in residential heat pumps? Or is every air-cooled compressor in typical working condition able to get the refrigerant to the ambient air temperature using the exterior fan and heat exchanger?

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