Geothermal AC/Pool/Water

11 years ago

I am planning a new house and pool in Florida. This is all new construction, so I want to incorporate all the best ideas for long term energy savings and reliability, and I'm willing to invest in good ideas that have long term payback.

I have discovered some companies like Hotspot Energy that use your pool as a geothermal heat sink for your air conditioner, but this only seems valuable in the spring and fall here. I've also toyed with the idea of Geothermal (ground temperature 75F here), but I'd really like to get the most out of it, if I can.

My Question: Is it possible to put separate heat pumps on my pool, AC, and water heater, all of which use the same geothermal ground loop and pump to either dump or draw heat? this would have the added benefit of transferring heat directly from the AC to the pool and water heater when on at the same time. I've drawn a diagram of what I'm imagining below, and I have to assume that either someone has created such a system before, or there's a good cost reason why this is a bad idea. Any feedback is greatly appreciated.

Featured Answer

fsq4cw

11 years ago

If only heated and not
heated & Chilled water is needed, then look to a ‘triple function’
geothermal unit with forced air heating & cooling, domestic hot water AND full
capacity hot water for pool/spa, radiant in-floor etc.

See page 20 of the following
link for schematic:

http://www.nordicghp.com/wp-content/uploads/2014/10/001223MAN-04-Modular-TF-Series-Two-Stage-R410a.pdf

If Hot AND chilled water are
required, a liquid to water geothermal heat pump is required, see link below
(see, “What is Simultaneous Heating and Cooling?”):

http://www.nordicghp.com/product/nordic-products/liquid-source-heat-pumps/liquid-to-water/emw-series/

Note the doubling of COP to
~8 when heating & cooling are demanded. This is far beyond the
efficiencies of any air-source technologies to date!

I suggest that you continue
to educate yourself; you’re on the right track.

The links to Nordic are for
illustration only, they are however proven, reliable heat pumps.

IMPO

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Comments (7)

Douglas
Original Author
11 years ago
Thanks SR! I cannot foresee wanting to chill the pool. I like it warm (~85 to 90F) and even in the summer the pool will likely not exceed low 90s as long as i'm not heating it.
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fsq4cw
11 years ago
I understand that you do not want to chill the pool.
However, you may want to cool the house. The concept is that heat extracted
from one place can be used elsewhere.

SR
Douglas
Original Author
11 years ago
Agreed. I was simply responding to your comment "If Hot AND chilled water are required..."

Thanks again!
ionized_gw
11 years ago
Using the pool as a heat sink for the house might be a good idea, but you might consider a dedicated solar pool heater. Do the calculations. Solar for pool is very inexpensive and could save a lot of wear on expensive heat pump equipment.
Douglas thanked ionized_gw
Douglas
Original Author
11 years ago
I have solar on my current pool, and here are my thoughts...

It cost about $5k to install, which is not too much considering the alternatives, but I do have to run my pump at a higher speed when in solar heating mode. the pump burns about 200w more at this speed, so if I had to give you a ballpark estimate, I'd say it costs me an extra $2/month in electricity costs. Free for all practical purposes.

On the downside though, it doesn't heat it enough for my liking from about Dec 1 to Mar 1. Definitely not in January.

My hope is investing that $5k in the geothermal solution will help offset some of that geothermal cost, allow me to swim in the winter months, and perhaps become cheaper in the long run, since it will sink heat for the AC.

You're right though, I need to pull out excel and do some estimates.
countryboymo
11 years ago
I guess I don't understand your statement ionized. I don't think any of this is for the 'pool comfort' as much as it is using the pool as a thermal battery to draw from or put heat. It would not put any more use on the home system than a pond geothermal, or shouldn't.

I would think in Florida you would have issues with over heating the pool in the summer and getting it too close to bath water. I bet if a 100 or 200' coil of regular geothermal pipe was used outside of the pool to circulate pool water through it would help. I am thinking of a ground temp of 50-60 though which it is like 75 there so it might need more.

I would make sure I have room for either a length of slinky pipe or a vertical bore would be best possibly two to supplement the pool. I think he is on to something incredible that would save thousands on install cost but I think a minimal amount of supplemental conventional geothermal bore hole or buried slinky might be needed to keep the pool from turning into a hot tub and killing efficiency especially during the hottest months.

It then would have to be decided what method would be best for efficiency and pool comfort. The borehole could be part of the loop distributing the heat from the house into the borehole first and then utilize the pool water or have the borehole on a separate system solely on the pool water and the pump only run as needed through the borehole to regulate pool water temp.

In my mind I like the latter best since the borehole or slinky could be used to keep the pool temp regulated and save $$ from unnecessary pumping.