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Old 08-02-2008, 10:09 PM   #1
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Radiant cooling--will this work?????


OK, it takes a while to lay this out. I've been scheming about a way to cool a moderately sized A-frame with recirculating cool water. It seems simple, but then I have virtually no HVAC education so I'm asking for opinions.

I believe enough thermal energy could be stored in a concrete slab to offer an almost endless supply of cool water--it might be as simple as encasing PEX in a concrete slab at the bottom of a swimming pool (or, a small pond if one has country property). All bodies of water have a thermocline, a point below which the water is usually much cooler (yeah, I know about inversions, but go with me here), so how about using a small pump to recirculate water through the slab and into some sort of ceiling mounted heat exchanger inside the house. If one wanted to use solar power for the pump, a small PV panel and a 12-V battery/pump might be a possibility.

What little I've found on the web says ceiling based systems suffer from condensation, but this house will (may?) be located in arid SW KS, where the relative humidity varied between 20% and 50% for the 6 weeks I spent there in June and July of this year. I figure for this pipe-dream to work in an A-frame, floor-based cooling is not an option.

Really, I'm not a trained engineer or anything like that, perhaps just a dreamer, so I'll not be insulted if responders want to explain why it won't work. If it makes any difference, the A-Frame will have a full basement.

Thanks for helping with this--I'm retired, so I'm interested in investing a significant amount at the time of construction to avoid having to power my heating/cooling functions with electricity or gas.

Dugly

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Old 08-03-2008, 08:10 AM   #2
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Radiant cooling--will this work?????


Keep in mind that thermoclines are natural events, once you disturb this natural event, everything changes. As long as your requirements for cooling are not 72 deg on a 90 deg day you would get a benefit from your idea, but only for a short period of time. You would need a puddle the size of Manhattan, a pump the size of a Volkswagon, and permission from everyones enviroment it effects to meet the demand. Size is the problem, bigger=$$,

Geo-Thermal heat pumps operate on the same principle, and based on the costs of installation, now your really out in left field, and competitive pricing makes solar/windmill a viable option.

Great idea, Why not just try it, thats how new ideas benefit all of us critics.


Last edited by 8 Ball; 08-03-2008 at 08:41 AM.
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Old 08-03-2008, 09:07 AM   #3
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Radiant cooling--will this work?????


I'd do the research before buying anything.

Quote:
Originally Posted by YerDugliness View Post
I believe enough thermal energy could be stored in a concrete slab to offer an almost endless supply of cool water
For cool water, it's actually a lack of thermal energy.

I did hear, many years ago, about a guy who pumped well water through an auto radiator mounted in his duct work and so had a very low power AC unit.
It worked fine, and others had a hard time believing it. It probably didn't dehumidify but it wasn't as damp as an evaporator cooler.
His duct output air temp was a constant 72F.

You also may want to bone up on the psychrometric chart. Goodheart and Wilcox publish some pretty good books on HVAC.

In your case, the concrete acts as a low pass filter, smoothing out temp variations.
Of course, if you have a prolonged hot spell, the system may not work so well, but I don't know what a "hot spell" means for ground temperatures, or what would cause it.
The Germans use the specific heat of stones and such to provide heat, based on the same principles. For the design specifics, I'd search for the German equivalent of ASHRAE. In this country, we're not so much into this yet.

You don't need so much climate data for your area as ground temperatures and its variations and the specific heats of the materials.
And some heat pumps use ponds so the heat pump people must have data on this kind of thing. The trick is to find it.

My first question would be "What performance can you expect?"

If you live near a college that offers courses in thermodynamics, almost any student or professor may have/probably has already studied this and the info might be free for the asking. It will save you from pursuing dead ends.
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Old 08-03-2008, 09:12 AM   #4
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Radiant cooling--will this work?????


Stone/solar collectors were popular 20 years ago. Problem again was mass.
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Old 08-03-2008, 09:39 AM   #5
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Radiant cooling--will this work?????


Quote:
Originally Posted by 8 Ball View Post
Stone/solar collectors were popular 20 years ago. Problem again was mass.
So, not feasible for Mr. Ness?
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Old 08-03-2008, 09:49 AM   #6
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Radiant cooling--will this work?????


Absolutely feasible. If the space is available, and the esthetics are acceptable. However, cooling may still be an issue.


Last edited by 8 Ball; 08-03-2008 at 09:54 AM.
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