Cooling cabin with cistern water

[slowrev]

Would this work ?
I have about a 5,000 gal underground cistern. Would circulating it thru a radiator with a fan behind it work for cooling ? and how many BTU's of cooling would be stored in there before the water all got hot. Remember it is under ground so some re-cooling of the water would happen.

Has anyone done this ?

 

[PineRidge]

Don't think your water would be near cold enough to get any benefit with the idea that you describe.

If you don't mind the extra humidity it could be used in a evaporative cooler. But it still isn't like an AC unit that's removing latent and sensible heat at the same time.

 

[Paddy]

There are several problems, water storage size is small, ele to run fans and ele to run pump. Feon is efficient because it draws heat via epaporation with very little volume of fluid.

To use water or cave air would require a constant run. You also need to have a radiator per room. Building under ground gets you in that nice temp zone w/o having to PAY to move it.

 

[knute_m]

We have a "guest house" with a 1600 gallon cistern here in the mountains of WV. This time of year, I think the cistern water is probably 55 to 60 degrees. I don't think it would take it many cycles through a radiator/fan assembly to quickly reach near air temperature. I'm not sure my half-acre pond would even help with much cooling.

Just my opinion.

Knute

 

[bjustice]

Would this work ?

Has anyone done this ?

I have not done it but here are some "ball Park" numbers to think about.
The cistern contains about 5000*8lbs*15=600,000 BTU of sort of "usable" cooling before it reaches 75 degrees. (That is what the 15 is in the above calc, 75 minus the starting temp of about 60 degrees) AS you noted, there will be some cooling from the tank being underground. This could be improved by running the feed and return lines underground in a large loop to pick up more cooling from the earth. There are 12000 BTU in a "Ton" of cooling. Would it work? The short answer is yes--but how well depends on the size of the radiator, the water cooling flow, the air flow, and the cooling load.

 

[tc35dforme]

The biggest problem is dehumidification. Unless you can get the air down to 50 - 55 F, you'll get cool wet air. Not very desireable. It'll be like a cave...cool and damp.

 

[Paddy]

Not saying it wouldn't cool some space. Just not near as efficient as a convential freon baced system. Even a Geo-thermal uses freon. The liquid in the pipes is far less than 1600 gl but, is spaced very far to get the entire field as a heat sink. A system that is over taxed, field is too small, will freeze the field in winter and over heat the field in summer.

I'll bet, You will get more cooling per kW in a window AC

 

[slowrev]

thanks all, especially for the BTU fogires Bjustice.

I thought it would work, and yes the lack of humidity removal would be an issue.
But it would still be better to be humid at 75 or so than humid at 95

I guess I will submerge a freon cooling line in the tank and make up a freon based system out of an old 18K window unit. The cabin is not often used, so I don't think the heat buildup in the cistern will be a problem. and wood heat is used during cold weather.
Plus with the freon based system I won't have to worry about the pipes freezing in the winter. The plumbing is designed to be easially drained out for unoccupied winter times.

 

[Paddy]

You will get humidity dripping off the radator just like a toilet tank drips in a house. A tray under it to colect it for you.

I like the feon coil in the tank of water direction. This would eliminate the fan of the outdoor heat pump concept. Some of the high end Geo-Thermal units use direct bury Cu lines of feon instead of water based solution.

I wonder if it would be as simple as removing the out side coil of a window AC unit and swaping it out for a long coil in the cistern?

 

[slowrev]

You will get humidity dripping off the radator just like a toilet tank drips in a house. A tray under it to colect it for you.

I like the feon coil in the tank of water direction. This would eliminate the fan of the outdoor heat pump concept. Some of the high end Geo-Thermal units use direct bury Cu lines of feon instead of water based solution.

I wonder if it would be as simple as removing the out side coil of a window AC unit and swaping it out for a long coil in the cistern?

That is pretty much what I am planning.

Head pressure on the system should be down compared to an air transfer type of condenser as well.

Yes the condensation tray would be mandatory. Especially with the freon based system as the condensation rate would be much higher.