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[donahuej]

Now that I can keep my house 73 degrees all winter  - I'm thinking of way to use the boiler infrastructure to cool the old homestead on those 100 degree July days.  Anyone every tried a geo setup up to pump cold water thru their line set in the summer?  In theory it's exactly what a conventional geothermal system would do pump and or circulate water in the ground.  Here is the idea:

Take 600-1000 feet of 3/4 poly burry it 6-8 in a trench - t off my 1" supply from the boiler to the line set in the house - pump the water to air exchangers and back to the return side of the boiler - push the water thru the underground loop instead of the boiler.  It's gotta take the heat out and cool the water right?   I mean we all have the effort and $$$ into our line sets, exchangers and pumps this should work.  I may need to mess with the pump and coil in the ground diameter/length by the theory seems sound to me.  Any HVAC guys out there that can help size a geo coil?

Ideas - thoughts - comments -

[yoderheating]

You would need some kind of A coil, with a flat coil you may have some sweating issues. 

[Bull]

This has been discussed on here but I don't remember where.

[willieG]

it may be possable but my geotherm unit uses 3500 feet of 1-1/4 in black pipe for gathering heat

you would need some sort of dehumidifier to drain the water from teh coil i think (im not sure)

[peacmar]

I've looked into this exact idea myself. It lead me into a summer long learning endeavour geared towards DIY geothermal and while the concept is very sound and will work I have found one major down fall. The ground will only cool your water to about 50-55 degrees. Great to remove the sensible heat, but does nothing for latent heat. In other words, you will have a cool but very damp home. A heat pump of sorts is necessary to drop the air exchangers coil cool enough to dehumidify at any reasonable rate. I could go on for hours about this as I was very seriously considering the project this summer but due to the size of the project I've decided to hold off for a future date. If you really want to give it a whirl start searching for DIY geothermal info. Keep in mind that it takes 600 ft of underground line per ton of cooling. If you really want to dive in, check out DIY R290 refrigeration. There are a few ppl out there who have done this, but trust me its not a simple project or for the faint of heart.

[dirtryder]

I have heard about the moisture problem too with trying to run cool water for A/C. Here is a good read about using cold "air" from underground. I found it to be a very informative and technical read, thought about it, but didn't want to take on a project like this..........just yet anyway....

http://mb-soft.com/solar/saving.html

[donahuej]

Thanks for the replies...I see some of the challenges...What if we build a loop to pull the heat out but run the regular Air conditioning to deal with the humidity and latent air?  I think the geo loop rad would have to be on the return side for this theory to work.  I know this summer was a killer here in NJ and anything I can do to help - I'm willing this theory just seems to right to be wrong....Off to read some more...

Thanks keep the ideas flowing....

[peacmar]

I have heard about the moisture problem too with trying to run cool water for A/C. Here is a good read about using cold "air" from underground. I found it to be a very informative and technical read, thought about it, but didn't want to take on a project like this..........just yet anyway....

http://mb-soft.com/solar/saving.html

The problem with the "air" systems is they promote mold and mildew growth when the humid air condenses on the walls of the air tubes and then puddles in them.

I'm trying to dig up something I read a while back where a guy took a 8500 btu window AC unit and ran a small water loop from the yard into a small box he built around the condenser coil. The neat thing about heat pumps is they are more than %100 efficient under the right conditions. This guys unit had a C.O.P. somewhere around 11 (750 watts to more 8500 btu) and by water cooling the condenser with 55 degree water instead of the 90 degree air he was able to hit a C.O.P. of almost 25 as he calculated his heat movement to be about 20000 btu and was able to pipe it into his forced air ducts and cool his 1800 sq ft house reasonably well. He spent a good deal of time on burying the black hdpe tubing but I believe the entire project cost was around $700 not including his personal time.

[donahuej]

Thanks I have six months to research....but the more I look into it - the more it seems it has legs....any info would be appreciated...

found this link describing it from a high level....

http://www.waterfurnace.com/how-it-works.aspx