Geothermal chiller

[VitaminD]

Building a new home, digging foundation now- was thinking if I ran pex tubing outside the walls about 6 ft down if that would make a good passive chiller. Any other ideas while digging and pouring slab is appreciated.

 

[Radman73]

Building a new home, digging foundation now- was thinking if I ran pex tubing outside the walls about 6 ft down if that would make a good passive chiller. Any other ideas while digging and pouring slab is appreciated.

Pretty good idea. Following along as I live in Central FL so a passive chiller would be excellent.

 

[ca1ore]

Depends on where you live, but 6' down here is CT stays at about 50-55 degrees year round. Imagine this would work as well or as poorly as using well water to cool a tank …. but without wasting water. I'd absolutely give it a shot. Use at least 3/4" pex though as a long run like that will put a lot of friction pressure on the pump. You thinking about running SW directly through the loop or using a heat exchanger inside the house?

 

[Gareth elliott]

Most places this should work, how are you planning water movement?
id imagine contact time would be important. Too slow and not enough tank water moves in a given hour to chill, too fast and the water may not have a chance to lower its temp.

Also head pressure maybe problematic for 12’ of vertical pipe plus whatever the distance from tank to start.

 

[VitaminD]

Pretty good idea. Following along as I live in Central FL so a passive chiller would be excellent.

I am installing potable water pex tubing in my slab anyway for radiant heat will just use my leftover for this experiment. Stay tuned.

 

[Radman73]

Depends on where you live, but 6' down here is CT stays at about 50-55 degrees year round. Imagine this would work as well or as poorly as using well water to cool a tank …. but without wasting water. I'd absolutely give it a shot. Use at least 3/4" pex though as a long run like that will put a lot of friction pressure on the pump. You thinking about running SW directly through the loop or using a heat exchanger inside the house?

Yeah, the issue is the heat transfer. I don't know of anything that's efficient at heat transfer that is also reef safe. I suppose you could paint metal tubing but I personally wouldn't trust it. What does a chiller use? Titanium? I suppose you could take the heat exchanger out out of an old chiller and drop it into a fuge. Then, if you were going to closed system, a positive displacement pump might work. Depends on flow rate required. I might need to do some digging and find heat exchange and flow calculations. I haven't done this stuff in nearly 25 years. A good positive displacement pump isn't cheap though, and they get very expensive when you need a high flow rate.

 

[VitaminD]

My tubing is from radiantec and part of my floor heating system . I will Split off from my basement return pump back to sump with a ball valve and a dig temp on outlet to adjust accordingly. 100’ of pex in 60 degree dirt cools well as it will heat in my slab

 

[ca1ore]

Also head pressure maybe problematic for 12’ of vertical pipe plus whatever the distance from tank to start.

No head pressure per se as long as the 6' down is offset by 6' up. Major friction though.

 

[ca1ore]

Yeah, the issue is the heat transfer. I don't know of anything that's efficient at heat transfer that is also reef safe. I suppose you could paint metal tubing but I personally wouldn't trust it. What does a chiller use? Titanium? I suppose you could take the heat exchanger out out of an old chiller and drop it into a fuge. Then, if you were going to closed system, a positive displacement pump might work. Depends on flow rate required. I might need to do some digging and find heat exchange and flow calculations. I haven't done this stuff in nearly 25 years. A good positive displacement pump isn't cheap though, and they get very expensive when you need a high flow rate.

If you do a search here for folks using a HW heater for their tank, there are some heat exchangers used that could work. Not many are using their well or geothermal for cooling though. I attempted it with a purpose built system …. hasn't worked well so far.