Geothermal temp control

I had an idea today. My fermentation area in the house is a little cubby behind the coat closet/under the stairs. We mostly use it for seasonal decorations storage, but there's enough room for a few fermenters. What I don't have room for is a fermentation cabinet. This little void in my townhouse happens to be on an exterior wall. I was thinking of burying a copper coil in the ground, drilling holes in the wall to run lines into the little void in my townhouse and then connecting those to another coil in the fermenter. I would circulate water through it with a pump that would be plugged in to a temp controller. I can get the copper for next to nothing. Seems to me like it'd work within certain limitations. Any thoughts?

I have a geothermal system for my house heating. They drilled four wells each 200 feet deep so that the heat exchange is spread around. There is approximately 800 feet of tubing for a 2000 square foot house. I assume that you are using the system for just cooling? You should go down at least 5 feet and then spread your coils. I would guess you could do it with about 16 feet of tubing in the ground?

That depends on where you live. What is your high and low ground temp. (can be found at your local ag. extension office) Is this location in the shade during summer? Thermal mass of wort as apposed to thermal mass of coil. As you can see, there are LOTS of variables. What you may consider is... bury a mass of some type of fluid that won't freeze in a 15 gallon drum. (malt drums from your LHBS would work) The heat exchanger would have PLENTY of thermal mass to work with then.

Also, don't use copper in your fermemtor. It needs to be a Stainless Steel coil unless you would like to poison yourself...

Copper Oxide is poisonous?

Why not put your fermentor in a water bath and use your geothermal system to keep the water bath at a lower temp? What would you use to control the temp?

Gonefishin said:

Why not put your fermentor in a water bath and use your geothermal system to keep the water bath at a lower temp? What would you use to control the temp?

Click to expand...

I like that idea...one less thing to clean/sanitize.

Chattan said:

Copper Oxide is poisonous?

Click to expand...

When soaked in alcohol it pulls something out of the copper that is really bad for you. . I'm sure someone else can chime in with a more technical explanation.
Rule of thumb... Dont use copper in post-fermentation applications.

Huaco said:

When soaked in alcohol it pulls something out of the copper that is really bad for you. . I'm sure someone else can chime in with a more technical explanation.
Rule of thumb... Dont use copper in post-fermentation applications.

Click to expand...

But copper is the goto metal for distilling. Anybody have resources they could cite?

Mischief_Brewing said:

But copper is the goto metal for distilling. Anybody have resources they could cite?

Click to expand...

In distilling you aren't storing the mash in a copper container for long periods of time. When you distill a mash the contact time isn't sufficient to pick up enough dissolved ions to make it even remotely toxic. Therefore copper kettles are OK in brewing, fermentors are not.

http://en.wikipedia.org/wiki/Copper_toxicity

It's the carbon dioxide and moisture that causes copper to make poison