Geothermal question

[zahc]

I live in Texas, where it is hot, and I'm faced with the challenge of keeping fermenting beer cool. I don't have a cellar because those are illegal in Texas, or so one would think since nobody has them. I can't just use my house because we keep the temperature in the high 70s or low 80s to conserve energy. The actual correct solution is to buy a chest freezer or refrigerator for the purpose, but at the moment I use a styrofoam chamber and gallon jugs of ice. It works ok.

Someone at work suggested that I could burrow down in my backyard and install a coolant loop under my shed. Since the ground stays cool, I could circulate water through the ground and obtain a year-round fermentable temperature that would neither freeze nor get hot. Everyone knows caves stay 56 degrees F year-round, after all.

So, how far down DOES one have to burrow in order to achieve stable, cool, cave-like temperatures? I have a feeling it's a bit more than 6 feet.

[Nick1911]

I would think below the frost line.  (If you have a frost line... you probably don't, thus explaining the lack of cellars...)

In HVAC, for ground source heat pumps, around here they drill holes straight down instead of opting for a horizontal loop.  This would probably be the most effective way to get deep enough.

But, a refrigerator or freezer off craigslist, coupled with an aftermarket thermostat would probably not cost much to run.  Your temp differential is only going to be what, 20 degrees?  Not hard to keep a styrofoam box at 65*...

For reference, I bought a thermostat that would work in this application (today actually) for $40 shipped.  And my kegerator refrigerator cost $30 off craigslist.

[drewtam]

My recollection is that at the very surface, the ground tracks very closely with air.
At around ~8', the ground temp approaches the yearly average air temp. For example Dallas would be ~66F.
http://coolweather.net/statetemperature/texas_temperature.htm

The space in between surface and 8ft deep will be a gradient from the air temp to the base average temp. The lower one digs, the slower temps change and the closer it holds to the average.

[K Frame]

You'd probably be able to do a better job with an evaporative cooling rig.

I ferment sauerkraut, which does its best work in temperatures similar to those that beer likes.

A couple of times I've been caught with temperatures that are too warm, but with low ambient humidity.

The fermenter crock goes into a shallow pan filled with water. Towels are wrapped around the fermenter and trail down into the water (capillary action is your friend).

A fan provides the needed evaporative boost.

It's worked like a charm to keep the temperature in my kraut between 64 and 68 degrees when the temperature has spiked.

[K Frame]

Depending on soil conditions and the area of the nation, ground temperatures go stable once you hit about 30 feet down.

Above that and the temperature is subject to fluctuation.

Most horizontal geothermal set ups I've seen bury the tubes anywhere from 6 to 12 feet. Deeper is generally better, but a lot more expensive.

[Tallpine]

The old adobe houses in New Mexico had food coolers that drew in air from under the mud floors.  I've seen them in Taos but don't remember exactly where the air came in.  I doubt the ground channel was very deep.

[HankB]

I live in Texas, where it is hot, and I'm faced with the challenge of keeping fermenting beer cool. I don't have a cellar because those are illegal in Texas, or so one would think since nobody has them.

In my area of TX, only a very few homes have basements - those built on lot where there's a steep slope back from the street. The problem is that once you get down past a couple of inches of poor soil and caliche, you hit solid limestone. And it's expensive to chop out a basement in that stuff and then deal with drainage issues.

As for cooling the beer . . . how big a batch do you brew up at once? Rather than a geo cooling system (which I suspect can get spendy in a hurry) I'd look into getting something like a wine cooler and remove the racks to make room for my fermenter. Or if that's not big enough, build an insulated cabinet/closet and install a cheap air conditioner. A former colleague actually did this with a small closet in his home - got a small A/C unit which does a fine job, and the running cost isn't too high since he's only bringing the temperature down 20-25 degrees from his home. (He said the ductwork was the only part that took a little effort, since he wanted to route the hot exhaust to the outside and the closet he was using didn't have an outside wall.)

[zahc]

My current system works OK; and if I was to upgrade I would probably go the cheap-fridge-route. It was more of a thought experiment. I have no idea how I would dig an 8-foot deep hole in my backyard, anyway. Post hole diggers are only like 5 feet long.

[cassandra and sara's daddy]

http://www.sustainablesupply.com/Nupla-69562-Post-Hole-Digger-72-In-p/w323085.htm?CAWELAID=1307515304


you can get 8 feet with these   but you will not enjoy it

[Fly320s]

Better off renting a trench machine. Or a baby backhoe.

[230RN]

My son who doesn't have a basement bought a used soda-pop vending machine for cheap at a farmer's flea market or on-line or someplace and stripped it out and uses that. I believe he rigged the thermostat for the appropriate temps and turned off the lights in it for efficiency.  I wasn't real interested in the process and the brewery setup was in a back room.  If you need more details, I can ask him.  Now he's into winemaking, but I don't know what he's doing about that.

So you might try contacting local vending machine operators to see what's up with used ones.  Beats digging (and undigging) holes, I guess, though it's not as "cool" as using geothermal techniques.

ETA afterthought triggered by Mike Irwin's remarks, probably not helpful: I recall an episode of M*A*S*H where Frank discovered a kimchi(sp?) pot buried and thought it was a bomb of some kind.  Seems to me it wasn't buried that far down, but it was a TV production, so who knows what liberties they took with fact.  Same temps?

More:  the cooling systems in office building water fountains have pretty small refrigeration units in them. Perhaps something like that might be an option if you can find used/obsolete ones somewhere and repurpose the cooling unit in one of those puppies. 

Terry, 230RN

[280plus]

I like Terry's water fountain idea. You could get a small pump and circulate water through it and tube in whatever box you might use.

[Nick1911]

I like Terry's water fountain idea. You could get a small pump and circulate water through it and tube in whatever box you might use.

Seems overly complicated.  You have a water reservoir and water loop and water pump - for what?  What does this buy you over a standard refrigerator?

[drewtam]

The problem is that once you get down past a couple of inches of poor soil and caliche, you hit solid limestone. And it's expensive to chop out a basement in that stuff and then deal with drainage issues.

DETCORD!!!

[280plus]

Seems overly complicated.  You have a water reservoir and water loop and water pump - for what?  Cooling the beer?

What does this buy you over a standard refrigerator? I don't know I just said I liked the idea. 

[MechAg94]

Get a really cheap little A/C from Wally World and install it on one small room in the house and keep that room/closet colder. 

In parts of Texas near the Gulf Coast where the humidity is higher on average, I don't think evaporative cooling rigs will work as well.

Where I grew up the water table started only a few feet below the ground level depending on where you were.  There was also a whole lot of wet gravel and clay.  I think that can make upkeep of a basement problematic.  Also, in the coastal areas, some areas have a lot of shifting soil problems as you go from wet times to dry times.  All that said, I think cost is a big factor when the land value allows extra square footage.

[Nick1911]

I don't know I just said I liked the idea. 

I mean, it'd look cool, all hollywood-style mad sciencey.  And, bonus points if you use etoh in the coolant water to keep it free of microorganisms! 

[280plus]

It would look cool! 

I'm thinking if it's a sealed system microorganisms should not be a problem. 

[Nick1911]

It would look cool! 

I'm thinking if it's a sealed system microorganisms should not be a problem. 

Ohh, throw a UV sterilizer in the loop!  Now that is looks cool! Just don't look at it too long, UVC is hard on the ol' eyes 

[seeker_two]

I live in Texas, where it is hot, and I'm faced with the challenge of keeping fermenting beer cool. I don't have a cellar because those are illegal in Texas, or so one would think since nobody has them.

Not illegal (unless your city has crazy building codes like Austin does), but not practical due to the limestone & drainage issues mentioned above. Best bet would be an old refrigerator or chest freezer with adjustable temperature. It's far cheaper than    building a cellar or storm shelter....

[280plus]

Ohh, throw a UV sterilizer in the loop!  Now that is looks cool! Just don't look at it too long, UVC is hard on the ol' eyes 

That WOULD be cool! But, my thoughts are a sealed system would soon be depleted of O2 and no life could exist. An OPEN system, however... Legionaire's disease heaven! (Caught it from a water tower once. Massive doses of erythromycin. (sp?) )

[Jamisjockey]

In my part of Texas a cellar would double as an indoor swimming pool!

[Tallpine]

Not illegal (unless your city has crazy building codes like Austin does), but not practical due to the limestone & drainage issues mentioned above. Best bet would be an old refrigerator or chest freezer with adjustable temperature. It's far cheaper than    building a cellar or storm shelter....

But could you crawl into old refrigerator or chest freezer and be safe during a tornado ? 

[Nick1911]

But could you crawl into old refrigerator or chest freezer and be safe during a tornado ? 

Yes.
http://www.youtube.com/watch?v=lbrzQMbTYZM

[280plus]

Amazing how all those cameras were in just the right spots to catch all that!