Not sure that I'm in the correct forum category but here we go ...
We have plans to build a garage 28' x 32' right next to our house. Within the footprint for the garage is an abandoned hand dug well. The well currently is topped with a removable 4" thick square of concrete. It appears to be brick/rock lined then mortared. It's 20' deep by 4' across with the static water level at about 15' (i.e. it has a consistent water depth of 15').
Our initial thoughts were to: a) fill the well in and be done with it or b) pave it over with a manhole access with the intent of using the water for whatever later.
Recently we came upon the idea of using the water column as a kind of geothermal heat source for heating/cooling the garage or perhaps only a conditioned room in the garage. I've inter-webbed and found references to using a well as an open loop "standing column" in combination with a water pump/heat exchanger. All of the references I found talk about a well or wells hundreds of feet deep.
Has anyone experience or thoughts on using a hand dug well as a ground source for a heating/cooling system in this way?
I have no experience to add but I would be tempted to look into closed loop systems so you aren't exchanging water with your ground water. Just in case of contamination.
That seems like a very interesting opportunity, good luck!
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5 feet of water column is not much to exchange heat with. My guess is it would not be worth the equipment to plumb it etc.
My parents have a closed-loop geothermal system with three 200 foot wells. It works well for the most part. They had one cold winter where the glycol going through the system actually froze the groundwater adjacent to all three wells.
The heat capacity of a shallow well wouldn't get you that much heat. Especially if the well isn't pumped. You get more heat if the water is pumped regularly
If you live someplace that isn't too humid and need cooling, this water could be used to mist your roof for evaporative cooling.
Run it through a radiator first ,blowing air over the radiator to capture the "coolth" before misting the water onto the roof.
Your hand dug well has a lot more capacity than (3) drilled wells into the earth (2200 gallons versus 900 gallons), but you lack the surface area to transfer that heat adequately like a narrow, but deep drilled well. What would probably happen is, you would just chill the water down in the winter as you tried to heat the garage, and in the summer slow heat the water in the well as you tried to cool your garage.
If you lived in Maine like I do, you probably could chill your garage in the summer because the water temperature here below frost line is 57 degrees, and by the time heat from the garage was transferred to the water, a well insulated garage would be chilled to a comfortable level, but heating a garage in the winter would be tough. Even well insulated, trying to heat a garage with a 2200 gallon "tank" heated to 57 degrees would be a tall order, and even if it could, it would still be 57 degrees. Better than -20 below outside, but not exactly a humans preferred temperature of 70 degrees either.
Would it be worth it though to take the garage from -20 degrees to 57, then supplement the heat with another traditional heating system? It may be..IF IT WORKED...because only a 13 degree rise in temperature would be needed. That is better than lifting the garage 90 degrees (from -20 to 70 degrees) for sure.
I am not sure if I was in your situation if I would or not. I say that because I have radiant heat and could easily build a compost heating system with my sheep farm manure, but I don't. Why? because for half the amount of time and labor I can just cut 4 cord of firewood and feed my woodstove. So it is not that it cannot be done, or not really help in heating your garage, but a matter of...would it be worth it if a different way is easier and less costly?
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