Greenhouse: Free Heating - Well maybe?, 1 by bwilliams

bwilliams wrote:
I have always paid a lot of attention to how other places heat their greenhouses. It is one of the most expensive or laboring parts of having a greenhouse. Over the years I have seen a lot of different techniques. Most involve boilers furnaces and stoves. Some of the more unique ones were greenhouses at our local city dump using the gas from the decaying trash to heat greenhouses.
One greenhouses was one in eastern Kentucky they had the greenhouse attacked to the side of a mountain once inside the very back wall had a huge fan in it. After talking to the people it seems the greenhouse was up against an old mineing tunnel. During the day the greenhouse would get hot they would pump 55F air out of the tunnel into the greenhouse cooling it off. In the winter the greenhouse would generate heat from the sun and the fan would push that air back into the tunnel. At night the fan was turned off and the warmer stored air would push back into the greenhouse. It was very interesting and seemed to work well. The problem is most people do not have a cave or mine shaft on their land.
More recently their has been talk about using geothermal heating. This is the same heat that was being used from the mine shaft, heat from the earth to keep my plants warm. The problem I have seen with Geothermal is the cost. It cost a lot of money to instal and it can take years to get your investment back. I have been trying to think of more simple easier ways to use geothermal heat with out the costs.

I drew up a simple sketch to show a friend my idea. The idea is to get a large pond lake spring or a well that does not dry up and place a pump in it at a good depth. The water flows through a pipe it should be 2 feet under ground once it is out of the well or pond and traveling to your greenhouse. The pipe then go into a heat exchanger system. I have a few of these they look like a car radiator with a fan that pulls the heat from the water and circulates the cold water out the other end taking all the heat from the water. The pipe coming out should then flow back into the pond or well. It is not recalculated like most geothermal heating systems, it just flow back usually away from the pump to allow it time to heat back up. I have not tested this method but it seems it should work. I am interested to hear what others think of the idea. I have never installed a geothermal heating system so their maybe a bit more to this than what I have shown. If so I am interested to hear more. The thought of not having to heat in the winter sounds great to me. My plants like 55f and to be able to cool the greenhouse down in the summer sounds good to and for it all to be basically free other than electric for the pump and fan on the heat exchanger. Maybe to good to be true?