R Scott wrote:Natural conduction is more than adequate for most greenhouses.
Gilbert Fritz wrote:I'm thinking about my future greenhouse again. It will have a large tank of water in it, probably a fish tank. What is the best way to move excess heat from the air into the tank? Bubbling lots of air through the water? Fountaining the water into the air? Running coolant through a radiator and back through a heat exchanger in the tank? Something else? An advantage of the first two is that it would aerate the fish tank. An advantage of the third is that the radiator fans would create air movement.
Which would be most efficient?
This is the basic concept of what I described above; and where the idea behind my post originated. Geoff Lawton also did a video about a greenhouse project at a school in my province that uses a similar system to Osentowski's. I don't know about the Colorado system but the B.C. system also have an insulated shutter that covers their curved sloped glazing at night. The purpose of the earth tube capture of heat in both of these greenhouse projects is not to heat an aquaponic tank, but to moderate the winter cold from the ground upwards with a slow release. In the case of heating the tank directly from the ground source, one can have all of the vent holes release upwards against the bottom of the tank. A person could have a simple baffle at a manifold in the system (operated by the pull or push of a metal rod) that could direct the flow outside, into another structure, or against the bottom of a second tank. This manifold baffle could also possibly be switched via a bimetalic thermostat, or another low tech thermostat when a certain temperature is reached in the tank.
Gilbert - Have you heard of Jerome Osentowski? He's in your neck of the woods. He uses the concept of moving heated air from the peak of the greenhouse through ground tubes buried under the greenhouse.
Joshua Parke wrote:There is a man in maybe Wisconsin or Minnesota doing the same concept. He grows citrus in an attached greenhouse and he put his earth tubes outside of his structure wrapping around his home. I may have seen video of it on youtube a few years ago....and/or read and saw pictures somewhere on the net. I can't recall exactly how to find that one....I probably learned about it from someone here.
About water vaporizing then condensing on the cooler surface of your he water, I am wondering, wouldn't the inside surface be cold enough to cause a lot more condensation, losing the heat to the outside? I am thinking that but for the aeration needs, it would be more heat-saving to keep the surface of the water covered.
Gilbert Fritz wrote:What is the best way to move excess heat from the air into the tank? ...Running coolant through a radiator and back through a heat exchanger in the tank?...
Mike Phillipps wrote:Let me know if you think I should continue working on developing a better solution. Any idea what a better solution might be worth?