[Market-farming] subterranean heated high tunnel
sandycharles at comcast.net
Sat Jan 7 17:02:25 EST 2012
The high tunnel is heated by warmer air that is drawn from a duct near the high point and sent underground to lengths of perforated French drain pipe that run the length of the tunnel. The ground acts like a "heat sink", never freezing even in our subzero temps. The subsurface air that is displaced by the warmer air is then exhausted into the growing space. The key I'm finding is to plant the kind of vegetables that will take extremes of temperature in a day, and not really mind freezing every once in a while. The greens I have growing can be frozen solid in the morning and thaw when the sun warms the space - and they remain in perfect condition.
I'm happy to relay more information if you like. I've been doing a formal study for the local university so have all kinds of data... I got the design for this system from this website, which goes into all the detail you'd ever need. http://sunnyjohn.com/indexpages/shcs.htm
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