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Old 01-21-10, 02:08 PM   #14
GaryGary
Apprentice EcoRenovator
 
Join Date: Nov 2008
Location: SW Montana
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Hi Mike,
I think that in your climate, you would need glazing over the tubes to get worthwhile heat out of it in the winter.

Collectors normally have fins on the pipes so that the sun that falls between the pipes gets transferred over to the pipes by the fins -- otherwise, you don't get much benefit from the sun that falls between the pipes.

Once you glaze the collector, the ABS is not likely to stand up to the temperatures inside the collector. It might be OK when fluid is being circulated, but if the fluid circulation stops for any reason and the collector stagnates, the temperatures inside the collector will go very high -- to high for ABS.

Half inch copper tubing is probably the best choice. Here is one way to do the tubes, fins, and manifold:
Experimental Solar Collector Using Hybrid Copper/Aluminum Construction

I think the storage in the pit would be OK if you insulate the walls and floor of the pit. That is, you want the stored heat to go into the shop and not be lost down into the earth.

Not trying to discourage you -- its a very workable idea with the right materials and construction.

Gary
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