Tuesday, October 11, 2011

Bill's Large, Closed Loop $1K Style Solar Water Heating System

This is a very interesting $1K style system from Bill with quite a few interesting design variations.  Among the unique features:
  • Closed loop rather than drain back for freeze protection
  • Glazed with dual wall polycarbonate glazing.
  • A unique collector frame that uses EPDM rubber roofing for weather protection.
  • Using a custom made PVC tank liner instead of the usual folded EPDM liner.
  • Lots of detail on roof mounting the collector, including the site made collector hoist shown just below.
  • A unique design approach to handing differential expansion issues in the absorber design.

Bill's system with the first collector in place

Bill used a closed loop system because he was not able to maintain a good slope on the plumbing to and from the the collector.  This requires adding a 2nd heat exchanger to the tank that transfers heat from the collector circuit (which has antifreeze) to the storage tank which is plain water -- this is Bill's heat exchanger arrangement:

The collector loop and domestic hot water heat exchangers in the storage tank.
Another unique feature of the system is the that Bill used a custom made PVC liner instead of the folded EPDM liner.  This is a picture of the liner:

Custom PVC tank liner
This seems like a good way to go if you can get a competitive price on the liner.

I also like the special hoist that Bill made to get the collector up on the roof:
Custom made hoist to lift collector to roof.
These collectors are heavy, and Bill has several of them to get up on the roof -- the hoist will save a lot of work and be safer.

Go here for all the details on Bill's system....

Go here for the details on a hundred or so other solar water heating systems...


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