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...



  1. This comment has been removed by a blog administrator.

  2. What a well thought out system, I really like the liner idear

  3. A few of us real old time solar guys use a special trick sometimes when you're "not able to maintain a good slope on the plumbing to and from the the collector."

    The trick is discussed at Heating Help, and I can get photos of a system I recently did that required it (if anyone is interested)


  4. Hi Kevin,
    Can you email me the photos? I'd like to add them to BIS along with the link to the heatinghelp piece.
    It sounds like you've used this on a few jobs, and it has a good track record?



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