Sunday, March 31, 2013

A 2 Year Update on Gordon's Unique Khanh Solar Water Heating Collector

A couple of years ago Gordon did a solar water heating collector for his home that uses the Khanh design.

This design improves the performance of conventional water heating collector by extending the area of the collector to include an air heating collector that warms the area around the water heating collector to reduce heat losses from the water heating collector.

The design is explained in detail in Shurcliff's book: New Inventions in Low-Cost Solar Heating

Gordon's original article on his implementation of the design along with construction details is here..

Its been two years and Gordon has a good report on the things that worked and the things that did not work so well and had to be fixed or improved.

The report covers: performance, a new differential controller, pumps, backup water heaters, and some plumbing issues.... 

All good stuff to know if you plan to use this design.

March 31, 2013

Tuesday, March 26, 2013

Rain Water Collection -- Year Two Update -- Freeze Problem

Our 2200 gallon rain water collection system has been working well, but we did have a freeze damage problem this winter.

The full rain water system is described here...

This winter the first flow diverter reservoir managed to fill up with water and freeze over the winter.  The expanding ice did an impressive job of breaking the large PVC pipe that serves as the reservoir.  The valve at the bottom of the reservoir was open for the winter, but must have plugged up and allowed water to accumulate.

Freezing water breaks the pipe that serves as first flow diverter.

For now, I've just removed the first flow reservoir where it threads into the collection plumbing and put a threaded PVC plug in to make the system functional, but with no first flow diverter.  Will need to work out a better system that is less subject to freeze damage.

A PVC threaded plug replaces first flow reservoir for now.

More details on the 2nd year of operation here...


Friday, March 22, 2013

Renewable Energy Magazine Article on DIY Renewable Energy

Richard Crume's latest blog for Renewable Energy Magazine is about the DIY area of renewable energy.  I'm happy to say the article features Build-It-Solar.

Richard describes some of the rewards of doing DIY renewable energy projects, and some of the achievements of the the DIY crowd.

One of the Richard's projects that is featured on our Solar Homes section is this article describing the this very energy efficient and very nice to live in house they built.


Sunday, March 17, 2013

Adding Glazing to the Off The Shelf Solar Water Heating System Collector

This is an update on the project to develop a simple, efficient, low cost and reliable DIY solar water heating system that is easy to install because it uses all off the shelf parts.

The system uses an unglazed pool heating collector because it is inexpensive, easy to install, and allows the system to qualify for the federal tax rebate.  The performance of this collector is good for warm and moderate climates, but falls down during the winter in cold climates.

This update covers adding glazing to the pool heating collector to improve its performance when when its cold and for part sun conditions.
The pool heating collector with glazing.

The glazing used is SunTuf corrugated polycarbonate, which was chosen because it is tough, long lived, readily available (eg Home Depot), and has a high service temperature.  The glazing is supported by a simple frame that just plunks down over the collector -- the weight of the glazing assembly is supported by the collector manifold, and the glazing assembly is held down by a couple of straps in the same way the the collector itself is held down.  The whole glazing assembly for the 4 by 10 ft collector is light weight and can be handled by one person.

The glazing includes some openings at the bottom and at the top that allow a controlled amount of air to circulate between the glazing and the absorber.  This is to mellow out the temperature that the collector gets to if the collector is stagnated (no water flow).   The idea is to keep this air flow small enough to not significantly effect collector performance, while at the same time keeping stagnation temperatures within bounds.

The link below gives all the details on the construction.

The performance of the system is definitely improved with the glazing in place.  For some conditions that are typical of moderate to cold climates, the improvement is of the order of 50% in heat output.
The link below gives complete performance details, and compares the performance of the glazed and unglazed pool heating collector to commercial flat plate and evac tube collectors on both heat output and heat output per dollar of collector cost.

Comparing efficiency of several collectors to our collector.

All the details on the updated collector with glazing...

The main page for the Off The Shelf DIY Solar Water Heating System....

Comments, suggestions, questions are most welcome.

March 17,2013

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