Wednesday, November 04, 2009

Refurbishing Our Solar Collector, Part 1

A lot of last winter's projects got cancelled because I built the Ark instead.  This winter I'm playing catch-up.  A timely project right now is getting our solar heater refurbished.

I built this heater in 1983, and it's been time to replace the translucent fiberglass panels for several years now.  I bought a 4x50-foot roll of fiberglass (Crystalite brand) right after Katrina in 2005.  Fortunately it stores very well.

This picture shows my first design mistake.  There's no on-off switch for a solar collector; the only way to turn it off is to cover it during the summer.  I used a split bamboo screen for this purpose because it's cheap, lightweight, and easy to store during the winter.  Unfortunately it lets in a lot of that hot summer sunlight, greatly shortening the life of the fiberglass.  This time I'll be using sheets of exterior siding which will be heavy, but will totally block off the sunlight for 7 months of the year.  Crystalite supposedly lasts 20 years, so maybe I'll get 40 years of use out of it if I only expose it to sunlight for 5 months of the year.  That means I won't have to replace it till I'm 103.

Here's the heater with the bamboo screen removed.  The heater is 6 feet high and 16 feet long.  It's aimed southwest due to the orientation of the house, which parallels the river.  It sure cranks out the heat during winter afternoons.  When new, it blew 160 degree air into the house.  That's the Ark in the background.

 The fiberglass has been removed, revealing the 2x4 framework.  Notice the dirt and sand in the bottom of the collector, courtesy of the 06 flood.  Also notice that bermudagrass has colonized the inside of the collector.  Design flaw #2:  back then I thought that regular lumber covered with 2 coats of oil-based paint was adequate.  These days I use treated lumber for all outdoor applications.  Live and learn.  The bottom plate has significant rot, but not bad enough to tear it down and start over.  Which is a good thing.  I doubt if I would have the time and inclination to rebuild it from scratch, at least not this year.

Laura wirebrushing the loose paint off the framework.  Back then I was into building colorful solar collectors.  Why be satisfied with basic black?  I painted my collectors brilliant yellow or bright red, which contrasted nicely with the black interior.  I wrote an article about "colorful solar collectors," but Mother Earth News turned it down.  Idiots.

This picture shows the air passageways I cut through each 2x4.  Cold air from the house enters the collector at the lower-right, is pulled through the collectors, and exits out the upper-left, through a 6-inch stovepipe behind Laura's head.  I use a bathroom exhaust fan turned backwards so it sucks air through the collector and blows the hot air into the house.

The black facing is 1/4" masonite, backed with 1/2" foam insulation.  We have yet to penetrate into the jungle behind the collector to repair the inevitable damage to be found there.  We'll get the front part up and running first.  After I repaint the masonite panels with a fresh coat of flat black paint, I'll install new sheets of fiberglass, some new brightly-colored molding, and we'll be back in business.  I highly recommend solar heaters.  They're fun and easy to build, and allow the builder to feel clever on cold winter days when the collector is delivering buckets of hot air for free.  Or almost free, at any rate.