SOLAR TODAY - Fall/Winter 2009

inside ases | chair’s corner
Always In Hot Water
The fuel is free. All you have to do is collect it.
By JOHN REYNOLDS,
FAIA

John Reynolds, FAIA,
is chair of the American
Solar Energy Society
Board. Contact him at
chair@ases.org.
The ad in the Whole Earth Catalog caught my atten- tion: “Free hot water” from a company called Fun ‘n Frolic Inc. It was a black plastic pad the size of a
one-person air mattress, but filled with water. Put it in the
sun, connect a garden hose at one end and out comes warm
water at the other. What could be simpler? I bought it, along
with a recycled half-barrel from a winery, and watched my
very young kids splash away. As the summer waned, I turned
my attention to all-weather solar-heated water.

This was the 1970s, and the OPEC oil embargo was fresh news. Our local solar advocacy group sponsored workshops for folks to build their own solar collectors. It was a great way to start, with a ready supply of materials. For instance, we had aluminum printing plates donated by the local newspaper, which we bent to fit snugly around copper pipes. Painted black, they formed the heat-collecting surface. Build a wooden case, put insulation behind the copper-aluminum collector plate, face it with glass from a double-glazed patio door (a manufacturer’s “second,” due to scratches or other defects), and you had a low-cost solar water heater.

We enjoyed the company of other collector builders. Together, we learned to solder copper pipe fittings and

related plumbing survival tips (never pull on

a pipe wrench towards your face!). Best of all

were the “collector-raising bees,” where we

all gathered at a home to hoist the collectors

onto the roof and drink celebratory toasts,

preferably after descending. We were reach-

ing for energy independence, reducing those

oil imports and collecting energy onsite that

was otherwise wasted.

nAnCy J. REynoldS

The end of a successful

solar collector-raising bee,

circa 1978.

This, my first serious solar water-heating system, was
a “drain back,” where the city water (at full pressure) was
circulated between the collector and a storage tank. A “dif-
ferential thermostat” compared outdoor and collector tem-
peratures and controlled the flow. When there was danger
of the water freezing in the collector, the flow was stopped,
and the collector then drained back into the storage tank.
After several years of service, one cold night, the water flow
cutoff failed, and I was greeted with an icy waterfall the next
morning. I got quite a bit of practice soldering small pieces
of replacement copper pipe.

My next solar water-heating adventure was teaching a class at a biology field station in the southeast Oregon desert. A group of architecture students had signed up for the chance to design and install a solar water-heating system for the director’s home. For academic benefit, we went the

extra distance and decided to install the collector so that it

could be tilted to match the season: nearer vertical in win-

ter, about 45 degrees in spring and fall and nearer horizontal

in summer. This was fairly simple using gooseneck plumb-

ing connections. What wasn’t so simple was the director’s

role, manually tilting the collector four times yearly. The

collector is heavy, so I hope he always has a helper. After

work, we enjoyed another natural source of hot water at

the local hot springs. It would have been paradise, if not

for the mosquitoes.

On my present house, I bought a new-style collector called a Copper Cricket. It circulated methanol rather than water, so freeze damage was not an issue. This unique system used the sun to pump the water using the principle of percolation. If there was sun enough to warm the collector, there was also sun enough to move the water. A thermostat was not required. I liked this system, enough to invest in company stock. Unfortunately, the company did not succeed. It was the early ’90s, and energy was not a major issue for most people.

After many years of service, I found that the system became prone to lose its charge of methanol. I donated the Copper Cricket to a local nonprofit and changed the collector so that a photovoltaic-driven pump now serves it. The fluid is a mixture of propylene glycol and distilled water. The PV module is as wide as the collector it serves and about 8 inches high. It’s a very small addition to the size of the collector on the roof. In this lovely arrangement, the pump “sings” to me. When the sun goes behind a cloud, I faintly hear the pump change pitch. As with the Copper Cricket, when there is sun enough to warm the collector, there is also sun enough to pump the water, no thermostat required. No inverter either, because the PV drives the pump with direct current; the stronger the sun, the faster the flow.

Another sensory clue is the temperature of our hot water. We keep our water heater temperature so low that, when we shower, we dial to maximum hot water. As the sun gets stronger, the storage tank temperature rises. We know we have had a good solar collection day when we have to dial toward cool.

Solar energy affects our lifestyle in many ways, including when we wash clothes and shower, so as to take advantage of optimum solar water heating and because we hang our clothes outside to dry in the summer and fall. And our front-yard vegetable garden is a quick-payback solar investment with multiple benefits.