inside ases | chair’s corner
Always In Hot Water
The fuel is free. All you have to do is collect it.
By JOHN REYNOLDS,
John Reynolds, FAIA,
is chair of the American
Solar Energy Society
Board. Contact him at
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
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,
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.
It’s pretty simple, this solar hot water approach. I hope
you will try it, if you haven’t already.