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GBlist: Batch water heating
I don't understand the 4" thick fabricated tank. I recommend buying a new
(or recycling an old) conventional electric water heater and pulling out
the tank. Paint it black. Put it flat black (stove paint) in an insulated
box with a glass side facing the sun. A foil-faced, rigid insulated cover
over the glass for nightime is often used, sometimes hinged to fold down in
fron of the batch heater and provide extra reflectance of solar radiation.
Yeah, closing and opening the covers and messing about with valves is a
pain, hence the old solar adage: Passive solar requires active users.
Passive users require active solar.
Lastly, the batch heater can provide REALLY hot water at its peak during
the afternoon and still be comfortably warm in the morning. Using it as a
preheater to an instantaneous gas (in your instance) heater to ensure
unlimited hot water
is a good combination. The only instantaneous heater I know of which
regulates the amount of gas flame depending on the incoming water
temperature (as opposed to providing a set temperature increase regardless
of the incoming temperature, which could be scalding as Marc Rosenbaum
pointed out) is the AquaStar.
The problem I've encountered over the years with a number of such systems
is that AquaStar regulation is done via a little plunger valve that moves
in response to the temperature of the incoming water temperature washng
over it. The problem is that over time, the hot water washes off the
silicone lubricant that allows the plunger to slide so easily (cold waer
doesn't effect it nearly as much). This valve assembly has to be taken
apart (enter the active user) a couple times a year and serviced
(relubricated). This problem may have been fixed by now by the
manufacturer, or there may be other such flash heaters out there.
Ron Hughes
THE WHOLE HOUSE
http://www.energyhome.com
P.O. Box 251416
Little Rock, AR 72225
501.666.4377 biz
501.666.8676 fax
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