Posted by gabrielfrieland on June 12, 2006, 9:08 pm
Say I were to build an integral passive solar water heater, such as
The article mentions nothing about different types of glass and their
magnification properties. I know nothing about this topic, but is there
a type of glass that magnifies the suns rays, making the stronger? If
there is, is such glass used in homes as well for greater heat, or
would that just make the summers too hot inside the house?
Posted by Gary on June 12, 2006, 10:39 pm
The function of the glazing in these water heaters is to reduce heat loss from
the water heating tanks to the outside air.
The thing you want to look for is glazing that transmits light well (ie does
not absorb a lot of light). For these types of heaters, probably the most
commonly used glazings are replacement sliding door glass units (which can often
be found surplus at your glass shop), or either single or dual wall plastic
glazing -- where the plastic must be polycarbonate to withstand the heat, and
must have a UV absorbing coating on the outer surface (like the type used on
You can get a sort of magnification by using reflective surfaces outside the
glazed in area to reflect additional sun into it. The link below has some
designs that do this.
The article in your link is by David Bainbridge -- you can download and read his
entire book on integral passive heaters here:
The book is very good, and has dozens of designs for simple integral passive
heaters. Say thanks to David for making it available!
More plans for solar water heaters here:
House glazing has become very involved with multiple layers, coatings, and tints
to control the transmission of sunlight through the window and loss of heat from
the room out the window -- www.EfficientWindows.org has a lot of information on
"Build It Yourself" Solar Projects
Posted by News on June 13, 2006, 12:03 am
Gary, even in solar, matters have on a bit in 25 years since the book was
written. Good book though.
Posted by Gary on June 14, 2006, 1:26 am
Actually, it seems to me that very little has changed in the last 25 years in
solar thermal. Seems like there was a great effort in the 70's and early 80's,
and much progress was made, but when low oil prices came back, it all came to a
It would be nice if rising oil prices and more awareness on climate change got
the solar "revolution" going again -- I think there is much that could be done
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Posted by Morris Dovey on June 12, 2006, 10:52 pm
| Say I were to build an integral passive solar water heater, such as
| this one:
| The article mentions nothing about different types of glass and
| their magnification properties. I know nothing about this topic,
| but is there a type of glass that magnifies the suns rays, making
| the stronger? If there is, is such glass used in homes as well for
| greater heat, or would that just make the summers too hot inside
| the house?
The short answer is "no". A transmissive glazing can't pass any more
energy to the inside than falls on the outside. No magic.
Gary's answer is helpful, if you're wanting to learn about collecting
heat - and he has an excellent web site with still more information.
Best of all, he's here to answer any questions his web site might
raise for you.
DeSoto, Iowa USA