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Summer only solar water heater

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Posted by Eric in North TX on March 25, 2009, 9:01 pm
 
I am thinking of building a solar water heater. My thoughts are:
normal input to water heater redirected to a line through the attic to
a home made panel located above the windows on the south wall (ranch
type with the roof ridge running N. S.) then an insulated return pipe
directed into the intake of the existing water heater (LP gas). Seems
like that would work, as it gets really hot here in the summer,
(really April to November). I would leave the water heater on, to
maintain the temperature at night and cooler days, it shouldn't have
much to do if I'm correct. My concern is that the panel may get too
hot and present a fire hazard, I was hoping to make it using mainly
wood for the frame & I've had mini blinds melt in south facing windows
if they were covered on the inside.

Posted by Cosmopolite on March 26, 2009, 11:05 pm
 
Eric in North TX wrote:

    Some kind of heat activated shutter system is all that I can think
of. Maybe a NO snap switch which would close at the overtemp condition
and switch a motor driven shutter or blind system.

Posted by jbclem on March 28, 2009, 12:50 am
 Why not try shade cloth such as is used over a greenhouse or a nursery.  It
comes in 40%, 50%, 60%, up to 90% shade producing weaves.  Most greenhouses
and nurseries here in S.Calif use 60% or so.  Built a frame so that it's a
foot above the solar panel to allow air movement above the panel.

jc





Posted by gary on March 28, 2009, 2:31 pm
 Hi,
I've never heard of a non-concentrating solar collector made of wood
catching fire.

But, if you are really concerned about that, you can make it from
metal.  Some people use the galvanized steel studs that are readily
available.  The metal sill plates actually work better, as they don't
have any prepunched holes in them.

If the collector is wall mounted (vertical) it will be less likely to
overheat in the summer, as the sun is high and makes a high incidence
angle with the the panel.  My vertical air heating collector stagnates
at about 185F in the summer.

You talk about mounting it above the windows on the south wall(?)  If
the roof has an overhang, make sure that the collector is not in the
shade of the overhang in the middle of summer when the sun is high.

I'm not clear on your storage mechanism?  If you are planning to just
run the water through the collector in a single pass before it gets to
the water heater, you won't get very good performance out of that.
The water needs to be circulated from some kind of storage through the
collector on a continuous basis when the sun is on the collector.

Gary





Posted by Eric in North TX on March 28, 2009, 11:07 pm
 On Mar 28, 8:31am, g...@builditsolar.com wrote:

Ok some good points hace been raised, as to this one (The water needs
to be circulated from some kind of storage through the

what about one of these pumps that is intended to keep the water hot
at the faucet?
http://www.rewci.com/whhohotwaci.html
not necessarily that one, & perhaps with a return line.

I've re thought the location and will likely move it to the south wall
of the 2nd story daaition to the North end of the house, (the exact
location where the mini blind melted). I eliminated the window from
that wall and studded out the openbing, siding over on the outside and
drywalling the inside. That location is hotter and closer to the tank.

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