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DIY solar water heater

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Posted by JIMMIE on July 4, 2009, 3:16 pm
 I helped my brother install some in the floor heating pipes the other
day using PEX tha twas snapped into metal radiator fins. I was
thinking that these should also work well in reverse for heating the
water. Instead of pex I plan to use copper pipe and maybe solder the
fins to the pipe for good thermal efficency. I plan on making the
collectors 4 X 8 ft to utilize stock material with the least cutting
possible. I am looking for as much info as possible on plumbing solar
collectors into my present sytem.


Posted by Gary on July 5, 2009, 2:03 am

Hi Jimmie,
I've been doing some work on similar collectors -- these links
describe the results, and provide some construction info and photos:





The first two links describe a solar water heating system (can be used
for domestic water heating or space heating) -- I consider these to be
fairly well proven, as the the prototypes and the final system have
been operating fine for nearly a year.

The "Small Panel Test" link shows how the performance of these
collectors works compared to commercial panels -- basically 96% of the
performance for 1/6 the  cost.

A number of people have built these systems, and some have provided
information on their systems here:
See "Working DIY examples ..."


Posted by JIMMIE on July 19, 2009, 12:47 am
I noticed in the video on soldering Cu pipes that a very important
point was missed which is the reason most people make a bad joint. The
hotest portion of the flame is just beyond the inner cone of the
flame. Most people new at soldering tend to hold the tip of the torch
much too close and the Cu does not get hot enough to make a good

I am going to try the Cu design, one modification I plan to make is to
place insulation between the wood and metal fins. I am also looking
for ways to increase the surface area of the fins while keeping them
in the same footprint. I think this could significantly increase

Other considerations have been plaing tubing in an asphalt driveway.
One added benifit of this would be you could use it to melt ythe snow
on your driveway in the winter. This splurge of energy use would be
more than offset by the savings made in the warmer months especially
in the places where you only get one or two snow falls annuallly.


Posted by Gary on July 21, 2009, 2:35 pm
 Hi Jimmie,


The only problem with doing this is that having the wood right under
the fin allows you to pull the groove in the fin into very tight
contact with the copper tube as you staple.  Its very important that
the gap between the fin and copper tube be thin to non-existent.  If
you don't get very good thermal contact between the fin and the tube,
the collector will not work well.

I am also looking

Posted by Robert Scott on July 21, 2009, 4:16 pm
Not only won't that increase efficiency, it could actual hurt efficiency.  If
increasing the surface area means that the heat has to travel further to get to
the collection fluid, then that will raise the temperature of the collector and
increase heat loss.

Robert Scott
Ypsilanti, Michigan

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