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Constructing collectors for a solar hot water system - Page 3

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Posted by nicksanspam on September 29, 2007, 6:43 am
 
 

I screw 2 flat parallel 1x3s to a 2x6, then lay 8" of 0.018" thick Al
roofing coil stock on top with the brown paint showing, then lay a 1/2"
copper pipe over that and pound it into the slot with a rubber hammer,
then remove the pipe and put a bead of silicone caulk in the groove and
push the pipe back in. Acetic silicone caulk etches aluminum.

The pipe thermal connection could be better, and we might add insulation
on the shady side, but a bare "Big Fin" collector like this can work well
in a sunspace that also collects warm air for a house.

Nick


Posted by Jeff on October 1, 2007, 5:29 am
 
nicksanspam@ece.villanova.edu wrote:

I've looked at a lot of flashing and absolutely everything I saw was
.01" to .011". Where do you find .018"?

   Jeff


  on top with the brown paint showing, then lay a 1/2"


Posted by Sundug on October 1, 2007, 4:17 pm
 
low cost thermal collectors

When I decided to put a flat plate collector system on my house-
http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_-_doug_kalmer.html
I called plumbers and roofers in the nearest large city, just by
looking in the yellow pages. Second call founda plumber who had a
stack of 3'x13' aluminum boxed, copper plumbed collectors, guarenteed
not to leak, for $00. That was over 16 years ago, and it`s still
working fine on my roof. I would call as suggested above, and if that
proves fruitless, try putting wanted ads in local papers and online.
  Failing that, and wanting to build collectors, consider doing what
these manufacturers did- use fin tube as the plumbing in the
collectors, the same as used in baseboard radiation. Just paint with
flat black high heat, or selective surface coatings. Doug

http://www.solarfacts.net/articles/diy/diy_solar_hot_water_heater_two_-_doug_kalmer.html


SDHW and house-
http://community.webshots.com/user/sundug



Posted by nicksanspam on October 1, 2007, 5:00 pm
 

For the whole stack? :-)


Nice...


I've never seen a commercial collector with baseboard fin-tube inside.
It's fairly expensive and doesn't collect well at low temp diffs.


Ideally, we'd want a small amount of fin-tube inside a large air heater, so
the fin color wouldn't matter much. David Delaney suggested something like
this with passive auto radiators and a vertical poly film airflow separator.



Lowes and Home Depot. With 2'x50'x0.018" rolls of Amerimax 69124 brown/white
coil for $8 and 10'x1/2" copper pipes for $0.85 and 3/4" pipes for $7.62
and 3/4"x3/4"x1/2" copper Ts for $.34, the materials for a 10'x10' bare
collector with 18 10'x6.4" fins would be about $8+$7.64+18($0.85+2x$.34)
= $75. Screwing it into 3 4'x8' sheets of 1/2" OSB into 3 4'x8'x1" foil-
polyiso boards onto a south wall might add $0.

A draindown version might look like this, viewed in a fixed font:

                              10'
in   -->-------------------------------------------
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  | <-- 18 vertical
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |        10' fins
         |  |  |  |  |  |  |  |4'x8'|  |  |  |  |  | 4'
    57.6"|  | a|  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |..|..|..|..|..|..|..|..|..|..|..|  
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |..|..|..|  |  |  |  |  |  |  |  |  |  |  |     10'
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |  |  |  |  |4'x8'|  |  |  |  |  | 4'
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
    57.6"|  | a|  |  |  |  |  |  |  |  |  |  |  |  |  
         |  |  |  |..|..|..|..|..|..|..|..|..|..|..|  
         |  |  |  .  |  |  |  |  .  |  |  |  |  |  |  
         |  |  |  .  |  | b|  |  .  |  |  |b |  |  | 19.2"
         |  |  |  .  |  |  |  |  .  |  |  |  |  |  |  
         |  |  |  .  |  |  |  |  .  |  |  |  |  |  |  
          -----------------------------------------|
             2'           4'               4'      |
out  --<-------------------------------------------

Cutting diagram:
                    19.2" 19.2"        57.6"
                   --------------------------------  
                  |     .     .                    |  
                  |     .     .         a          | 2'
                  |     .     .                    |  
               4' |  b  .  b  .....................|  
                  |     .     .                    |  
                  |     .     .         a          | 2'
                  |     .     .                    |  
                  |     .     .                    |  
                   --------------------------------  
                                  8'

This might be inside a 12'x12' frame on a south wall covered by 3 $4 4'x12'
sheets of U0.58 Thermaglas Plus twinwall polycarbonate with 80% transmission.

In 250 Btu/h-ft^2 sun and 34 F outdoor air on an average December day in Phila,
140 F fins with lots of water flow would gain 0.8x250x100ft^2 = 20K Btu/h with
144-100 = 44 ft^2 of parasite heating and no heat loss to 140 F frame air, so
back insulation is useless. If we simultaneously collect frame air to warm
the house and lower the frame air temp and raise the overall solar collection
efficiency, back insulation can raise the water collection efficiency.

Nick


Posted by nicksanspam on October 2, 2007, 4:08 am
 
Oops. This might drain better:


Or this, with some pipe squeezes (how deep?) on the left to equalize flow:



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