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solardan1959

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Reply with quote  #51 
Hi everyone,
   Was surfing yesterday looking for info on cold air traps after Lance's questions about the one I built in my shed, see link Solar Web Page > Forums > Member Projects! > SolarDan's projects
  
Anways, I ran across the solar sponge again.


While there is not remarkable about this design, it's a fairly common channeled empty box, I found some of the information on their page interesting.  The page is here Solar Sponge, and some of the information about fans and the use of them in parallel and series with flow characteristics, the laminar flow issues they had, and the unused heat in the collector, (see below), may apply to all of us at different times.


  I kind of like the low profile flat design and think it would be good for a steel stud track frame with a polyiso back and polycarbonate glazing for an under seventy dollar collector. but was thinking that a wavey metal lath running along the channels may help collect and transfer heat better.  (It seems like a little more fan would have helped also).  Also some insulation in the box, He seems to think it is not needed in Australia.  Actually I completely disagree with statements he made here: http://www.solarsponge.com/update.htm 
when somebody asked him about insulation and heat loss aout the uninsulated metal back.  I think the loss out the back would be huge as well as the metal backing being a cold sink into the box.  (different climates, different needs, but insulation would help most people).
  This was my attempt at diversity as not everybody wants or needs to use screen and here was a clean simple option along with some good information.
Dan

solardan1959

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Reply with quote  #52 
Been thinking of two project to improve the pole barn heater system

The first idea is to improve flow and better preserve heat that I collect in the transfer to the pole barn from the collector.  This shows my current 3, 6 inch into 1, 8 inch output plenum. (minus insulated flexible ducts.


I was thinking I may be loosing quite a bit of heat through the 6 and 8 inch flexible ducts, I think it is R6 rated,  If I built a larger rectangular duct that fit mostly in between the steel rafters, I could probably get more and better flow and at least go to an R13 for less heat loss.  I would also double the vent size through the wall.  8 inch duct = about 50 square inch flow, 16 X 8 = 128 square inches.  A larger duct would also give me room to grow and add more collectors since it appears I need more heat for the barn.

  On that subject I was thinking of something and my boy suggested the same thing,  This is right down your alley Hermit.  I was thinking of adding some foam board insulation a few inches under most of the tin roof on the overhang/lean to.  I would leave about 2 inches of space between the foam board and the tin and have some type of long plenum on both ends.  I could do several things with this, one would be to leave the top /near wall plenum open and then use this all as a preheater to feed the pole barn heater panels via a plenum on the other end.
   The other option is to leave the other end open and suck air from there to the wall and then into the barn, or I can bring air down through a duct to the end plenum, heat the air up as is travels back to the barn, then into the barn.  It may not be a very efficient collector but 300 feet work of tin may do pretty good when it's clear of snow.
   Then the last option would be to add a layer of suntuf on top of the tin making like a real collector, (a real big one).
Dan
Garage_Hermit

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Reply with quote  #53 
Dan, that sounds like a great idea !
Tin-suckers guide to Solar Nirvana !
I don't know the area of your tin leant-to roof, but insulating it from below sounds like a smart idea !
Good news is, you dont have to do the entire area in one go, neither - U could start with just a restricted area around, say, take a ten-foot wide (or whatever the width of your triplex collector is), back from the outboard side at the collector, to the barn wall.  Then clad this with insulated board like you say, with a 2" air gap. This swathe not only acts as a Tin Roof Collector, it also serves as the DUCT between the collector and the inboard wall. Two functions in one structure. (You would need also to seal it along the two vertical "side" edges also, to stop air leaking in from the "untreated" area of roof).  Maybe in winter you would need some sort of snow-remover on this area; otherwise, in a perfect world, the hot air from the collector "might" just keep it snow-free ! Reckon you would need some hefty PUMPS to handle all tha volume of air !


G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
solardan1959

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Reply with quote  #54 
Hermit,
  Yep, a 12 foot wide section might be a good start to experiment and still not break the bank, especially if I had the suntuf on top.  (though that may be a fall thing)
  The pole Barn itself may also be a great candidate for a huge attic collection system, I could have over a thousand feet of hot tin and just pump that into the lower insulated part of the barn.  All for the price of some plastic or reflectix, though that is a lot more expensive), and a large fan.
  I will replace the pole barn fan with the below fan and use this for an attic fan:

This is at menards on sale for about 58.00 dollars and puts out 1050 cfm. http://www.menards.com/main/building-materials/roofing-soffits-gutters/ventilation/gable-mount-power-fan-1050-cfm/p-1697278-c-5820.htm

Dan - new self appointed leader of "Roof suckers united" (the American branch)
Garage_Hermit

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Reply with quote  #55 
Dan

Beautiful thinking, you made my day !

That is not a catalogue cut, that is a Work of Art
(I believe they use the same ones on the ISS)
(International Simply Solar-Powered Space Station)
G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
72chevel

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Reply with quote  #56 
I was wondering about using 24 gauge sheet metal instead of aluminum sheets in a collector. Think it will have much negative effect?
solardan1959

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Reply with quote  #57 
Been thinking the same thing, do not know what gauge it is but the steel sheeting for roofs and pole barn walls.  I was thinking about using it with cvpc for a water collector.
Dan
72chevel

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Reply with quote  #58 
Yea I am going to give the steel sheets a try also cpvc for me.  I found some IBC storage tank totes for $50 each on craigslist any one tried those for water storage?
Lisa

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Reply with quote  #59 
Thank you for hosting this page.  I have been using and selling solar products for awhile.  The general discussion is very helpful.

I would love to hear your thoughts on energy storage or batteries.  New ideas or how you decided on the ones that you use.

Thank you!
Lisa

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Reply with quote  #60 
Quote:
Originally Posted by netttech
John Johnston...how ambitious are you?

You mention a passive panel to collect heat & eletricity.

How good is your soldering skills?? Solar PV 'cells' produces a lot of heat. I'm envisioning a panel using the cells as the collector. The cells would need to be suspended in the panel to allow air flow on front & back side.

Here's the kicker. You have to solder the indivual cells together. I honestly don't know if it would generate as much hot air as a dual screen or other type of hot air collector. However it would provide the electricity you mentioned.

It's a ton of work soldering those cells together. Oh yea, they are extremely fragile. I included a picture of a Solar PV panel I built a few years ago. It's the best picture I have showing the size of the wiring.

Buying solar cells (on ebay) isn't cheap!

It's an idea though if you are really, really ambitious!

Jeff
Central IL
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