solar heat from pop cans...

[erthymom2]

if you google mother earth news and go into their web site archives, there is a very simple solar air window unit similar to the soda can one, but you don't have to use the cans - you can use old panes of windows and simply build a 2x4 frame and add black paint.

go take a look, i'm going to try it this winter in my second smaller coop to measure performance.


Update: it's like this one: Heat Grabber see MOTHER EARTH NEWS EDITION NO. 47, page 101

 

[2manyhats]

I have been trying to figure this out since the spring when I got chickens. They are selling these things on ebay as space heaters. I would love to make some of these. Keep the good info coming, please. And if someone can, could we get a parts list and how to plan. That way we don't all have to recreate it. Thanks so much BYCers!

 

[erinm]

someone here also posted a slightly different one a while back. i don't think it had a fan Erinm

 

[Sylvie]

I love this thread!
We don't drink anything from a can but will start asking family and friends for them to build one.
Once a year there is a statewide solar tour where homeowners and businesses open their doors to show off their alternative energy applications. I have yet to see this pop can heater. We are thinking of listing our coop for next year's tour because of the window placement and recycled building materials but we might incorporate the pop can heater as well.

 

[Anny]

Quote:
if you go to the link I posted in the first page (the start of the thread) , it is a how to list giving you step by step how to build it.

 

[rhetoric]

Here's a drawing that lets you see how the air enters and exits the box. They actually do so right next to each other just inside the partially opened window in this design. Because heat rises, as long as the warm exhaust is on top, the bottom will always pull in cooler air from the bottom. For that reason, you have to insulate and caulk the box well so you are sucking in cold outside air.

There's no reason you couldn't cut one low hole right in the side of the coop (intake) and one high hole (heat exhaust) if you don't have a convenient window, I just don't want to have the panel on the coop permanently. I will do that some day when I install one on my home. That would also save you having to build the intake chamber.

So yes, as you can see from the diagram, you are heating coop air. My little model was just a proof of concept and it is only heating outside air. But I will take that window (it's just a freebie doublepane vinyl clad window), build a 2/6 or so box, insulate the back and sides of the box, put my metal collector inside the box (with a 2 or so inch gap behind the collector for air intake), and then build a little divided chamber that sticks inside the partially opened window (bottom pulls in cold air via thermosyphon from the hot air that is exhausting just above).

By the way, I saw a youtube of some energy company that took and existing window in their shop, boxed it in w/ a metal panel, and put a fan on it. Quite frankly, I'm not seeing how that produces a radical benefit (except that it insulates the window, I suppose). The energy of the sun is already going in that window -- the collector doesn't make any more. What you need to do is get more windows. By putting the collector on the wall (or below the window as I plan to do) you are, in effect, INCREASING your window area and, hence, your passive energy absorption. Cover up an existing window w/ a box and you'd lose light and as I understand it, you don't want to cheat your girls out of light.

And one more p.s. This is our first year with chickens. We have 16 and yesterday we got 10 eggs -- new day total. Whoo Hoo. But I tried to carry them all at once and broke two. Boo Hoo.

I agree...fun thread. I'll post pics when I get my box done -- maybe this weekend (famous last words).

 

[rhetoric]

Quote:
This is a problem I'd like to solve too, Wayne. Certainly it increases the efficiency if there is some sort of "solar tracker," hand cart or otherwise. I'm just not sure how to do that AND not botch up the piping/chambers/intakes and exhausts that get the air into the coop.

 

[cheeptrick]

I have a question...
AFTER the sun goes down...does the temperature decrease? Can you plug the hole so as not to loose heat during the night?

Or does it not matter?

 

[the1much]

it wouldnt hold the heat for long,,,, and plugging the inlet hole would only help for a small amount of time.

on another note,,,, i think the reason for the cans,, are to act like a baffle, without baffles in there slowing the air down, the air wont heat as much,, or it would move through so fast it wouldnt have time to get warm , and would just be called a "draft" then ,, hehe

 

[DrakeMaiden]

My husband, who has a degree in physics, said that the reason for aluminum cans is that aluminum is one of the best materials for transfering heat from (in this case) the black surface of the paint to the air. Hope that clarifies why the soda cans are used.