Questions about the Pop Can Furnace

I had a nice note from Mark in Ontario and I thought I'd share his questions and my answers about the pop can solar furnace... It's been cloudy for a few days, so I'm not getting any free heat this week!

Hi,

I saw your popcan solar furnace on your lowerfootprint.blogspot.com blog , and thought it was unique because all the other solar furnaces are for exterior installation and drilling holes in the house etc. Since we don't have any blank wall space on the south side, those plans aren't too useful. However your window version would work for us.

I'm hoping you wouldn't mind answering a few questions.

Did you put any covering over the pop cans?

What kind of hole did you put in the bottom of the cans and what tool did you use to make it?

Did you make a larger hole in the top of the cans?

What kind of glue did you use to join the cans together?

Thanks for the info.

I had the energy audit too (it cost me $375 in Ontario), and will be adding insulation to bring my attic to R50 this year.

Cheers,
Mark

Here's my response:

Hi Mark...

My second version will be a vertical window one, so I'll post more when I do that one...

1) Currently no covering on the pop cans. They're painted with heat-heat black bbq paint though.

2) The bottom of the cans were punched out using a "churchkey"... the can opener you'd use for opening a can of apple juice. The excess was simply folded into the can.

3) No extra hole in the top. It was part laziness, but also helps to cause some turbulence in the airflow, helping to pick up more heat perhaps. They weren't lined up or anything.

4) I taped the columns from side to side with black electrical tape. This first model is shockingly crude, but hey, it will built in about two hours, start to finish.

The new model will be an enclosed box, sized to fit vertically into a window in my solarium. It will have a glass or plexi front and top and bottom vents. I'm considering a set of shelves inside it, made of perforated material for airflow (possibly wood and my drill). The shelves would allow me to experiment with cans filled with water. I have a row of them on the windowsill and they get quite hot, but of course, keep the heat much longer.