Solar Heater - Glazing Choices?
 

Just wondering what the best thing to use for glazing on a solar pop can heater might be? I've got a couple of big dual pane picture windows that are split into 3 sections, I was hoping to use them as they were free... could i silicone the joints together?

or else I've got some 4 ft aluminum frame slider windows (single pane) that I was also thinking i could just leave in the aluminum frames and silicone them together?

any idea if joining these materials together is just going to cause me sealing issues or if anyone has used these successfully long term? I can get polycarbonate glazing but it's pretty pricey, trying to keep the payback down on this project.

Pretty much anything will do. I even proposed an ultra cheap design where the front was covered with plastic. It would have needed a fan to keep temperatures down, but I'm sure it would have worked.

I think the glass will work out fine for you. Just make sure you secure it well to the frame. I would use more than just silicon. All the expansion and contraction from extreme heat/cold cycles will want to move things around.

I hear you about the polycarbonte being expensive. That was 1/2 the costs of building my pop can solar heater. With the new 20 watt solar panel to run the fan I have $500 invested in mine, but if it keeps my garage from dropping below freezing this winter I will consider my investment paid for by spring time. I was using propane to heat garage and it got stupidly expensive. The last 100 lb propane bottle I bought was $160.00 CAN and it only lasted 2 weeks and that was with the furnace just running on pilot light. It wouldn't take many propane refills to pay off what I have into my pop can heater.

I have used a mastic "tape" to set replacement windows in aluminum frame. It was approx. 3/4" wide,and came in a roll with a wax paper carrier. It applies to the flat of the edge, and stays soft enough to flex with thermal expansion and contraction. You will probably have to got to a window supplier's shop to get some, I don't recall ever seing any on a hardware store shelf.

I think the stuff you were using might of been called butyl, it was what they used to hold windsheild in cars in the 70's and 80's before they went to urethane. You could get this stuff in different dimensions, I should have used that to seal the glazing on my pop can heater.

The stuff I was using was about a 16th of an inch thick, and was light gray in colour, and was supplied by a local window shop. It was for replacing the glass in aluminum framed single pane, horizontal sliding residential windows, close match to the OEM stuff. I remember the butyl rubber stuff, not the same product. The butyl would probaly work just as well though.

The butyl would be nice if you could get it in 1/8 x 3/4, I'll have to see if I can find some, I just used silicone on my pop can heater and the first day the bottom seal let go as the polycarbonte heated up, so then I used some drip edge for roofing and used it as a type of clamp to hold the polycarbonate in place. I'll take some close up pictures and post over here
http://ecorenovator.org/forum/solar-...ar-heater.html I hope this works.

I was originally thinking I'd just leave the glass in the aluminum frames, but I'd have to grind off all the protruding edges that were originally intended as handles and slider stops. I took one piece of glass out of the aluminum frame b/c I thought the rubber seal would just melt at high temps, but doing so ended up leaving a couple cracked edges that I'm sure will continue to spread with the heating/cooling cycles...

Now I'm thinking about going back to polycarbonate. madmike, know any good sources here in Canada? I've checked Home Depot but they only have 3x6ft pieces.

And is there much difference performance-wise between Lexan and Polycarbonate?

I got my polycarbonate from Speedy Auto Glass, I checked every where locally and Speedy was the cheapest in town. From what I was told by the guy at Speedy the lexan will turn yellow and cracks easier then the polycarbonte. Make sure you specify UV stabilized.

Get this... Speedy in Scarborough ON (got transferred there by mistake the first time), $110 for a 4x8 sheet. Speedy in Winnipeg MB, $391.44!!! Yikes!

Then I went hunting in the Yellow pages, found a couple local plastics manufacturers... I can get Lexan with a 5yr non-yellow wty for $83.00 or Acrylic with a 10yr wty for $110. No brainer!

I'm thinking 1/8" thick will be sufficient, what are you using and did you need to put in a support brace to keep the panel from buckling in the wind?