This thread's a little old, but winter approaches, so here goes.<div>I've been researching solar space heaters for several years on & off and this year I'm gonna make it, by golly.</div><div>The beer can heaters, they're sexy, but not the best method if you are going to go through the trouble of making a heater from scratch. If you're in a permanent home with lots of room, heck, make way too much sq. footage of those, they'll work. But in vehicles, space for such things are limited. They get a lot of web coverage because of the "cool" aspect, but they are ALOT of work.</div><div>IMHO, in my years of searching, I have found the best info at 3 places. </div><div>#1, <a href="
http://tech.groups.yahoo.com/group/SimplySolar/" target="_blank">yahoo group SimplySolar</a>, they are great, lots of experience from lots of people and real research, not simply "hey, I drunk all these beers and made a heater, works!"</div><div>#2 <a href="
http://www.builditsolar.com/" target="_blank">Builditsolar.com</a>, the website owner Gary is also a member of SimplySolar, the info bleeds over back & forth.</div><div>#3 <a href="
http://www.redrok.com/main.htm" target="_blank">Redrok.com</a>, this guy makes & sells sun tracking controllers, gives the info away if you want to try & duplicate without buying. He's also got lots of good info, although it's not organized for easy searching.</div><div>All three of these are very knowledgeable, helpful, non-profit oriented sources.</div><div>If you read through the posts at SimplySolar you will soon find that the most effective "breadbox" type space heater is also the easiest and also the cheapest next to the beer can idea, unless you value your time at more than $.10/hr., then it beats the beer cans.</div><div><a href="
http://www.builditsolar.com/Experimental/AirColTesting/ScreenCollector/Building.htm" target="_blank">What is it</a>? Charcoal black aluminum window screen, stapled 3 layers thick, .5 inch apart on a cheap wood frame. Just put that in the box instead of the beer cans. That lowly little window screen, got lots of surface area and air transferring thru gets alot of contact.</div><div>There is about 1KW of sun energy/sq. yard, decreasing as you go north. 1 watt=3.41 btu. Most decent solar air space heaters are about 50% efficient, some a little more. So you can use that to figure out what you need.</div><div>I'm torn between the simplistic window screen heater and a design I've been working on that emulates the latest solar plants being made, called CLFR (not carriage return line feed, <a href="
http://en.wikipedia.org/wiki/Compact_linear_Fresnel_reflector" target="_blank">Compact Linear Fresnel Reflector</a>). The screen heater is simple, cheap, but a bit bigger than I would like to cart around (2'x4' would probably work pretty good for me, like a big stereo speaker, but 6" deep). The CLFR design is smaller, but more expensive, more complex and a bigger footprint on my roof, as it is all mounted flat there. But very low wind load, which is nice. The "speaker" could go anywhere and although it's larger, still has about the same footprint, since it stands perpendicular to the sun, between 45 & 60 degrees for me here. Gonna catch the wind like <a href="
http://www.freakingnews.com/The-Flying-Nun-Pics-81653.asp" target="_blank">The Flying Nun</a>, but it can be tamed easily. And no tracking required, unless you want to squeeze every last btu out of the sun. The CLFR would require at least 1 tracker, and more if you want to completely automate it and get maximum efficiency.</div><div>Another intriguing design I explored recently, like the beer cans, using cheap recycled materials is what I call "The Atlantis Death Ray Heater." Cover a satellite dish with reflective mylar, build an absorber out of copper pipe painted black, point it at the sun. This will work well, but the 18" dishes available here in SoCal only seem to get about 700btu, I'd need a couple or a bigger dish. And many downsides: would attract ALOT of attention, not stealthy at all, atrocious wind load, must track the sun in 2 directions and finally, although they are quite efficient, would even boil water, produce steam, that kind of high heat is not required for this purpose, and the efficiency, although apparently awesome, actually goes down the hotter you get things, as now insulation, conduction & convection become much more relevant losses than with a lower grade heat.</div><div>Well, that's a quick rundown of where I'm at on the issue. Food for thought, even if it's nonsense <img border="0" align="absmiddle" src="
https://vanlivingforum.com/images/boards/smilies/wink.gif"></div><div><br></div>