soda can passive hot air panel, worth the hassle?

[russ]

Hi Pappio - Welcome to Solar Panel Talk!

It just depends on how much time you want to spend on the unit.

The downspout with baffles would be much quicker and easier - unless one is constrained on space the area can easily be taken care of.

[smokie]

can heater

I made one and I like It a lot. Its gotten up to around 95 on 30 degree days. I think it would put out more if I could get more air flow. I just have a small 12 volt pc fan, ran off a small solar panel.

[Denver Dave]

My obstacle is the mounting board

I did a test 2 years ago with a 2 ft x 2 ft x 1 inch silver covered foam board and about 50 or so beer / pop cans painted black with holes punched in the bottoms. I wrapped the entire thing in window shrink wrap and cut air slits in the top and bottom for the air.

On fairly cold days in Colorado, but with good sun, and calm wind, the panel put out air at the top at 180 degrees. For this prototype, there was no fan, but the hot air was definitely coming out. My concern and my obstacle was that I was concerned that under certain conditions that the foam board might catch on fire. I've been trying to find a fire resistant light foam board or Insulate http://www.energyboom.com/emerging/insulation-mushrooms become available in my area, but I haven't found anything. Any ideas?

For my next prototype I have an 8 ft by approx 2 ft by 2 inch foam board and one clear 8 foot ridged roof panel. I think I'll get another one that is dark for the bottom. I don't think this will catch on fire, but how sure am I. I'm planning on a small fan (ideas?), but this could fail and the panel overheat. The south wall under the eaves, get's quite warm, even in the winter - not a good place for a fire.

= = = = = =
Also fire resistant foam panels that are not toxic when heated might be handy for insulating interior north walls.

[russ]

Just use Dow XPS foam board - easy to find and cheap - won't burn when you put a match to it.

[MikeSolar]

Here is the original one with patents and real testing. It is quite copyable, although they might complain

http://www.cansolair.com/

[RecBeatriceb]

Soda can heater

My son made me a soda can heater for the chicken coop at the end of last winter. He said it cost $50 and when he tried it in his drive way in Portland, Maine in was below freezing and the air coming out registered 115 degrees. The coop is 8 by 10 and He's afraid it might "cook" the hens. I am planning on having three more made for the house.
Love free heat!

[SolarHeater]

Soda Can Heater Alternative

Hi Mike,

I am currently editing a new manual I've written on how to build a better and easier solar air heater. I am a former industrial oven builder and have taken the same concepts we used in industrial ovens and created a very simple and affordable design for my heater.

I started out trying the soda can method first, but I quickly lost interest in the process due to the labor and mess involved. Knowing how to build a simple heat plenum, I thought of an alternative to cans that anyone could build using common materials available at the local building store.

I also didn't want to use glass in the design as glass is expensive and of course dangerous to work with for the average person. It's also very heavy and doesn't lend itself to building a very portable heater. And of course, a good hail storm or stray baseball can break the glass.

And finally, I decided right away that there would be no wood in my solar heater design, as wood is also expensive, requires power saws and it is also heavy.

I've gotten temperatures up over 220 degrees on fall days, and about 150 on below freezing days, so this thing gets really hot. I include a link to a fantastic blower with temperature controller as well as a standard blower available at the building store. It can be easily run with a solar panel if one wants to use it off grid say for an RV or at the cabin etc.

[...]

[confused]

Mike
tried it, fiddled with it, swore at it, tore it down!

To be fair I didn't use a fan but by then I was already disenchanted by the whole thing.

Regards
Confused

[MikeSolar]

Mike
tried it, fiddled with it, swore at it, tore it down!

To be fair I didn't use a fan but by then I was already disenchanted by the whole thing.

Regards
Confused

I haven't actually made on myself but I make a sorts of things and failed more times than I can count You need to use a fan to create the turbulence which promotes heat transfer. I am a wet head (generic term for water heating guy) and not so fond of air heat but if it works...it works.

[confused]

Haaaa!!!


In that case if you ever get the idea that you can get free additional air by using an orifice plate and a check valve, based on the venturi effect, into the airline from your compressor, don't act on it.
That was my latest wheeze, which was dead before the starters gun went off.
Happily it cost me a 5 cent coin with a hole drilled in it and a check valve which I can use when I get another gift from the Muse's of madness.
Regards
Confused (and likely to stay that way)


ps
It will work fine if your working into ambient pressure, like a compressed air blower.

[russ]

Solar air heaters work well - the soda pop can version is just the cheapest version around.

The fan is to get flow through the unit - nothing to do with turbulence.

[confused]

Solar air heaters work well - the soda pop can version is just the cheapest version around.

The fan is to get flow through the unit - nothing to do with turbulence.

Thank you for taking the time to the reply but I will have to convince the Mrs ( 'er in doors ) that me bashing yet another hole through the wall of the house is
a) a good idea
and
b) that it will work this time

In the interests of machismo I should point out that I had to drink large quantities of strong hearty ale, not soda pop, to manufacture the beast.

Regards
Confused (or is that hungover?)

[green]

Easier way to use cans for heater

I just found two big sheets of tempered glass for free, and I was already considering building one of these. I'm going to go with the soda cans slid inside of the downspouts idea I saw Rich Allen use on YouTube. You get the good heat transfer from turbulence of the cans and the ease of building with downspouts. Looks like the way to go, no gluing the cans together. Check it out.

http://www.youtube.com/watch?v=2Cm-cbOWvSs

[SolarHeater]

Build a Can-free, Wood-Free and Glass-Free Solar Air Heater.

Hi guys, it's Eric and I also built a soda can and a downspout style heater. I should say, I started the soda can one. But I gave up after immediately insisting there had to be a better way. I wasn't yet sure how, but I knew there was a better design to be made. The second time around, I skipped the soda cans altogether and built a downspout style plenum. I still have this heater and it works great. However, I'd have a hard time believing anyone else would like to go through that process again or be able to follow it easily. I certainly wouldn't want to again. So again, I went back to the drawing board.

I used to be a metal fabricator for an industrial oven company as well as another large machine manufacturer so it was not a real problem for me to build any style heater, but, after building one and a quarter solar heaters similar to what I found on Youtube, I decided that the easiest and SAFEST way to build an efficient heat-capturing plenum was to build it like we did at the oven company. My problem was, I no longer had access to a sheet metal sheer (cutter), a sheet metal break (bender), welders, and etc. and neither do most homeowners. So I set out to design a homeowner-friendly solar heater that could be reproduced easily with easy to follow instructions and without all the expensive, dangerous tools and without the time consuming hunt all over town for materials.

Then the ideas came to me for the perfect choice of materials that were readily available at the local building centers. All the materials should be able to be picked up in one stop. Because stock of certain materials may differ from store to store, you can ask your local store to order an item if not in stock.

Safety was a major concern. I cringed when I watched folks on Youtube drilling cans with hole saws and drill presses while wearing gloves (a big no-no), loose-fitting gloves no less! This is very dangerous and great way break one's wrist or fingers or worse. The factory I spoke of had an accident where a female worker got her glove caught in a drill press and it nearly killed her. So skip the gloves when using power drills. Ok, and the average homeowner isn't going to be too keen on cutting a zillion cans (or 101) as in the video in this thread. Although I love his ingenuity and his heater sure heats well, I'd not want to build it that way for sake of speed, safety, and other factors.

My manual teaches my design that is wood-free, can-free and glass-free. Wood is heavy, expensive, isn't weather resistant, and for many, dangerous to saw. So I decided right away that there would be no wood in my solar heater design.

Although beer and soda cans might become the only materials left to scavenge from the rubble in coming years (I hope not), today the average homeowner's neighbors really aren't going to be very excited to stare at that "beer can sculpture" you built across the street for the next 30 years. If you're up in the north woods, you might be fine. But in the city, no way. So I wanted the design to look professional "factory" as my former boss liked to call it. So cans and wood boxes are out, for now.

Okay, glass was the next obstacle. For the first two heaters I made, I scavenged for glass, I searched on Craigslist for it, and ended up paying $50 for a dual pane patio slider door (super duper heavy!), and had to dig the second out of a 40 yard dumpster I happened to see near my home. Both had to be taken apart and carefully moved around. A huge pain. Again, the average homeowner isn't going to want to hunt for glass like this and then have to "build to" the size of the glass they end up with. And how easy is it to hang a 200 plus lb. box on one's home or move to a new home someday?

My solution to glass was a super light weight dual-walled 4'x8' polycarbonate panel readily available for just $39. It's surprisingly inexpensive at less than half the price of a 3'x7' piece of plexiglass that's $99 at the same store. The polycarbonate panel is 'bomber' and I think it says something like 100 times stronger than glass on the package. You can throw a baseball at it with all your might and it just bounces off. Plus, it's two layers and offers an insulating value and super rigidity to the heater itself. And it looks great from across the street!

Because my design is built in the same manner as a typical oven plenum, there aren't a whole lot of parts to it and therefore the heater can be built much faster, safer and much much easier. Plus, there's very little mess afterward. No sawdust or foam particles all over the place. My first two heaters destroyed the entire garage!

My heater is made from only light weight parts you pick up at the store. Everything you need fits right on those lumber carts you are certainly familiar with. My manual lists on one page everything you need to pick up from one store (depending on their stock of course), remember you can order all of the parts to your one location. I also show you where to order a computer-controlled fan controller that is specifically designed for solar heaters. The controller reads the internal temperature of the solar heater and slows the fan down if a cloud passes in front of the heater, speeds it up when the sun is strong, and shuts off the fan when the sun is not shining. The fan comes with a sleek inlet and outlet grate with a filter so it looks like any other air vent in your home, and keeps the interior of your heater and your home filtered. The other fan I show you is about $18 and is available at the same building store and it certainly does the job. Both can be run with a solar panel if you want to or need to be off-grid. I show you my simple set up and everything is available at the one store.

The end result is a heater you can pick up and carry by yourself, bring along on your next RV trip or connect to the ice fishing shack. It's rock, baseball and hail-resistant, and it looks like a standard skylight or window when completed because the flashing you'll use is powder-coated and looks fantastic. . It will be easier to build than the soda can and/or downspout styles. And when it hails, you won't be biting your fingernails praying all your hard work won't be in a million pieces.

How hot does it get? Last winter during my testing in Minnesota, I had 22.5 degree F outside air pumping directly into the bottom of the heater (normally, you'll pump floor level air from inside your home outside and into the heater), the air coming out of the heater during the test held at 155 degrees F. That's 15 degrees hotter than your standard furnace.

During the fall, I tested it with 55 degree air pumping directly into it and the output was over 220 degrees F as it buried the needle on the meat thermometer. Too hot to even touch. Amazing.

Don't forget, you can easily connect yours to the inlet on the back of your clothes dryer all year long, so build one for your dryer as well. (Although you do not have to alter your dryer at all, do ensure that your warranty will not be adversely affected before taking this step). We're installing one to the clothes dryer in Phoenix at the moment. I'm simply taping a turkey basting tray over the inlet on the back of the dryer and running the tube into it. So no permanent alteration. No more sending air conditioned air into the back of the dryer to be reheated and sent outside! How ridiculous is that when you think about it? Also, this heater has been sitting in the Phoenix sun for 4 months now and the polycarbonate panel still looks great and has not yellowed or cracked whatsoever. So I am confident that this design will last for many years. I hope you will want to build it for your home.

I just found two big sheets of tempered glass for free, and I was already considering building one of these. I'm going to go with the soda cans slid inside of the downspouts idea I saw Rich Allen use on YouTube. You get the good heat transfer from turbulence of the cans and the ease of building with downspouts. Looks like the way to go, no gluing the cans together. Check it out.

http://www.youtube.com/watch?v=2Cm-cbOWvSs

[russ]

Don't get suckered in to paying for a design - they are available for free on the net.

Polycarbonate has reasonably good light transmission characteristics and some formulations are UV resistant - the mfg tells you this.