Solar hot air heater results

[myxpykalix]

Here are some pictures of the results I got with a jerry-rigged fan so its not optimal.

I'm waiting for my 4" fans to come from amazon. I went and took a 6" fan that was just positioned by the hole to blow air in which is not getting a great flow of air (if you look at the picture). Also the trees are blocking a portion of the box (see shadow).

Today it is 93 degrees here. However even with those conditions I uncovered the box (had tarp over it) and by the time i got my extension cord and thermostat rigged up (15 minutes) it was phushing air out at 160 degrees this thermometers limit. So the temp of the air was probably way hotter then 160. I have a oven thermometer I didn't have room for that i may try to put in somehow.

It was amazing to watch how when the clouds would pass from in front of the sun the tempurature would instantly drop several degrees and then come right back up when the sun came back out.

The real test will come in the middle of winter. It seemed to be a successful test so if you guys want heat in your shop for free start designing your boxes and drinking your beer:D

[kevin]

Jack
Remember the angle of the sun is different in the winter than the summer .Mine harly work now
It looks right

The oly thing differnt is there is curve on the glass plus it has a coating that maginifys the sun

[myxpykalix]

one of the things i was researching but couldn't find the answer to was, what advantage do you get by having the curved glass front?

Also i was researching sun angles for the winter in my part of the country for optimal angle and placement. I know it is different then in the summer.

[Greencarvings]

How about a giant fresnal lens?

[kevin]

I'am not shure the advantage of the curve I didn.t make it .I think it lets you keep it vertical with out tipping to get maximun

[ssflyer]

The fresnel lens would probably work great - if ya wanna melt your cans! :D

[myxpykalix]

Patrick, like Ron says:D if you want to start a fire use a fresnel lens, i've seen them start wood on fire or bake food, fry fish in a skillet, ect:eek:

[ssflyer]

Jack,

A bit off topic, but couldn't resist...
Back in the day, I was manufacturing satellite dishes - from 12' - 18' diameter. I ran a test on a new 12' mold, and forgot the graphite reflective layer. The dish sat around for quite awhile, until I decided to do something about it. I bonded aluminum foil to the surface and was going to paint it. I decided to point it toward the sun to see what kind of heat it would generate. WOW! I used a long rod to put a few things in the focal point. Wood almost instantly burst into flame! No problem melting aluminum. :cool: I wish I had a high temp thermometer.

Ron

[Brady Watson]

Jack,
Find out how the sun tracks in the Winter on the side of the house you want to use it. The sun is actually more direct in the Winter, even if it is further away.


I bonded aluminum foil to the surface and was going to paint it. I decided to point it toward the sun to see what kind of heat it would generate.

Ron,
It's been on my 'mad science' list for a while now...except my use will be a little more practical than just burning ants etc :D

-B

[myxpykalix]

Ron,
That is funny you mention about satellite dishes because in the late 70's and 80's I used to sell 12'-18' satellite dishes from my video stores. I remember ones that had a aluminum mesh, and solid ones called "Birdview" satellites. Then they started making them out of fiberglass.

I think i still have a satellite positioning arm along with the positioning controller. The satellites would follow a particular arc in the sky. There was like 24 transponders per satellite but if you had one of these dishes all the programming was free!
I still have a satellite signal descrambler.

[ssflyer]

Jack :D I also designed and manufactured the first positioning arm that I know of - Called it the Dish Drive. Rack and pinion, with simple limit switches and micro switches for locating the sats. Then I got fancy ;) and designed one based on a Commodore VIC 20. It didn't have enough RAM *something like 3.8K) so I made an add-on board with a whopping 16K of RAM and extra video processing, and bought game cartridges from a Silicon Valley game manufacturer to hold my circuit boards. You could program up to 3 automatic changes a night, to record different programs on your VHS or Beta :) It showed a house at night, with twinkling stars, and your dish moving, when actuated. A lot of fun!

Brady - I alway wanted to make a tracking solar collector with it - would have been trivial with the hardware I already had, but somehow never got around to it!

Ron

[gerryv]

A few thoughts:
- Unless you're increasing the capture area with a fresnel bigger than your "box" you will only be increasing the temperature in localized spots at the expense of less heating between them but no gain in actual BTU's which is what you're really after unless you're goal is to cook something. And it will add to your cost.
- A bigger fan will not transfer any more BTU's. only more CFM but at a lower temperature so again, no net gain - but it will cost more energy to run so potentially a net loss, albeit small. That said, too small a fan or similar means of removing BTU's could cook your box :-)
- Low-e glass will work against you; low iron glass in your favour.

I'm open to dissenting opinions though as I'm on the learning curve as well.

[myxpykalix]

The glass itself looked clear, its not double paned with gas inbetween or anything. It was the glass insert from a aluminum screen door i bought up at the habitat store for $20.00. I was given the insulation free, I bought the pressure treated wood, high heat paint, thermostats, ducting, silicone, beer/soda cans FREE, and spent at least $100.00 for everything.

[jerry_stanek]

Back in the 70's we built some solar heaters out of wood and they didn't hold up all that well. We had to add dump doors for the summer but they still dried the wood out and made a fire hazard.