solar air heater

[super windy]

Hi everyone @fieldlines

Just a quick video of my home made solar air heater, its working perfectly, it definatelly more than doubles the temperature outside, tell me what you think:

http://www.youtube.com/watch?v=173owKST-w4

cheerio

super windy

[freeEnergy4me]

That is cool as hell....er hot as hell, lol.

I am going to try one! I live in Michigan, similar to the UK. And heat prices here are outrageous. I know the heeat from the sun is extraordinary. My roof melts ice when it's below freezing and my cheapo panels will fully charge 3 12Vs in a day and a half.

This should work. The only issue is a ventilation system. I can picture using a PC fan for low volts. Since heat rises, going from a roof to a lower floor would require a suction type apparatus otherwise the heat would never go down. Some type of "heat pump" as it were. Maybe a fan would be the wrong thing to use?

I realize this really only is benefitial in sunny days and only during the day. And one suggestion is always to have large windows facing south and let the sun just heat your house through windows.  But this would be great for the hidden areas of your home that don't get direct sun.

And importantly for a cheapster like me, its CHEAP!!

I would probably use PVC over copper (too expensive). I will definately look into it.

This is similar to the solar water heating systems.

[freeEnergy4me]

I realize you have a PC fan, after looking at the other videos you posted.

An alternative would be a vacuum pump on the inside of your house.

Reason being, if you could control air flow from inside.

A cheap option would be this:

http://www.amazon.com/Coleman-5999C120-Electric-Quick-Pump/dp/B0009PURX6/ref=pd_sbs_sg_img_1

It is a reversible pump. You could turn it on for a short period then let the air heat and turn it back on. With a long chain of cans, you could pull in air for a few minutes then close the valve and shut off the suction.

The vaccum is low energy, not free. Just an alternative to the fan. And if you had really tight seals from can to can, the suction would move the heat along faster.

Just a suggestion. I will definately give this a try tho.

[ZooT]

I've got a two by four foot panel hanging in a south window now.....and I use a 12vdc@120maH muffin fan and two of those cheapo HF 1.5 watt panels to curculate the air through it......er uh.....I put boith the panels and the fan inside it, with the panels being at the bottom of the collector and the fan sucking air out of the collector and blowing it into my trailer.......

Don't need no temp switch because the fan won't run unless the sun is shining into the collector.......

[Bruce S]

Hey ZooT;

  you have those panels inside with the air heat? Those panels might get a bit too hot on long sunny days. Even in the winter, if the inside is getting up like his is on the video.

They will over heat the panels and not conduct after a while.

If yours is all closed up and sealed then it might not be worth while moving them out, but if not you might want to measure the power output once they've been heated to see if they're losing power output.

This is fairly the same as having bigger panles up on the roof with not enough clearence and they heat up the backsides.

Original Poster!!

That was a very nice video, I liked it when you shaded it and showed the differences in heat.

Nice panel setup too!

Cheers

Bruce S

[freeEnergy4me]

I was up late last night looking at options for heat.

I think a cool option would be some type of ceramic that gets very warm in the sun then cools very slowly....so even when the sun goes down it is still radiating heat.

I've been next to some buildings with cinderblock walls that even after many hours into the night they are warm/hot from the sun during the day.

If you could do that on a small scale. I was looking at things like heat absorbing glass used in optics. If you could have a big piece of that on a roof top and just have a fan/vacuum pulling air across it, that would generate some decent heat.

Obviously these are not cheap options unless the ceramics/glass were something easily made/purchased.  

I was also thinking of making a concentrator and using thicker aluminum. You can buy that spray on mirror paint to cover pre-cut panes of glass. And have them focus on one line of cans. So it would be fewer cans, but much hotter. I guess you would have to mess with it to see how fast the air would need to be put thru to get the most heat.

Some great ideas!  I think if you get a lot of sun during the day, you can almost heat your home (if well insulated) with direct sunlight. The key is to find a material that absorbs the heat for a long time.

[TomW]

Ceramic that heats and radiates over time...

Look up "Trombe wall".

Not sure how efficient they are but its that same concept and its from the '60's or so.

Just an idea.

TomW

[freeEnergy4me]

I noticed you put aluminum foil behind the cans. Had you thought about covering the foil in black paint as well?

It would heat the air in the box which on a cold day would slow the can cooling.

There are so many variables, such as speed of air flow, etc. that may maximize heating.

[zeusmorg]

  Why not just use convection to pull the air thru?

  Build an insulated box that pulls air off near the floor of the room, then have a rear passage in the box leading down to the bottom outside edge. your front passage contains your solar collactor be it aluminum cans or a black corrugated metal. Then the hot air exits into the room at window level, no moving parts, and it shuts itsef down when there's no sun..simple.

[tbb42]

I got to make one could you put step by step and material you used or give me a link to where I get dimentions and step by step.

[ZooT]

Try here:

http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm#Passive

There oughta' be something that interests you there

As far as putting the panels and fan inside the box goes my reasoning was that the fan keeps the air circulating and the panels are in the very bottom, lower than the aluminum flashing "collector" is....

And yeah, I could thermosiphon but having a little fan just "seems" better..

[AL is my name]

Again with a usless link. Did you think maybe he has read the article already? maybe thats why it's not a Trombe wall.

[TomW]

Seeya, Al.

Your contributions will be missed.

TomW

[ZooT]

Because I don't want to cut holes in the walls.

The one I built hangs in the window like an air conditioner.....and that way I can take it out in the summertime

[freeEnergy4me]

I'm in the process of making my own version. I am going to stick with the PC fan also, that inflator is too noisey. Also, you can find 3-speed PC fans to increase flow if you want. Instead of in the box, I'm going to have the fan at the end of the output

Instead of the pipe, I'm using flexible hose.

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&ca
talogId=10053&productId=100119536&N=10000003+90072

And putting the small fan at the end of it. It should almost fit perfectly across it.

As a twist, tomorrow is going to be a very sunny day so I'm going to fill one of the black cans with engine oil. I want to see how hot the engine oil will get.  If it gets very hot, it will be a great way to trap the heat for later in the evening when the sun is gone.

I'm also painting some aluminum flexi-tubing black to see how that works. Then instead of connecting cans, maybe making a bunch of lines of tubing instead. That way you don't have to mess with silicon and you have one tube from input to output.

http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&ca
talogId=10053&productId=100010697

The flexi-tubing is very cheap and really easy to work with, I'm kind of excited to see how that works.

Another alternative would be placing the flex-tube thru the cans which contain engine oil. So you would have the air surrounded in hot oil at the end of the day and could pull the unit inside and cycle the inside air through the hot oil.

Water gets to 110F with a decent solar setup, if oil got that warm it make be good for heat several hours after it is in the sun.

[Birdmanuk]

Hi Super Windy,

                 I really like this design for your heater, have you any heat output details for sunny winter days where the outside temp is below 0? I'm guessing you will still see a massive increase in temp, but is it enough to heat a room?

I'm still collecting cans :-)

[fcfcfc]

Hi:

Late to the party here, sorry. It looks nice but from an engineering perspective there are allot of things done incorrectly....sorry.... When using air DIRECTLY as the heating medium, the inlet and outlet ports want to be fairly large so that low pressure large volume fans can be used which reduce the electrical energy to run the panel. As an example, a 32 sqft collector should probably have nothing less than a 4" pipe in and out, better 6" though. That's 12sqin's to 28sqin's for each of the two ports. Secondly, when assessing whether a collector is "doing well" under no-load as shown conditions, if it is a clear sunny day, temps should reach 160DegsF at the output port. This assumes a good selective surface absorber design, heavy insulation for the back and sides and a double wall front glazing like twin wall three skin poly carb... or Teflon two skin, low iron glass etc.. there are lots of choices there... Hot air collectors have a lower COP than liquid systems so you want to make it as easy for the air to move through the unit as possible, but with enough turbulence for good heat transfer.... it's a balance as always...

.....Bill