Urban solar air heater

We've been experimenting with solar air boxes for the last two years. Here's a link to the latest designs built by my hubby:
http://www.evsroll.com/DIY_Solar_Air_Heater.html

Not only are you getting outside air into the house in winter, but the computer fans used to draw the air in take very little electricity. On sunny days when it's
10 to 30 degrees outside, we've been getting air coming in at around 130! Often we're surprised when we go outside that it's actually cold!

The boxes also heat up when it's hazy... Managed to save $40 on our gas bill in January...

Johanna, one of my uncles had a very simple one of these attached to his house and it was amazing how much heat he moved through it.
My brother built one and it got so hot that it melted the plastic and insulation!

Does the plastic tubing give off any gases or smell?

Johanna - thanks for posting this! Looks like something that would be doable in Phoenix as well.

...and I have the same question as Miles - does the plastic give off any sort of smell? I wonder if metal painted a mat black (like for solar chimneys) would eliminate outgassing in high temps (I'm wondering out loud here). What are your thoughts?

How about just using the black iron from a smoke-straight-out-of-the-chimney fireplace?

Hi Charles - I don't have a fireplace, could you explain a little further what you mean?

Someday I plan on upgrading from my fireplace to a masonry build. Right now I just have a trapezoidal box made out of blackened steel with a flue pipe poking out the top of it. I imagine that if you paired one or two of these boxes with a reclaimed storm window that may trap the heat you need without off-gassing.

Thanks Charles - I get it now!

Jennifer and Miles,

Read somewhere today that outgassing doesn't occur until the corrugated pipe is around 140 degrees. We did smell that a little the first time the air got that warm when the pipes were new but no smell since. We have mostly been getting lower temperatures than that - usually between 80 and 130 over a six hour period - but that will probably change once temperatures hit into the 50s next week. Will let you know how that goes...

BTW, last year we used a thick clear vinyl to cover the boxes (without using the piping) and a faint vinyl smell was prevalent the whole time - I tend to be sensitive to chemical smells and did not find it too obnoxious - also neither of us experienced any apparent ill effects and we're both prone to headaches. The greenhouse plastic we're using now isn't coming into contact with the air since it's just traveling through the pipe so that should not be a factor.

Thanks Johanna. Like you, I am sensitive to smells and prone to headaches. And some gases can't be smelled either. I appreciate your insight on the various adaptations to the project. I'm a big fan of experimentation!

Jen

You're welcome, Jen - more will be revealed!

You could easily make that a passive system (no fan), but it would delete the fresh outside air that is part of your design criteria. It may help someone else pondering this, so i'll continue.
Put the heat collector below the window. Two pipes come out of window. The low pipe goes to bottom of collector - cold air falls.
The higher pipe goes to top of collector - hot air rises.

You'd be heating 60 degree air instead of 30 degree air. No power needed. I like the design with the pipe. Most passive systems are custom built to width of window. Your design allows for larger collector area.

Wayne, your idea sounds like it would work for situations where fresh air is not desired. We are however, hung up on it.

Re update on the design - Once the temperatures hit in the 50s, the angle of the sun was higher and so we were getting less heat in than previously. In fact, now that the sun is even higher, it is not heating the box at all so we decided to leave it on the side of the house for the summer. The white color of the greenhouse plastic actually seems to be reflecting light and heat so is keeping that side cooler than previous years... The only thing we did was cover some holes with super strong duct tape - the parts where the plastic is in contact with wood have abraded a little.

Currently using the solar cooker my hubby built a couple of years ago for most of our baking and cooking. Love the power of the sun! Am planning to build a large solar dehydrator so I can make dried apples and kale chips, and experiment with other things. It looks like there will be an abundance of apples this year...

its funny you mentioned a dehydrator. the day I commented, I had a sleepless night thinking of solar passive heating. It occurred to me that a dehydrator could be incorporated into the heater. Take one or two sliding glass door panels at a 45degree angle, but basically make it a closet with an angled door on the side. Install grates as the absorber area, maybe some corr metal on back wall painted black. An open vent on bottom, then vented on top into the house. open the door and put the apples on the grate.

Solar heat, dehydrator, and aromatic house. lol.

The fan might be needed for dehydrating, but this seems like a cool idea. a 3 for 1

Interesting idea, Wayne.

Is it possible to use this technology when the temperature dips below freezing point.

Does it work during the night?

Angelika, it will not work when the sun is not shining so will not work at night - it will work on hazy days and partically cloudy days. The beauty if it, however, is that the box stays there waiting for the sun - all you need to do is turn on the little computer fan to draw the air in once it gets warm enough (i.e., warmer than inside the house). For our area this is usually between 9:30 a.m. and 3:30 but this might be up to an hour later as the angle of the sun changes over the winter and spring.

Sophia, see above - you can use this solar air heater any time there is sunshine - how hot it actually gets depends on the square footage and the designs you use, as well as the angle of the sun (or the angle of the box), the materials. The thing to do is try it out and experiment... Even 70 degree air coming in would be better than minus 20 outside...

We don't heat here during the day (sometimes maybe). And even in the North you heat mostly at night. You could heat up either water or another thermal mass that gives you the heat at night.
You could put a water tank (the tanks used for the roof water) inside the house or in the basement and heat this water. I have no idea if that is bad for the water quality then, this heating up and cooling down. You would have to be more careful with the tank material. And you have to deal with different water level in case you have no rain.