Solar Air Heater

These things sell for ungodly amounts of money for what they are. Anyone can build one very easily with very few tools and readily available supplies and with little invested. Some of the materials I've listed below are for movement of air and are always extra with bought units. I put an * beside these items to indicate even if you buy a prebuilt unit you will still need these items separately.

I've seen two thousand cornball designs on the net that look like crap not to mention very inefficient and this is 90% of why you never see anyone build one of these. The picture is the first one I built installed on my roof. As you can see it looks much like a skylight. If you take your time, you can build one that looks just as good or better and will heat VERY well on cold days.

I'm going to attempt to illustrate the basics of building an extremely efficient model that nearly anyone can build. I built my first one and learned some things along the way. I wish so badly someone had been there to walk me through it and tell me what I was doing wrong along the way. I'll try to make it clear where I went wrong on my first build to help you avoid the same mistakes. I only made a couple of mistakes but they were bad enough to cause me long term headaches.

Supplies:

• 1 sliding glass door
• 1 4x8 piece of matte black cinefoil
• 1 sheet 4x8 1/4 inch plywood or wood paneling (not particle board) Thicker OK but will be heavier.
• 1 sheet 4x8 foam insulation with reflective surface
• 3 1x6's 8' long
• 2 1x3's 8' long
• 3 1x1's or 2x2's 8' long (preferably 1x1's)
  
• 1 tube outdoor construction adhesive
• 1 tube silicone rubber adhesive
  
• 2 6 inch floor duct adapters*
• 6" duct to length applicable*
• 6" duct fan*

The most obviously expensive item on this list is a sliding glass door. However, if you look around you can find people throwing these out regularly. They are easy to find in local shopper papers and many carpenters in the local area can tell you where to find them all the time. I found three sets in one day of looking. People love these doors until they have them. They wear out and are difficult to secure and are an eyesore on many homes.

First and foremost, your finished heater will weigh less and look better if you take the time to remove the glass from the frame of the door. If it's double paned glass all the better, as all you are concerned about is the rays that pass through glass readily. The extra layer will help keep the heat in that's generated. However be very aware this glass is HEAVY and you may need help building this.

You want to take the 4x8 sheet of plywood or whatever material you chose as the backing -the lighter and more rigid the better- and cut it down to the exact same size as the glass you removed from the door frame using the glass as a guide if you like. If you didn't remove it frome the frame you will have to make it the same size as the aluminum frame surrounding the glass.

Then you want to build a basic square box using the 1x6's that outside edge is exactly equal to the size of the glass from the door. Use construction adhesive and nails at each of the corners to seal the box. Be sure the construction adhesive is outdoor quality or it will leak. It is very important the finished box must be air tight! Coat one edge of the frame of the box that you just built with construction adhesive and apply the backing that you cut previously and use tacks or nails to secure. I would personally use the rule of applying a nail (with a head) or a long roofing tack about every two to three inches and allow a day to dry after checking that the entire assembly is equal to the size of the glass once more just to be sure. Mistakes will be very hard to compensate for.

At this point you should have a box that looks like a big rectangle with sides six inches tall. Now you want to take the 1x3's and start to make the inside pieces. FIRST make the longest cut. If you don't you may run short on your materials. You'll see why later. Measure roughly eight inches in from the end across the short side of the box. You have to cut a piece of wood to fit inside and attach to both side of the long sides. This piece will be turned flat side up towards the glass. See the picture. Do not install this at this point. We will install this piece later. Using the remaining 1x3 material proceed to cut four more pieces one foot shorter than the last cut.

Now to assemble. First you want to make sure each end is large enough for your duct adapters. Again see the picture. If these ends do not accommodate your adapters you will run into airflow or duct installation problems. Do not install the duct adapters yet.

Install the previous five pieces you cut according to the illustration below. Here is where it gets tricky. You need some small wood to attach the cinefoil to later in all of the locations shown. Using the 1x1's cut and attach in shown locations appropriately. Since the easiest method to apply the cinefoil is by a stapler later this step is necessary. Now cut the hole for your duct adapters in shown opposing corners of your box. If your backing material is thick enough you can just nail them to the back later. If not, then you may have to insert them through the front now allowing the lip to hold them in place. This is the best way to install them regardless but it makes handling the box more difficult.

Now using the foam cover the entire inside walls of the box including the nailing strips applied to make the box as insulated as possible.

Apply the cinefoil to the top of the surface and around the piece going slightly underneath. This is difficult to do neatly. Now apply the cinefoil carefully to all exposed areas and slightly underneath the flat piece on the bottom of the box to hide the insulation.

Apply the glass to the top of the box using silicone rubber. Your finished.

The box will still look rough around the edges. What I did was hire a carpenter to bend me some aluminum flashing to cover the edges of the box and now it looks completely professional. This last step didn't cost much at all I think he charged me $25. There are a ton of ways to make this look good at this point without hiring anyone. Use your imagination.