Greg's Solar Air Collector
Greg describes the construction of his 18 square foot solar air heating collector that provides some of the heat for his shop addition. This shows how simple and effective solar air heating collectors can be.
Thanks very much to Greg for providing this!
Air enters at the
lower right and makes its way
around the baffles to exit on the upper left.
I have another wall mounted TAP on the back south facing wall designed like the one you have on your shop though not as big. It starts to kick in good after the active one is shaded. The addition I'm heating is approximately 200sq.ft. and is yet to be insulated.
Photo 1: Layout of collector on the wall.
Photo # 1: I marked my level and plumb lines for the inside measurements of the frame. I'm using 2x4's for the frame. Making sure that the first vertical line is plumb and also that the first horizontal line is square with the vertical. I'm sure you know that you'll be sorry if they're not. The little tool in the photo is a Dremel tool I used to cut out the inlet and outlet ports. A jigsaw will work just as well. I like the dremel tool because it cuts such a nice circle.
Photo 2: Cutting the inlet and exit vent holes.
Photo # 2: For this collector I cut 5.25"(13.3cm) inlet and outlet holes because the fan I'll be using has a 5"(12.7cm) diameter blade.
Photo 3: Installing the collector frame on the wall.
Photo # 3: The frame is 39.75"(1meter) x 64.25"(1.63 meters) inside measurements because of the glass I have on hand. I used 4"(10.16cm) ex. decking screws counter sunk 1"(2.54cm) to attach the first vertical frame member to an existing stud behind the wall, for the horizontal one I put screws in every stud I could hit. One vertical member didn't land on an inside stud so I attached it from the inside using 2"(5.08cm) sheet rock screws. I primed all frame parts before attaching them then filled all screw holes with caulking.
Photo 4: Installing the absorber and baffles.
Photo # 4: I then used 1/2"(1.27cm) R-MAX foil faced insulating board inside the frame for the absorber. I then installed the baffles which are 5" shorter than the inside vertical measurement, and 7 7/8"(20.2cm) on center. I sprayed the inside with Rustoleum high heat flat black paint (with a spray gun). After the paint had dried I caulked all cracks and seams with 100% silicone caulk. Do not skimp on caulking for your collector, you'll be sorry.
Photo 5 -- Finished Collector
Photo # 5: Glass installed, turning vane at bottom right to help the air have a smooth entry. The glass I used had a 7/8" frame around it with enough room for me to drill pilot holes for screws to attach it to the frame. I then caulked all around the exterior of the metal. The funny looking white lines you see behind the glass is weather stripping to make a good seal on the baffles. The only fan I had on hand to power this with was (believe it or not) a microwave fan which turned out to work very well. The length of run through the baffles is 26' 8" (8.12meters). The collector glass comes out to be 40" x 64" (17.77sq.ft.) Collector is 3"(7.62cm) deep making for 4.4cu.ft volume.
March 21, 2008
You can send email questions to Greg here:
gwest77 AT netscape DOT com (substitute @ for AT, and a period for DOT")
Be sure to include "Solar Air Collector" in the subject line.
This is another illustration of how simple solar heating can be. For only about $2 per square foot for materials and a few hours of labor The collector makes a significant contribution to heating his addition.
Some things to consider:
You might want to make it larger.
The area Greg is heating is not too large, will be insulated, and he has an
additional solar heater on the other wall, so this is probably a good size
for his situation. But, In general, it does not take a lot more work
to build a large collector than to build a small collector, and the heat you
get out depends directly on the area. In most situations, you won't be
sorry you made the collector large.
The style of collector in which
the air to be heated passes behind a sheet metal absorber is generally
thought to be somewhat more efficient than this style because the heated air
is not in contact with the glazing. But, Greg's collector is simpler,
cheaper, and easier to build, and the use of double glazing will reduce heat
loss out the front of the collector.
If you want to examine more of the ins and outs of fan forced air collectors, this is a good reference ...
Gary March 21, 2008