Save Those Beer Cans - Build a Solar Heater! - Page 2

The goals of the project were twofold:

1. Design a passive solar unit which could provide some useful measure of auxiliary heat.

2. Design something relatively simple and affordable to construct.

The solar heater essentially consists of two main parts - the solar heater box and the solar heater collection unit (found inside the solar heater box.) The solar heater box acts as a frame to hold the entire device together and to contain heat. It is basically a rectangular box consisting of wood sides, a wood back, and a glass top - very minimal construction needed here. The solar heater collection unit is a series of aluminum cans (in this case a few soda cans and plenty of Milwaukee's Best Light beer cans), aligned in rows/columns and secured in place. In addition to the two things mentioned above, you also need some sunshine. This venture doesn't work in the dark.

Anyhow, our project began at the transfer station metal pile (where all quality home improvement projects start.) Here we found a single double paned glass slider door. The door was obviously once part of a normal two-door slider, the rubber trim/gaskets were torn but the frame and glass were in great shape. This particular door was quite heavy and measured 36" x 80". Despite its weight and lack of gaskets, it was the perfect unit to create our solar heater box - mainly because it was free.

We built our solar heater box sides out of 1"x12" common pine, nailed together in a simple rectangle shape. The back of the box was constructed of a standard piece of ¾” plywood, which was nailed to the rectangular frame (we were lucky in that we had all of this wood leftover from another project, but had we not, it's relatively inexpensive stuff and wouldn't have added much to our total cost of construction.) The frame was made so that the glass door would fit snugly against the box and flush with the top of the sides. The door panel was set on 1"x3" strapping screwed to the inside of the four sidewalls to help secure it in place. Across the width of the bottom of our solar heater box we inserted two support pieces of 1"x4" pine. The bottom and sides were then covered with 3/4" foam insulation, which was then covered with heavy duty aluminum foil. A round outlet hole large enough to insert 4” diameter aluminum dryer vent hose was cut into the top of our solar heater and another rectangular hole was cut into the back of the box near the bottom. This rectangular opening was cut large enough to fit a flexible downspout hose (we wanted to try out both hose types.)

Our solar collection unit inside the heater box is comprised of a chicken wire cage/suitcase holding 192 aluminum beer cans (soda cans will work too if you prefer - but beer makes for a better conversation piece and tastes better.) The 192 cans were aligned in 12 columns, with 16 cans piled on top of one another in each column. Each can had a 5/16th inch hole drilled into the bottom to improve circulation with the cans above and below. Our theory being as the sun heated the air in the cans it would rise into the one above and so forth. The cans were held together with aluminum duct tape, laid across and up and down. While Milwaukee's Best Light is a fine looking can and a great tasting domestic beer, we opted to spray paint the cans black before finishing our project. Not only does this improve the aesthetic appeal, but more importantly, it helps heat the aluminum. The entire caged unit was then placed inside a rectangular box made from standard home downspouts. The entire collection unit was then placed inside the solar heater box, with the glass door then put into position and screwed into place. All seams were caulked with exterior caulking.

The unit was then placed into position. The bottom inlet went through an opening in our rear basement slider door, and the outlet went by way of dryer vent hose through some stovepipe (for added stability) into our kitchen window. So how did the newly constructed heater perform? Answer: Drink up.

An oven thermometer located inside the heater has indicated that our solar heater reaches temperatures in excess of 160 degrees on sunny March days. Our inside thermometer, located at the window of the heater outlet, has indicated that at times the air coming into the house from the heater has exceeded 120 degrees. Toward the end of the season we added a small computer fan into the window opening to move the air into the room. This fan is also powered by the sun using a small solar panel; thus the fan only comes on when the sun is also heating the solar furnace.

Next year we will likely modify the unit a little and mount it higher on the side of the house to increase the exposure to sunlight, and will insulate the inlet and outlet hoses. While this homemade unit on its own may never fully heat our house, the project was certainly successful and the added warm air decreased the amount of time our conventional heat came on, thus we saved money!

If this article has been a bit confusing...it's understandable and perhaps some photos would help. Please visit the Media Gallery for some step-by-step pictures of our solar heater.

We here at CapeCodWeather.net encourage you to build a unit of your own or work on modifications of our design. We will gladly post some photos of your design next season.