Build A Solar Space Heater

Somewhere in my piles of notes, I have a plan for solar space heater.  I tore it out of a newsletter ages ago.  Well, I was researching some big passive solar projects for an outbuilding and there it was on the Build It Solar website.

Of course, it wasn't exactly the same.  There were a few minor differences (the version I have stashed away used metal cofffee cans as thermal absorbers), but it was the same concept.

The great thing about these is that they are so easy to make and they put out a lot of heat for free.  And that means Texas electricity savings.  The bigger the collector, the more heat it will put out as long as the sun shines on it. 

First of all, you need to build a box frame.  It should be long enough to reach the ground from sitting flush in the space of an open window.  For the most part, it will be at a 30 degree angle to better catch the sun's direct rays.  The box should be rigid with a plywood back and 8 inches deep.  Inside, the box's depth is divided into uppoer and lower plenums (chambers) by 1/4 inch plywood.   Dividing the upper plenum, a piece of flat-black painted sheet metal acts as the thermal absorber (it gets hot).  A sheet of acrylic covers the top to let in the sun light. For it to work efficiently, all joints must be sealed with caulk and it must be well insulated with rigid foam.

How it works:

Sun shining through the acrylic heats the black-painted sheet metal. As air is heated in the box around the sheet metal, it rises and flows out of the box through a hole on top of the box panel inside the house.  This causes a vaccuum in the box.  Cold air is pulled into the box from holes in the underside of the box panel inside the house. It passes down to the far end of the box where it emerges from under the plywood divider.  It is then heated over the sheet metal as it rises in the box and passes back into the house.

A completely passive system, a modest-sized one can be built for under a $100 with wood, foam insulation, caulk, and a clear acrylic panel from your local home center.  They cost nothing to operate, make no emissions, and can be stored away when not in use.  They also help you conserve Texas Electricity.  And because they are very simple to build, they make a great educational project teaching children the possibilities of solar heat and green energy.

Comments

[Freeheat]

You may want to help your readers by directing them to www.solarwindowheaters.com. I'm sure after you review their information and visits their blog you may want to build and test their solar air heater profiles. Mine works great!