There is a post down page, discussing ways to stay warm and fed this winter, as heating oil, natgas and electricity costs are all on a wild rise. Here's one small way to help lower your heating bills on the cheap.

via Mother Earth News

Some of the climatologists are predicting that the coming winter could well be colder than the last one. But even if that forecast comes true, you'll be a lot warmer during the clear-but-below-zero sieges ahead than you were during the frigid weather of last January and February, if your house or apartment has one or more unshaded southfacing windows and if you outfit those windows with the Heat Grabber. (See the bottom of the article and the Image Gallery to the right for Heat Grabber construction details and an explanation of the unit's operation.)

Believe it or not, this simple and effective "window box" solar collector can be fabricated in just under an hour by an experienced home craftsman (or in less than two hours by the more fumble-fingered among us) for the astonishingly low price of $32.18 (see materials breakdown on next page, prices are from 1977). And once constructed, this sturdy unit should give years of dependable service.

The secret of the Heat Grabber's quick assembly and low cost is a new rigid foam insulation board manufactured by Celotex. This board, trade-named "Thermax TF-610," is impregnated with glass fibers for strength, faced on both sides with heavy aluminum foil, and available in thicknesses ranging from 3/8" to 1-7/8". Celotex actually markets the material as a replacement for the pressed fiber sheathing or "blackboard" now used by contractors in the construction of wood framed houses and does not recommend it for any other purpose. Mother Earth News researchers, however, have run heat and other tests on the insulation board and found it near-ideal for use in quick, easy and low-cost solar collectors such as the Heat Grabber.

HOW IT WORKS...

The Heat Grabber is nothing but a weathertight box that's insulated on the bottom and sides and topped with glass. An insulated divider is positioned inside this box and brought out its top to form an open "lip" at the box's upper end. This lip is designed to hook over a windowsill so that the window itself can be pulled down snugly onto the glass which covers the top of the Heat Grabber, leaving the main body of the solar collector "leaning against" the south side of the house at a 45°-or-better angle.

The operation of the unit is just as simple. When the sun shines, its rays pass through the glass on top of the Heat Grabber, strike the upper surface of the divider (which is painted black), and warm the aluminum foil covering on that divider. As the foil heats up it, in turn, warms the air next to it. And that air, as might be expected, rises up the face of the divider and begins to pour out the opening at the Heat Grabber's top.

But, of course, that hot air can't move up the face of the divider unless it pulls cool air around the divider's foot to take its place. Which pulls even more cool air in through the lower opening at the collector's top (the only place that cool air can enter the otherwise airtight unit) and down under the central divider.

What we have, then, is a "convective loop" solar room heater that operates automatically on nothing but the sun's energy. Whenever the sun shines, this clever little unit (which, as near as we can tell, seems to be an old Steve Baer design modified by William A. Shurcliff and further refined by some of Mother Earth News' research staff) just sits there happily pumping thousands of Btu's of heat into the house. And when the sun quits shining? The air in the box cools and tries to sink to the collector's foot, which "shuts off" the whole convective loop. (The Heat Grabber, in other words, will spew heat into the room when the sun shines, but it won't pull heat from the room when the sun doesn't shine.)

More, and directions at the link. Now, what I need is a low-budget AC augmenter.