An Inexpensive Way to Let Sun Provide Heat

QUESTION: I would like to use some type of solar heating to help heat my house, but I don’t want to invest several thousand dollars in a large system. Is there a simple solar system that I can make myself?

ANSWER: A standard contractor-installed solar system can cost thousands of dollars, and can take many years to pay back its cost with energy savings. It is usually most effective when combined with water heating for year-round use.

If you want to use a solar system to heat your home and are on a limited budget, then you should be able to build a small air-type of solar system yourself. With about $50 in materials, a little sweat and bruised knuckles, you can build one that will pay back its cost quickly.

One of the simplest and most effective solar systems is a solar window heater. You can use these in your south-facing windows to get the most solar heat. On a bright winter day, a small do-it-yourself solar window heater can provide most of the heat needed for an average-sized room.

This solar window heater is basically an insulated flat wooden box with a glass top. You mount one open end of the box in your window and angle the other closed end down to the ground. This tilts and faces the glass top up toward the sun.

Split the solar box lengthwise with a horizontal plywood divider, so that you have two flat chambers inside. Paint the top surface of this plywood divider, which faces the glass, flat black. The divider should be several inches shorter than the box, leaving a gap at the lower outdoor end.

When the sun shines on the black divider, it gets hot and heats the air above it. Since hot air is less dense than cold air, it flows up and out the open end into your room.

Then, the cooler room air, near your floor is drawn into the bottom chamber of the solar window heater. It flows around the gap at the bottom of the divider and into the hot sunny top chamber. When the sun shines very brightly, you’ll be surprised at how much heated air flows out into your room. At night, block off the indoor opening.

For summertime use, you can mount a special vent door in the top of the box outside your window and close off the top indoor opening. When the sun shines, it will naturally create a breeze by exhausting warm air out the vent while drawing cool air in through your home. It works just like an exhaust fan, but it uses no electricity.

You can write to me for Utility Bills Update No. 004, showing simple do-it-yourself instructions and diagrams for making an inexpensive solar window heater. Please include $1 and a self-addressed business-sized envelope. Send your requests to James Dulley, c/o Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

Noisy Furnace Calls for Professional Inspection

Q: We have a forced-air furnace and it sometimes makes a loud banging sound when it comes on or goes off. What is causing it?

A: There can be several possible causes, and you should call your serviceman to have it inspected. One serious and potentially dangerous cause may be improper combustion or a leak in the combustion chamber.

That noise may also be what is known as “oil canning,” which won’t hurt your furnace. When the blower in your furnace kicks on, the air pressure in the ducts changes. If you have large flat ducts, the surfaces can buckle in and out like the bottom of an oil can causing the noise.