Let the Sunshine Do the Cooking in Summertime

QUESTION: My kitchen gets hot in the summer when I cook and bake. Is it possible to build some type of simple solar device myself that I can use to cook food outdoors in the summer?

ANSWER: You can easily build a solar oven yourself for about $50 in materials. On a bright sunny day, the temperature inside the solar oven can reach 350 to 400 degrees. You can add adjustable vents to control the temperature. Its small size makes it ideal for camping too.

Not only will your kitchen stay cooler, but your utility bills will be lower too. In addition to the energy used to heat your kitchen range oven, your air conditioner must run longer to remove that heat from your house.

A solar oven does not produce pollution as do conventional gas and electricity production and consumption. In the long run, we all pay directly and indirectly for the cleanup of the environment.

The basic design of a solar oven is a small, black, insulated plywood box with a slanted glass front. It has a door on the back and a rack inside to hold the cooking pots. The insulation holds in the heat, so the oven temperature won’t vary much if the sun occasionally goes behind clouds.

A common size is roughly an 18- to 24-inch cube, but any size to meet your cooking needs is acceptable. You can make it a little larger in order to put a few bricks or rocks inside it. These get hot and hold heat, so the temperature inside the oven stays more constant.

You can increase the effectiveness of the solar oven by adding cardboard reflectors that are covered with aluminum foil or reflective Mylar. These catch more of the sun’s heat and provide a longer cooking day. Using pop rivets, you can make more-durable ones from aluminum sheet metal.

Since the oven gets hot, you should use rigid fiberglass duct-board insulation. Common foam board insulations would not stand up to the heat. Line the entire inside surface of the plywood box with the insulation. If the insulation has a foil facing, paint it flat black.

During the summer, the glass should be tilted from horizontal at an angle equal to the latitude of your area minus 10 degrees. With the reflectors, you should be able to use the solar oven from early spring to late fall. In spring and fall, tilt the back of the oven up a little so the glass faces the sun, which is lower in the sky.

You can write to me for Utility Bills Update No. 346 showing do-it-yourself instructions and diagrams for making a solar oven. Please include $1 and a self-addressed envelope. Send your requests to James Dulley, c/o Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

Insulation in Wall Not Easy to Detect

Q: I just bought a house and was told there was insulation in the walls. When I pulled off an electrical outlet face plate to do some painting, I didn’t see any insulation. Could it still be there?

A: The seller may not have lied to you. Builders often pull insulation away from the electrical conduit box in the wall during construction.

Shut off the circuit breaker or take out the fuse to that outlet. With a knife, shave away a little of the dry wall so you can see inside the wall. Don’t cut away too much or the face plate won’t completely cover the hole.

Bend a small hook on the end of a long stiff piece of wire and probe around inside the wall for some insulation. If you still don’t find any insulation, you might consider calling your real estate agent and lawyer.

Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.