Q: I like to do things the natural way. My kitchen gets really hot when I cook, so I want to try a solar oven. Is it really possible to cook with solar and can I make one myself?
A: It is possible to cook almost anything in a solar oven. Millions, if not billions, of people around the world use solar ovens exclusively because they have no other fuel source. All the energy on the Earth, including fossil fuels, wood, etc., actually came from the sun at one time so all cooking is actually solar cooking.
I have used a solar oven for years during the summer and on bright sunny winter afternoons. Mine will steam brown rice in about 90 minutes. The inside temperature of the solar oven easily gets hot enough to bake bread, roast meats, etc. There is a learning curve to determine how long various foods need to cook based upon how sunny it is that day.
When you cook indoors on a stove or in the oven, all that heat and humidity eventually transfers to the air in your kitchen and then throughout your house. By not having a kitchen oven hot for hours, you will have additional savings on your air-conditioning costs.
There are several designs of very effective solar ovens you can make yourself with simple hand tools. There also are many commercially available solar ovens with double-insulated glass tops and special solar-absorbing paints so that they cook faster. My solar oven has extra reflective side panels to direct more solar heat into the oven when the sun is not as strong.
The simplest design of solar oven consists of two cardboard boxes, one large and one small, without tops. Old Amazon shipping boxes are strong and work well. The larger box is lined with crumpled up newspaper for insulation and the smaller box is placed in it. Old fiberglass wall insulation is even better. Line the inside of the smaller box with aluminum foil and paint the bottom flat black.
Cover the top of the boxes with a sheet of clear acrylic (Plexiglas) plastic. Use shiny foil duct tape on one edge of the top to function as a hinge. This simple oven will probably not get hot enough to roast meat or bake bread, but it will be adequate to steam rice and vegetables and heat a cup of tea. Use a covered pot that is painted flat black.
To attain higher temperatures, use plywood to make the boxes and stuff high-density fiberglass or rock wool insulation between them. Make the boxes deep enough to add a slanted shelf. This shelf allows you to tilt the box so the clear top faces the sun more directly without the pot sliding off the shelf or spilling.
To improve efficiency, use two layers of clear acrylic separated by a small edge spacer for the top. This creates an air gap similar to double-pane windows. This slightly reduces the amount of solar energy that gets into the oven, but greatly reduces the amount of heat lost back out through the top.
Also, add reflective side and back panels to increase the effective solar energy collection area. Cardboard covered with shiny aluminum foil is effective. Don't use a standard glass mirror. Mirrors reflect visible light, but not heat energy, so little additional heat will be gained.
For some serious solar cooking, select one of the professional solar ovens. I use a hybrid model by Sun BD Corp. that has a built-in electric heating element in case clouds roll in while you are cooking. It includes an adjustable mirrored top and side panels and can cook anything you like. All the various solar oven designs collapse for easy mobility and storage.
The following companies offer solar cookers, kits and plans: All Season Solar Cooker, (760) 695-2104, www.allseasonsolarcooker.com; Clear Dome Solar, (619) 990-7977, www.cleardomesolar.com; Haines Solar Cooker, (858) 834-1293, www.hainessolarcookers.com: Solar Cookers International, (916) 455-4499, www.solarcookers.org; Sun BD Corp., (315) 651-8821, www.sunbdcorp.com; and Sun Ovens International, (800) 408-7919, www.sunoven.com.
Q: Our central air conditioner seems to be running fine, but there is some liquid leaking out from the bottom on the floor. I think it might be Freon. Is this a dangerous problem?
A: A Freon leak would not appear as a wet spot on the floor. Also, if Freon is leaking, the working pressures would be incorrect and it would not cool properly. It probably is a clogged drain tube from the pan under the evaporator coils.
Mold can grow in the pan and clog the opening to the tube. Try running a straightened coat hanger or a flexible wire up from the drain tube outlet. This should dislodge the clog.
• Write to James Dulley at 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit dulley.com.