QUESTION: I am going to replace my central air conditioner and furnace soon. Are there types of air conditioners that can run on solar, gas or oil instead of electricity? Would they be less inexpensive to operate?
ANSWER: There are alternative types of air conditioners that use energy sources other than electricity. Gas, oil, LPG (bottled gas), solar or wood-powered air-conditioning systems can cut your cooling costs and they can heat your house in the winter, too.
These integrated heating and cooling units use desiccant-type air-conditioning systems.
Solar power is an ideal energy source for air conditioning because the energy output from a solar collector is greatest on hot sunny days when your cooling needs are greatest.
Desiccant cooling is not a new or complicated process. A desiccant is a material that absorbs moisture from the air. Not only is the air cooled, but it is highly dehumidified for maximum comfort. Desiccant systems use your existing furnace and air-conditioning duct system.
One desiccant air-conditioning system combines very energy-efficient fresh air ventilation with the cooling. Fresh outdoor air is circulated past a large desiccant wheel. The wheel absorbs moisture from this incoming air. In the heating mode during the winter, the desiccant wheel is bypassed.
At the same time, water is evaporated into the outgoing stale room air. This causes the outgoing air to cool, the way it does when you sweat. In a special heat exchanger, the fresh, dry incoming air gives off heat to the stale outgoing air. As a result, the incoming air is cooled and dehumidified.
In addition to very comfortable cool and dry air, the air inside your house is changed about five times an hour. This filtered air reduces the problems of indoor air pollution from cooking, chemicals and aerosols.
The energy source, whether gas, oil, solar, or wood, is used to dry out (recharge) the desiccant wheel. Then, as it rotates, it can dehumidify more air. Since it rotates very slowly, it is very quiet.
The actual amount of savings you can realize from a desiccant system depend on the relative cost of the gas, oil or wood, compared to your electric rate. The small motors in the unit use only 1,250 watts of electricity, about as much as a hand-held hair dryer.
If you use solar collectors or have an inexpensive source of firewood, your air-conditioning costs can be minimal. It is also possible to use solar cells (photovoltaic panels) to produce free electricity to power the motors. Since no Freon is used, the earth's ozone layer is not damaged.
You can write to me for Utility Bills Update No. 375, which includes specifications on a desiccant air-conditioning and heating system, and an operating cost comparison with conventional electric systems at various electric rates. 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.
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.