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AN AIR CONDITIONER POWERED BY GAS MAY BE A MONEY SAVER

Q. - I have been considering replacing my old electrical central air conditioner with a new, gas-powered absorption one. Could you explain how gas can run an air conditioner, and are they very energy efficient? T. Z.

A - Gas-powered absorption central air conditioners have been used for many years, and they are energy efficient. They can be powered by either natural gas or bottled gas (propane).The utility bills savings by using a gas-powered absorption system depend on the relative costs of gas and electricity in your area. The gas burners in the outdoor unit can also be used to heat your house in the winter. Hot water is circulated into the blower instead of cold water. This eliminates excess air infiltration and risks from carbon monoxide poisoning.

Many gas utility companies offer greatly discounted summer rates if you use a gas-powered air conditioner. This can make it less expensive to operate than a typical electric central air conditioner. Contact your local gas utility company about special summer rates.

Other advantages of an absorption system are its simplicity, low regular maintenance and its reliability. Other than a small pump and fan, there are only three moving parts in the entire cooling system - two check valves and a diaphragm. With no large motor and high-speed compressor, it operates very quietly. A life of 20 years or more is not unusual.

An absorption system uses an ammonia/water solution instead of the environmentally damaging freon in electric air conditioners. The ammonia and natural gas (or propane) stay in the central unit outside your house.

Water, chilled in the unit to 40 degrees, is circulated through a standard PVC plastic pipe to the heat exchanger in your indoor blower compartment to cool your house. This also dehumidifies the air.

In the outdoor unit, the solution is boiled and the ammonia separates from the water. As the warm ammonia is condensed to a liquid, it gives off heat to the outdoor air. Then it passes through a restrictor/evaporator where it cools to 34 degrees. This cold liquid ammonia chills the water that is circulated into your existing blower heat exchanger inside your house.

Another type of gas-powered central air conditioning unit uses a desiccant process. Since it doesn't require as high an operating temperature as an absorption system, a desiccant system can be powered with wood, solar or oil. It can also be used to heat your house in the winter.

You can write to me for UTILITY BILLS UPDATE No. 312 showing product information and specifications on a residential gas-powered absorption and a desiccant air conditioning/heating system and operating cost comparison charts with standard electric central air con-di-tioners. Write to James Dulley, The Deseret News, 6906 Royal Green Dr., Cincinnati, OH 45244. Please include $1.25 and a self-addressed business-size envelope.

Q - I have a room with many south-facing windows that we use as a greenhouse. What is the best type of paint for the indoor trim? Y. S. .

A - Latex paint resists fading from the sun better than oil-based paint. It is also easier to clean up, and it dries faster than oil-based paint. If you are allergic to paint, you will usually be less sensitive to latex.

Oil paint produces a harder, more durable finish. If the windows in your sunroom are operational and you open them often, oil paint is a better choice. You should install some type of shading or awnings for summer heat control. This also helps to protect the wood trim from the sun's rays.