Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SUNDAY, May 27, 1990                   TAG: 9005280158
SECTION: HOMES                    PAGE: D-1   EDITION: METRO 
SOURCE: JAMES DULLEY
DATELINE:                                 LENGTH: Medium

NEW AIR CONDITIONERS CUT COSTS

A: The most recent major design innovation for central air conditioners is a high-efficiency scroll compressor in place of a standard piston-type compressor. A new scroll-compressor air conditioner can cut your cooling costs by as much as half and minimize maintenance costs.

Several air conditioner manufacturers are now using scroll compressors with seasonal energy efficiency ratios (SEER) up to 12. Your old unit may have a SEER as low as 6. SEER relates the amount of cooling output of a central air conditioner to the amount of electricity it uses.

By its design, the scroll compressor is very reliable. Unlike conventional compressors with many moving parts - pistons, valves, seals, etc., a scroll compressor has only four moving parts.

As it gets older, the few moving parts of a scroll compressor actually wear in and operate better. It is also more tolerant of foreign matter and fluids in the system.

Without the pistons and valves used in a standard compressor, a scroll compressor operates quieter and more vibration-free. This is an advantage both for you and your neighbors.

The operating principle of a scroll compressor is simple. Two spiral-shaped members fit together. One remains stationary, while the other orbits relative to it. This creates gas pockets which gradually decrease in size to compress the freon.

Since several pockets of freon are compressed simultaneously in the scroll members, it produces a smooth and nearly continuous compression cycle. In contrast, a standard piston compressor produces fewer and larger compression pulses per cycle.

When you select a new central air conditioner, have your contractor do a detailed heat gain analysis for your house. Many use computers and sophistocated programs. An improperly sized central air conditioner not only wastes electricity, but doesn't provide the best comfort level.

Q: I have heard that some states require smoke alarms that are powered by both batteries and regular house electricity. Since these operate continuously, will they be expensive to operate? S.B.

A: The amount of current usage is very low and the operating cost is negligible. The reason for requiring two power sources, batteries and house current, is that people often let the batteries run down. They plan to replace them, but never get around to doing it and then they forget. Without power, the smoke alarm provides no protection.

To keep people from removing the batteries to avoid annoying false alarms when cooking, some new smoke alarms offer a hush control. This allows you to press a button to temporarily decrease the sensitivity of the alarm. It resets to normal sensitivity automatically.