QUESTION: My old central air conditioner still works, but I wonder if I should replace it with a super-efficient one. How much can I expect to save on my electric bills? Are the new natural gas cooling units efficient?
ANSWER: Your old air conditioner probably has a SEER (efficiency ratio) of about 6 or 7. A new super-efficient electric unit has a SEER of 15. Installing one can cut your cooling costs by more than 50%. New natural gas central air conditioning units have an equivalent SEER as high as 27.
New super-efficient electric air conditioning units use two-speed compressors and variable-speed indoor blowers. On the low energy saving speed (runs at high speed only on the hottest days), each cycle run time is longer. Indoor temperature swings between on-off cycles are virtually eliminated.
The air gently circulates almost continuously and noise is reduced. With soft start, the initial burst of warm (cold in the winter) air from the ducts is eliminated. This is ideal for allergy sufferers because air cleaners are more effective and humidity levels, mold, mites, etc. are reduced.
The indoor blowers use special electrically commutated motors. These not only provide true variable-speed operation for better comfort, but they use less than half as much electricity as standard blower motors.
The most efficient single-speed air conditioning units use scroll compressors. Scroll compressors have fewer moving parts than standard reciprocating piston compressors. Without pistons and valves, scroll compressors are quieter too.
As scroll compressors wear over years of operation, they seal better and operate smoother than when they were new. Their basic design is reliable, and they should continue to operate at high efficiency levels for many years.
If you have natural gas, there are gas-powered air conditioning units that use a no-compressor absorption process. These also heat your house in the winter.
Another super-efficient gas central air conditioning and heating unit uses a compressor. With an equivalent SEER of 27, it can cut cooling costs by 75%. It looks just like a standard electric central air conditioning unit outdoors and is quieter.
A small natural gas-powered engine runs the compressor. Since an engine can run at any speed, its microprocessor continually, fine-tunes the cooling output (17 levels) to the precise cooling needs of your house.
In the winter, this year-round gas air conditioning unit heats your house at more than 100% efficiency. It combines the heat pump principal with the excess heat from running the engine. This can cut your heating costs by half too.
Write for Update Bulletin No. 528 showing a buyer's guide of super-efficient gas and electric central air-conditioning manufacturers listing efficiency, cooling capacity, compressor type and number of speeds, features and a savings-selector chart. Please send $2 and a business-size self addressed, stamped envelope to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.
What Sun Room Design Is Most Efficient?
Q: I am planning the addition of a sun room to my house. I will use it for growing some plants and hope to get some free solar heating in the winter from it. Should I get one with a slanted or vertical front?
A: Get one with a vertical or near vertical front. Although the slanted front designs are usually less expensive, they tend to overheat in the summer, even in northern climates.
If you plan to use your sun space to help heat your house in the winter, include adequate solar mass. This is often accomplished with a heavy brick or concrete floor. You will also need a fan to move the warm air indoors.
Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.