Ductless cooling is efficient and quiet


August 24, 1991|By James Dulley

Q: I want to add air-conditioning to a large family room and both heat and air-conditioning to a bedroom addition. What is the best type to use for extra-quiet and efficient operation?

A: There are some new types of large super-energy-efficient room air conditioners and heat pumps that are extremely quiet and very energy efficient. The seasonal energy efficiency ratios (SEER) are as high as 12, higher than many central air conditioners.

These are called ductless or mini-split systems because they are designed like central air conditioners and heat pumps. The noisy compressor and condenser fan unit is located outside your house on a concrete pad. It can be as far as 100 feet from the quiet indoor cooling blower unit.

A ductless system is ideal if you don't currently have a central forced-air heating system. To add central air-conditioning, you would generally have to install ductwork throughout your house. With a ductless system, you can run just the small refrigerant lines to the indoor cooling units in several rooms. The electric wiring for the indoor units comes from outdoors too.

The resultant comfort level is excellent and you can "zone cool" your house. This saves electricity by cooling only the rooms that are used at various times of the day and night.

For air conditioner-only use, the small indoor blower unit (13 inches high by 31 inches wide by 7 inches deep) is usually located high on the wall. This allows the cooled air to naturally drop and circulate throughout the room. When using a ductless heat pump for heating too, it is sometimes located lower on the wall.

Since these units are often located high out of reach, the entire system is controlled by a TV-type hand-held remote control. From your sofa, this control allows you to set blower speeds, temperature settings, automatic nighttime setups, etc.

Most systems employ a rotary compressor to minimize outdoor noise and vibration. Others use either a standard reciprocating compressor or a new super-efficient and quiet scroll compressor.

The ductless heat pumps provide both high-efficiency heating and cooling. You can also get units with electrical resistance backup heating elements for areas where the heating load is substantial in the winter.

You can write to me for "Utility Bills Update No. 308," including a buyer's guide to ductless mini-split system air conditioners and heat pumps, and listing manufacturers, addresses, telephone numbers, model numbers, compressor type, capacities, efficiency levels and specifications on several models. Please include $1 and a self-addressed stamped business-size envelope.

Send questions to James Dulley, c/o Baltimore Sun, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.

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