Dear Jim: I am thinking of installing ductless central air-conditioning instead of a regular system so I can set different temperatures throughout my house. Is it quiet and efficient and is this a good idea? – Andy R.

Dear Andy: Installing a ductless central air-conditioning system that allows you to vary room temperatures in different rooms can cut your utility bills and improve your comfort over a standard system.

There is no need to keep bedrooms very cool during the day or the living or dining rooms cool overnight. Although ductless central air-conditioning systems are often installed in homes without existing warm-air heating ducts, a dual- or multizone ductless system is an excellent option for any home. Many new efficient homes are being built with warm water or electric radiant heating that does not have a duct system.

A ductless system works in a similar manner to a standard ducted central air conditioner. There is a small compressor unit located outdoors on the ground or mounted against a wall. Heat pump models or ones with built-in resistance heaters are also available for efficient winter heating.

Instead of having pipes with the cooling refrigerant connected to the heat pump or furnace blower duct system in the utility room, attic or basement, they are attached to a minicooling blower unit in a room(s). Only a 3-inch-diameter hole needs to be drilled through the wall for the pipes.

The individual indoor blower units can be mounted on the ceiling or high on a wall. They are typically only about 3 feet long, 1 foot high and very shallow so they are not readily noticeable. Some other designs can be recessed into the ceiling or hidden away in a corner near the ceiling.

These indoor blower units are not noisy like window air conditioners because the compressor is located far away outdoors. You can select models with adjustable louvers to direct the cool air where you need it. Other models have an oscillating setting to automatically move the louvers. If you have allergies, select a model with an efficient built-in air cleaner.

A dual- or three-zone system should adequately cool most homes. This is similar to having two or three separate small central air conditioners, each with its own adjustable thermostat. Although cool air naturally circulates throughout all the rooms in your home, you still can cool some areas more than others to realize savings from zone cooling.

For the greatest convenience and comfort, select a system with additional hand-held remote controls. This allows you to set the room temperature, time schedule for the cooling, louver direction and motion, etc. from an easy chair. If you prefer drier indoor air, select a model with a special low-humidity setting.

Write for (instantly download – www.dulley.com) Update Bulletin No. 421 – buyer’s guide of nine ductless air conditioner-heat pump systems listing cooling-heating outputs, efficiencies, comfort features, zones available, diagrams and a payback-savings chart. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244.