Dear Jim: I want to replace my old central air conditioner with one that provides better comfort and is quieter. Lower electric bills are also a concern. What new designs for the Year 2000 are best? — Karl G.

Dear Karl: The primary design improvements for the Year 2000 are that more air conditioner manufacturers are now offering models that use ozone-friendly R410A refrigerant. Over the next decade, by law, models that use old R-22 (freon) refrigerant will be phased out of production.

Most air conditioner models that use R410A refrigerant have a special scroll compressor made by Copeland. With a standard furnace blower, these units have efficiencies, or SEER ratings, typically at 13. If your old air conditioner runs at a SEER of 7, then the savings on your electric bills should exceed 40 percent.

In addition to not damaging the ozone layer, R410A compressors run at higher refrigerant operating pressures. This higher pressure requires heavier materials in the compressor and condenser coils making them run about 4 decibels quieter than an R-22 unit. This is noticeable at night.

Several air conditioner manufacturers still offer two-stage central units for people wanting the maximum comfort and savings. Some use special two-speed compressors while others use two separate compressors in one outdoor enclosure.

The primary advantage of a two-stage central air conditioner is that it adjusts the cooling output to the changing needs of your house throughout the day and night. In mid-afternoon, the cooling requirements can easily be more than double what is needed in early morning or later in the evening.

The majority — 70 to 85 percent — of the time, a two-stage compressor runs at its most efficient slower- or lower-output first stage. Although it runs longer on the first stage, the overall electricity usage is less.

This provides excellent comfort because the frequency of on-off cycles of cold air blasts are reduced. With the unit running more continuously, the room temperatures stay more even. If you have allergies, the increased running time makes an air cleaner more effective and better controls indoor humidity.

All two-stage air conditioners use super-efficient, variable-speed indoor blower motors. The blower speed must change for effective cooling at each of the two stages. They are usually special direct current, or ICM, motors.

These are called “smart motors” because they sense the instantaneous conditions and automatically adjust their speed. These can also be used on single-stage air conditioners for greater efficiency and comfort. If you plan to use the most efficient furnace in the winter, this type of motor is needed.

Write for (instantly download — www.dulley.com) Update Bulletin No. 994 — buyer’s guide of the 15 most efficient one- and two-stage central air conditioners, cooling output ranges, SEER’s, comfort features, warranties and a savings chart. Please include $3.00 and a business-size SASE.

James Dulley, Newspaper Name, 6906 Royalgreen Dr., Cincinnati, OH 45244

Dear Jim: I was considering buying a real massage chair instead of spending the money at the massage therapist. Those chairs seem to have a lot of motors in them. Do they use a lot of electricity to operate? — Suzi G.

Dear Suzi: At $50 per hour for a therapist, using a massage chair can quickly recover its initial cost. As you mentioned, these real massage chairs have many motors for a true massage, not just vibrators to relax.

I have an Interactive Health massage chair and it uses only 60 watts of electricity. This costs less than a penny per hour used. The “human touch technologies” use several motors and electronics inside to provide various massage actions.

Dear Jim: My water heater is fairly old, but it does not leak. I was told that the anode rod will prolong the life of the water heater. Does an anode rod really help? How does it stop corrosion in the tank? — Ron M.

Dear Ron: All new water heaters come with an anode rod. This is a mineral rod that hangs down from the top of the tank. It is a sacrificial piece that gradually corrodes itself away thereby protecting the tank.

They do eventually corrode or dissolve into the water to the point that they should be replaced. If you turn off the water heater and drain the water from the plumbing, you can remove the old one and slip in a new one.