Dear Jim: I cannot stand the heat and humidity any longer. Our older house was not designed for ducted central air-conditioning. Are the high-velocity systems very effective and are there any other options?

- Bob J.Dear Bob: Your problem is not unique. There are many older houses with hot water heat (no ducts) or just an ineffective duct system that would not distribute the cool air well. Installing a completely new duct system or improving an old one can be a very involved and expensive project.

High-velocity air-conditioning systems are effective and relatively easy to install in any home. They can use any standard high efficiency outdoor central air-conditioning unit. Although often installed for cooling, they are ideal year-round systems for hot water heating and heat pumps too.

Using high-velocity air flow, these units have special cooling/heating coils that can remove 30 percent more humidity from the air. This allows you to set your thermostat higher for a large summer electricity savings and still be comfortable. With a heat pump in the winter, the output air is warmer, too.

Instead of using standard large round or rectangular sheet metal ducts, a high-velocity system uses small two-inch diameter pipes to distribute the cool air. The blower unit and main duct are often located in an attic. The small pipes run from the main duct to each room.

There are no large wall or floor registers. Several flat five-inch diameter faceplates with a two-inch outlet hole are located near the ceiling in the corners. The outlet faceplates are attractively finished (some offer 24-karat gold plating). They can also be painted or wallpapered.

A high-velocity system provides comfortable cool air circulation in the room. The quiet high-velocity cool air outlet, through a natural aspiration process, draws the rest of the room air into the cool air stream. This eliminates drafts and the gentle mixing produces even room tem-per-a-tures.

If you have a two-story house, which many older houses are, the small pipes are usually run down through the corner of a closet to the first floor. The outlets are mounted in the ceiling with minimal remodeling work needed.

High-velocity systems are no more noisy than conventional systems. The last several feet of the pipe near the outlet uses sound-deadening materials.

Another option is a mini-split ductless system. It uses outdoor compressor units connected to cooling blowers in several of the rooms. It will not cool all the rooms as evenly as the high-velocity system, but it is usually adequate. Your local heating/cooling contractor should be familiar with these systems.

Write for (or instant download - www.dulley.com) Update Bulletin No. 900 - buyer's guide of high-velocity air-conditioning systems, sizes, features, installation details and a list of mini-split ductless systems. Please include $3 and a business-size SAE.

James Dulley, Deseret News, 6906 Royalgreen Drive, Cincinnati, OH 45244

Dear Jim: We are designing our dream house and we want it to be efficient. I want to make many of the material decisions. What is the difference between drywall, sheetrock, gypsum panels, wallboard, etc.?

- Bob H.

Dear Bob: It is a good idea that you research and make or at least are involved in making the material decisions. Builders are understandably cost conscious, but you have to live in the house for the next 30 years.

All of the words you mentioned are just different names for the same basic wall material. Sheetrock is a trademark of USG's gypsum wall panels which use recycled paper and synthetic gypsum, an otherwise disposed of material.