High-Velocity Air-Conditioning a Cool Option

QUESTION: 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?

ANSWER: Your problem is not unique. There are many older houses with hot-water heat (no ducts) or just an ineffective duct system that cannot 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 water heating and heat pumps too.

Using high-velocity air flow, these units have special cooling / heating coils that can remove 30% more humidity from the air. This allows you to set your thermostat higher, lowering your summer electricity bill, 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 2-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 5-inch-diameter faceplates with 2-inch outlet holes 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 cool-air outlet draws the rest of the room air into the cool-air stream. This eliminates drafts and the gentle mixing produces an even room temperature.

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.

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Write for (or instant download https://www.dulley.com) Update Bulletin No. 900, a 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-sized self-addressed envelope and mail to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, OH 45244.