Retrofitting an old house with air conditioning


One little-known system does not require big, unsightly ducts

May 02, 1999|By Karol V. Menzie and Ron Nodine

IF YOU LIVE in a part of the country where spring is about 10 minutes long, and then summer comes roaring in, you may already have started thinking about the approaching air conditioning season.

If you live in an old house, you may also already know that retrofitting can be a problem.

However, you do have a number of options.

The easiest solution is to simply install window units. The advantage is that they are economical to use: You cool only the room you want, and only when you want it.

The disadvantages are that they are unsightly from the outside, and hard to seal against the weather so they usually need to be removed and reinstalled each season.

Despite the disadvantages, window units are the most common because they are so easy to install and cost a lot less than a central system.

If you decide on window units, do some research to make sure you are getting the proper size for the most efficient cooling.

Measure the rooms where you plan to install them, and select the exact number of Btu (a measure of heating and cooling units) recommended.

A slightly larger unit is more efficient than one that's slightly too small. Even though the smaller one may be less expensive, it won't cool the space.

If central air is what you want, in most cases a system can be installed in an existing house. However, there are many things to consider.

If you have an existing forced-air system for heat, you may think all you have to do is add the cooling coil, right? Wrong.

A forced-air system that is designed only for heat is different than one designed for heating and cooling. The main difference is the way the return-air is set up.

With heat, the return air is drawn from a low position -- because heat rises and you want to draw the colder air away.

For cooling, the return works best when it's high -- to draw away the hotter air at the ceiling. So even if you have ductwork, some modifications will have to be made.

When you add central air to a house with radiators or baseboard heat, you will have to make a decision. Should you keep the boiler system for heat and add air only, or replace the whole thing?

Most people really like the heat you get from the hydronic (water-based) system.

Depending on the condition and fuel source of the existing system it may or may not make sense to change it. You should discuss all the options and pros and cons with your heating-ventilation and air-conditioning contractor.

A major part of the cost of installing central air in an existing house is cutting and enclosing the new ductwork. You may have to live with some obnoxious bulkheads or give up some closet space to accommodate the installation.

However, there is an alternative system that is far less intrusive and easier to install.

It's been around for decades, but for some mysterious reason, isn't used very often. It's called SpacePac, made by Hydrotherm Inc. of Westfield, Mass.

This system uses high-pressure ductwork. The inside diameter is only 2 inches, making it easy to install in an existing closet or joist space without taking up a lot of wall or ceiling space.

The SpacePac fan coil unit fits neatly in a small horizontal space.

It may be installed in an unconditioned space such as an attic, garage, or crawl space, as long as it is protected from weather. It may also be installed in a basement, closet or utility room.

This system is ideal for homes that can't accommodate conventional systems, such as ductless homes heated with hot water, steam or electric radiant heat; older homes with limited space, and historical landmarks where architectural integrity has to be preserved.

For information about the system, you can call 413-564-5530, fax at 413-568-9613, or check out the Web site at

Ron Nodine is owner of American Renovator Inc., a Baltimore design-build remodeling firm, and former president of the Remodelors Council of the Home Builders Association of Maryland. Karol V. Menzie is a feature writer for The Sun.

If you have questions, tips or experiences to share about working on houses, e-mail Ron at or Karol at Or write c/o HOME WORK, The Sun, 501 N. Calvert St., Baltimore, Md. 21278. Questions of general interest will be answered in the column; comments, tips and experiences will be reported in occasional columns.

Pub Date: 5/02/99

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