- The Washington Times - Wednesday, August 28, 2002

Retrofitting a house to have central air conditioning is a daunting thought to many a homeowner: the money, the mess, the time. Then again, hot summers, like this one, are convincing some that cool air flowing through the entire house is appealing enough to make it worth facing the challenge.

For Mike Abert, who bought an older Cape Cod-style house in Northwest last fall, installing central air conditioning was a "no brainer."

"Window units don't really cool the whole house, and they're noisy," Mr. Abert says. "Plus, you increase the resale value of your house" by installing central air conditioning.

A more difficult choice for homeowners may be what kind of central air conditioning to select. Several kinds are on the market. Among the considerations in deciding on a certain type are:

• The amount of money the homeowner wants to spend.

• The amount of space the homeowner is willing to give up to ductwork.

Air conditioning celebrated its 100th anniversary this year, but it wasn't until the 1960s, and in some cases the 1970s, that central air conditioning was installed routinely in new single-family homes. That's why most homes that are retrofitted are at least 30 to 40 years old, says Glenn Hourahan, vice president of research and technology at the Arlington-based Air Conditioning Contractors of America (ACCA). This national trade organization for heating, ventilating, air-conditioning and refrigeration contractors has 9,000 members.

Conventional air conditioning, the type most new homes have, consists of 12-inch-by-12-inch ducts supplying the air from an air handler the unit that cools (in conjunction with the outside condenser) and blows the air into the ducts.

However, because the ductwork is extensive and has to go through walls and closets, many homeowners who live in older, smaller homes, opt for less obtrusive systems. They simply don't have the room for the ducts.

One type is called a ductless minisplit system, which can be more or less expensive than a conventional duct system, depending on how many units the homeowner needs. As the name indicates, it doesn't have ducts, which is an advantage if the home is small, but this system may require a cooling unit which is about the same size as a window unit in each room. This may not be aesthetically pleasing to everyone.

Mr. Abert chose what's called a high-velocity system, through which the air moves faster than it does through a conventional system (hence the name). Also, the ducts are made of a flexible fiberboard material, as opposed to the conventional sheet metal, which enables the contractor to snake them through joists without cutting large holes in several walls, floors and ceilings.

The high-velocity system usually is more expensive and a bit noisier than the conventional duct system. The noise, caused by the fast-moving air, can be reduced by adding mufflers to the flexible tubing.

The outlets are in the ceiling corners and are 5 inches across. The simplest ones are white and made of plastic, but they also are available in such materials as cherry wood or brass for those who are willing to spend a little more.

The main reason Mr. Abert chose the high-velocity system for his 1,400-square-foot home was that it seemed the least obtrusive, he says.

"We chose it because we didn't want any destruction to our home, and we didn't want to lose any closet space," Mr. Abert says.

Bob and Catherine Webster, who live in a 3,000-foot house in Old Town Alexandria, agree.

"We didn't even consider the conventional system because we didn't want to tear apart our entire home," Mr. Webster says.

Mr. Abert got a couple of estimates from contractors and decided to go with Alexandria-based Krafft Service Corp.

One of the first things a contractor such as Jay Krafft of Krafft Service Corp. determines is how powerful a system a specific house needs. In Mr. Abert's case, his house was well-served by a 2-ton system.

A 2-ton air-conditioning unit is one that can pull enough heat out of the air in one hour to melt a 2-ton block of ice.

The Websters' 3,000-square-foot home, on the other hand, required two 3½-ton high-velocity systems.

What determines the size and power of the system is not just the square footage of the house. The type of windows, the direction the house faces (east to west are hottest) and insulation are among other factors that determine the size of the cooling system.

Once Mr. Abert's system had been picked out and the ductwork, or tubing, had been delivered, it took five days to install the air conditioning. Mr. Abert did not have to move out of the house and says he was never bothered by the ongoing work.

"We had no disruption whatsoever of our daily lives," Mr. Abert says. "They were very tidy and worked between 9 a.m. and 3 p.m. every day."

Most jurisdictions require permits for the installation work and send inspectors to make sure the job is done adequately, Mr. Krafft says.

The price of the high-velocity system can be prohibitive, and some say the noise can be as well. The parts, including the flexible ducts and air handler, can be about 25 percent more expensive than the conventional air-conditioning system, Mr. Krafft says.

However, since it is less obtrusive than the conventional duct system, it requires less, if any, carpentry work once the installation is done. Therefore, the total price for a conventional system and a high-velocity system may be about the same, he says.

"If you have small house, you're not going to want to lose any closet space," Mr. Krafft says. "What the high-velocity system can do for your house is worth the cost."

Mr. Abert spent $12,000 on his central air conditioner. Mr. Krafft, whose company did the installation, estimates that a conventional system might have cost Mr. Abert about $7,500 or $8,500 (before any reconstructive carpentry work) and that the ductless minisplit system might have been about $9,000.

The cheapest air-conditioning units are window units, which are still popular, says Mr. Hourahan of ACCA.

"People still use window units," he says. "In fact, six million units were shipped last year."

A window unit can cost a couple of hundred dollars. The high-velocity system starts at about $11,000.

Window units, however, don't control humidity or clean or circulate the air as well as central air-conditioning systems (conventional, high-velocity or ductless minisplit systems), Mr. Hourahan says.

Also, window units are exempt from federal clean-air standards, though new central air-conditioning systems have to comply with them.

Whatever type of central air-conditioning system a homeowner is interested in having installed, he or she should be sure to do some research before deciding on a specific contractor, Mr. Krafft says.

"I think they would want to get more than one estimate, and they may want to look and listen to a unit," he says. "And don't hesitate to ask for references. This is a big commitment, and you want to make sure you are making a good decision."

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