This old house getting too warm?

Home Work

June 08, 1996|By Karol V. Menzie and Randy Johnson

Owners of old houses know the sometimes intriguing, sometimes agonizing truth: There's no such thing as a "simple" project. Repairing a bathroom tile can lead to ripping out a wall, replacing a sink and redoing the floor. Enlarging a window can lead to the discovery there's no header, so the joists of the floor above are not adequately supported, which means that the wall has to be rebuilt Sometimes it's a question of deciding just how broke something has to be before you really need to fix it.

That's the case for a reader in Baltimore County, who sent an e-mail letter: "I live in an old house (1906), 15 rooms heated by steam (gas boiler) radiators. We have 7 room [air conditioners] placed throughout the house, one in each bedroom upstairs and one in the kitchen, family room and office.

"How do I go about determining the costs for replacing the room units with central air and determining the number of years it will take to see a return on investment in a new central unit?

"Am I paying more in electrical costs using individual units rather than a central system? I would like to investigate the notion of a two-zone central system to see if that might work."

It takes a lot of details to calculate energy needs and expenditure. Everything about the house makes a difference, from the size and number of windows to the amount of insulation it has.

But before you start measuring, there are other considerations in whether you convert an old house to central air-conditioning.

According to Mark Duerr, of BGE's marketing department, switching to central air can result in "significant energy savings."

In addition, Duerr said, central units tend to last longer, with a life span of 15 years or so, compared with 10 or so for a window unit.

But he noted that installing central air, particularly in an old house, can be expensive. The unit itself will cost $2,500-$3,000. Because the reader's current system uses radiators, he would need all new ductwork.

"Ductwork is really pretty expensive," Duerr said.

If you have elaborate old trim or crown moldings, installing ductwork could destroy some of it. Even if the house doesn't have any characteristic woodwork, building the chases and bulkheads to house the ducts and cold-air returns could substantially alter the look of the interior. It could be that the aesthetic costs would far outweigh the energy savings.

Calculating the cost can certainly help make a decision to go ahead or not. The first step is to find an air-conditioning contractor who will work with you to minimize damage to your house.

Check with friends and neighbors for recommendations, and, if possible, visit the houses where the work was done so you can gauge the extent of architectural destruction and the efficiency of the system. Temperatures should vary no more than 5 degrees from floor to floor. If the upper floors are noticeably hotter, there is something wrong -- usually it's inadequate cold-air returns on the top floors.

You'll also need a good carpenter to put the house back together -- to build the chases and the bulkheads and to patch the plaster or drywall.

Get estimates. Once you have those figures, a good heating-air-conditioning contractor should be able to calculate cooling costs for central air. Divide the yearly cost savings of central air, assuming there are savings, into the total cost of the project to determine how many years it will take to recoup the cost. Don't be surprised if it works out to 20 or 30 years.

The heating contractor can also help decide if the cost of extra equipment for a two-zone system would be worthwhile.

If the whole-house and two-zone systems are too expensive, you might consider using central air for just the first floor.

Johnson is a Baltimore construction manager. Menzie is a feature writer for The Sun.

Pub Date: 6/08/96

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