Radiator heat has a reputation for being comfortable and dependable, a lot like the older homes in which it’s usually found.
“It’s a more steady heat, so it seems like a more comfortable heat,” says John Katrakis, a senior engineer with Chicago’s Center for Neighborhood Technology, a not-for-profit technical assistance corporation for Chicago residents.
“And it’s a very efficient and very dependable heat,” he adds.
That may be so, but even routine maintenance of the systems is often as mysterious to homeowners as the knocking and clanging sounds they hear when the heat is coming up.
It helps to know a little about the systems-the different types and how they work-before you tackle the maintenance. Understanding how your system works can also help you increase its efficiency.
The reason radiator systems may feel more comfortable is because they actually offer two types of heat: convection and radiant.
“As the heat from the radiator rises, a vacuum is created below the radiator that draws air from the room toward and around the radiator, where it’s warmed,” says Al Rozo, a research architect with the University of Illinois at Chicago’s Energy Resources Center.
This creates a very inconspicuous but effective circulation of air, he says.
And because of their mass, radiators stay hot even after the furnace has shut off, radiating warm air into a room (hence the name radiator).
“As a result, radiator heat feels more constant and less drafty than forced-air heating, where a fan blows hot air around a room,” says Ed Kuhn, president of the Plumbers Contractors Association of Chicago and Cook County, a trade organization for the plumbing, heating and cooling industries.
“You have a cyclical type effect with forced-air heat,” says Rozo. “If you set the thermostat at 70 degrees, the furnace will pump 85- to 90-degree air into the space to reach that setting, then shut off. So your temperatures will dip and rise.”
As far as energy usage, there really is no cost advantage to radiator heat over forced air: Both systems burn about the same amount of natural gas to reach the same temperature, heating experts say.
A major drawback to a radiator heating system, in addition to taking up floor space, is the lack of air ducts, which are vital to the installation of central air conditioning. These ducts, of course, are integral to forced-air heating systems.
“In a climate such as Chicago’s, it’s much more economical to have both the heating and cooling work off the same ductwork system,” says Kuhn, owner of Kuhn Plumbing Corp. in Chicago. “That’s why radiators are not being installed in new homes.”
Hence, most radiator systems are found in older Chicago area homes, those built from the late 1800s to the 1940s, when residential air conditioning became popular.
Hot water and steam
There are two types of radiator systems-hot water and steam.
With a hot water system, water is heated by a boiler and usually pumped via pipes to radiators throughout the house. A second, return pipe may carry cool water back to the boiler.
With the less common steam system, water is heated in a boiler until it becomes steam, which then travels by its own pressure up a pipe system to radiators throughout the house. As the steam cools and turns back into water, it returns to the boiler via gravity. Steam radiators must slope slightly toward the piping and the piping must slope toward the boiler.
Maintenance and repair
Radiator systems are fairly self-reliant, says Katrakis. “There are no filters to change, and no motors to replace as with a forced-air system,” he says. “You don’t have to play with the room registers and you don’t need to have a humidifier installed.”
The most common repairs made on radiator systems involve leaks, says Kuhn. “Sometimes a leak will occur on a radiator valve where the supply pipe connects to the radiator-either on the coupling nut or on the packing nut on the valve itself.”
Often, the leak can be stopped by simply tightening the connection, says Kuhn. Hold the body of the valve with a pipe wrench and use an adjustable wrench to tighten the nut. “Sometimes, fixing the leak requires taking the valve apart and putting on some pipe joint compound,” says Kuhn. “It’s similar to repairing a water pipe.”
If the leak persists, the valve probably needs to be replaced.
Steam heat radiators have air vents opposite the supply pipe that also can leak.
“The vents have a valve that allows air in the radiator to escape and steam to move in (from up the pipe),” says Kuhn. “From expansion and contraction, the metal in the valve will wear and you can get some water leakage. That’s a minor repair, which usually requires turning the air vent until it comes out and purchasing a new one at a hardware store. It needs to be installed hand-tight.”
Another common problem in steam radiators is knocking, which occurs when trapped water strikes the radiators or pipe as steam tries to get by. To fix it, make sure the radiator slopes slightly down toward the inlet pipe. A small wood shim under the feet on one side of the radiator should accomplish this. Some radiators have bolts on their feet with which to adjust the height.
If the knocking still occurs, the inlet pipe may not be sloping correctly toward the furnace. This may require professional help to correct.
On hot water systems that have a circulation pump, lubricate the pump once a year to keep it working properly. Check the system’s owner’s manual for more information on this procedure.
To keep the system operating efficiently, the boiler should be checked, cleaned and tuned up once a year, Kuhn and the other experts recommend.
“An annual tuneup can cost from $175 to $250 to really service the boiler,” says Kuhn. “But that money usually comes back to you as the boiler runs more efficiently and uses less energy. Plus, you don’t have to worry about the boiler going out on the coldest day of the year.”
Maximizing efficiency
There are a number of additional steps you can take to boost the efficiency of your radiator system.
About the easiest is not to block the radiators with furniture or draperies. “You want to make sure there is an avenue for air to get to the radiator in the convection process,” says Katrakis.
“You don’t want your furniture to absorb the radiant heat. The objective is to have it warm people, not the furniture,” says Kuhn.
Radiator covers, although aesthetically pleasing, may also impair the flow of warm air.
“The distribution of heat is not as effective if the convection process is restricted,” says Rozo. “If you’re going to use a cover, a mesh cover is better than a solid cover.”
Painting radiators is not as detrimental as once was believed, the experts say.
“Theoretically, radiators are supposed to be left completely uncovered,” says Rozo. “But the paint adds such an insignificant amount of retention that it’s OK to paint them. And they never get hot enough to ignite any paint.”
And because there is air movement around them, it’s a worthwhile effort to vacuum out the radiators every so often, especially if you have pets.
To improve efficiency, deflectors or reflectors between the radiator and an exterior wall are good devices to direct radiant heat back into the center of the room.
“It is a good idea when there is no insulation in walls of the house,” says Katrakis. “The energy savings documented are small but if you do it yourself, it’s a worthwhile endeavor.”
Katrakis recommends buying foam insulation board with a reflective material on one side and fashioning that into a reflector. “It’s best to use a quarter-inch piece of insulation,” he says. “And make sure that it’s designed for the temperature of a radiator.”
A simple deflector can even be fabricated out of heavy cardboard and aluminum foil.
And if you have exposed radiator pipes in the basement, cover them with insulation or pipe jackets to reduce heat loss.
As with a forced air heating system, you can also boost the efficiency of your radiator system with a number of home energy-saving steps.
Adding insulation, installing a programmable thermostat and making sure doors and windows are securely sealed will help save energy dollars and make your radiator system keep you feeling more comfortable, says Rozo.
Many of these steps offer a distinct payback, he says, with a return on your investment in energy bill savings.
With radiator heat, it’s especially important to insulate and seal the first floor, says Katrakis.
“Radiator heat creates a stack effect in which warm air draws up to the top of the building and cold air is drawn in at the bottom of the building,” he says. “So it’s best that the lower floors-including the basement-get the most attention as far as weatherstripping and storm doors and windows.”
If you have ceiling fans, you can also try boosting the circulation of a room to see if that feels more comfortable.
You can also balance radiators on a system so that they heat each specific room properly. Balancing valves, inlet valves and adjustment air vents can all be adjusted to regulate heat from each radiator.
Such work is best done at the beginning of a heating system. Again, check your system’s owner manual for more information, or consult a heating contractor.
