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What’s Old is New Again: The Comfort of Radiant Systems Spurs Increasing Demand


By Sheryl S. Jackson
Naylor Association Solutions Contributing Writer

Dan Foley installed his first radiant heating system in 1991. Since that time, he has installed more than 1,000 radiant systems – small and large.

“This work is a labor of love,” says Foley, owner and president of Foley Mechanical in Lorton, Virginia, and recipient of the PHCC—National HVAC Contractor of the Year for 2017. The use of radiant heating or cooling systems is not new technology, but it is seeing a resurgence of interest as homeowners look for ways to ensure a comfortable temperature in their homes.

Radiant heat is a good technology to apply to renewable energy sources such as solar, geothermal or heat pumps, points out Foley. “Radiant systems require a lower water temperature to produce warmth,” he explains. While he has not installed many systems to work with solar energy systems, Foley says that geothermal energy systems can produce water temperatures between 100 and 115 degrees Fahrenheit, which is a perfect match for radiant systems. “Most radiant systems’ hot water is provided by gas boilers,” he adds.

“I am seeing a greater interest in radiant heat over the past several years,” says Foley. “When I first suggested the technology in the early 1990s, people did not want to be guinea pigs for a new approach,” he says. As the systems began appearing in more home renovation shows – primarily “This Old House” – people became more comfortable with the systems.

“Radiant heat was used in the 1930s through the 1950s, but the systems relied on iron and copper pipes, which deteriorated over time,” says Foley. “Today’s PEX piping and tubing is strong and meant for installation underground or in concrete,” he explains. “The pipes do not react to concrete, which means that they don’t break down.”

Comfort is Key

Although radiant systems allow homeowners to heat or cool their homes more efficiently because they keep a room’s temperature stable versus the up and down temperatures of forced air, Foley says that the number-one reason to choose radiant systems is comfort. “When it is a cold winter day, and you can step out of the shower onto a warm tile floor or sit in the living room and feel warm without waiting for air to blow from vents, you realize the value of radiant heat,” he explains.

Radiant systems are best suited for new construction, but that does not mean only new homes, points out Foley. “It is difficult to retrofit an existing home, so a whole home remodel or construction of an addition is the best time to consider radiant heat for an older house,” he says. “You also do not have to install a whole-home system; radiant can be installed in a new addition only,” he adds.

Radiant Cools, Too

While they are less common in residential settings, radiant cooling systems are also gaining traction in the marketplace, says Foley. The price of controls for radiant cooling systems is still high enough that the primary customer is commercial with large spaces to cool. “A residential home must be big enough that the controls do not blow the budget,” he explains.

Foley has had such a customer: a 28,000-square-foot home with 17-foot tall windows that faced west. “There was no overhang and no shade to reduce the temperature, and forced air systems alone could not keep the room comfortable,” he says. A radiant cooling system throughout the walls of the room maintained a temperature that allowed the forced air system to keep the room cool.

Aesthetic Flexibility

When working with David Jameson, an architect whose buildings are works of art, Foley finds that radiant systems provide the aesthetic flexibility that Jameson wants. The system is located in the walls and floors so spaces can be open and unobstructed, he explains.

Because radiant heating systems are installed in the floor, the choice of floor covering is important to maximize efficiency. “Radiant systems work under carpet or hardwood,” says Foley. Although hardwood and tile work best, carpet will work if the pad used is a dense rubber cushion and the carpet is low pile, such as Berber, he adds.

“There are misconceptions about radiant heat under wood floors,” admits Foley. “The surface temperature never goes above 80 degrees, so wood flooring will not warp,” he explains. Changing the perceptions related to radiant heat is an ongoing educational effort with architects, general contractors, flooring company representatives and consumers, he says. “In fact, most of my systems are installed under oak flooring.”