SACRAMENTO, Calif. — According to the 4th edition of the Webster’s New World™ College Dictionary, “mild” is described as “not extreme in any way; moderate; temperate (amildwinter).”

Ken Barney gave his own interpretation of mild temperature climates as those that don’t vary over 20 to 30 degrees from overnight to daytime temperatures. A number of attendees at Barney’s seminar at the 2003 Annual Radiant Panel Association (RPA) Conference didn’t agree with those calculations. One audience member said that in his area in California, morning temperatures can be as low as 25 degrees while afternoon temperatures average 65 degrees. Regardless of the definition, Barney made some observations about installing radiant in “non-extreme” climates.

Barney, an employee of Thornton Plumbing and Heating in Midvale, Utah, is big on radiant heating — very big.

“A well-designed, well-insulated, and well-balanced radiant heat system should be the most comfortable system available,” he said. He also said that being on-site and designing a radiant system has its rewards, too.

“There is something to be said about standing in a home and looking around, rather than reading off a blueprint,” Barney said.

Challenges For Mild-Temp Radiant

Barney said the biggest challenge for radiant installed in slab on grade in mild temperatures is posed by the solar gains. “When the sun hits the windows, there is a jump in solar gains. The concrete floor is a thermal mass that retains the heat.

“Solar gain can be controlled by lowering the room temperatures or by zoning. But the ideal system for mild climates is slab on grade, despite the solar gains.”

Barney offered two examples of controlling temperatures in mild climates:

  • Thin slab — There is a quicker response time because tubing is installed in an area of less mass, resulting in rapid heat-up time and shorter cool-down time.

  • Staple-up plate system — It is tubing wrapped in aluminum or metal to spread out the heat; it’s not necessary to change the building structure to add this.

    “It is important to always insulate between the floors and know what type of floor covering will be used,” he stated. “Without insulation, the heat can transfer to the basement and not efficiently heat the floor above.”

    Barney said that a common misconception is that a radiant heated floor will always be warm. “It won’t always stay warm unless the system is designed that way.”

    According to Thornton’s Web site (, “Radiant floor heating systems heat objects, not air, to provide superior comfort. Our radiant heating systems work by circulating warm water through PEX or rubber tubing encased in the floor. People are completely surrounded with radiant warmth, and the air temperature is uniform from floor to ceiling.

    “Because the systems require only low water temperatures, a variety of energy alternatives are available. We have been involved in radiant floor heating systems that utilized active solar, geothermal sources, and wood-fired boilers.

    “Radiant floor heating can provide substantial energy savings over other heating systems such as forced air and convected heating systems. Case studies have indicated that radiant floor heat is as much as 40 percent more efficient to operate.”

    Barney said that a properly educated consumer is one that appreciates the features of radiant heating. “We provide customers with an owner’s manual on the project. This includes warranty information and troubleshooting.”

    For more information, visit or call 801-565-7948.

    Publication date: 07/14/2003