You Look Radiant

Q: We’re trying to build a really small house and be economical as we do it. Radiant-floor heating sounds practical for the first floor, although it’s expensive. What do you think?

Kerry
Florence, Massachusetts

How I have coveted a nice radiant floor! This system heats your floor (and thus you) directly, instead of blowing hot air around.

     In a classic installation, the subfloor is topped with insulation, then the hydronic tubing that carries heat to your floors is arrayed atop the insulation. Concrete is poured on top to form the body of the floor; sometimes tiles are a final touch. A boiler or solar-heating system attached to the tubes circulates warm water through them, which warms the floor, which warms you as you happily scoot about on your bare feet.

Electric radiant tubing exists but is less common. If your floor surface is already finished, you can install these tubes from below between the joists of your wooden subfloor, if you have access there. “Wet” installation in concrete is considered the most efficient use of the technology, however.

Radiant-floor heat has many advantages: You feel warmer with the thermostat at the same temperature, there’s less dust because there’s no forced air recirculating, it’s silent, and there are no heat registers or radiators to block your ideal furniture arrangement. It’s great for someone who likes to lie about on the floor—and all the advertisements depict dogs and crawling babies partying down.

These systems are usually more efficient than forced air, partly because hot air cools as it flows through forced-air ducts before it reaches its target. Also, radiant floors reduce cold-air infiltration from outside—known as the “stack effect”—created when hot air rises and exits the house, pulling cold air inside. This happens less with radiant heat because the house air is never hotter than the thermostat temperature. Some radiant-floor owners claim they feel warmer at a lower thermostat setting, but this is largely unproven.