With this method of heating, the entire floor is used as a heating panel. In most radiant-floor systems, a pump moves hot water from a boiler through tubing in the floor—where it releases its heat—then back through the boiler to be reheated. The tubing can be embedded in a concrete slab or attached to the underside of a wood floor system.
With radiant heating, heat is transferred from a warm surface, via infrared energy, to objects (and people) in a room. Thus, radiant heating is said to heat objects, not air. With radiant heating, people can be quite comfortable even when the air temperature is lower. So, utility bills with radiant heating can be lower than with forced-air heating (if the fuel cost, and heating efficiency is similar)—but actual savings are difficult to document.
With radiant floors, nothing is visible in the living space, so there are no restrictions as to where furniture can be placed; the system is very quiet, and dust isn’t blown around the room. Even when they are well-insulated, unheated concrete floor slabs can feel cool to the touch, but radiant floor slabs are warm and comfortable to walk on, so they are especially popular in bathrooms, where bare feet are common. Radiant heating can also be used to melt snow from sidewalks and driveways.
Many people claim that radiant heating is more comfortable and healthful than forced-air heating. While the physics of making a human body comfortable are rather complex, there are reasons why radiant heating can be more comfortable. And people who have radiantly heated floors generally like them a lot. Whether or not radiant heating is actually healthier is a different matter.
Disadvantages? Radiant systems can have a high installation cost. Radiant floors must be designed so they are not too warm, and the designer must take into consideration whether or not a floor will be covered with carpeting (which acts as insulation). A radiantly heated concrete slab will respond slowly to a change in the thermostat’s setting because it takes so long to warm up the slab. Ventilation and air conditioning can’t be combined with radiant heat, so they must be separate systems. In the past, water leaks were not unusual, but the tubing used today is much more durable and resistant to leakage. But if a leak does occur inside a concrete slab, it can be difficult to repair.
A radiant heater can sometimes accelerate the outgassing of furnishings. This is because furnishings can get warmer with radiant heat than they would with another form of heating. In addition, the materials actually making up a radiant floor will be warmer and subject to increased outgassing. For this reason, materials should be chosen carefully. For example, a radiantly heated ceramic-tile floor would be fairly inert, but a plywood subfloor covered with synthetic carpeting could be problematic.
