Radiant heat is a comfortable, even type of heat that is radiated into living spaces by hot water, steam, or electric elements.

With a hydronic radiant system, a central boiler heats water; the resulting hot water or steam then circulates through a system of pipes to room radiators or through circuitous routes of tubing that wind beneath a floor's surface to emit heat.

Electric radiant systems may have electric-resistance baseboard or wall registers or a system of electric cables or foils hidden beneath floors or above ceilings. When an electric current runs through an electric-resistance element, cable, or foil, it generates heat--and that heat is radiated into the room.

Because radiant heating systems have very few moving parts, they rarely fail (most failures are caused by circuit overloads).