Electric resistance heaters use panels to radiate the heat from a very hot electric element or transfer the heat by conduction to the air. Some systems rely on convection to distribute the warmed air as it rises and circulates within a room. Others may also use fans in “air-handlers” to expedite the heat transfer to the air and the circulation within a room—a method that is much faster than relying on convection alone to circulate the air.
Most heat pumps (typically, “mini-splits” powered by electricity) use similar “air-handlers” to transfer the heat from a very hot electric element or hot liquid to the air. Heat pumps are often mounted on walls or built into walls and ceilings where they transfer heat to air that passes through ducts and is ejected rooms through registers or grills.
However, some heat pumps using the air or the ground as the source heat produce very hot water. Additionally, many combustion heat sources deliver heat through very hot water. Special equipment safely and efficiently transfers the heat in the water to the air inside the home.
Some of these hydronic systems are modern radiators. They radiate the heat through space—warming objects even a distance from the radiator.
In addition to free-standing radiators, radiators can be built into the floor, walls, and ceilings of a house.
A side benefit of some of these systems is that in summer, heat in the air in the room will radiate to a slightly cooler wall or ceiling and be absorbed by cool water circulating through the same system. These two-season systems provide efficient, silent, and even cooling without air movement.
