Hot water wall radiators distribute radiant heat to a room using water heated by a boiler and pumped through a closed loop that includes the radiator. They are a quiet way to heat the home and more efficient than most forced-air systems.
Earlier radiant heating systems used a boiler to produce steam that rose naturally through the pipes and radiators to provide heat. These hissing radiators were often noisy due to leaks, water locks and steam plugs.
With hot water systems, the water serves as a heat transport medium. As it passes through the radiator, it releases the heat it contains and follows the closed loop back to the boiler for heating again. The system uses no fans, so it operates quietly and without stirring up dust, which are problems common to forced-air systems. They are up to 30 percent more efficient, because they eliminate the heat loss due to ducts.
While older radiators were large and clunky pieces of cast iron, modern wall radiators are available in many styles as of 2015. Units for the bathroom have optional towel and bathrobe bars for a touch of luxury. They are made of anodized aluminum, making them easier to transport and install. They fit just a few inches from the face of the wall, preserving valuable floor space.