Room heaters are used to heat a small space on a portable or wall-mounted basis. Most heaters use gas or electricity. Room heaters are comfortable devices that provide concentrated and localized heat. An electric heater is an electrical device that converts electrical current into heat. Ambient radiators distribute heat through a metal coil. Using a small heater allows you to lower the central thermostat and heat only the rooms you use most often, saving energy throughout the house. Not only does this lower your monthly utility bill, but it also reduces greenhouse gases in the environment.