Patent US 5,489,765

Compressed air-driven electrical generator supplies electric current to resistance heating element on demand in a baseboard heating system. A thermostat in communication with an air valve actuator, allows compressed air to flow from an air holding tank to an air motor which drives the electric generator whenever the temperature in the control space drops below a pre-selected temperature. An electrical relay switch in series with the electric generator and an electrical resistance heating element opens the electrical circuit between the electric generator and the heating element whenever the temperature sensed by the thermostat drops below the pre-selected temperature.