Abstract: A programmable device for controlling the amount of heat supplied to a building by a circulating medium by enabling a circuit to a heater such as an oil or gas burner, or a steam valve to open and close during predetermined times and in response to the temperature of the outside air and the temperature of the medium. The predetermined times can occur during a multi-day cycle such as a week. As the outside air temperature rises and falls, the circuit will be opened or closed depending on whether the device is at a predetermined time and whether that temperature falls above or below a predetermined value and depending on the temperature of the circulating medium. Additionally, the device can be set so that when the outside air temperature falls below a predetermined level the circuit is closed to add heat to the building without regard to where in the program cycle the device is.

Abstract: A programmable device for controlling the amount of heat supplied to a building by opening and closing a circuit to a heat source such as an oil or gas burner or a steam valve during predetermined times and in response to the temperature of the outside air. The predetermined times can occur during a multiday cycle, such as a week. As the outside air temperature rises and falls, the circuit will be closed later or sooner, respectively. Additionally, the device can be set so that when the outside air temperature falls below a predetermined level the circuit is closed to add heat to the building notwithstanding where in the programmed cycle the device is. Conversely, the device can be set so that when the outside air temperature reaches a predetermined maximum, the circuit is opened to halt the addition of heat to the building notwithstanding wherein the programmed cycle the device is.