Abstract: A control valve apparatus has an in line ON/OFF valve and an ON/OFF and modulating valve made by placing actuator members in a non-magnetic material tube and surrounding the tube with electromagnetic coils and an iron casing. Openings at each end provide for connections to a gas supply and an outlet for an appliance.

Abstract: A control system for an induced or forced draft combustion apparatus has a single pressure transducer for providing an electrical signal indicative of pressures by alternately responding to the fuel pressure to the combustion apparatus and the fuel pressure plus the induced draft lower suction pressure. The signal output of the transducer is connected to a controller for controlling the fuel flow to maintain a predetermined fuel/air ratio for efficient and safe combustion of the fuel in the combustion apparatus.

Abstract: A multistage thermostat is operated by comparing the thermostat setpoint and the sensed temperature over a continuous series of discrete intervals of time. When a sudden change occurs between the sensed temperature and the setpoint, the magnitude of this change is evaluated in a comparator means and if necessary the system is reset to compensate for the change to operate in the most efficient manner. The adjustment of a constant supplied to an integrating circuit that forms part of a signal processing circuit means for the thermostat means provides the adjustment when the predetermined level of change is made.