Abstract: An anti-ice control system for controlling flow of heated air in response to the temperature of the heated air and ambient air.

Abstract: A burner control system for a hot water boiler is responsive to both outlet water temperature and return water temperature to provide a relatively constant outlet water temperature regardless of variations in heat output requirements. A first thermistor responsive to return water temperature is effective to provide on-off control of gas flow to the burner. A second thermistor responsive to outlet water temperature is effective to vary the rate of gas flow to the burner so as to maintain a predetermined outlet water temperature. A timing circuit is effective each time the burner is turned on to delay a high rate of gas flow to the burner.

Abstract: A control valve for controlling refrigerant circulation in a vehicle air conditioning system has an inlet port and an outlet port for connection to the evaporator and the compressor inlet respectively of the system, and a valve controlling communication between these two ports. First control means in the valve body control the valve in dependence upon one or more external controls including manual controls and second control means control the operation of the valve in dependence upon the thermodynamic conditions, such as the temperature, of the refrigerant fluid.