GB1119807A - Thermostatic control device - Google Patents

Abstract

1,119,807. Valves. ROBERTSHAW CONTROLS CO. 28 Feb., 1966 [3 March, 1965], No. 8737/66. Heading F2V. A valve 90 controlling the fuel or electricity supply to a water heater is controlled by a rod and tube thermostat 124, 126 through a snapacting mechanism 102 while a valve 36 upstream of the valve 90 normally held open by a coil 48 energized by a pilot flame thermocouple 60 is caused to close if the water temperature reaches a dangerously high value by a bimetallic switch 138 which also controls the energization of the coil 48. A manually-actuated plug cock 88 is also included in the fuel line while a manually actuated push-button 84 permits the valve 36 to be held open until the pilot burner is lit and the coil 48 thereby energized. The bimetallic switch may be arranged as shown in Fig. 5 to open circuit the coil 48 or to short circuit the thermocouple 60 and is provided with tabs to engage the thermostat tube which is wholly immersed in the water tank and connected thereto by a threaded shank 128. A rubber seal 174 prevents contamination of the switch contacts while an earthing screw 172 connects a bracket 170 at the inner end of the switch to the shank 128. The switch may close the valve 36 at a temperature of, say, 210‹ F., while the thermostat closes the valve 90 at a temperature which may be adjusted by a knob 122, a shaft 118 and a lever 112 and is normally about 140‹ F. The blade 138 of the switch has opposed arcuate portions 140 crimped around the end of conductor 136 and, except for its movable end, is surrounded by an insulating covering 144.