GB776821A - Improvements in or relating to temperature control mechanism - Google Patents

Abstract

776,821. Valves. ROBERTSHAW-FULTON CONTROLS CO. July 31, 1953, No. 21373/53. Class 135. A temperature control device, e.g. for a gas water-heater, comprises control means movable between on and off positions to control the supply of operative energy to the heater, e.g. the valve 40, thermal means 68 for moving the valve through a lever 72 adjusting means 76 for altering the fulcrum of the lever and setting the temperature at which the valve is normally actuated, setting means, e.g. the screw 74 screwed inwardly beyond its normal movement to position the lever away from the fulcrum, e.g. to engage a pivoted hook 92, and permit a temperature rise above that normally set by the adjusting means, and resetting means 84 for automatically returning the lever to the fulcrum when a predetermined temperature higher than that set by the adjusting means has been attained. On turning and depressing the knob 22 of the cock 18 a plunger 32 rotates the lever 62 against a spring-loaded armature stem 58 of an electromagnet 56 controlled by a thermo-couple heated by a pilot burner. When the magnet 56 is energized a spring 64 loading the valve 40 is relieved and the valve may be opened by the thermal element 68 acting through a lever 72, a snap-acting device 50 and an over-ride device 46. For normal operation the pivot of the lever 72 is on the end of a temperature-adjusting screw 74. Should a tank full of water at a higher than normal temperature be required the lever 72 is moved by the screw 74 to engage a pivoted hooked bell-crank 92. When the high temperature has been reached a collar 88 on the element 68 moves upwardly and turns a lever 84 about a pivot 86 which through an adjusting screw 85 disengages the hooks 92 from the lever 72 to allow it to re-engage the screw 74 under the action of a leaf-spring 78 for normal temperature control. A separate spring-loaded push button and lever may be used in place of the screw 74 for moving the lever 72 into its high temperature position.