GB703455A - Improvements in and relating to controlling devices for gas water heaters - Google Patents

Abstract

703,455. Thermally-actuated valves. VAILLANT, H., [trading as VAILLANT KOMMANDIS-GES., J.]. Oct. 23, 1951, No. 24712/51. Class 135 A control device for gas water heaters in which the gas supply is adjusted automatically in dependence upon the water outlet temperature is characterized by the gas supply being controlled by two thermal elements disposed in the water outlet, one of which increases the gas supply with increasing water outlet temperature during the heating-up period until a desired water temperature is reached whereas the other throttles the gas supply as the desired temperature is exceeded. Water at A passes through ports 38, a valve 2 controlled by a thermal element 3, and a heat exchanger 4 to the outlet D, the pressure drop across the valve 2 being kept constant by a piston 40 controlling the ports 38 and actuated by a spring-loaded pressure-responsive disc 39 in a by-pass around the valve 2. Gas passes from E through a water deficiency valve 43, a valve 7 controlled by two thermal elements 19, 21, in the outlet, a passage 49 and ports 50 to the burner 9, the pressure drop across the valve 7 being kept constant by a sleeve 51 controlling the ports 50 and actuated by a weighted pressure responsive disc 46 in a by-pass around the valve 7. During the heating up period as a desired water temperature, determined by a spring 27 loading a bellows 22 connected to the thermally lagged element 21, is approached the bellows moves a bail 28 downwards to open the valve 7. When the desired water temperature, determined by a spring 30 loading a bellows 20 connected to the unlagged element 19, is exceeded, the bellows 20 raises the valve 7 through a stop 36 away from the bail 28 and closes the valve. When the desired outlet temperature is increased by increasing the loading of the spring 30 through a screw 54, bevel gearing 53 and handle 12, the valve 2 and thermal element 3 are raised by gearing 56 and eccentric 55 to throttle the inflow of water so as to maintain the heat-load of the heater constant, the heat load being the product of quantity of water flowing per unit time and the temperature difference between the inflowing and outflowing water.