| 摘要 |
630,684. Thermally - actuated valves. BARNES, N., WHITAKER, A., and JESSEL, R. Aug. 14, 1946, No. 24190. [Class 135] A water-heater has the heating means controlled by a device responsive to the pressure difference across a Venturi through which water to be heated flows, the Venturi being provided with a byepass controlled by a valve operated by a thermal device responsive to the outlet temperature of the water. As shown, water from a domestic hot water system or the mains enters a casing 8 at 9 and passes via the outlet 10 and Venturi 12 to the pipe 17 leading to the heatexchanger of the heater and back at 23 to the casing and outlet 24. When the water flow exceeds a certain minimum value, the pressure difference across the Venturi moves a diaphragm to open the gas valve so that the burners are ignited by a pilot light. If the outlet temperature of the water exceeds a predetermined value, the bellows thermostat 21 opens the valve 18 controlling the flow through a pipe 16 byepassing the Venturi, so that the flow is reduced through the Venturi but more water passes through the heater to maintain the predetermined outlet temperature. In a preferred form, when the valve 18 has been fully opened, the flow in the Venturi is insufficient to maintain the gas supply which is therefore cut off. In another modification, when the valve 18 approaches the fully-open position the gas supply is reduced. The water passing to the heater may be controlled by an auxiliary valve. Specification 436,773 is referred to. |
