GB682312A - Improvements in or relating to water heaters - Google Patents

Abstract

682,312. Valves. PARNALL (YATE), Ltd. June 17, 1949 [June 17, 1948 ; Feb. 25, 1949], Nos. 16323/48 and 5231/49. Class 135. A water heater has a venturi through which the water flows to control, by a diaphragm, the heating means and a valve governing the flow through the venturi, and a thermally-responsive device controlling a by-pass round both the valve and the venturi. Water passes from the inlet 1, through the conduit 3 to the lower part of the chamber 4, past the flow control valve 6 and through the venturi 8 to the outlet 9 leading to the heat-exchanger. The pressure difference across the venturi moves the diaphragm 5 to operate the gas valve by the rod 14, and to bring the valve 6 into operative position. The heating means gives a constant heat input while the valve 6 maintains a constant flow so that a predetermined outlet water temperature is obtained. Should the outlet temperature increase, a phial and bellows thermostat 32, 27, Fig. 8, opens the valve 26 to allow inlet water to by-pass the valve 6 and venturi by flowing from the conduit 3 to the casing 10, through the valve 26 to the outlet 9 thus reducing the outlet temperature by allowing more water to flow through the heater. Should the temperature rise unduly, the by-pass is opened sufficiently to starve the venturi and thus close the gas-valve. The valve 26 is balanced hydraulically by having a spring-loaded bellows 33 opposing the thermal bellows, the outlet temperature being determined by the loading of the spring 34 adjusted by a screw 35. Specifications 630,684 and 636,258 are referred to.