GB650058A - Improvements in or relating to the control of liquid heating systems - Google Patents

Abstract

650,058. Centrol systems for fluid heating. OLDHAM, F. E. Jan. 10, 1948, No. 841. [Class 38 (iv)] [Also in Group XXIX] A fluid heating system includes a control valve having an element sensitive to the kinetic energy of flow of the fluid, a supply valve for the supply of fluid to the system, and servomotor means adapted to be operated by movement of said element in response to fluid flow, so as to open, or further open, the supply valve. In the arrangement shown in Figs. 3 and 4, hot taps 55 are fed from a boiler 52 and associated hot water storage tank 53, the boiler having an electric heater 60 and having a cold water intake pipe containing a normally closed valve 51 by-passed by a flow-controlled valve 50 (see Group XXIX). Thermostat 53a, having contacts 171 in the coil circuit of a relay 131-135 controlling the connection of heater 60 to a source 101, 102, maintains the boiler and storage tank at a temperature of 130‹ F. under normal conditions of low demand by the taps 55. Under heavier demand conditions a delayed relay coil 121 is energized over contacts. 112 which are closed by movement of the flowcontrolled valve 50, the relay contacts 122.then closing to provide an energizing circuit for relay coil 131 independent of the thermostat contacts, so that the heater 60 is automatically connected to the source. Energization of a further relay 141, 142 follows (over contact 134) and causes the opening of inlet valve 51 and deenergization of relay coil 121 (at contact 142). Contact 122 is now open and control of the heater by a thermostat 52a, having contacts 161 and set to operate at 140‹ F., is initiated. When the water reaches this temperature, contacts 161 open and interrupt the holding circuit (over contacts 135) of coil 131, so that the system returns to its normal condition.