Patent GB-980499-A (GB)
Title: Improvements in or relating to hot water installations
IPC: F24D19/10
Filed: 1962-10-16
Abstract: 980,499. Valves. ASCOT GAS WATER HEATERS Ltd. Oct. 16, 1962 [Dec. 7, 1961], No. 39161/62. Heading F2V. [Also in Division F4] In a heating installation comprising a water heater having a fuel burner, a central heating circuit including a cold water inlet point and a draw-off point for hot water from the circuit, means are provided for controlling the flow of fuel to the burner in dependence on the rate of draw-off of hot water from the circuit or the rate of circulation therein. In the form shown water is circulated around a central heating circuit 1 by a pump 2. The circuit includes a heater 4 having a fuel burner 5, a draw-off point 7 for hot water and a cold water supply pipe 8 upstream of the heater 4. To relieve any excess pressures occurring in the circuit 1 the supply pipe 8 is fitted with a non-return valve 9 and a safety valve 10 connected to a discharge pipe 11. Control of fuel to the burner is through a thermostatically controlled valve 36 actuated by a thermostat 35 and by means of an on-off valve 24 actuated by means of two differential valves 14, 15. Operation of the assembly is as follows: Suppose, initially, that the water in the radiators is sufficiently hot (the pump 2, controlled by a thermostat, not shown, being then stopped) and that no water is withdrawn from 7. No water then flows in the heater 4 or in the cold water supply pipe 8, and the differential valves 14, 15, are subject to equal pressures on either side of their diaphragms 18, 29 respectively. The fuel conttol valve 24 is held on its seat by spring 25 and burner 5 is not alight. If, starting from the initial condition, the temperature of the water in the radiators falls, the pump is started by the thermostatic control and water flows through the heater 4. This flow of water through the heater 4 causes a pressure difference to occur between opposite sides of the diaphragm 18 of the valve 14, which is connected on the one side upstream of the heater and on the other side downstream of the heater. The diaphragm 18 flexes, raises the valve 24 and causes fuel to flow to the burner 5. The reverse operation causes extinction of the burner when the radiators have attained their desired temperature. If, starting from the above-mentioned initial condition, hot water is drawn off from 7, the pressure of cold water admitted to the circuit 1 closes a non-return valve 3 in the portion of the closed circuit 1 containing the radiators. Thus only an amount of water equal to that drawn-off passes through the heater 4. This amount will be insufficient by itself to initiate the lighting of the burner by the valve 14 but is sufficient to open the valve 24 via the valve 15. The valve 15 is regulated to open the valve 24 when the draw-off reaches a reasonable value, the valve being of a standard Venturi type. If it is desired to draw-off hot water and to re-heat the water in the radiators at the same time, the closure of the valve 3 automatically delays the start of the re-heating of the radiator water until the draw-off of hot water is completed, the pump 2 meanwhile running idle.