GB1526378A - Central heating and water heating system - Google Patents

Abstract

1526378 Combined central heating and domestic supply hot water system SAUNIER DUVAL 11 May 1976 [27 May 1975] 19403/76 Heading F4A A water heating system, in which water heated in a boiler heating element 4 by a gas fired burner 3 is selectively circulated by a pump 21 through either a central heating circuit 7 or a domestic water heating circuit 8, includes a regulating control system comprising a domestic water tank thermostat 25<SP>1</SP>, a circulating water thermostat 32<SP>1</SP>, means 24 connected to electric supply U, in series with the contact 25 of thermostat 25<SP>1</SP> to operate or change over device 10 to select between the water circuits 7 and 8, a manual two-position switch 28 to connect the pump 21 either in series with contact 25<SP>1</SP> or direct to the electric supply, and a solenoid gas valve 30 for the burner which receives power from between the pump and switch 28 either directly or via the contact 32 of the thermostat 32<SP>1</SP> depending on the position of the device 10. The switch 28 has summer E, and winter H positions and in the Figure shown the winter position is selected. The device 10 is arranged inside a valve casing 1 and is operated by a rod 12 secured to a membrane 13; the rod 12 being normally biased by a spring 22 to the position shown so that water is circulated to radiators 9 in the central heating circuit 7. A rectifier bridge 29 feeds power to the solenoid gas valve 30 of the burner 3 via a switch 31 connected to be operated by the rod 12. In the system shown an additional thermostat 26<SP>1</SP> senses the outlet temperature of water circulated through the heater in the domestic water tank 20 and its contact 26 is arranged in series with contact 25. The pump remains on all the time and while contacts 25, 26 are open (as shown) thermostat 32<SP>1</SP> controls burner operation. When the temperatures sensed by thermostats 25<SP>1</SP>, 26<SP>1</SP> drop below predetermined levels their contacts 25, 26 close and a solenoid valve 24 is actuated to move down a member 18. This movement unblocks a pipe 16 and closes an opening 19 within the casing 1. A pressure differential is thereby created between chambers 14 and 15 of the casing 1 which moves membrane 13 and its rod 12 to the right to change over the switch 31 (making the solenoid gas valve electric supply independent of thermostat 32), and to move the device 10 (diverting water through circuit 8 to the tank 20). When the summer position H of the switch 28 is selected (Fig. 2, not shown) the electric supply to both the pump and burner is dependent on operation of the contacts 25, 26.