Honeywell Central Heating Cooker Natural Gas - Manual (Page 30)

30
WIRING ‘Y’ PLAN
Independent control of space and water heating circulation ina
fully pumped system with one motorised diverting valve (See
System Diagram 3)
This scheme provides control over a fully pumped instalation by
means of a single motorised diverting valve. This provides flow to
the space heating circuit or to tyhe water heating circuit. The valve
also has a mid position to enable circulating water to flow to both
circuits simultaneously. Control is via room and cylinder
thermostats.
The method of operation is that when the room thermostat calls
for heat, the valve motors over so that the port serving the space
heating circuit is opened and the pump and boiler are both
switched on. If the cylinder thermostat calls for heat, the valve
motors over to open its domestic hot water port only, and again to
switch on the pump and boiler. If both thermostats are calling for
heat, the valve motors to open both of its ports and to switch on
both pump and boiler. When both thermostats are satisfied, the
valve motors to the closed position and the pump and boiler are
switched off.