Modulator
Wires
Ignition
Lead
Electrical
Plug
Earth Wire
Inlet Pipe
Gas Feed
Pipe
Fig. 56
Flow Pipe
Safety
Thermostat
Temperature
Sensor
Fig. 57
Gas Valve
12.0 CHANGING COMPONENTS
12.8Gas Valve (Fig. 56)
1.Undo the nut on the gas feed pipe at the tap rail under the boiler.
2.Completely undo the securing screws and hinge the facia panel down.
3.Disconnect the wires from the valve modulator and the ignition lead from the spark generator. Disconnect the pressure sensing pipe from the valve. Undo the screw securing the spark generator electrical plug to the valve and disconnect the plug.
4.Pull the earth wire off the spade terminal on the valve.
5.Remove the screws securing the inlet pipe flange to the tap rail and those securing the outlet manifold to the burner manifold.
6.Remove the valve from the boiler.
7.Note the orientation of the inlet pipe and outlet manifold. Undo the securing screws and remove the pipe and manifold.
8.Examine the ‘O’ ring seals for damage, replacing as necessary.
9.Fit the inlet pipe and outlet manifold to the new valve, ensuring that the ‘O’ ring seals are in place.
10.Reassemble in reverse order and check the burner pressure (Section 9.2).
12.9Temperature Sensor (Fig. 57)
1.Ease the retaining tab on the sensor away and disconnect the electrical plug.
2.Unscrew the sensor from it’s pocket and reassemble in reverse order. The plug will only fit one way.
12.10Safety Thermostat (Fig. 57)
1.Pull the two electrical connections off the thermostat.
2.Remove the screws securing the thermostat to the mounting plate on the flow pipe.
3.Reassemble in reverse order. The thermostat is not polarised - either wire can fit either terminal on the thermostat.
32 | Publication No. 5111811 |
