11.0 Changing Components
29
11.4
Gas Valve
(Fig. 54)
1. Undo the two screws securing the outercase
bottom panel and remove the panel (Fig. 53).
2. Disconnect the wires from the valve modulator
and the pressure sensing tube and earth wire
from the valve body.
3. Note the position of the ignition lead and earth
wire on the valve NAC and disconnect them.
Undo the screw securing the NAC to the valve
and draw it away.
4. From beneath the appliance undo the four
screws securing the gas inlet pipe manifold to the
valve.
5. Undo the screws securing the combustion box
front panel. Remove the panel, being careful not
to damage the seal.
6. Disconnect the gas supply from the burner inlet
manifold taking care not to damage the sealing
washer. Remove the pipe grommet from the
combustion box lower panel.
7. Carefully manoeuvre the gas valve and outlet
pipe from the appliance, taking care not to
damage the ‘O’ ring seal in the gas inlet pipe
manifold. If necessary remove the gas inlet pipe
from the pipe bracket.
8. Undo the four screws securing the gas outlet
pipe manifold to the valve. Remove the outlet
pipe taking care not to damage the ‘O’ ring seal in
the outlet pipe manifold.
9. Examine the ‘O’ ring seals and replace them if
necessary. Reassemble in reverse order,
ensuring that the washer is in place between the
gas supply and the burner inlet manifold. Replace
the washer if it is damaged in any way.
10. Ensure that the gas pipe grommet is correctly
located in the combustion box lower panel.
11. Check the burner pressure as described in
Section 9.2 and recommission the boiler.
Fig. 53
Fig. 54
Gas Valve
Sensing Pipe
‘O’ ring seal
‘O’ ring seal
Inlet Pipe
Outlet Pipe
Bottom Panel
Screws
Sealing Washer
Earth Wire
Ignition Lead
