Technical data

42
12.0 Changing Components
12.23 Gas Valve (Fig. 68)
1. Turn the gas cock off and undo the nut on the gas feed
elbow under the boiler.
2. Remove the screws securing the inlet pipe flange to the
boiler bottom panel.
3. Pull off the earth lead and sensing pipe.
4. Undo the nut on the venturi inlet pipe and slacken the nut
on the venturi. Ease the pipe aside and remove the gas valve.
5. Remove the outlet adaptor and inlet pipe and transfer them
to the new valve. Examine the ‘O’ ring seals, replace if
necessary.
6. Reassemble in reverse order.
IMPORTANT: The CO
2
must be checked and adjusted as
detailed in Section 13.0 Combustion Check
12.24 Expansion Vessel (Fig. 69)
1. Drain the primary circuit and undo the nut on the vessel
connection pipe.
2. Undo and remove the locknut and spring washer securing
the vessel spigot to the boiler air box.
3. Remove the bracket and vessel from the boiler.
4. Locate the retaining bracket on the upper flange of the
vessel and fit to the boiler.
5. Reassemble in reverse order.
Gas Valve
Valve
Inlet Pipe
Gas Feed
Elbow
Fig. 68
Ignition Lead
Expansion Vessel
Boiler Chassis
Lock Nut
Spring
Washer
Fig. 69
Retaining Bracket
Sensing Pipe
Venturi Inlet
Pipe
Outlet Adaptor