Potterton HE Plus Installation & Service Instructions Manual page 44

Sensing Pipe
Ignition Lead
Valve
Inlet Pipe
Gas Feed
Elbow
Fig. 86
Retaining Bracket
Boiler Chassis
Fig. 87
44
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Supplied By www.heating spares.co Tel. 0161 620 6677
Venturi Inlet
Pipe
Outlet Adaptor
Gas Valve
Expansion Vessel
Spring
Washer
Lock Nut
14.0 Changing Components
14.20 Gas Valve (Fig. 86)
IMPORTANT: After replacing the valve the CO
checked and adjusted as detailed in Section 15.0
Combustion Check. Only change the valve if a suitable
calibrated combustion analyser is available
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.
14.21 Expansion Vessel (Fig. 87)
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.
must be
2