9.3.7
Expansion vessel
Warning
Take precautions to protect other components from water damage
when removing the expansion vessel.
1. Close the flow and return isolation taps and drain the boiler primary
circuit.
2. Relieve the pressure from the expansion vessel.
3. Remove the silencer.
4. Prise off the securing clips and disconnect the braided hose from the
vessel and hydraulic inlet assembly, taking care as water may still be
in the vessel.
5. Ensure that the braided hose is free of restriction, as a boiler with a
blocked hose will exhibit symptoms similar to one with a failed vessel.
Important
Where the hose is found to be blocked, it must be cleared or
replaced and the vessel recharged to 1 bar.
6. If the hose is clear support the vessel, undo the locknut and
manoeuvre the vessel out of the boiler.
7. Replace the expansion vessel with the new one and reassemble in
reverse order and recharge to 1 bar.
9.3.8
Gas valve
Tab.22 Characteristics of combustion
15
18
CO
2
% (maximum) 9.0 + 0.3 – 0.2
9.0 + 0.3 – 0.2
% (minimum) 8.5 + 0.1 – 0.4
8.5 + 0.1 – 0.4
Diameter of coaxial discharge pipes
mm
60/100 & 80/125
60/100 & 80/125
Important
After replacing the gas valve the CO
2
must be checked and
adjusted. Only change the valve if a suitable calibrated
combustion analyer is available, operated by a competent person.
1. Undo the screw and disconnect the electrical plug.
2. Turn the gas cock off and undo the nut on the gas valve inlet
underneath the boiler.
3. Undo the nut on the gas valve outlet. Ease the pipe aside.
Important
The gas nozzle injector is inserted in the gas valve outlet.
4. Remove the screws securing the gas valve to the boiler bottom panel.
Remove the valve.
5. Transfer the gas nozzle injector to the new valve, ensuring it sits in the
valve outlet. Examine the sealing washers, replacing if necessary.
6. Reassemble in reverse order.
Important
Check gas tightness and combustion.
Fig.52
Remove expansion vessel
PN-0000378
Fig.53
Removing the gas valve
PN-0000308
9 Maintenance
53
Main Eco Compact
System
