Gas Valve; Domestic Hot Water Heat Exchanger; Electrode Assembly; 10Pressure Gauge - Worcester ZWBR 7-28 HE plus Installation And Servicing Instructions

Maintenance
9.3.7

Gas Valve

y Check that the gas cock is turned off.
y Lower the control panel. Refer to fig. 55.
y Pull off the solenoid connections at the rear of the
valve.
y Undo the union, within the inner casing, securing the
valve to the gas/air tube. Refer to fig. 54.
y Remove the white plastic cap from the gas valve.
y Release the gas inlet union at the manifold assembly.
y Unscrew the two screws securing the gas valve
assembly bracket to the back panel and withdraw the
assembly.
y Transfer the bracket and inlet pipe assembly to the
new gas valve.
y Check for gas soundness when the new gas valve
has been fitted.
y Recheck the combustion performance as described
in section 8.1.
6 720 610 602 - 04.1O
Fig. 57
44
9.3.8

Domestic Hot Water Heat Exchanger

y Refer to section 9.2.
y Use new seals when fitting the new heat exchanger.
9.3.9

Electrode assembly

y Refer to section 9.2.
y Use a new seal if the existing seal is damaged.
9.3.10 Pressure gauge
y Drain the appliance.
y Lower the facia. Refer to fig. 55.
y Twist the pressure gauge head anti-clockwise to
release it from the casing. Refer to fig. 2.
y Disconnect the capillary head from the rear of the
diverter valve by withdrawing the clip and pulling out
the head. Refer to fig. 56.
9.3.11 Expansion vessel
y Drain the appliance.
y Undo the union connection at the base of the vessel.
Refer to fig. 2.
y Unscrew the top and bottom fixing screws and
remove the vessel.
y Set the pressure of the new vessel to that required by
the system.
9.3.12 Pressure Relief Valve
y Drain the appliance.
y Disconnect the drain pipe from the valve. Refer to
fig. 29.
y Pull-out the clip securing the valve.
y Pull-out the valve.
y Ensure that the replacement valve is fully entered
before fitting the clip.
9.3.13 Burner
y Refer to section 9.2.
6 720 610 597 GB (01.07)