Bosch Greenstar ZWBR 11-25 A31 Installation And Servicing Instructions Download

Page: 27 / 32

Burner Assembly

Remove the inner case cover.
Unscrew the fan assembly. Refer to Fig.19.
Remove the split pins from the front fixings of the burner
assembly and unscrew and remove the fixings. Loosen the rear
fixing nut, it is not necessary to remove this nut, and carefully
remove burner assembly.
The perforated burner flame strip can be removed.

NOTE: The burner flame strip must be replaced as shown in
Fig.20.

When replacing the burner assembly hand-tighten the front
fixings before adding just suffucient extra force to allow the
fitting of new split pins.
Do not overtighten the rear fixing.
Do not forget to refit the seal between the burner body and fan
assembly.

Fan

Remove the inner casing cover.
Pull off the lead at the fan. Refer to Fig. 31 and 32.
Release the two extended screws securing the fan.
Lift the fan assembly off the gas inlet pipe. If necessary unscrew
the gas pipe at the gas valve after pulling out the plastic air
ditributor from the valve to gain access to the nut.
Unscrew the three screws to separate the fan from the mixing
tube.

Siphon

Disconnect the pipe to the siphon.
Remove the yellow plug to drain the siphon.
Unscrew the securing nut from beneath the the side facia and
remove the siphon. Refer to Fig.33.
Refit and prime the siphon.

Relief Valve

Drain the appliance.
From beneath dis-connect the relief valve drain pipe and
unscrew the valve. Refer to Fig.24 and 33.
Refill, vent and re-pressurise the appliance. Prime the siphon.

Diverter Valve

Drain the appliance. Lower the facia and unplug the electrical
connections at the valve.
Disconnect the union connections. Refer to Fig.24.
Unscrew the four screws securing the valve to the mounting
plate and remove he valve by firmly pulling it from the
connections.
Refill, vent and re-pressurise the appliance. Prime the siphon.

Pump

Drain the appliance. Unplug the electrical connections at the facia.
Lower the facia and remove the cross brace. Refer to Fig.15 and 24.
Remove the plastic side facia panel by unscrewing the fixing screw.
Refer to Fig 23.
Undo the manual air vent union and the pump union connections
to remove the pump.
Alternatively unscrew the four Allen screws and replace the pump
head (model 15-33/50).
Refill, vent and re-pressurise the appliance. Prime the siphon.

Auto-Air Vent (Expansion Vessel and DHW Heat Store)

Drain the appliance. Unscrew the vents from the top of the
appropriate vessel. Refer to Fig.14.
Refill, vent and re-pressurise the appliance. Prime the siphon.

Domestic Hot Water Heat Exchanger/Store

Drain the appliance. Lower the facia.
Remove the siphon and expansion vessel. Remove the automatic
air vent and lock nut from the top of the DWH heat exchanger.
Unscrew the water connections at the bottom of the heat
exchanger.
Unplug the connectors from the two sensors at the base and
remove the heat exchanger. Refer to Fig.14.
Transfer the sensors. Refer to Fig.28.
Refill, vent and re-pressurise the appliance. Prime the siphon.

Fig. 33. Condensate drain/siphon

arrangement

Fig. 32. Fan assembly.

Fig. 31. Fan assembly fixing screws.

Gas valve
flange joint nut

Restrictor

Mixing tube

Air Flow
Sense
Connection

Fan assembly
fixing screws
(3)

Fan assembly

Connection to
Heat Exchanger

Condensate
Drain Union
Connection