33
Note: Use silicone grease to ease the fit-
ting of any push fit connections.
6.1 Expansion
Vessel
– Isolate power supply
– Remove boiler cover
– Isolate flow and return valves
– Drain boiler using fitted drain vent
– Disconnect expansion pipe
– Remove expansion vessel securing nut
– Remove vessel
– Check new vessel for correct pressure
1- 1.25 bar
– Refit in reverse order.
6.2 Ignition/Ionisation
electrode
– Isolate power supply
– Remove boiler cover
– Remove sealed chamber cover
– Remove PCB cover
– Disconnect ignition lead
– Carefully remove lead through PCB
cover and burner compartment
– Remove electrode fixing screw and
remove electrode from burner
– Replace in reverse order.
6.3 Main
Burner
– Isolate power supply
– Isolate gas supply
– Remove boiler cover
– Remove sealed chamber cover
– Remove burner cover
– Disconnect gas connection to burner
– Remove locknut securing burner assem-
bly
– Remove ignition/ionisation electrode
– Carefully lift out burner assembly
– Refit in reverse order
– Test for gas tightness.
6.4 Fan
assembly
– Isolate power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect wiring to fan
– Remove two fan fixing screws
– Carefully pull fan forward and to the
right to disconnect fan from post con-
denser
– Remove air pressure switch sensing
tube
– Apply light coating of silicone grease to
nozzle of new fan
– Refit in reverse order.
6.5
Main Heat Exchanger
– Isolate power supply
– Isolate gas supply
– Isolate flow and return valves
– Drain boiler using drain vent
– Remove fan assembly as described in
6.4
– Remove 4 screws and remove fan
mount ing plate
– Disconnect thermistor (SM sensor)
– Disconnect flow and return connections
– Lift out heat exchanger
– Refit in reverse order.
6.6
100°C Limit stat
– Isolate power supply
– Remove boiler cover
– Remove sealed chamber cover
– Remove fan as described in 6.4
– Remove wires from 100°C stat
– Remove stat fixing screws
– Apply heat sink compound to new stat
– Refit in reverse order.
6.7
Air Pressure Switch
– Isolate power supply
– Remove boiler cover
– Remove sealed chamber cover
– Remove screws securing air pressure
switch
– Note position of wires before removal
– Note position of sensing tube before
removal
– Refit in reverse order.
6.9
Thermistor (SM sensor)
– Isolate power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect thermistor
– Refit in reverse.
6.10 Gas
Valve
– Isolate power supply
– Isolate gas supply
– Remove boiler cover
– Disconnect wiring from gas valve
– Disconnect sensing tube
– Remove gas valve
– Refit in reverse order ensuring seals are
replaced as required
– Recommission boiler and adjust gas
pressures as described in section 4.2.2
– Check for gas tightness
6.11 PUMP
HEAD
– Isolate boiler
– Remove cover
– Isolate flow and return valves
– Drain boiler using drain vent
– Remove electrical lead from pump
– Remove 4 x fixing screws from pump
housing catching any excess water
– Pull pump forward
– Refit in reverse order
6.12 DOMESTIC
HEAT EXCHANGER
– Isolate boiler
– Remove cover
– Isolate flow and return
– Turn on D.H.W tap
– Close cold water supply isolation valve
– Drain boiler using drain vent
– Remove 2 screws securing plate heat
exchanger
– Remove plate heat exchanger catching
any excess water
– Ensure that the four O rings are remo-
ved from the technil assembly
– Fit new O rings supplied with new heat
exchanger to the heat exchanger
– Refit in reverse order
6.13 SAFETY
VALVE
– Isolate from mains
– Remove cover
– Isolate flow and return valves
– Drain boiler using drain vent
– Disconnect pipe from safety valve
– Remove safety valve securing clip
– Remove safety valve
– Refit in reverse order
6.14 DIVERTER
VALVE
MOTOR HEAD
– Isolate mains
– Remove cover
– Remove pin from valve head body
– Disconnect lead
– Lift motor upwards
– Refit in reverse order
6.16
AUTO AIR VENT
– Isolate boiler
– Remove cover
– Isolate flow and return valves
– Drain boiler using drain vents
– Pull clip forwards and lift auto air vent
upwards
– Refit in reverse order
6.17
DIVERTER CARTRIDGE
– Isolate boiler
– Remove cover
– Isolate flow and return valves
– Drain boiler using drain vent
– Remove air inlet duct
– Disconnect return pipe from pump hou-
sing
– Disconnect water gauge pipe from
pump housing
– Unplug pump removing top cover
– Remove 2 x screws holding pump and
pull forwards catching any excess water
– Remove motor head as 6.14
– Remove pin lift cartridge housing
upwards catching any excess water
6
REPLACEMENT OF PARTS
