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5.1
DHW expansion vessel
– Turn off power supply
– Remove boiler cover
– Isolate cold water supply
– Drain storage cylinder
– Disconnect DHW expansion pipe
– Remove expansion vessel locking nut
– Lift out expansion vessel
– Check pressure in new vessel (3 bar)
– Refit in reverse order.
5.2
CH expansion vessel
– Turn off power supply
– Remove boiler cover
– Remove front panel
– Isolate flow and return valves
– Drain boiler using drain vents(do not
use pressure relief valve)
– Disconnect expansion pipe
– Remove expansion vessel locking nut
– Loosen fixing bracket screws
– Remove expansion vessel
– Check pressure in new vessel (1bar)
– Refit in reverse order.
5.3
Ignition electrode
– Turn off power supply
– Remove boiler cover
– Remove sealed cover
– Disconnect electr ode fr om ignition
transformer
– Pull lead through grommet
– Remove electrode fixing screws
– Remove electrode
– Refit in reverse order.
5.4
Ionisation electrode
– Turn off power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect lead from ionisation elec-
trode
– Remove electrode fixing screws
– Remove electrode
– Refit in reverse order
5.5
Main burner
– Turn off power supply
– Isolate the gas supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect gas connection at burner
– Disconnect air sensing tube
– Disconnect two plugs at fan
– Disconnect Ignition electrode at ignition
transformer
– Pull lead through grommet
– Disconnect ionisation electrode
– Remove 6 x 10 mm nuts securing burn-
er to heat exchanger
– Carefully lift out burner assembly
– Refit in reverse order
– Test for gas soundness.
5.6
Main heat exchanger
– Turn off power supply
– Isolate gas supply
– Isolate flow and return valves
– Drain boiler using drain vent(do not use
pressure relief valve)
– Remove main burner as described in 5.5
– Disconnect 90° stat
– Remove auto air vent
– Disconnect condensat e drain fr om
burner
– Disconnect flow and return connections
– Remove two fixing brackets
– Carefully remove heat exchanger, to
avoid damage to rear seal
– Refit in reverse order
– Re commission boiler
– Test for gas soundness.
5.7
95° Smoke stat
– Turn off power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect 95° stat
– Unscrew stat from smoke chamber
– Refit in reverse order.
5.8
90° limit stat (dry pocket)
– Turn off power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect wiring to the 90° stat
– Unscrew the 90° stat
– Refit in reverse order.
5.9
100° Safety stat
– Turn off power supply
– Remove boiler cover
– Remove sealed chamber cover
– Disconnect wiring to 100° stat
– Remove fixing screws
– Refit in reverse order.
5.10
Thermister (SM sensor)
(wet pocket)
– Turn off power supply
– Remove boiler cover
– Isolate flow and return valves
– Drain boiler using drain vent(do not use
pressure relief valve)
– Disconnect thermister
– Remove thermister(catch any water
lost)
– Refit in reverse order.
5.11
Gas valve
– Turn off power supply
– Isolate gas supply
– Remove boiler cover
– Remove 2 screws securing control
panel
– Lower control panel to horizontal posi-
tion
– Disconnect electrical wiring
– Disconnect sensing tube
– Disconnect gas connection to gas valve
– Remove gas valve securing nut
– Disconnect burner connection
– Refit in reverse order ensuring seals
are replaced as required
– Recommission boiler
– Check for gas soundness.
5.12
Printed circuit board
– Isolate boiler from power supply
– Remove 2 screws securing control
panel
– Lower control panel to horizontal posi-
tion
– Remove PCB cover
– Disconnect all wiring to PCB
– Remove heat control knobs
– Remove PCB securing screws
– Transfer trimmer spindles to new PCB
– Ensure PCB links and switches on new
PCB are in correct positions
– Refit in reverse order
– Recommission boiler
5.13
Fan control board
– As PCB 5.12.
5.14
Pump (same procedure for
both pumps)
– Turn off power supply
– Isolate flow and return valves
– Remove boiler cover
– Remove 2 screws securing control
panel
– Lower control panel to horizontal posi-
tion
– Drain boiler (do not use pressure relief
valve)
– Prot ect wiring from any wat er los t
when removing pump
– Remove electrical connection to pump
– Re m o v e p u mp c o mp l e t e w i t h n o n
return valve and air separator
– Transfer non return valve and air sepa-
rator to new pump using new washers
as required
– Refit in reverse order
5.15
Top Auto air vent
– Turn off power supply
– Remove boiler cover
– Isolate gas supply
– Isolate flow and return valves
– Drain boiler using drain vent(do not use
pressure relief valve)
5
REPLACEMENT OF PARTS
