20 Auto Air Vent
Remove the complete pump assembly as described in Section
16.18. Take care not to strain the electrical connections.
Pull out the clip securing the auto air vent cartridge. Refer to Fig 52.
Do not omit the O-ring when fitting the new cartridge.
Refit the pump assembly as described in Section 16.18 preceding.
21 Primary Heat Exchanger
Check that the appliance has been fully drained.
Remove the temperature sensors as described in 15.15, 16 and
17 preceding.
Remove the combustion chamber cover, fan and flue hood and
burner as described in Section 15.3, Inspection and Servicing.
Remove the combustion chamber insulation side panels.
Prise off the fixing clips securing the copper pipes.
Remove the heat exchanger.
Do not omit the O-rings when fitting the replacement heat
exchanger. Refer to Fig. 61.
Check that the rear seal for the flue hood is in good condition
and secure before replacing the flue hood.
22 Air pressure switch
Pull-off the silicone sensing tubes.
Unscrew the fixing bracket and remove the pressure switch. See
Fig 62.
Unscrew and remove the fixing clip and fit to the new air pres-
sure switch ensuring that the orientation of the switch to the air
connections is the same.
Refit the switch assembly.
Remove the electrical connections from the old switch and fit to
the new switch in the same position.
Refit the silicone sensing tubes - the red tube fixes to the rear of
the switch.
23 Sight Glass
Remove and replace the inner casing cover complete.
Inspection and Servicing. Refer to Section 15.
30
Fig. 61. Primary heat exchanger
1
2
3
1. Heat exchanger
4. Overheat thermostat
2. O-ring (4)
5. Central heating flow and return
3. Fixing clip (4)
6. Domestic hot water inlet and outlet
Fig. 62. Air pressure switch
1
2
3
4
5
1. Air pressure switch
2. Tube connectors
3. Electrical connections
4. Air pressure switch fixing bracket
5. Fixing screw
OPAQUE
RED
6
4
5