18
6.7
BOTTOM AUTOMATIC AIR RELEASE VALVES
(fig. 21)
Carry out component removal procedure as de-
scribed in 6.4. Remove the expansion pipe locking
pin
(
D
)
from the pump assembly and remove the
expansion pipe. Locate and remove the AAV lock-
ing pin (
G
) from the pump assembly and remove the
AAV assembly (
H
). Replace in the reverse order.
6.7.1
TOP AAV (fig. 22)
Carry out component removal procedure as de-
scribed in 6.4.
Remove the drain pipe
(A)
. Unscrew the top AAV.
Replace in the reverse order. Loctite or similar
should be used as a thread sealant for the AAV.
6.8
WATER PRESSURE SENSOR/GAUGE (fig. 23)
Carry out component removal procedure as de-
scribed in 6.4. Locate and remove the locking pin
(
C
) from the water pressure sensor/gauge assem-
bly. Remove the wiring. Carefully withdraw the
assembly. Replace in the reverse order.
6.9
PRIMARY THERMISTOR (fig. 1)
Carry out component removal procedure as de-
scribed in 6.4. Unclip and remove the air chamber
front cover. Unclip the primary thermistor from the
flow outlet pipe. Disconnect thermistor electrical
plug. Replace in the reverse order.
6.10
RETURN THERMISTOR (fig. 1)
Carry out component removal procedure as de-
scribed in 6.4. Unclip and remove the air chamber
front cover. Unclip the return thermistor from the
return inlet pipe. Disconnect thermistor electrical
plug. Replace in the reverse order.
6.11
PRINTED CIRCUIT BOARD (fig. 24)
Carry out component removal procedure as de-
scribed in 6.4. Lift the control fascia upward and rotate
it. Locate and remove the screws (
A
) which secure the
PCB cover, push the clips (
B
) and remove cover, after
carefully taking note of all wiring connections, discon-
nect all wiring from the PCB, locate and remove the
PCB securing screws, remove the required PCB.
Replace in the reverse order.
6.12
GAS VALVE (fig. 25)
Carry out component removal procedure as de-
scribed in 6.4. The gas valve must be changed as
complete unit. Disconnect the electrical plug and
leads from the gas valve, slacken and unscrew
gas valve inlet and outlet connections.
Please
note,
the sealing washers (
B
) must be discarded
and replaced with new sealing washers. Discon-
nect the compensation pipe (
C
). Locate and re-
move gas valve retaining screws (
D
) on the under-
side of the boiler if required, the gas valve can now
be removed. Replace in the reverse order. Check
and adjust burner pressure settings.
WARNING, A GAS SOUNDNESS CHECK MUST
BE CARRIED OUT.
6.12.1 INJECTOR (fig. 25)
Carry out component removal procedure as de-
scribed in 6.4. Unscrew and remove gas pipe
connections (
A & E
). Locate and remove the
injector (
F
) inside the pipe. Replace in the reverse
order. Check and adjust burner pressure settings.
WARNING, A GAS SOUNDNESS CHECK MUST
BE CARRIED OUT.
6.13
ELECTRODE & CONDENSE SENSOR (fig. 26)
Carry out component removal procedure as de-
scribed in 6.4.
Unclip and remove the air chamber front and RH
side covers. Disconnect the electrode lead and
ancillary wiring from their respective connectors.
Remove the 2 retaining screws (
A
) for electrode
(
B
) and remove. Remove the retaining nut (
C
) for
condense sensor (
D
) and remove.
Fig. 24
A
B
Fig. 22
A
Fig. 23
C
A
B
Fig. 25
D
A
F
E
C
B
B