
S
E
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VICI
NG
& S
PA
R
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S
INSTALLATION & SERVICING INSTRUCTIONS
34
INSPECTION & SERVICE
6-720-611-730b (12.05)
INSPECTION & SERVICE
Checking the ionisation current:
Select service function
3.3
(use the service
function procedure as described in Service
Function).
If the display shows
2
or
3
, the ionisation current
is OK.
If the display shows
0
or
1
, the electrode
assembly (A) must be cleaned or replaced:
1
Pull off the leads from the electrodes.
Unscrew the two fixing screws and carefully
remove the electrode assembly (A).
Clean the electrodes with a non-metallic
brush. (The spark gap should be 4.5mm
±0.5mm).
Replace and re-connect the assembly taking
care not to mislay the inspection window.
Primary Heat Exchanger:
There is a special accessory kit available (No. 840)
specifically designed for cleaning the heat
exchanger. If required order 7 719 001 996.
2 Check control pressure on the air-gas mixer
unit at max. rated heat output using an electronic
manometer. See 'Setting the gas/air ratio'.
The heat exchanger should only be cleaned if
the pressure is -2.2mbar or less.
3 Remove the cleaning access cover (B), seal
(C) and metal plate (D) securing it, if present.
4 Unscrew the condensation trap and place a
suitable container underneath.
To Remove Condensate trap:
Remove access panel (E) at the base of the
inner casing.
Remove screw (F) retaining bracket, rotate
and push trap downwards until clear.
Remove trap from boiler and disengage pipe
to condensate pump (G).
Clean trap and check that that the connection
to the heat exchanger is clear.
After servicing the heat exchanger, fill the
condensate trap with approximately 1/4 litre of
water and refit in reverse order.
To Clean the Heat Exchanger:
5 A Loosen any deposits in the heat exchanger
from top to bottom using the cleaning blade.
Clean the heat exchanger from top to bottom
using the brush.
Refit the clean out coverplates in reverse order
using a new seal (C) and tighten screws to a
torque of approximately 5 Nm.
A
B C
D
1
2
3
E
5
1, 2, 3
G
4
E
F