Viessmann VITODENS 200 WB2A, Installation & Servicing Instructions Manual

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a)
Gain access to the relevant components by following steps (b) and (c) in
section 9.1.
b)
Pull the electrical cable connector from the gas valve (C).
c)
Disconnect the gas inlet union from the gas valve.
d)
Disconnect the plastic pressure sensing pipes leading to the pressure switch
from the gas valve.
e)
Release the three Torx screws securing the gas valve to the venturi assembly
and remove the gas valve taking care not to lose the gas restrictor.
f)
Replace the gas valve in reverse order taking care to replace gaskets, restrictors
and ensuring that the pipes to the pressure switch are not interchanged.
g)
Finally, ensure that the outer casing is secured in position and carry out a
combustion check as in 5.6.
a)
Gain access by removing the burner assembly as described in section 9.1,
steps (b) to (g).
b)
Remove the detection electrode by releasing the 5mm socket head screw and
withdrawing the electrode.
c)
Fit a new electrode assembly using a new gasket and check all clearances. If
the gaps are not as specified align the electrode. Tighten the electrode fixing
screw preferably to a torque of 2.5Nm.
d)
Check the combustion chamber gasket for any damage and reassemble in
reverse order.
e)
Finally, ensure that the outer casing is secured in position and carry out a
combustion check as in 5.6.
9.5 Detection Electrode
9.6 Gas Control
9 Replacement of Parts
56