Viessmann VITODENS 200 WB2A, Installation & Servicing Instructions Manual

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a)
Gain access by following step 9.1(b).
b)
Isolate the central circuit by closing the flow and return valves. Drain the
appliance using the drain point situated underneath the appliance at the bottom
right hand side.
c)
Slacken the two socket head screws clamping the bottom flange of the
expansion vessel.
d)
Remove the securing clip from the water connection between the flexible hose
from the expansion vessel to the flow pipe and disconnect.
In the unlikely event of failure of the expansion vessel diaphragm it is acceptable to leave the
vessel in position and to fit a replacement vessel (of similar or greater capacity) external to the
appliance but as close as possible to the central heating return connection.
If replacement is desired (or necessary due to a leaking vessel), proceed as follows.
a)
Isolate the central circuit by closing the flow and return valves. Drain the
appliance using the drain point situated underneath the appliance at the bottom
right hand side.
b)
Unscrew the automatic air vent situated at the top of the boiler behind the
flue connector.
c)
Replace the automatic air vent and reassemble in reverse order.
d)
Connect the filling loop, open the CH flow and return valves and re
pressurise the system to design pressure using the filling loop valves and
venting as necessary. Check all connections for soundness and then
disconnect the filling loop.
9 Replacement of Parts
9.22 Auto Air Vent
9.23 Expansion Vessel
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