Viessmann VITODENS 200 WB2A, Installation & Servicing Instructions Manual

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9 Replacement of Parts
a)
Close the isolation valves between the boiler and the central heating system.
Attach a suitable hose to the drain point on the lower right hand side of the
boiler and drain the boiler.
b)
Gain access by following step 9.1(b).
c)
Isolate the DHW circuit closing the DHW inlet valve. Drain the DHW circuit by
opening any DHW tap below the level of the boiler.
d)
Refer to Figure 9/B. Remove the leads from the surface mounted comfort
sensor on the front of the heat exchanger.
e)
Remove the clip and the siphon (C). Remove the siphon pipe (D) from the heat
exchanger, together with the inlet ferrule
f)
Disconnect the gas inlet union from the gas valve, release the gas pipe union
above the pipe connection frame and remove the gas connection pipe together
with its rubber bulkhead seal.
g)
Pull forward and remove the thermal insulation from the plate heat exchanger.
h)
Release the four screws (G) and pull the plate heat exchanger (H) forward.
NOTE: There may be a small discharge of water hence precautions should be taken
i)
Replace the DHW heat exchanger using new gaskets with lubricant and
reassemble in reverse order.
j)
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. Open the DHW inlet valve. Check all connections for soundness,
and then disconnect the filling loop.
g)
Finally, ensure that the outer casing is secured in position and carry out an
ignition and control check.
9.16 DHW Heat Exchanger (Combi Only)
63