VITODENS 200 WB2A - Heatingspares247.com

9 Replacement of Parts9.22 Auto Air Venta) Isolate the central circuit by closing the flow and return valves. Drain theappliance using the drain point situated underneath the appliance at the bottomright hand side.b) Unscrew the automatic air vent situated at the top of the boiler behind theflue 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 repressurise the system to design pressure using the filling loop valves andventing as necessary. Check all connections for soundness and thendisconnect the filling loop.9.23 Expansion VesselIn the unlikely event of failure of the expansion vessel diaphragm it is acceptable to leave thevessel in position and to fit a replacement vessel (of similar or greater capacity) external to theappliance 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) Gain access by following step 9.1(b).b) Isolate the central circuit by closing the flow and return valves. Drain theappliance using the drain point situated underneath the appliance at the bottomright hand side.c) Slacken the two socket head screws clamping the bottom flange of theexpansion vessel.d) Remove the securing clip from the water connection between the flexible hosefrom the expansion vessel to the flow pipe and disconnect.68