Checking The Flow Limiter (Only For Combi Boilers); Checking The Expansion Vessel And System Pressure - Viessmann VITODENS 200-W Installation And Service Instructions Manual

Commissioning, inspection, maintenance
Further details regarding the individual steps

Checking the flow limiter (only for combi boilers)

Checking the expansion vessel and system pressure

Note
The diaphragm expansion vessel can
lose some charge pressure over a time
in use. When the boiler heats up, the
pressure gauge will indicate a higher
pressure of 2 or 3 bar. The safety valve
too can respond and discharge excess
g ).
volume (only
Check whether the installed diaphragm
expansion vessel is adequate for the
system water pressure (only g).
Carry out this test on a cold system.
46
1. Switch OFF the control unit, shut off
2. Undo Allen screws A.
3. Remove flow switch B and take out
4. Check flow limiter C; replace if
C
B
A
1. Drain the system or close the cap
2. If the pre-charge pressure in the
(cont.)
the cold water line and drain the DHW
side of the boiler.
Note
Residual water may escape during
dismantling.
flow limiter C downwards.
scaled or damaged, then re-insert.
Refit flow switch B.
valve on the expansion vessel and
reduce the pressure until the pres-
sure gauge indicates "0".
expansion vessel is lower than the
static system pressure, top up with
sufficient nitrogen to raise the pre-
charge pressure 0.1 to 0.2 bar higher
than the static system pressure.