Operating instructions

46
Checking the flow limiter (only for combi boilers)
C
B
A
1. Switch OFF the control unit, shut off
the cold water line and drain the DHW
side of the boiler.
2.
Undo Allen screws A.
Note
Residual water may escape during
dismantling.
3.
Remove flow switch B and take out
flow limiter
C
downwards.
4.
Check flow limiter C; replace if
scaled or damaged, then re-insert.
Refit flow switch
B
.
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
volume (only
g
).
Check whether the installed diaphragm
expansion vessel is adequate for the
system water pressure (only
g
).
Carry out this test on a cold system.
1. Drain the system or close the cap
valve on the expansion vessel and
reduce the pressure until the pres-
sure gauge indicates "0".
2. If the pre-charge pressure in the
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.
Commissioning, inspection, maintenance
Further details regarding the individual steps
(cont.)
5772 909 GB