Checking The Expansion Vessel And System Pressure - Viessmann Vitodens 222-F B2TA Installation And Service Instructions Manual

Further details regarding the individual steps

Checking the expansion vessel and system pressure

A
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 (0.2 or 0.3 MPa).
The safety valve too can respond and
discharge excess volume (only
Commissioning, inspection, maintenance
Check whether the installed diaphragm
expansion vessel is adequate for the
system water pressure (only g).
Note
Carry out this test on a cold system.
1. Drain the system until the pressure
gauge shows "0".
2. If the diaphragm expansion vessel
pre-charge pressure is lower than the
static system pressure: Top up with
nitrogen at connection A until the
pre-charge pressure is 0.1 to 0.2 bar
(10 to 20 kPa) higher than the static
system pressure.
3. Top up with water until the charge
pressure of the cooled system is 0.1
to 0.2 bar (10 to 20 kPa) higher than
the pre-charge pressure of the dia-
phragm expansion vessel.
Permiss. operating pressure: 3 bar
(300 kPa).
g ).
(cont.)
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