Checking The Diaphragm Expansion Vessel And System Pressure; Checking The Safety Valve Function - Viessmann VITODENS 111-W Installation And Service Instructions Manual

Installing the burner
3. Tighten 4 screws
A diagonally.
!
Please note
Tighten screws just enough
to ensure the components do not suffer
damage and will function correctly.
4. Fit electrical cables to fan motor
and ignition electrode
5. Reopen the gas supply and switch ON the power
supply.

Checking the diaphragm expansion vessel and system pressure

Note
The diaphragm expansion vessel can lose some
charge pressure over time. When the boiler heats up,
the pressure gauge will indicate a higher pressure of 2
or 3 bar. The safety valve may also respond and dis-
charge the excess pressure.
Check whether the installed diaphragm expansion ves-
sel on the heating water side is adequate for the sys-
tem water volume.
Carry out this test on a cold system.
Fig. 28
Test connector, heating water expansion vessel
A
Test connector, DHW expansion vessel
B

Checking the safety valve function

(cont.)
, gas train
D E
.
F
B
A
Commissioning, inspection, maintenance
6. Check the gas connections for tightness.
Danger
Escaping gas leads to a risk of explosion.
Check the fitting for gas tightness.
!
Please note
The use of leak detection spray can result in
faulty operation.
Leak detection spray must not come into
contact with electrical contacts or seal the
diaphragm opening on the gas valve.
7. Push grommet
C up again.
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 until the pre-charge pressure
is 0.1 to 0.2 bar (10 to 20 kPa) higher.
3. Top up with water until the charge pressure of the
cooled system is at least 1.0 bar (0.1 MPa), and is
0.1 to 0.2 bar (10 to 20 kPa) higher than the pre-
charge pressure of the expansion vessel.
Permiss. operating pressure: 3 bar (0.3 MPa)
35