Viessmann Vitodens 111-W, Installation And Service Instructions Manual

Page: 36 / 60

36
3. Tighten 4 screws
A
diagonally.
!
Please note
Tighten screws enough
to ensure the components do not suffer
damage and will function correctly.
4. Fit cables to fan motor
D
, gas train
E
and ignition
electrode
F
.
5. Reopen the gas supply and switch on the power
supply.
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 block the
diaphragm opening on the gas valve.
7. Push grommet
C
up again.
Checking the diaphragm expansion vessels and system pressure
B
A
Fig. 29
A
Test connector, heating water expansion vessel
B
Test connector, DHW expansion vessel (if instal-
led)
Diaphragm expansion vessel on the heating water
side
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.
1. Drain the system until the pressure gauge shows
"0".
2. If the pre-charge pressure of the diaphragm expan-
sion vessel is lower than the static system pres-
sure, top up with nitrogen until the pre-charge pres-
sure 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)
Diaphragm expansion vessel on the DHW side (if
installed)
See page 20.
Checking the safety valve function
Commissioning, inspection, maintenance
Installing the burner
(cont.)
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