Checking The Diaphragm Expansion Vessel And System Pressure; Checking The Connections On The Heating Water And The Dhw Side - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Commissioning, inspection, maintenance
Further details regarding the individual steps
6. Check gas connections for tight-
ness.
Danger
Escaping gas leads to a risk of
explosion.
Check the fitting for gas tight-
ness.

Checking the diaphragm expansion vessel and system pressure

Note
The expansion vessel can lose some of
its charge pressure after some time in
use. When the boiler heats up, the pres-
sure gauge will indicate a higher pres-
sure of 2 or 3 bar (0.2 or 0.3 MPa). The
safety valve can respond and discharge
excess pressure.
For this reason, check the expansion
vessel pre-charge pressure annually.
Check whether the installed expansion
vessel is adequate for the system water
volume (GB only).
Carry out this test on a cold system.
1. Drain the system until the pressure
gauge shows "0".
Alternatively, close the cap valve on
the expansion vessel and reduce the
pressure until the pressure gauge
indicates "0".
Checking the connections on the heating water and the DHW
side
Check all connections and lines on the
heating water and DHW side (including
inside the appliance) for tightness and
possible damage.
58
(cont.)
!
Please note
The use of leak detection
spray can result in faulty oper-
ation.
Leak detection spray must not
come into contact with electri-
cal contacts or seal the dia-
phragm opening on the gas
valve.
2. If the pre-charge pressure of the
expansion vessel is lower than the
static system pressure, top up with
nitrogen until the pre-charge pres-
sure is 0.1 to 0.2 bar (10 to 20 kPa)
higher than the static system pres-
sure.
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 expan-
sion vessel.
Permiss. operating pressure: 3 bar
(0.3 MPa)