Viessmann Vitovalor 300-P Installation And Service Instructions For Contractors page 85

2-yearly maintenance of fuel cell module
Checking the diaphragm expansion vessel and system pressure
A
Fig. 80
Note
Carry out this test on a cold system.
The system must be shut down.
1. Drain the heating water buffer cylinder until pres-
sure gauge shows "0".
A
2. Check the pre-charge pressure of the diaphragm
expansion vessel. Set value: 0.9 bar (0.09 MPa).
Commissioning, inspection, maintenance
(cont.)
B
3. If the charge pressure of the diaphragm expansion
vessel is lower than this, recharge with nitrogen via
connection .
B
4. Top up with water. Observe the specifications for fill
and top-up water; see page 55.
Operating pressure: 1.0 bar (0.1 MPa).
85