Checking The Diaphragm Expansion Vessel And Pressure In The System Separation Circuit; Check The External Diaphragm Expansion Vessel (Heating Circuits) And The System Pressure - Viessmann Vitovalor PA2 Installation And Service Instructions For Contractors

Commissioning, inspection, maintenance
Checking the diaphragm expansion vessel and pressure in the system
separation circuit
Fig. 43
Note
■ Carry out this test on a cold system.
■ The system must be shut down.
1. Remove the top front panel and the programming
unit mounting bracket: See page 25 and page 38.
2. Undo the screw cap on drain valve
the drain hose to the drain outlet.
3. Open the drain valve by turning the top of fitting
anti-clockwise.
4. Drain the system separation circuit until pressure
gauge indicates "0".
C
Check the external diaphragm expansion vessel (heating circuits) and the
system pressure
Note
The expansion vessel can lose some of its charge
pressure over time. When the boiler heats up, the
pressure gauge indicator may rise to 2 or 3 bar (0.2 or
0.3 MPa). The safety valve may also respond and dis-
charge the excess pressure.
Therefore check the expansion vessel pre-charge
pressure annually.
54
D
5. Check the pre-charge pressure of the diaphragm
expansion vessel once a year. Set value: 0.6 bar
(0.06 MPa).
6. If the pre-charge pressure of the diaphragm expan-
sion vessel is lower than this, recharge with nitro-
gen via connection
A and connect
7. Filling the system separation circuit: See page 43.
Note
B
If the diaphragm expansion vessel is being replaced:
■
Only use the gasket supplied with the spare part.
■ Replacing the diaphragm expansion vessel: See
page 81.
Check whether the installed expansion vessel is ade-
quate for the system water volume.
C
B
A
D .