85
A
B
C
Fig. 78
Note
Carry out this test on a cold system.
The system must be shut down.
The top panel can be removed for easier access. See
page 52.
1.
Drain the system separation circuit at valve
A
until
pressure gauge
B
indicates "0".
2.
Check the pre-charge pressure of the diaphragm
expansion vessel once a year. Set value: 1.0 bar
(0.1 MPa).
3.
If the pre-charge pressure of the diaphragm expan-
sion vessel is lower than this, recharge with nitro-
gen via connection
C
.
4.
Top up with water. Observe the specifications for fill
and top-up water; see page 62.
Operating pressure: 1.5 to 1.6 bar
(0.15 - 0.16 MPa).
Note
If the diaphragm expansion vessel is being replaced:
Only use the gasket supplied with the spare part.
Checking the external diaphragm expansion vessel (heating circuits) and
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.
Check whether the installed expansion vessel is ade-
quate for the system water volume.
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".
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 pressure is 0.6 to
0.7 bar (60 to 70 kPa) higher than the static system
pressure.
3.
Top up with water until the charge pressure of the
cooled system is at least 1.7 bar (0.17 MPa), and
is 0.6 to 0.7 bar (60 to 70 kPa) higher than the pre-
charge pressure of the expansion vessel.
Permiss. operating pressure: 3 bar (0.3 MPa)
Checking the safety valve function
Commissioning, inspection, maintenance
Checking the diaphragm expansion vessel and pressure in the system
separation circuit
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