13
Pump-controlled pressure maintaining
systems with atmospheric degassing
through cyclical pressure release create
a central post-venting of the heating
system. However, this does not
represent oxygen removal in the sense
of corrosion protection according to VDI
2035 sheet 2.
Note
Carry out all checks in accordance with
manufacturer's instructions.
!
Please note
Cyclical pressure fluctuations
and more significant pressure
differentials point towards a
system fault. Such faults will
result in damage to other heating
system components.
Limit pressure fluctuations to the
lowest possible differential.
Diaphragm expansion vessel
1. Drain the system or close the cap
valve on the diaphragm expansion
vessel and reduce the pressure, until
the pressure gauge indicates "0".
Note
The pre-charge pressure of the
diaphragm expansion vessel (p
0
)
comprises the static system pressure
(p
St
) (= static head) and a supplement
(p
0
= p
St
+ supplement).
The supplement is subject to the
adjustment of the high limit safety cut-
out. For a high limit safety cut-out set
to
■ 100 °C: 0.2 bar
■ 110 °C: 0.7 bar.
2. If the pre-charge pressure of the
diaphragm expansion vessel is lower
than the static system pressure, top
up with sufficient nitrogen to raise the
pre-charge pressure higher (0.1 to
0.2 bar) than the static system
pressure.
The static pressure corresponds to
the static head.
3. Top up the heating system until the
filling pressure of the cool system is
higher (0.1 to 0.2 bar) than the pre-
charge pressure of the diaphragm
expansion vessel.
Permiss. operating pressure: 6 bar.
Commissioning, inspection, maintenance
Further details regarding the individual steps
(cont.)
5692 798
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