Checking The Diaphragm Expansion Vessel And System Pressure; Pressure - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Further details regarding the individual steps
6. Check the gas connections for tight-
ness.
Danger
Escaping gas leads to a risk of
explosion.
Check all fittings for gas tight-
ness.

Checking the diaphragm expansion vessel and system pressure

Note
The diaphragm expansion vessel can
lose some charge pressure over a time
in use. When the boiler heats up, the
pressure gauge will indicate a higher
pressure of 2 or 3 bar. The safety valve
too can respond and discharge excess

pressure.

Check whether the installed diaphragm
expansion vessel is adequate for the
system water volume.
Carry out this test on a cold system.
1. Drain the system or close the cap
valve on the diaphragm expansion
vessel and reduce the pressure until
the pressure gauge indicates "0".
2. If the pre-charge pressure of the dia-
phragm expansion vessel is lower
than the static system pressure, top
up with nitrogen until the pre-charge
pressure is raised by 0.1 to 0.2 bar.
Commissioning, inspection, maintenance
(cont.)
!
Please note
The use of leak detection
spray can result in incorrect
functions.
Leak detection spray must not
reach electrical contacts or
seal diaphragm openings on
the gas valve.
3. Top up with water until the charge
pressure of the cooled system is at
least 1.0 bar and 0.1 to 0.2 bar higher
than the pre-charge pressure of the
diaphragm expansion vessel.
Permiss. operating pressure: 3 bar
Note
Using key A supplied, the gas combi
boiler can be recharged at the fill valve.
A
33