Checking The Diaphragm Expansion Vessel And System Pressure - Viessmann Vitocrossal 300 Service Instructions For Contractors

Commissioning, inspection, maintenance
Further details regarding the individual steps
3. If required, retighten the flue gas col-
lector seal A at the tensioning tog-
gles E or replace. Replace lip seal
D in case it leaks.
Note
Prior to removing the flue gas collec-
tor, pull the plug at flue gas tempera-
ture sensor F.
4. Check the fittings on the water side
for leaks and replace the seals/gas-
kets if required.
Danger
There is a risk of injury when
working on pressurised com-
ponents.
Only open the connections on
the heating water side after
the boiler has been de-pres-
surised.
Only drain the boiler with a
suction pump when the boiler
air vent valve is open.

Checking the diaphragm expansion vessel and system pressure

Note
Carry out this test on a cold system.
1. Drain the system or close the cap
valve at the diaphragm expansion
vessel to depressurise the system
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.
26
(cont.)
5. Check the boiler thermal insulation
for good fit and correct if required or
replace if it is damaged.
3. Top up your heating system with
water until the filling pressure of a
cooled system is 0.1 to 0.2 bar higher
than the pre-charge pressure of the
diaphragm expansion vessel.
Permiss. operating pressure: 3 bar
Min. operating pressure: 1 bar