Viessmann VITOCAL 222-S Installation And Service Instructions Manual page 75

Further details regarding the individual steps
Commissioning, inspection, maintenance
(cont.)
3. Fill (flush) and vent the secondary cir-
cuit:
■ Slightly open the quick-action air
vent valve (see safety assembly,
chapter "Connecting the secon-
dary circuit"); it remains open.
■ Open the DHW heating air vent
valve (see following chapter); it
remains open.
■ To vent, move the 3-way diverter
valve for "Heating/DHW heating"
with the lever to its centre position
and click into place (see diagram).
!
4. Please note
To prevent equipment dam-
age, check the flow and return
connections of the secondary
circuit at the heat pump for
leak tightness.
In case of leaks, switch off the
appliance immediately, drain
the water and check the seat-
ing of the seal rings. Always
replace dislodged seal rings.
5. Check the system pressure and top
up with water if required.
Minimum system pressure: 0.8 bar
Permiss. operating pressure: 3 bar
75