Checking The Expansion Vessel And Heating Circuit Pressure; Cleaning The Interior - Viessmann VITOCAL 350-A Installation And Service Instructions Manual

Commissioning, inspection, maintenance
Filling and venting on the secondary side
3. Fill the secondary circuit via the on-site BDF valve
(flush) and vent the circuit.
4. Check the system pressure at the pressure gauge.
Top up with water if required.
Minimum system pressure: 0.8 bar (80 kPa)
Permiss. operating pressure: 3 bar (0.3 MPa)
!
5. Please note
Leaking hydraulic connections lead to appli-
ance damage.
■ Check the internal and on-site hydraulic
connections for leaks.
In the event of leaks, switch OFF the appli-
■
ance immediately. Drain off liquid via the
drain valve. Check the seating of seal
rings. Always replace displaced seal
rings.

Checking the expansion vessel and heating circuit pressure

Carry out this test on a cold system.
Note
Only use anti-corrosion agents that have been
approved for heat pumps with DHW heating via single-
walled heat exchangers (DHW cylinders).
1. If an on-site shut-off valve is installed, close it.
Otherwise drain the heating system on the heating
water side 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 sufficient nitrogen to raise the pre-charge
pressure of the expansion vessel by 0.1 to 0.2 bar
(10 to 20 kPa) higher than the static system pres-
sure.
Example:
Static head (distance between the heat source and
the highest heating surface) 10 m
Equivalent to a static pressure of 1 bar (0.1 MPa).

Cleaning the interior

!
Please note
Deposits from cleaning agents or chemicals in
the interior can cause appliance damage.
Only clean the interior with clean water; maxi-
mum temperature 50 °C.
76
(cont.)
6. Close drain & fill valve.
7. Connect on-site hose to manual air vent valve
and open the valve.
8. Close manual air vent valve
been completed.
9. Check the system pressure. Top up with water if
required.
3. Top up with water until the filling pressure exceeds
the pre-charge pressure of the expansion vessel.
On a cold system, the charge pressure must be
approx. 0.2 bar (20 kPa) higher than the static
pressure.
4. During commissioning, mark this value on the
pressure gauge as minimum charge pressure.
B
after venting has
B