Viessmann CU3, Service Instructions Manual

Page: 7 / 56

7
Initial start−up, inspection and maintenance
Further details regarding the individual steps
(cont.)
Checking all safety equipment
Check the following settings:
High limit safety cut−out
max. 110
º
C
. .
Control thermostat max. 95
º
C
. . . . . . . . .
Check the control unit adjustments
and change them, if required.
Control unit installation and
service instructions
Filling heating system and checking ventilation air supply
1. Check that the ventilation air
supply is completely
unobstructed.
2. Check the inlet pressure of the
diaphragm expansion vessel when
the system is cold.
Please note:
If the charge pressure of the
diaphragm expansion vessel is
lower than the static system
pressure, top up with sufficient
nitrogen to raise the charge
pressure (0.1 to 0.2bar) higher
than the static system pressure.
The static pressure corresponds to
the static height.
3. Open any check valves that may
be fitted.
4. Top up your heating system with
water and vent until the filling
pressure is higher (0.1 to 0.2bar)
than the inlet pressure of the
diaphragm expansion vessel.
5. Mark this pressure on pressure
gauge
A
.
Permiss. operating pressure 3bar
. . . .
6. Return the check valves to their
operating position.
5692500GB