Heat-Up Preparations; Switching The Heating System On And Off; High Limit Safety Cut-Out - Viessmann VITOLIGNO 300-C Operating Instructions For The System User

Heat-up preparations

Fig. 8

Switching the heating system on and off

To switch the heating system on and off, press
"START/STOP" on the boiler.
Steps to take in the event of overheating
The high limit safety cut-out protects your boiler from
overheating.
Note
Modifications to this component are not permitted.
They will render all guarantee/warranties void.
Replace faulty components only with genuine spare
parts from Viessmann.

High limit safety cut-out

The reset button of the high limit safety cut-out is loca-
ted behind the boiler casing.
Triggering the function
If the boiler water temperature exceeds 100 °C the
high limit safety cut-out responds.
Note
The high limit safety cut-out can only be reset man-
ually.
1. Check the heating system pressure at pressure
gauge :
A
The system pressure is too low if the indicator
points to the area below the red field. Top up with
water or notify your local heating contractor.
Minimum system pressure: 1.0 bar (0.1 MPa)
2. Check that the vents in the installation room are
unrestricted.
Note
With open flue operation, the combustion air is
drawn from the installation room.
3. Verify that the heating system or the heating water
buffer cylinder is drawing off heat. Open the ther-
mostatic valves on the radiators if necessary.
4. Ensure that all heating flow and heating return
shut-off gate valves are open.
5. Check that all covers on the boiler are closed.
6. Ensure that power is supplied to the boiler.
Note
If the boiler overheats again after a short time or over-
heats regularly, notify your heating contractor.
Cancelling the function
Note
The high limit safety cut-out can only be reset
(unlocked) once the boiler water temperature has
reached approx. 70 °C.
After each triggering of the high limit safety cut-out,
check that the thermally activated safety valve is reset.
Start-up/shutdown
15