Start-up, calibration and operation of the burner
5
5.9
Measuring the ionisation current
The burner is fitted with an ionisation system to check that a
flame is present. The minimum current for control box operation
is 6 µA.
The burner provides a much higher current, so controls are not
normally required.
However, if it is necessary to measure the ionisation current,
disconnect the plug-socket (2)(Fig. 35) on the ionisation probe
cable and insert a direct current microammeter (1)(Fig. 35) with
a base scale of 100 µA.
Carefully check the polarities!
1
2
5.10 Checking the air and gas pressure on the com-
bustion head
Gas pressure
+
_
D8715
Fig. 35
+
Air pressure
D8716
Fig. 36
5.11 Final checks (with burner operating)
Open the thermostat/pressure switch TL:
Open the thermostat/pressure switch TS:
the burner must stop
Rotate the maximum gas pressure switch knob to the mini-
mum end-of-scale position.
Rotate the air pressure switch knob to the maximum end-of-
scale position.
the burner must stop in lockout
Switch off the burner and disconnect the voltage.
Disconnect the minimum gas pressure switch connector.
the burner must not start
Disconnect the ionisation probe wire.
the burner must stop in lockout due to ignition failure
Make sure that the mechanical locking systems on the differ-
ent adjustment devices are fully tightened.
_
23
GB
6463