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 opera-
tion 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, dis-
connect 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
+
_
D8697
6461
D8696
Fig. 35
+
_
Air pressure
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.
24
GB