Unigas RG91, Manual

Page: 37 / 108

PART IV: MAINTENANCE
37
Replacing the ignition electrodes
To replace the ignition electrodes, proceed as follows:
1
remove the burner cover;
2 disconnect the electrodes cables;
3 remove the combustion head (see par. “Removing the combustion head”);
4 loose screw (B) that fasten the ignition electrodes;
5 remove the electrodes and replace them, referring to the values quoted on Fig. 5.
To guarantee a good ignition the measures (in mm) shown on the next pictures must be observed. Be sure to tight the screw on the
electrodes group before reassembling the combustion head.
Fig. 5
Checking the detection current
To check the detection signal follow the scheme in the picture below. If the signal is less than the value indicated, check the position of
the detection electrode or detector, the electrical contacts and, if necessary, replace the electrode or the detector.
Minimum detection signal: 3.5Vdc
Fig. 6 - Detection with detector QRI...
ATTENTION: avoid the ignition electrodes to get in touch with metallic parts (blast tube, head, etc.), otherwise the boiler’s
operation would be compromised. Check the electrodes position after any intervention on the combustion head.
TTENZIONE
A
9x: A = 5
5xx: A = 8 ÷ 10
9x-5xx: B = 3 ÷ 4