Logano G334X Installation And Service Instructions Manual - page 33
9
Boiler inspection and maintenance
Logano G334X – 6 720 811 237 (2014/05)
33
9.7
Troubleshooting the G334X
Required material:
• Circuit diagrams (
page 36)
• Voltmeter 120 VAC and 24 VAC
Fig. 46 Troubleshooting the G334X
Start
Close gas valve. Set thermostat
(control) to require heat (flue
baffle open).
Switch on power.
Observe ignition sparks in gap
between electrode and sensor
through sight glass.
•
Check electrical power supply, low-voltage transformer, thermostat
(control) and wiring. Check that the vent damper (if installed) is open and
the limit switch is present.
No
No
No
Open main gas valve. Pilot flame
is burning.
•
Check that all manually operated dampers are open; check that gas
connections and pressures are correct and that ignition gas orifice are not
blocked.
•
Check electrical connection between automatic ignition and ignition timer
on the gas valve.
•
Use MV-MV/PV terminals to check 24 V alternating current at the
automatic ignition. If the voltage is correct replace gas valve, otherwise
replace automatic ignition module.
No
System operates until the heat
requirement ends.
•
Check ignition wiring and ground for continuity. Note: If the ground is
weak or faulty, the system may switch off at random, even if the heating
system operates correctly when checked.
•
Check that the pilot flame surrounds the electrode and burns evenly with
a bluish flame. If OK replace electrode.
•
If everything is OK replace automatic ignition module.
No
Heat requirement ended, system
switches off, vent damper
closes.
End of troubleshooting
Repeat procedure until heating system operates correctly.
•
On models with vent damper check that it operates and lmit switches are
present. If necessary, replace vent damper.
•
Check ignition wiring, ceramic insulator of ignition electrode and ignition
gap, adjust if necessary.
•
Check the ignition cable contact for signs of scorching or kinking.
•
Replace automatic ignition unit.
No
Ignition spark stops as soon as
pilot flame burns.
•
Check ignition wiring and ground for continuity.
•
Check ignition electrode.
•
Check electrical connections between ignition electrode and automatic
ignition.
•
Check whether the ceramic insulator in the ignition electrode is broken.
•
Check that the pilot flame surrounds the electrode and burns steadily with
a bluish flame.
•
Adjust pilot flame.
•
If this does not correct the fault, replace the automatic ignition unit
module.
No
Main burner ignites.
•
Use MV-MV/PV terminals to check 24 V alternating current, closed
current circuit at the automatic ignition. If there is no voltage, replace
automatic ignition.
•
Check electrical connection between automatic ignition module and gas
valve. If OK, replace gas valve.
•
Check operation of thermostat (control).
•
Disconnect 24-V connection to gas valve. If gas valve closes, check
thermostat and connection line again.
•
If the gas valve does not close, replace gas valve.