Troubleshooting - Buderus Logano G234X Installation And Maintenance Instructions Manual

8
Heating system inspection and maintenance
8.7

Troubleshooting

Required tools: wiring diagrams (
voltage testers 120 VAC and 24 VAC.
Steps for troubleshooting
1. Beginning of troubleshooting
2. Close the gas shut-off valve.
Set thermostat (control unit) to
heat requirement (vent damper
opens).
Switch on power.
3. Observe ignition sparks in gap
between electrode and sensor
through inspection hole.
4. Open the gas shut-off valve.
Ignition flame is burning.
5. Ignition spark stops as soon as
ignition flame burns.
6. Main burner ignites.
7. System operates until the heat
requirement ends.
8. Heat requirement ended, system
switches off, vent damper closes.
9. End of troubleshooting
42
page 61 and 62) and
Measures to remedy faulty function
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.
On models with vent damper check that it is functional and limit switch is present.
If necessary, replace vent damper.
Check igniter sensor cable, grounding, ceramic insulator of ignition electrode and ignition
gap, adjust if necessary.
Check spade connector of the igniter sensor cable contact for signs of scorching or
kinking.
Replace ignition control unit.
Check that all manually operated vent dampers are open; check that gas connections and
pressures are correct and that main orifices are not blocked.
Check electrical connection between ignition module and connection on the gas valve.
Use MV-MV/PV clamps to check 24 V AC at the automatic ignition. If the voltage is
correct replace gas fitting, otherwise replace automatic ignition.
Check ignition/monitoring cable and grounding for continuity.
Check the ignition and monitoring electrodes.
Check electrical connections between ignition/monitoring electrode and ignition module.
Check whether the ceramic insulator in the ignition electrode is broken.
Check that the ignition flame surrounds the electrode and burns steadily with a bluish
flame.
Adjust pilot flame.
If this does not correct the fault, replace the ignition module.
Use MV-MV/PV clamps to check 24 V AC closed circuit at the automatic ignition. If there
is no voltage, replace ignition control.
Check electrical connections between automatic ignition and the gas fitting. If OK
replace gas valve.
Check ignition/monitoring cable and grounding for continuity. Note: If the grounding is
weak or faulty, the system may switch off at random, even if the heating system operates
correctly when checked.
Check that the ignition flame surrounds the electrode and burns evenly with a bluish
flame. If OK replace electrode.
If everything is OK replace ignition module.
Check function of thermostat (control unit).
Disconnect 24-V connection to gas fitting.
If gas valve closes, check thermostat and connection line again.
If the gas valve does not close, replace gas valve.
Repeat procedure until heating system operates correctly.
Logano G234X - Technical specifications are subject to change without prior notice.