Fireye NX6100 (Nexus) fault F30: Gas Proof of Closure fault
F30 means the proof-of-closure (POC) signal from the gas main valve 2 did not behave correctly: the controller could not confirm the valve was closed when it should be, or the signal did not change as the valve moved. The subset is the burner status at the fault.
Diagnose this with AI
Try Free Boiler Diagnostic Upload a keypad photo, the fault history or a parameter export from your Fireye NX6100 (Nexus). InduQT compares the evidence and suggests the next useful checks.
When it happens
- Before start-up, when valves must be proven closed
- At shutdown, when the valve should return closed
Reading the subset
| Subset | What it tells you |
|---|---|
| Burner status number | Where in the sequence the POC signal was wrong |
Where it sits in the burner
Supervised function: Valve proving and proof of closure.
| Component | Signals to look at | How it fails |
|---|---|---|
| Main safety shutoff valves | Main fuel valve output, Valve proof of closure | Valve seat leakage or slow closing; Fuel valve not opening fully; Welded, jumpered or miswired contact |
Likely causes and checks
1Valve not closing fully or slowly
- Points to it
- Fault at shutdown or just before start.
- Check
- Have the valve actuator and seat inspected; time the closing stroke.
2POC switch adjustment or wiring
- Points to it
- Valve closes but the signal does not change.
- Check
- Check the POC switch and its wiring to the controller input.
Telling it apart
- F30 is gas valve proof of closure; F31 is the oil valve equivalent. F42 is the gas leak test.
Evidence to collect
- Subset
- Valve and POC switch model
- Valve closing time
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.