HVACopediaNTI · Boiler · Ignition
Failed ignition and lockout
What happens, in order
- Burner fails to light.
- Control runs ignition trials. Trials after the first are not immediate.
- Blower runs after each failed trial to purge the system.
- If the burner lights on any trial, normal operation resumes.
- If the burner does not light after the fifth trial, the control locks out.
- Lockout indicates a problem with the boiler, controls or gas supply. Call a service technician.
- If RESET is not pressed, the boiler resets automatically after one hour (codes 501 and 503).
Timings and thresholds
| Item | Value |
|---|---|
| Blower purge after a failed ignition trial | about 5 seconds |
| Ignition trials before lockout | five in total (four more after the first) |
| Automatic reset after lockout if RESET is not pressed | one hour |
Codes you may see during this
501 503
Applies to: TRX150
More NTI boiler sequences
- Combustion checking procedure · Startup
- Power-on and mode sequence · Startup
- Power-up and what lets the boiler start a call · Startup
- First ignition start-up · Ignition
- Light-off sequence and retries · Ignition
- Central heat call (CH1) from call to satisfied · Heating
- Indirect tank (DHW) call · Domestic hot water
- Circulator outputs and their fuses · Pump/purge
Related
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Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: NTI TRX150 manual, p. 97. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.