HVACopediaNTI · Boiler · Standby/shutdown
Demand satisfied and shutdown
What happens, in order
- Thermostat or aquastat opens or the setpoint plus off hysteresis is reached
- Gas valve closes and flame goes out
- Combustion blower runs its post-purge
- Blower should then be idle; a blower running at high speed with the burner off points to a loose signal cable or missing 24 VAC at the control
- Before servicing wait for the post-purge to finish, then shut off gas and power
Codes you may see during this
Hold / Lockout 67
Applies to: Trinity Tft60, Tft85, Tft110, Tft155, Tft175, Tft200, Tft250, Tft300, Tft399
Models
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
- Failed ignition and lockout · Ignition
- 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
Related
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: NTI Tft60-399 Installation and Operation Instructions (rev. 2012-04-09), Sec. 8.0 Lighting, Sec. 10.0 Piping, Sec. 15.0 Troubleshooting. 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.