Power-up and what lets the boiler start a call

What happens, in order

1. Power is switched on at the breaker and the switch on the front of the boiler
2. Display opens on the Summary page showing demand source, burner state, sensors and pumps; any active alert or lockout is shown
3. Control looks for a call CH1 (24 VAC from R through a dry contact), CH2 lead-lag input, or DHW (contact closed between terminals 6 and 9)
4. 24 VAC from R must reach LIM (factory jumper) and the rest of the ILK string including the internal low water cutoff must be closed, otherwise the burner stays off and Lockout 67 ILK OFF is shown
5. Burner switch must be on in the controller; if it is off the Summary page says burner switch off
6. Burner will not start while an anti short-cycle hold (Hold 61) is counting or while safety settings are waiting for verification (Lockout 2)
7. Burner will not start while outlet temperature is above setpoint minus on-hysteresis
8. If all of that is satisfied the control goes to the ignition sequence

Timings and thresholds

Codes you may see during this

Hold 61, Hold / Lockout 67, Lockout 2

Models

More NTI boiler sequences

• Combustion checking procedure · Startup
• Power-on and mode sequence · 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
• Circulator outputs and their fuses · Pump/purge