Gas heat call, ignition and retry (direct spark)

What happens, in order

1. Thermostat W closes; control first confirms the pressure switch is open
2. Inducer starts on high speed for pre-purge
3. Pressure switches close; on the 802PA board the inducer then drops to low speed
4. After the 30 s pre-purge the gas valve opens and the spark igniter fires for the 8 s trial for ignition
5. Spark stays on for up to 7 s after the valve opens
6. Flame sensor must prove flame by rectification at the 8 s mark, for 1 s
7. Main blower starts about 20 s after burners light
8. If no flame at 8 s valve closes, igniter off, inducer stops (can take up to 20 s to spin down) and control checks that the pressure switch reopened
9. Control repeats pre-purge and trial; up to 4 attempts in total
10. After the 4th failed try the control goes into a 1 hour lockout (codes 10 and 11 alternate)
11. Call for heat ends valve closes, flame goes out, inducer runs a 10 s post-purge and pressure switch opens
12. Main blower keeps running until the heat off delay set on the board expires

Timings and thresholds

Codes you may see during this

10 11 12 13 14

Models

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