EL296UHV: normal gas heat sequence (what should happen after a call for heat)

What is going on

Use this to see where a stuck furnace is stopping. Times are from the manual for this series.

Check in this order

1. Thermostat calls for heat. The control first checks that both pressure switches are open. If the low one is already closed, it will not start.
2. Combustion air inducer starts on low speed.
3. Low pressure switch closes, then a 15 second pre-purge runs.
4. If the low switch does not close in cold or low voltage conditions, the inducer goes to high speed, runs 10 to 20 seconds, then drops back to low.
5. Ignitor warms up for 20 seconds.
6. The gas valve opens and a 4 second light-off attempt begins. The ignitor stays powered until flame is proven.
7. No flame the control tries again up to four more times with a 35 second purge and warm-up in between (five tries total).
8. After five failed tries the control locks out (flame failure watchguard) and tries again after 60 minutes.
9. Blower starts 30 seconds after the burners light (fixed). It stops after the heat blower-off delay set on DIP switches 3 and 4 (default 90 seconds).
10. With a single-stage thermostat the furnace lights on low and moves to high after the SW2 delay (7 or 12 minutes). If both stages are called together it lights on low and moves to high after 30 seconds.

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