Call for heat, Control performs safe-start check. If safe-start fails, control locks out.
 If the air proving switch is open, the motor will start.
Once the air proving switch closes, pre-purge will begin (lasting 30 seconds). Pre-purge or ignition timings will not start until the air proving switch closes.
When pre-purge is completed, the control turns on the igniter and the gas valve. MV LED will turn on. Spark continues until end of ignition timing or until flame is proved.
Once flame is proved, The Flame LED is turned on and the spark is turned off. The gas valve and MV LED remain energized.
When the call for heat is ended, the gas valve, MV LED, Flame LED, Status LED and motor turn off.
Quick Status Check Quick Reference
7590D Configuration for CG4 Burner
Note: Pre-purge or Ignition timing will not start until pressure switch goes from open to closed.