Parts4heating.com: Teledyne Laars E2105500 Diagnostic Board

Troubleshooting
The amber “Ready” light on the front panel indicates that the control system is energized. Upon a call for heat from the pool temperature control, the green “Heat” indicator on the front panel will light. The green “Pump” indicator on the front panel will light. Once the water flow switch makes, and if all of the safety interlocks are closed, the ignition module(s) will energize the blower(s) for a 15-second pre-purge, followed by a 20-second period to allow the ignitor(s) to heat. Energizing the blower pressurizes the air box (which supplies air to the burners) and closes the normally-open contact(s) of the airflow pressure switch(es). This allows the ignition module to proceed with the ignition sequence.