Cause of error code A20

False flame detected before ignition

- Unexpected flame signal detected before opening the gas valve.

Solution for error code A20

- Check for the presence of flame in the combustion chamber.
- Check igniter for a short to ground.
- Check flame sensor for a short to ground.
- If a flow switch is not connected to terminals #11 & #12, change to LWCO in User Menu under burner settings (managing burner).
- If a flow switch is connected, check for continuity across terminals #11 & #12 with the pumps off. Possible blocking of flow paddle due to dirt or debris in the system.
- If a flow switch is not connected to terminals #11 & #12, change to LWCO in User Menu under burner settings (managing burner).
- If a flow switch is connected, check for continuity across terminals #11 & #12 with the pumps on. Possible blocking of flow paddle due to dirt or debris in the system.