Cause of error code A23

Flow sw not open.

- Boiler flow switch is not open with pump turned off.

Solution for error code A23

- 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.