Flow sw not closed.
- Boiler flow switch is not closed with pump turned on.
- 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.