This indicates the flow switch is not activated.
- Ensure boiler contains water and all valves are open.
- Check the boiler circulator and ensure it is in good operating condition (operating, wiring intact, etc.).
- Inspect the wiring to the flow switch for damage and repair as necessary.
- Disconnect one wire from the flow switch and test for continuity across the switch while flow is confirmed to be present.
- Remove flow switch and inspect switch paddle for proper operation.
