Return (inlet) temperature sensor exceeds 230ºF.
- Check circulation pump operation.
- Assure there is adequate flow through the boiler by accessing the status menu and assuring that there is less than a 50ºF rise from the return thermistor to the supply thermistor.
- Check direction of flow on boiler circulator (see PIPING DETAILS in this manual).
- Troubleshoot thermistor by following steps in F02.
