The outlet water temperature has exceeded the setting of the manual reset high limit.
- Adjust the set point of the manual reset limit to a higher setting up to a maximum of 210°F.
- Verify that the system is full of water and that all air has been properly purged from the system.
- Verify that the boiler is piped properly into the heating system.
- Check 120 vac to boiler pump motor on a call for heat. If voltage is not present, check wiring back to the main control board.
- If 120 vac is present on a call for heat and the boiler pump is not operating, replace the pump.
- If the system pump is a variable speed pump, ensure that the system flow is not less than the boiler flow.
- If operating on something other than an outlet sensor, check temperature setting of the main control board.
- Check resistance of water sensors. Replace sensor if necessary.
- Replace the main control board if necessary.
