The fan is not running at the speed determined by the control. Fan speed has been more than 30% faster or slower than the commanded speed for more than 10 seconds. This is a serious safety issue as indicated by the illuminated red light and the word LOCKOUT flashing on the display. This boiler will not restart until a technician determines and repairs the cause and pushes RESET on the display. During this lockout fault, the pump will be on.
- Check the combustion fan wiring.
- Measure DC voltage from the red fan wire to ground while it is connected to the fan. It should be between 24 and 40 volts. If it is lower than 24 volts, check for excessive external loads connected to the boiler sensor terminals
- Disconnect the 5 pin plug from the fan and check the voltage on the red wire again. If it is now between 24-40 volts, replace the fan. If it is still below 24 volts replace the boiler control board.
