Display Screen is Blank

• A blank display screen on your Weil-McLain Ultra boiler may be indicative that the control is not receiving 120V of power. Check all power connections, breakers and fuses. This issue can also be caused when the communication between the U-control to the display is lost. Ensure there are no loose connections and that there is a correct pin alignment on the U-Control's plug P9 and on the rear of the circuit board.
  
  

Temperature is Rising Too Quickly

• The temperature in the Ultra boiler can rise too quickly when the water in the heat exchanger rises faster than 2 degrees F per second during the first two minutes of operation. Your display panel will warn you about this problem. Ideally, your unit will automatically reset after a one-minute delay. If it does not reset after five attempts, you will need to manually reset it. Your owner's manual will have instructions on how to do this. Always verify that the pipe size for the Ultra boiler loop is at least 2 inches.
  
  

Temperature Sensor Problems

• Your display panel will read "Temperature Sensor" if the sensor has electrically shorted or become disconnected. The Diagnostics-Temperature menu will tell you which sensors are "short" or "open." Decide which sensors are causing the problem and measure their resistance value. Your owner's manual will have instructions on how to do this. You may need to repair or replace the sensors. Once you are done, reset the sensor using the manual reset screen on the display panel.