1. Check every water level gauge to confirm whether the water level rises really or not and check the load changes. 

2. Check whether the electric regulating valve of the water intake is opened wide or wrongly operated. If the electric valve is abnormal, it shall be changed to bypass valve for manual adjustment. 

3. If the water level rises due to the tripping of water pump or wrongly closing of the valves of water supply system, the causes shall be immediately found out, and the corresponding measures shall be taken to deal with as soon as possible. 

4.If the water level rises and exceeds the overflow water level, but the overflow device does not act, then the water level shall be manual controlled. If necessary, open the water draining valve to drain water and pay close attention to the water level of the deaerator. 

5. Check whether the water level of the deaerators in parallel is balance or not, if it is unbalanced, the causes of the imbalance shall be found out. 

6. If the water level rises to the limit, the monitor shall be notified to stop the deaerator.