The low water pressure alarm protects the hydraulic circuit from operating with insufficient filling.
Possible causes
Leaks, incomplete filling, air in the system, or an incorrect sensor reading.
Expansion vessel
Incorrect pre-charge can cause large pressure fluctuations between a cold and hot system.
Sensor check
The reading is compared with a reliable pressure gauge.
Correct approach
Simple refilling should not be performed without checking the cause when the pressure drops repeatedly.