The most common reason for a low tank level is a coolant leak somewhere in the chiller loop. Even a small leak, over time, will lead to a significant drop in water/glycol level. Check connectors, hoses, and equipment served by the chiller for any signs of leaking water.
If the system was recently serviced or opened, air might have been purged and the level dropped subsequently. Pure water systems can also slowly lose water to evaporation (if vents are open to atmosphere), though in closed loops this is minimal.
It's less likely, but the water level switch itself could be giving a false alarm. However, one should always assume the level is actually low and visually confirm before suspecting the sensor.
If this is a new system or recently commissioned, it might not have been fully topped up. As air worked its way out of the piping, the level could have fallen enough to trigger the alarm.
Walk along all piping, pump connections, fittings, and the tank itself. Look for dripping water, puddles, or rust/scale trails that indicate water has been leaking. If you find an active leak, stop and plan to repair it – simply refilling the tank without fixing the leak will only be a temporary solution.
Once any leak is addressed (or if none found), add the appropriate coolant (water or water/glycol mix) into the tank until the level is between the recommended min and max marks. Use the same concentration of glycol as existing, if applicable. The alarm may clear automatically as the float rises. If not, you'll reset it after filling.
Acknowledge and reset the AL364 alarm on the control panel after the level is corrected. Usually this is done by pressing the alarm reset button. The alarm should clear if the level switch is now satisfied (closed). If it doesn't clear, double-check that the float switch is actually floating and functioning.
Turn the chiller/pump back on and observe. The pump should run smoothly without sucking air. Check the sight glass or any flow indicators for steady flow. Also monitor the tank level momentarily after restart – it might drop slightly as circulation resumes and air is purged, so top up again if needed.
If your system has manual air bleeders on the highest points, open them to release any trapped air. An air-bound chiller can give false level readings and cause poor cooling. Make sure the system is fully purged.
Do not run the chiller with a known leak long-term; apart from the mess, introducing air can cause corrosion and other issues. A professional can perform a pressure test on the system to find slow leaks or inspect components that may not be visibly leaking but losing water under operation.
