Evaporative Condenser Water Level Control Guide
Evaporative condenser water level control is the system that keeps the recirculating spray water basin within its operating range: filling it as water evaporates, alarming when the level leaves that range and, when specified, reporting status to the building automation system. The basin needs a dependable operating level whenever the equipment is running.
Too little water can create problems for the spray pump. Too much water can waste makeup water or cause overflow. A good level control specification addresses normal filling, alarm conditions and the information that operators need remotely.
Establish the Normal Basin Level
Begin with the evaporative condenser manufacturer’s approved operating water level.
Do not choose the fill stop point from the height of the overflow connection alone.
EVAPCO operation and maintenance literature states that the overflow sits above the normal operating level, and it lists different operating levels for different equipment lines.
The approved equipment drawings and manufacturer’s instructions should determine the final setpoints.
Replace Mechanical Makeup Control When Appropriate
Mechanical float valves remain common in evaporative equipment, but electronic control is also widely available.
EVAPCO states that a mechanical float valve assembly is standard equipment unless the unit is ordered with an optional electronic water level control package or arranged for a remote sump.
Waterline Controls manufactures cooling tower and evaporative condenser level controls for cooling towers, remote sumps, evaporative condensers and closed circuit fluid coolers.
Electronic level controls are an option for new projects and replacement work where electronic alarms and remote signaling are useful.
Add High and Low Level Alarms
The fill start and fill stop points define the normal operating band.
Alarm points should sit outside that band.
A high alarm can identify uncontrolled filling or another condition causing the basin to rise. A low alarm provides warning if water continues falling after the fill system should already have responded.
The WLC-5000 fill controller provides automatic fill with high and low alarms, using separate probes for fill start, fill stop, high alarm and low alarm.
Connect Useful Information to the BMS
Facility operators should not have to visit the condenser to discover that the water level is abnormal.
Dry contacts can report fill activity, high level, low level and controller power loss, depending on the selected Waterline Controls model.
The BMS point list should state exactly what each contact represents and whether the point is a normal status or an alarm.
This makes troubleshooting easier when a problem occurs overnight or during peak refrigeration demand. For a full point list, see which BMS points a water level controller should report.
Consider Winter Operation
Evaporative condensers operating in cold climates may also require basin heaters and low water protection.
BAC offers basin heater controls that supervise both water temperature and water level, including low water cutoff protection. On the level control side, the WLC-6100T controller with basin heater control combines fill, high and low alarms, basin heater cutoff and basin heater control in one panel.
If a heater is part of the project, coordinate its control with the condenser manufacturer’s requirements rather than treating it as a separate accessory.
Review Water Supply and Valve Operation
Electronic level control still depends on a reliable source of makeup water.
Check the valve, strainer, supply pressure and piping.
If a valve cannot deliver enough water during heavy evaporation, the controller may call for fill continuously while the basin still falls.
Likewise, a valve that leaks through after being de-energized can cause a high level condition even though the level controller is functioning correctly.
Commission Under Operating Conditions
Test the system with the condenser running.
Verify fill start, fill stop, high alarm and low alarm. Confirm the BMS receives the correct signals.
Where basin heating is installed, verify the associated low water protection according to the approved sequence.
Evaporative Condenser Fill, Alarm and Heater Controllers
Waterline Controls manufactures frequency-based electronic water level systems for evaporative condensers, cooling towers, remote sumps and closed circuit fluid coolers. Models are available with automatic fill, multiple alarms and BMS dry contacts, and basin heater control is available on the WLC-6100T. For remote sump arrangements, see the cooling tower remote sump level control guide. Call 480-905-1892 to discuss the condenser model, normal operating level, sensor arrangement and required control sequence.
References
Cooling tower and evaporative condenser level controls
WLC-5000 fill controller with high and low alarms
WLC-6100T fill, alarm and basin heater controller
EVAPCO: Operation and Maintenance Instructions for Closed Circuit Coolers and Evaporative Condensers