Air Cooler Water and Power Consumption, Measured
Catalogue figures are measured under test conditions. What your unit consumes depends on the airflow you actually run, how dry the incoming air is and how the bleed-off is set. Both numbers are straightforward to measure on site.
Quick answer: Electrical consumption is the fan plus the pump, and it is dominated by fan speed. Water consumption is what evaporates into the airstream plus what you deliberately bleed off to stop salts concentrating. Measure power with a plug-in energy meter and water by timing a known refill volume.
Where the electricity goes
An evaporative cooler has two electrical loads. The fan or blower moves the air and accounts for most of the draw. The pump lifts water to the distribution system above the pads and is comparatively small.
Because fan power rises steeply with speed, running one size larger at a lower speed is often quieter and cheaper than running a smaller unit flat out for the same airflow. Where models offer speed control, most of the day rarely needs maximum.
Where the water goes
Water leaves the system in two ways. Evaporation into the airstream is the useful part and is the mechanism that produces cooling: the drier and hotter the incoming air, the more water evaporates and the greater the temperature drop.
The second is bleed-off. As water evaporates, dissolved solids stay behind and concentrate in the tank. Bleeding a small continuous flow to drain, or dumping and refilling the tank on a schedule, keeps that concentration down. Skipping it is the most common cause of scaled pads and short pad life, particularly on hard water.
How to measure power on site
Fit a plug-in energy meter between the supply and the cooler for single-phase units, and read consumption over a full working day rather than instantaneously. That captures the mix of fan speeds actually used.
For hard-wired or three-phase industrial units, take the reading at the distribution board or use a clamp meter, and record the fan speed the reading corresponds to. A power figure without the matching airflow is not comparable between suppliers.
How to measure water on site
Start with a full tank, run the unit under normal conditions for a measured period, then refill with a marked container and record the volume. That gives litres per hour including whatever bleed-off is set.
Repeat on a dry day and a humid day. The difference is instructive: consumption tracks how much cooling the machine is actually delivering, so lower water use in humid weather is a symptom of reduced cooling, not a saving.
Reducing consumption without losing cooling
Clean pads and an even water distribution do more for efficiency than any setting. A pad that is dry down one edge is wasting both fan power and pad area.
Draw the coolest, driest air available, usually from a shaded outside wall rather than a sun-facing one. Keep the exhaust path clear so the machine is not fighting its own humid air. And service on a schedule rather than on failure; the maintenance guide sets out the routine and the intervals to plan around.
Common questions
How many units of electricity does an air cooler use per day?
Multiply measured power by running hours. Because fan speed dominates consumption, the honest answer for any given site comes from a day of metered readings rather than a catalogue figure.
Why does my cooler use more water on hot dry days?
That is the machine working as intended. Evaporation is the cooling mechanism, so the drier and hotter the incoming air, the more water evaporates and the more cooling you get.
What is bleed-off and do I need it?
Bleed-off is a small continuous discharge to drain that stops dissolved salts concentrating as water evaporates. It is strongly recommended, especially on hard water, and skipping it shortens pad life.
Does a bigger tank reduce water consumption?
No. A bigger tank only extends the interval between refills. Consumption is set by evaporation and bleed-off rate.
Related cooling information
Running cost vs air conditioning
Where the power gap comes from.
Pad maintenance
Cleaning, water quality and replacement.
Cooler range
Confirmed capacities and features.