Sizing commercial evaporative coolers

Sizing commercial evaporative coolers is much easier than it is for a conventional refrigerated air conditioning system.

Evaporative air conditioners generally deliver warmer air than refrigerated air conditioners and therefore need to deliver more air to do the same job. The rule of thumb is to:

'always use the biggest evaporative cooler available'

A large evaporative cooler with a high output fan, large cooling pads and a low horsepower motor is more efficient than a smaller cooler with a high horsepower motor and small cooling pads.

Evaporative cooler sizing is based on the airflow per square foot of floor area, and the conditions in the area being cooled. The formula for sizing evaporative coolers is:

The number of commercial evaporative coolers required is determined by dividing the total CFM needed for the area by the output of the air output of the evaporative cooler:

Number of evaporative coolers required = Total CFM needed / Output of cooler in CFM

The following table gives the maximum air output for Activair portable evaporative coolers:

Example

Calculate how many Waycool portable evaporative air coolers are required to cool a 'hot area' measuring 30ft by 60ft.

Maximum coverage for Activair commercial evaporative coolers

We are often asked what the maximum coverage for one of our commercial evaporative coolers is.

Table 3 below gives the maximum coverage for our evaporative coolers under different conditions:

Minimum ventilation requirements

To operate at maximum efficiency commercial evaporative coolers require a constant source of fresh air, such as an open door or window. Without it, the air in the room becomes damp; the cooling effect is reduced and eventually stops altogether.

Allow 2 sq. ft. of unrestricted openings (open doors, windows, etc.) per 1000cfm of evaporative cooling.

Table 4 below gives the minimum area required for our evaporative coolers to maintain efficient cooling:

Conclusions

The size of commercial evaporative cooler needed is based on the size of the area and conditions. Generally, the best advice is to use the biggest cooler possible.

Using the largest cooler available has no detrimental effects, it will increase the cooling efficiency, and possibly reduce energy consumption.

Whatever size of evaporative cooler is selected, it is very important that adequate ventilation is provided to achieve the maximum cooling effect.