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Evaporative Cooling

CFW supplies a variety of evaporative coolers (also called swamp coolers) for homes and industries. This is a cost-effective and efficient way of relieving the discomfort of summer heat. Visit for more information.

How does Evaporative Cooling Work?

Evaporative cooling occurs where the evaporation of liquid cools objects that come into contact with the vapour. Heat energy is absorbed from the air or gas into which the liquid evaporates. The potential cooling effect increases with the difference between the actual temperature (or dry-bulb temperature) and the temperature that it would have if it evaporation were to continue until the air is moisture-saturated (the wet-bulb temperature). Thus, the wet-bulb temperature represents the limit of the cooling effect possible through evaporation.

Typical Cooling Units

Domestic and industrial evaporative coolers typically use direct evaporative cooling, where the liquid evaporates into the air to be cooled directly. This form of evaporative cooling results in cooler and moister ambient air and typically raises the relative humidity to 70-90%. A centrifugal fan or a blower enclosed in a vented box blows air out, through cooling pads that are kept wet with a water pump. The unit can be installed on the wall or the roof. Building vents are needed to draw air into the building. This air should only enter the unit once, as subsequent passes will result in a lower cooling effect due to the higher moisture content the incoming air has. Fifteen air changes per hour is a common figure for spaces that are cooled in this way.

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    Cape Town, South Africa (HQ)

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    Cape Town, South Africa (HQ)

     Johannesburg, South Africa

    Mailing address:

    P.O. Box 1542, Parow, 7499, South Africa