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Guide to Evaporative Coolers: How They Work and Why You Should Consider Buying One

Guide to Evaporative Coolers: How They Work and Why You Should Consider Buying One
September 12, 2018 gnuworld
evaporative coolers

Evaporative coolers are an economical, eco-friendly and energy-efficient alternative to air conditioners. They harness the natural process of evaporation to filter and cool the air.

Install the system into your home or office, and you’ll benefit from a constant stream of cool, fresh air that acts as a comfort buffer against South Africa’s soaring summer temperatures.

How evaporation cools the air

The natural evaporation process uses latent heat as an energy source to convert water, in its liquid state, into gas or water vapour. As water effectively absorbs heat in order to evaporate, the temperature of the surrounding air cools down significantly.

How evaporative coolers work

Evaporative coolers work using exactly the same principle. Hot, dry air is sucked in from outside, and circulates through a cooling pad saturated in water. As it moves through the pad, the water evaporates into the filtered air.

The energy powering the process naturally absorbs heat from the air. Entire indoor areas are ventilated by a cool, comfortable and humidified breeze that’s free of dust, pollen and pollutants.

When an evaporative cooler is the best choice

Evaporative coolers function optimally in dry, arid climates. The drier the air, the greater the level of water vapour that evaporates into the air, and the cooler the resulting temperature.

In South Africa, the climatic conditions in the Karoo, the Free State, the North West Province and the Western and Northern Cape are ideally suited to this clean, green and low-cost air-cooling solution.

Types of evaporative coolers

Many types and models of evaporative coolers are available, but all use one of three key approaches.

Direct evaporative cooling

Direct evaporative cooling is the simplest and most popular. It involves using a fan to draw air through a damp, spongy pad and then distributing the resulting, cooled air to an interior space, either directly or via ducts.

Indirect evaporative cooling

Indirect evaporative cooling involves using a heat exchange core, with two separate streams of air. One stream of air is used to cool the core through evaporation. The other stream of air is drawn through the system, cooled by the core and then distributed into an interior.

For example, the heat exchanger may take the form of a set of metal tubes with wet surfaces. One stream of air is directed over the tubes. The evaporative process makes the tubes cold, and the air is vented out of the system.

Separately, air from outside is drawn through the insides of the tubes, which cool the air. That air is then vented into the interior space.

Indirect evaporative cooling is more expensive and uses more electricity than the direct cooling process. However, a potential advantage is that it adds less moisture to the air. This makes it ideal in humid climates and situations in which it’s not desirable to add humidity to an indoor space. For example, extra moisture in the air can encourage growth of mould spores and mites, undesirable for those who suffer from asthma, allergies or other respiratory issues.

Two-stage evaporative cooling

A third option, two-stage evaporative cooling combines both direct and indirect cooling approaches. First air is cooled via an indirect process. This air then passes through a second, direct cooling system.

This type of evaporative cooling system is best in hot, dry climates. It’s the most expensive and does add humidity to indoor air, but offers the most effective cooling.

Tips for choosing a suitable evaporative cooler

The best way to choose an evaporative cooler is to match the nominal air flow rate with the size of the space you want to chill.

A portable unit with a nominal airflow of around 3,300 m/h, for example, won’t make much impact in a large open-plan area, but it’ll work wonders in a single room.

An evaporative cooler installed on your roof, and featuring an output of between 12,000 and 16,800 m/h, is more than adequate to cool an entire home.

Industrial models are capable of chilling large spaces of up to 150 square metres with a power packed output of 18,000 m/h.

Benefits of using an evaporative cooler

Why should you consider buying an evaporative cooler for your living or work space?

Along with the obvious comfort and health benefits, evaporative coolers are much cheaper than traditional air conditioning. You’ll cash in on savings of up to 87 percent on your electricity costs, and roughly 50 percent on installation and operating costs. You’ll also enjoy a cooling system that’s clean, quiet and non-invasive.

Evaporative coolers are easy to maintain, and great for the environment. Unlike refrigerated systems, no noxious chemicals are released during the chilling process, and carbon emissions are comparatively low.

Last but not least, you’ll always enjoy fresh, hydrated air in your home or office. Evaporative coolers don’t re-circulate the air but rather replace stale air with fresh air from the outdoors, filtered for good measure.

Turbovent specialises in providing affordable and efficient cooling systems – including evaporative coolers – to South African homes and businesses. Contact us online or call 0860 266 537 to discuss your cooling needs.