It’s hot, hot, hot, and we’re all looking for ways to keep cool. While portable air conditioners are the simplest way to lower the temperature of a room without requiring professional installation, it’s hard to miss the alternatives that are pushed: evaporative coolers.
Also known as air coolers, or misting fans in the UK, and swamp coolers in other parts of the world, these devices use a tank of water and are sold as being able to cool the air they blow. With prices way lower than even the cheapest portable AC unit, such as the Vonhaus 12000 BTU High Performance Air Conditioner, are these devices worth it?
The answer, as with so many things, depends.
How evaporative coolers work
You might think that air conditioning works by blowing cold air into the room, but the cold air you feel is actually a byproduct of the process. As explained in our guide to how portable air conditioners work, AC moves heat from inside your house to outside it. So, the cold air you feel at the front is just the hot air that was sucked in, only with the heat removed.
An evaporative cooler is different. As the name says, these coolers use evaporation to cool the air. It’s easy to explain with us humans as a reference. When it’s hot you sweat. As the sweat evaporates, the process cools you down.
An evaporative cooler works on this principle. Air is blown across a moisture-infused material, wetted via the tank of water. This causes the moisture to evaporate, reducing the temperature of the air that’s blown.
A misting fan, built for indoor use, such as the Dreo TurboCool Misting Fan 765S, pushes fine water droplets into the air, which evaporate and create a cooling effect.
How effective are evaporative coolers?
How much the air temperature drops depends on the room’s heat and relative humidity, but you can usually expect air from an evaporative cooler to be between 2°C and 6°C colder than ambient temperature.
As humidity goes up, the effect of the coolers reduces as there’s less evaporation. That’s why, when it’s humid, you feel hotter, as sweat can’t evaporate.
A side-effect of evaporative coolers is that they add moisture into a room, so increase humidity, therefore decreasing their effectiveness over time.
In the UK an evaporative cooler will struggle to lower the temperature of a room, and they’re much more effective in hot and very dry environments. However, in a typical UK home, they will blow colder-than-ambient-temperature air at you, so they can feel more pleasant than a regular fan.
And, you can use them with a window open, whereas with portable AC, you need to shut everything up.
Evaporative coolers are also very cheap to run, with running costs similar to those of one of our best fans, making them a lot more economical.
If you want cheap running costs and want cool air directed at you, a misting fan or evaporative cooler is a good choice. If you want to lower the temperature of a room to make it cooler, you’ll need a portable air conditioner.
