They are cheap, mobile, often quiet and energy-efficient and still cool the air noticeably: air coolers. We show you what to look out for when buying.
This is how air coolers work
The transition of a substance from a liquid to a gaseous state without reaching the boiling point requires energy. The substance obtains this from the ambient temperature. This lowers the room temperature. Colloquially, this effect is called evaporation. Our body also makes use of this principle. When it is hot, sweat forms on the skin, which evaporates and cools. If a little wind blows, for example via a fan (purchase advice), evaporation is further stimulated and cooling is improved.
Now there are more and more inexpensive fans on the market that distribute fine water particles in the air, which then turn into a gas. This increases the humidity and lowers the temperature. In buildings, mainly well-sealed new buildings that already have a problem with excessive humidity, they should not be used or only with the windows open, which in turn reduces the cooling effect ad absurdum at high outside temperatures. In such environments, a dehumidifier (guide) or a split or monobloc air conditioner (purchasing guide) can help.
Keep an eye on the humidity
Indoors, the optimal humidity should fluctuate between 40 and 60 percent. If the air humidity is too low, breathing capacity is reduced. In addition, dryness can lead to skin irritation and irritation and dry out the mucous membranes, which significantly increases the risk of infection for flu and other colds. Excessive relative humidity impedes sweating, which regulates body temperature. The well-being and thus the performance is impaired. In addition, the circulation is strained in rooms that are perceived as muggy.
Added to this is the risk of mold formation indoors caused by high humidity. Mold spores and VOC gases when inhaled can cause a variety of ailments in addition to allergies. These include migraines, asthma, coughs and colds, conjunctivitis and skin changes, joint pain and gastrointestinal complaints.
House dust mites multiply particularly quickly at high humidity levels of over 60 percent. As a result, the little roommates give off more allergens, which is particularly troublesome for allergy sufferers.
Air cooling effect
Evaporative coolers are inexpensive and comparatively mobile. You don't need a fixed installation like a split air conditioner, and you don't need a hose leading to the outside for the exhaust air like a monobloc air conditioner (guide). Usually there is a bowl for the water, which is pumped out and sprayed in front of a fan. This then distributes the tiny drops of water in the room. These devices also generally work much more quietly than, for example, monoblock air-conditioning devices.
The cooling effect is measurable. For this purpose, we place a digital temperature sensor half a meter in front of various evaporative coolers: the powerful Sichler LW-61 and Honeywell CS10XE variants, the two tower fans Sichler 3in1 WLAN air cooler LW-480.wlan and VT-560.app as well as the Sichler WLAN stand -Spray fan VT-480.app. The following values are comparable for the devices; we limit ourselves to the Honeywell CS10XE as an example.
We measure 24.1 degrees with the air cooler switched off. If we turn on the ventilation function, the temperature drops to 23.4 degrees after 30 minutes. If we now activate the cooling function, i.e. the spray mister with evaporation effect, the temperature drops to 20.4 degrees. These three degrees compared to pure ventilation are clearly noticeable. You immediately feel a refreshing and cooling breeze.
Air cooler at 37° Celsius on the terrace with solar generator
This not only works in rooms, but also to a limited extent on balconies or terraces. Here, however, you should rely on a device with sufficient performance. For this we used the Sichler LW-61 with a maximum power consumption of 130 watts. At a barbecue party and an outside temperature of over 37 degrees Celsius, the device provides a cooling performance that guests find pleasant – even at the lowest and particularly quiet fan level. And if you want to operate the Sichler LW-610 in a particularly environmentally friendly way, you can connect the device to a solar generator (theme world) previously charged by a solar panel, as we did in the test. With the Flashfish UA550 model (test report) used for this purpose, it cools the air for more than five hours.
Evaporative coolers should be cleaned regularly. Bacteria can form in the water tank and spread through the fan in the air. If you feel a biofilm on the water-covered inside of the tank, cleaning is urgently required. In areas with hard water, you should also regularly remove limescale from the devices. Regular cleaning with a little vinegar helps against both bacteria and limescale. Some users even add a few drops of vinegar to the water.
Evaporative coolers are cheap and available from around 12 euros. They usually use a USB port for power supply, which makes the small refreshers primarily suitable for the desk. They contain a wet pad in a water container, past which a fan directs an air flow. The liquid evaporates and cools the air slightly.
In most cases, they offer multiple speeds. The lowest should be quiet enough to run on the bedside table in the bedroom on very hot nights without disturbing sleep. Below we show the cheapest table fans.
Floor fan with air cooler
Floor fans with air coolers start at around 70 euros, but can also cost over 200 euros. As an example, we looked at the Sichler WLAN stand spray mist fan VT-480.app, it costs just under 150 euros at Pearl. They have one major advantage over tower fans with a cooling function: they are usually quieter in operation. We can confirm that in the test. At the lowest level, the fan gently whirrs air through the room. If you turn on the humidification function, it gets a little louder. Nevertheless, the Sichler VT-480.app belongs to the quiet air coolers. When the humidification function is activated, atomized water emerges from the center in front of the fan and is distributed throughout the room. This is clearly visible as a fog and is a pretty cool effect.
Visually, the Sichler VT-480.app takes some getting used to. Colleagues compare it to a robot from the Star Wars parody Space Balls. His foot is knobbly reminiscent of an oversized drop of water. The spray device with black hose looks like a trashy copy of the Darth Vader mask. Elegant is different.
If desired, the Sichler VT-480.app connects to the home WLAN and can be controlled via the Tuya-compatible (adviser) apps Tuya Smart, Smart Life and Elesion from Pearl. It also responds to Alexa and Siri voice commands. Its fan head has a diameter of 40 centimeters. It shouldn't be smaller either, otherwise the noise development will increase. If desired, it automatically rotates back and forth horizontally at a 90-degree angle. When buying, you should pay attention to this function, known as oscillation, as the cool air is better distributed in the room. Its water tank holds almost four liters. We do not recommend buying devices with significantly smaller tanks, as these would otherwise have to be refilled too often.
Tower fans with cooling function
Most large evaporative coolers come in a plastic box similar to a tower fan. This makes them more compact than the air-cooled fans discussed above, but also louder. We looked at the Honeywell CS10XE and the Sichler variants LW-480.wlan, VT-560.app and LW-610.
The Honeywell CS10XE does a lot of things right. It's quite powerful at 100 watts, has a large ten-liter water tank, oscillates the air at a 90-degree angle, and comes with an ionizer to improve air quality. However, it has two major disadvantages. For one thing, it doesn't come with any smart features. At its price, we wish we could control it with voice commands. none. The second and much more important point: The Honeywell is really loud even on the lowest level. Sleeping next to him will not be possible for many. Even when watching TV, the whirring noise is annoying.
The slightly smaller Sichler LW-480.wlan is less powerful at 65 watts, but quieter, although not quite as quiet as a fan with a cooling function. Its tank holds four liters, an ionizer is supposed to clean the air, and the swing function goes up to 60 degrees. In contrast to the expensive Honeywell CS10XE, it listens to Alexa and Siri, and it also comes with its own app.
The Sichler VT-560.app also listens to Alexa and Siri and offers its own app. It offers real oscillation up to 45 degrees thanks to a motor. An LED display shows the current room temperature. A dust filter is designed to filter dirt particles out of the air. The manufacturer specifies its evaporation volume as 322 milliliters per hour. However, the water tank only holds two liters.
Even at the lowest level, the cooling capacity is sufficient to develop a cooling effect on the terrace that is perceived as pleasant at over 37 degrees, as in the test. The Sichler LW-610, which costs almost 250 euros, is also characterized by quiet operation – at least in the lowest fan level. It might still be too loud for most people in the bedroom at night, but it doesn't get in the way when watching TV in the living room. In addition, at this outside temperature, he keeps the indoor thermometer in a well-insulated, 35-square-meter room at a constant 28 degrees – and thus almost 10 degrees lower than outside. However, the LW-601 only offers a remote control, but no control via app. Due to the function-related increase in air humidity, the use of a dehumidifier can be useful.
Automate room climate
In order to automatically keep the room climate at an optimal level, suitable sensors and actuators such as air purifiers (guides), humidifiers and dehumidifiers must be able to be seamlessly integrated into the smart home control center used. Unfortunately, this is rarely the case. In general, the Tuya platform (test report) has the largest selection with over 400,000 compatible devices. The platform offers all device groups – this also includes the Sichler variants with app control mentioned in this report, which can be used to automate control of the room climate. More information is available in our guide Fighting mold, protecting health: Smart technology for a good indoor climate from 20 euros.
Cheap air coolers are also useful – if you sit directly in front of them. The evaporating liquid ensures effective cooling on particularly hot days – more than a fan without a water atomizer. However, most evaporative coolers are unsuitable for lowering the overall room temperature. Only high-performance devices such as the Sichler LW-601 keep the room temperature constant at just under 28 degrees in a well-insulated apartment with an outside temperature of 37 degrees. However, due to the function, the humidity increases, so that the use of a dehumidifier may be necessary. If you need a higher cooling capacity, you have to use the monoblock air conditioning system (purchase advice). Here, however, the humidity can drop so much that a humidifier is necessary to ensure an optimal indoor climate.
For offices that are not air-conditioned, users could be happy with a table fan with a cooling function, precisely because their purchase price is very low at less than 20 euros. Better than nothing is the conclusion here.
If you want a big solution, tower evaporative coolers are for the most part fancier, but unfortunately also significantly louder than fans with a water atomizer. In both categories you have to reckon with a stake of at least 50 euros. High-performance models are significantly more expensive at more than 200 euros.