Consumer Electronics and Tips

How to choose bathroom extractor fan

An extractor fan in the bathroom, toilet or another wet room isn’t luxury – it’s a must because of the moisture and unpleasant odors that accumulate making the air unbreathable. Furthermore, over time moisture leads to the growth of mold, which is a source of harmful spores that cause respiratory troubles.

Some bathrooms have outside windows that let fresh air in when open. Nevertheless, mechanical ventilation should be considered even there because often weather conditions such as rain or snow, combined with wind or extremely low temperatures, prevent the natural air circulation. In other words, if it’s 10 degrees centigrade below zero outside, you wouldn’t want your bathroom window to stay open.

Here are some of the most important features to consider when choosing a bathroom fan, along with our hints and tips.


Basic parameters when choosing a bathroom fan:


  • power
  • diameter of the duct opening
  • noise level
  • degree of automation – moisture sensor, timer, light sensor, odor sensor
  • degree of dust and moisture protection
  • non-return valve to prevent contaminated and/or cold air from coming back from the ventilation shaft
  • electric energy consumption.


See all bathroom fans in Vikiwat HERE


Power: It is determined by the device’s flow rate. In simple words, this is the amount of air that the device is able to extract in one hour, in cubic meters (m3/h). According to the Bulgarian legislation, the ventilation of a bathroom, a toilet or a wet room requires 90 m3/h. This parameter is set as a requirement for architectural designs for new buildings but is optional when selecting a fan for your bathroom. More important in everyday life is how many people make up the household and how often the bathroom is used. The fan power can also be determined depending on the air change rate in the bathroom per hour. For a bathroom, it is recommended to provide an air change rate of 5; for the toilet it should be 7, and for service premises 5.

In addition to the flow rate there is a pressure (mechanical pressure). It is determined by the duct. It is denoted by the symbol Pa. The higher the duct, the higher the suction force, and the lower the air resistance: the chimney effect.

To determine the flow rate, you will need to calculate the volume of the bathroom. To do that, multiply the length by the width and the height. From the resulting value, you can subtract the volume of the furniture as in some bathrooms there are different cabinets, washing machines or other objects that reduce the volume of air in the bathroom.

For best results, it is important to select the right place to install the extractor fan, if we have different options, of course. Preferably, it should be installed as far as possible from the source of fresh air that will replace the air extracted by the fan. In larger bathrooms, it is recommended to install two smaller fans, which will produce less noise than one big, powerful fan.

It should be known that once the fan has extracted the moist air from the bathroom into the duct, fresh and dry air has to flow in somehow. Since modern door and window seals are quite tight, the flow of fresh air should be considered. The easiest way is to let the door to other rooms open, but this is not always the best solution, the more so that moist air could flow to the rest of the flat, at least in the beginning. If you don’t want to think constantly whether you’ve left the bathroom open or closed, you may want to install a decorative grille in the lower part of the door. It will let in fresh air to compensate the extraction of the fan.

How to choose bathroom extractor fan 1

Air duct size

Most air ducts are of diameter 100 mm or 120 mm. Before you go to the store or shopping online, check the diameter of your duct. There are also transition rings that will allow you to fit a 100 mm fan on a 120 mm air duct. You should also check the installation depth. It is usually 60-80 mm. That much space is generally available but this shouldn’t stop you from double checking.

How to choose bathroom extractor fan 2

Noise level

The noise level of a good quality bathroom fan shouldn’t exceed 30 dB. For fans with higher flow rates, the noise level is inevitably higher. The noise is caused by the vibration of the fan. It is preferable to choose a fan with bearings rather than a bushing, since the bushing after wear may cause a significant increase in noise and may require lubrication and cleaning.



The choice is huge, but it should be noted that a fan, like any other device, with more sensors and electronic components is more subject to failure, not least because it operates in wet environment. Besides, the price of a fan that is activated automatically upon moisture detection, with a movement sensor, a time and a touch screen for monitoring of parameters, could be double or triple. It is recommended to choose a fan with a timer or a humidity sensor (humidistat) that is switched off automatically upon reaching the parameters set because a fan with manual switching and no timer is easily forgotten on. For those who are fans of digital technologies, there are devices that can be remotely controlled through a smartphone application.


Degree of protection

The index of protection (IP) has been devised by the European Committee for Electrotechnical Standardization (CENELEC) and is defined in international standard IEC 60529. There is a blog article that focuses specifically on the degree of protection. We will only mention here that in most cases the degree of protection consists of two numbers, preceded by the letters IP (Ingress protection):

  • The first number shows the degree of protection against dust penetration. For a bathroom fan this number should be at least 4;
  • The second number shows the degree of moisture protection. For a bathroom fan, known to operate in a quite wet environment, this number should preferably be at least equal to 6.Thus, what you should be looking for on the fan’s specifications label is IP46 or IP56. You might also see IPX5, which means that the fan has no dust protection and its moisture protection degree is 5.5 (as second number) means: protected against low pressure jets of water from any direction, limited ingress;6 (as second number) means: protected against brief immersion in water; e.g. on ship decks; possible limited ingress

    Protection is important because the bathroom fan is an electrical appliance placed in a wet room where a person goes barefoot. In the case of a short circuit or leakage and poorly fitted fuse and fault current protection, the risk of electric shock and even death can be very high. The advice is always to choose an appliance from a reliable, reputable manufacturer and trader with high levels of dust and moisture protection.

    Non-return valve

    This is a mechanical device which, when the fan is switched off, prevents the return of air from the ventilation shaft into the bathroom and the release of heated air from the bathroom into the duct. When the fan is switched on, this valve opens automatically and allows the humid air from the room to be drawn out. Most modern bathroom fans are fitted with such a valve, but still, our advice is to ask whether the fan is equipped with one if it is not explicitly mentioned in the specifications.

How to choose bathroom extractor fan 3

Electricity consumption. Generally, fans are low-power electrical appliances. The more powerful the fan is, the more current it will consume, but the usual numbers are about 8-25W, with a power of 8-10W providing a flow of about 90 m3/h and 18-25W providing 160 m3/h. However, if there is a buildup of dust around the fan axis, or if the blade partially touches the pipe in which it is placed, it is possible that the mechanical force caused by this problem will significantly increase current consumption and will be characterized by an increased noise level. Therefore, if you notice a significant increase in noise, it is better to stop the appliance and call a specialist to have it checked.


See all bathroom fans in Vikiwat HERE


When choosing a fan, also ask about the warranty, which is measured in hours or years of operation. It is desirable that the fan can be operated for at least 30,000 hours or at least 2 years. These are the usual levels of warranty that serious manufacturers provide.

How to choose bathroom extractor fan 4


Having considered all the above parameters and practical tips in the text and choosing a fan with the characteristics you want, the required flow rate, proper diameter, good protection and low noise, you can still choose from dozens of fans with beautiful colors, grille shapes, body material and brand. Obviously, you need to match the color and shape of the fan to the color of the tiles and the style of your bathroom. Therefore, we wish you a pleasant shopping and a successful choice.

Text: D. Kostov

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