How to choose an exhaust fan in the bathroom

Calculating the capacity

To create a proper exhaust for any fan needs proper calculations of its performance. Otherwise it may not be able to handle the loads and the efficiency will be low. The capacity of the exhaust unit must be calculated taking into account the type of room and the volume of the air mass to be renewed.

According to normative calculations, in the kitchen the air must be exchanged at least 9-14 times per hour by the ventilation device. In the bathroom, the air renewal can occur less often, about 5-8 times per hour. At the same time when using the shower, this value should be increased to 17-20 times per hour.

For toilets usually enough 5-9 updates in the above time interval. To correctly calculate the minimum fan capacity, you must first calculate the volume of the room to be served, and then multiply by the required amount of air mass replacement per hour. For example, in a kitchen with a volume of 30 m³ the required minimum fan power should be 30 m³ x 14 = 420 m³/hr.

The location of the unit also plays a big role for full extraction. After all, the air removed from the room must be completely replaced with fresh air. Usually this takes place through gaps in the door or specially provided for this purpose holes in the wall. And when the device is near the exit to the street, it will only create air exchange in the vicinity and will not be able to affect the rest of the air mass in the room.

Specialists recommend placing the fan upstairs to draw in warm air, with the source for the air intake in front of the appliance.

In the kitchen, it is advisable to install the exhaust fan near the stove, as this will contribute to additional extraction of harmful odors from cooking.

If there are devices with a chimney in the room, then the fans should be located so that carbon monoxide from the chimney is not sucked back into the room. Such requirements do not apply to boilers with a distributed draft, in which the exchange of fresh air with exhaust gas inside the tube.

What is better than forced extraction in the bathroom

Natural ventilation is quite capable of bringing fresh air into living areas. But it is far from perfect. After all, the main condition for its work is the temperature difference between outdoors and in the room. But in the warm season there is almost no difference. Therefore, for a complete air exchange is best combined (mixed) ventilation in the bathroom. When the inflow is natural, and removal of air masses provides special devices. Why this is done? Do we need fans in the bathroom or can we do without them??

  • According to the sanitary standards (MGSN 3.01-01, Appendix 7) in the bathroom must be provided with a hood that removes a volume of air from the room at least 25 m ³ / hr in case of separate bathroom, and 50 m ³ / hr in case of adjoining.
  • The inflow of fresh air must be within the same limits: at least 10-20 m ³ / hr in a separate room, and not less than 50 m ³ / hr in the adjacent.

The bathroom exhaust fan must not allow for backflow of air. A non-return valve installed in the exhaust ducting prevents this problem.

Only in this way one can ensure complete removal of excess water vapor, and a normal microclimate.

Excess moisture can lead to rot and mold on the bearing wall structures.

So, what is better than mounted forced air extraction in the bathroom from its natural counterpart?

  • Constant or periodic removal of damp air from the room, so that no condensation forms on the walls.
  • A forced-air hood for the bathroom will work in any climatic conditions and temperature limits.
  • You can accurately calculate the amount of air exchange by simply matching the power of the device to the area of the bathroom.
  • A forced-air hood in the bathroom will prevent air from passing from the bathroom to the living areas. Excess moisture is quickly removed.

Today in the offer there are many different types of devices for air exchange systems. Which of them to choose, and what is best for the bathroom?

Advantages and disadvantages

If you are still in doubt about the advisability of installing such fans in the bathroom, it will not be out of place to familiarize yourself with the advantages of exhaust devices:

    on the walls and other surfaces will cease to accumulate condensation, dampness from the room will go away;

Without a fan in the bathroom is very damp, mold can appear

The extractor on the bathroom ceiling fits perfectly into the interior

The cooker hood is easy to install with your own hands

As for the disadvantages, there are very few:

  • Fans can not work completely silently, and some consumers may be annoyed by their humming;
  • The power consumption increases, although not significantly;
  • The device requires regular cleaning and lubrication for normal operation.

If you don’t clean your hood, it will stop working

It also depends on the installation: If the fan is not positioned correctly, the air circulation is impaired and there is no quality hood to speak of.

Checking the ventilation with a lighter. The flame is not deflected, indicating a lack of draft

How to choose a fan for the bathroom?

If you ever chose a fan in the bathroom, then you know how difficult it is to make a choice. All fans look and perform plus-minus similar to each other. Choose only by appearance overhead fan wrong, this kind of technology should be safe and preferably durable, so he worked until the next repair in the room, which is at least 5-7 years.

If you’ve ever chosen a bathroom fan, you know how difficult the choice can be. All the fans are similar to each other in appearance and characteristics, plus or minus. Choose only by appearance overhead fan wrong, this kind of technology should be safe, and preferably durable, so he worked until the next repair in the room, and that is at least 5-7 years.

Of course, you can trust the recommendation of the manager in the store. But the trouble is that employees of big chain stores can not know all the nuances of each product. The result can be both inefficient operation of the fan, and its rapid failure. That is why we recommend before buying a fan in the bathroom to seek advice from a specialized climatic company, or try to understand the matter yourself.

How to choose an exhaust fan in the bathroom

Exhaust ventilation in bathrooms have higher requirements in terms of moisture protection, as this equipment is constantly working in conditions of high humidity. Considering how to choose an exhaust fan for the bathroom, pay attention to such points:

  • Performance. To calculate, you should use the formula given above. Do not forget that the air exchange rate for showers and bathrooms is 7 to 9. If the shower room is combined with a toilet, it is better to focus on the frequency of air exchange of 8-10. A capacity of 100 m3/h is sufficient for a standard bathtub.
  • Type. For a small room is suitable axial or duct (if there is a possibility of installation directly in the shaft) fan. For blocks of flats with long ducts or premises larger than 8 m2 it is better to choose a centrifugal fan. It costs more, but it shows a higher efficiency.
  • Moisture resistance. Since bathrooms are among the most humid environments, moisture protection is a must for the fan. The manufacturer always indicates whether the equipment has this protection. In order to prevent premature product failure, the minimum degree of protection IP 44 is required. If the exhaust sump opening is located near a water source and direct splashing is possible, IP 45 or IP 55 equipment is recommended.
  • Humidity sensor installation. The main task of a fan in the bathroom is the removal of air masses with excessive humidity. Having a humidity sensor will allow the fan to turn on only when the humidity level exceeds a preset threshold, such as 60-70%. Fan will be switched off automatically when humidity falls to the normal level.
  • Switch-off timer. This option allows you to manually set after how long after you leave the fan will turn off by itself. Almost always a delayed switch-off timer is equipped with light, motion and moisture sensors.

Duct fans: which one to choose??

There is no unambiguous answer to this question, because the performance of these fans must be sufficient for.к. Many productive, reliable and quality duct fans are designed for different purposes. For each type of fan has its own job and its own advantages:

  • Deciding which channel fan to choose for the bathroom, you should give preference to inexpensive and low-powered axial fans. Their performance should be enough for a kitchen hood, and for a shower room, and even for a home bath. one can, of course, choose more productive radial fans, but there is no need to do it. In addition, axial fans are more compact, simpler, easier to repair and can be reversed
  • Centrifugal fans are very productive and work quietly, but cost more than axial fans, so they are used where there is a need to move large volumes of air: in long pipelines of residential, industrial and public spaces. This technique is very diverse in shape and arrangement of blades (vanes), so depending on the task you can choose the model that provides either the highest flow rate or the highest energy efficiency. The performance range of radial fans is so wide that you must carefully match them to the anticipated objectives. A common disadvantage of centrifugal duct fans is their size and mounting method. both of which force you to look for installation space, so they are good for rooms where there is enough of it;
  • Diagonal fans are a compromise between axial and centrifugal. They are compact, efficient, little sensitive to pressure differentials, and operate quietly at high speeds. As duct fans, they are versatile, but traditionally they are ordered for industrial premises, although there are no restrictions for installing them in residential spaces. as long as their high performance is justified.

How to Choose the Right Bath Fan

Other types of fans. tangential and lobe fans. are not used as ducted fans themselves. The first ones are appropriate only in combination with the climatic equipment, the second ones are just experimenting with.

Answering the question, what is the best duct fan, you should pay attention to the following characteristics.


State building codes define the level of air exchange needs of different premises. it determines the capacity, indicating the volume of air (cubic meters) moving per 1 m.m) moved per 1 hour. It is a product of the internal volume of the room and the air exchange ratio, determined for each type of room.

The formula itself looks as follows:

,where V. volume of a particular room in m3;k. required coefficient of air exchange ratio for the room.

The air exchange ratio is different for each room. For example, for toilets, baths and showers in private homes, the air exchange ratio is at 5. 10 units, indicating how many times in one hour should change the entire volume of air. Laundries as well as public baths need 1.5 times the air exchange rate. For the visitors area of restaurants and cafes this figure is 10. 12. the lowest values are in bedrooms (2 to 4 units) and the highest in industrial kitchens (20 or more).

For example: We need to calculate the productivity of a duct fan in a garage, for which, according to a technical assessment, the norm of air exchange of 4 units at the dimensions of 3, 4 and 2.5 meters:

  • To begin with, we calculate the volume of the room: 3x4x2,5=30 cu.м.;
  • We multiply 30 cu.м. by the air exchange rate of 4 and we have 120 cubic.m/hr. the nominal capacity of a necessary inlet duct fan. The same formula is used for exhaust, but with different air exchange rates.

Bath Exhaust Fans: DIY Size, Select, Install, Test, and Control

The example we have given is very relative, t.к. in practice different air exchange rates are used depending on the type of air pollution (pollutants, dust), the number of occupants or personnel in the room and even the area of the water surface (swimming pool, baptismal font).

Airflow rate

The recommended values for this parameter are in the range from 11 to 14 m/s. Fans with lower air velocity outputs are not as efficient. At speeds higher than 14 m/s the noise level increases.


Before installing a duct fan, you need to know their other features:

  • Shape and connection sizes. For circular fans, the connecting diameter is important, for rectangular and square fans, the linear dimensions of the connecting duct;
  • The way of orientation during installation. Never hurts to clarify whether you can install a duct fan vertically: Despite the fact that most modern models allow different ways of positioning, still there are not quite universal models. Roof fans, on the other hand, are installed only horizontally;
  • Motor type: AC and EC. The former are cheaper, the latter are more economical in terms of energy consumption and durable. There’s even an EC motor that can accelerate above rated capacity within the same power consumption;
  • Motor protection class, which determines whether the duct fan can be installed outdoors or closer to the outside wall of the building. It is indicated by the letters IP and two digits after it. The former indicates the level of protection against solid objects, the latter against moisture. The larger is each digit, the higher is the protection class, and the deciphering of these parameters can be found on the Internet;
  • Possibility to connect additional equipment: temperature and humidity sensors, speed regulators, remote controls and other automation features which make sense during integration into the “smart house” system;
  • The possibility of purchasing and connecting additional accessories to the fan: filters, silencers, recuperators, etc.д.;
  • Duct air pressure. Each fan gives a different head in different ventilation systems. Lack of pressure reduces performance, so to determine if a particular fan is suitable for a particular ventilation system, you need to make a fairly complex calculation using special pressure charts;
  • Acoustic characteristics. At the design of ducts necessarily carried out acoustic calculation, which shows what fans on the noise level allowable for installation. Well-designed ducting reduces fan noise at design points, while poor ducting increases it;
  • Voltage. Before you connect a duct fan, you must first compare their parameters with the characteristics of the network.

Types of Exhaust Fans

All bathroom forced-exhaust units are divided into several types:

  • By starting method. Without control and with control by sensors and remote control.
  • By mounting location. For extraction are often used wall fans, they can be easily removed if necessary, to make preventive maintenance or to change.

But there are also ceiling venting devices, they have many advantages:

  • large capacity;
  • easy installation;
  • the possibility of hiding the fan housing behind the false ceiling;
  • pleasant design.

Also ventilating hoods are subdivided according to the depth of installation. There are overhead fans and built into the wall at the same level.

In order to understand which fan is best suited for bathroom and toilet hoods, you need to imagine their device.

There are four of them in total, but only two types are used in the household:

  • Axial. The most popular model for use in bathrooms, because it is the easiest to install. The device is a cylinder inside which there is a motor with paddles on the shaft. You just have to insert it into the vent hole and fix it.
  • Radial (centrifugal). It receives such a name because of its principle work, when the air mass rushes outward due to the centrifugal force.

There are also ducted units. These ventilation devices are used for ventilation in hospitals, schools, kindergartens and other institutions.

Industrial units are also used. As the name suggests, these fans are used in production shops, factories, etc.

Rating of the best manufacturers of fans for the bathroom

Manufacturers produce several types of devices, but what are the best and quality fans suitable for the bathroom of an apartment or home? Check out the user rating that details the features and price range.

Budget models

Inexpensive ventilation units that are easy to install.

VENTS 100 Quiet

Exhaust model with non-return valve for 2 thousand. Power is 7.5 W, and capacity. 97 m3/hour, noise level. 25 dB. Due to the short spigot (8.1 cm) is suitable for installation in a shaft or duct. Protection class IP 45 to avoid overheating. Ball bearings work without interruption 40 thousand. hours. Supplied from a room switch.


  • tightness of the motor due to the rubber-metal bushings
  • quiet operation;
  • performance. both moisture and specific odors are eliminated;
  • easy installation;
  • stylish design.
  • versatility. suitable for all domestic premises;
  • the option of mosquito netting;
  • Safety and durability (35 ths. hours continuously);
  • ease of use;
  • eliminates cigarette smoke well.

Medium price range

If you expect to buy a good and functional exhaust fan to install it in the bathroom, refer to the list of models below.

SolerPalau Silent 100 Design 3C

Designer axial fan for 2.5 thousand. With 8 watts power and a noise level of 27dB. Weatherproof housing, available in white, gray, steel, beige and red. In 1 hour the unit processes 95 cubic meters of air masses. Control is mechanical, complete with colored strips. Surface mounted.

Cata CB-100 Plus

Duct machine cost about 3 thousand. Small in size and weighs in at 900 g. Designed for mounting in a hole with a diameter of 10 cm. Productivity is 130 m3/h, power. 28 W, noise. 49 dB. Protection class against dust and moisture. IP X4. Motor protected against overheating, no return flow due to valve design.

  • compact dimensions;
  • An excellent, powerful and compact fan designed for the kitchen, bathroom and toilet
  • Is connected to the network through a standard and a separate switch;
  • high pressure level;
  • High-quality evacuates specific odors.

Premium models

Which luxury fan would be best for a modern bathroom. choose from a list of expensive devices.

Systemair CBF 100 LS

  • built-in humidity adjustment mechanism from 45-90%;
  • universality of installation;
  • sturdy plastic housing;
  • long ductwork.

SolerPalau Silent 100 CHZ

Powerful and functional bathroom fan with humidity sensor. It costs 6.5 thousand. The motor with ball bearings is designed for a service life of 30,000 hours. Continuous running hours. Equipped with a timer for up to 30 minutes. Performance is 95 m3/h. Noise level of about 27 dB.

  • starts up when humidity is high;
  • optimal for a 2×2 m bathroom;
  • quiet operation;
  • durability and reliability;
  • Energy efficiency. consumes 8 watts.

Electrolux EAF-150

Priced at around 4,000 Euros, it is ideal for bathrooms with large bathtubs and intensively used sanitary facilities. has a non-standard color panel. Motor power is 25 W, noise level 35dB. Moisture-proof and designed for mounting on walls, ceilings, air ducts. Capacity is 320 cubic meters per hour.

How to Choose a Bathroom Exhaust Fan | Ask This Old House

choose, exhaust, bathroom
  • Suitable for a spacious bathroom and a heavily used bathroom;
  • the ease of replacing the panel yourself;
  • ease of operation;
  • high-quality engine assembly.

Fans differ in productivity, power, diameter, installation method, noise level, the presence of additional options.

Calculation of necessary capacity

First you need to determine the exact volume of the room, that is multiply the area of the room by the height of the ceiling. This figure is needed for further calculations. According to SNIP, the air renewal in the bathroom and toilet should take place 6-8 times per hour (the more people live in the apartment, the more often there must be an exchange). The volume of the room is then multiplied by the frequency of exchange.

For example, if there are 3 people living in the apartment, the bathroom is 6 m2 and the ceiling height is 2.6 m, the fan capacity should be: 6 m2 X 2.6 m X 6 times/hr = 93.6 m3/h., Which means that an air change of 100 m3 /h will be enough. These are the parameters have most of the extractor fans for bathroom and toilet. Particularly powerful models, for example. Electrolux EAF-150, can quickly refresh the air in the combined bathroom area of about 20 m2.

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