How to calculate the power of the bathroom fan

How to choose an exhaust fan?

Not everyone understands how important it is to maintain the right microclimate at home, therefore they forget or ignore the installation of exhaust ventilation. This is a serious mistake. Good ventilation provides a normal influx of fresh air and the removal of spent or contaminated air masses. In addition, the installation of forced exhaust ventilation allows you to not depend on the weather and control the ventilation modes of the premises at your discretion.

It is recommended to install exhaust ventilation in those rooms where there is no natural air supply, as well as where the air is too contaminated or there is excess humidity. Such premises include a bathroom, bathroom or shower, kitchen and wardrobe. But you need to know how to choose a fan for exhaust ventilation so that it works with maximum efficiency. But excessive performance will lead to the fact that the room will be cold and drafts will appear. Therefore, we will consider in more detail how to choose an exhaust fan.

Types of bathroom ventilation

The ventilation parameters are regulated by the current SNiP 41–01–2003. The standard prescribes several types of ventilation and the frequency of air exchange.


Using special holes in the bathrooms, a flow of fresh air is provided and the removal of the worked out. The exchange occurs due to the pressure difference. Warm air from the room rises up and is thrown into the atmosphere through ventilation ducts. Fresh air enters from below through holes in the door. The dimensions of the holes are calculated taking into account the climatic zone of the placement of buildings, the volume of the room and the frequency of the metabolism. In bathrooms, air should change 6-8 times per hour.

Natural ventilation in the bathroom

How to Replace a Bathroom Exhaust Fan

The advantages of such a system are the simplicity and autonomy of functioning.

calculate, power, bathroom

Disadvantages. A big dependence on weather conditions, the probability of reverse traction. The air is not pulled out of the room, but is pumped out. As a result of this phenomenon, humidity in all rooms increases.

High humidity. The cause of mold and fungus

Another drawback is large heat loss. In conditions of constant increase in energy prices, the costs of premises increase. Housing owners with various methods try to reduce losses. You need to do this skillfully, as a result of unprofessional intervention, instead of the desired savings, you can get serious losses. Will have to repair the walls and ceilings of bathrooms.


Fans are used for supply/hoods. The exhaust fan for the bathroom removes air only in a given period of time or with certain values ​​of air humidity (depending on the type and capabilities of the device), the flow of fresh is provided by special poor. For the method of supply or hoods of air, forced ventilation can be exhaust, supply or supply and exhaust. If the fan only removes the air, the system is forcibly exhaust, if it is overtaken. Forcedly supply. If there are two fans, one of which serves, and the second removes, then the system is called the supply and exhaust.

Using the forced ventilation system of the bathroom allows you to achieve the regulated humidity with minimal heat loss. Which type of ventilation to choose depends on the capabilities and wishes of the owner of the apartment and the architectural features of the building.

The right choice of the fan

In order to choose the right fan for ventilation of the bathroom, it is necessary to take into account a number of factors, namely:

  • The noise of the fan. Such a parameter can be found directly when buying, indicated on the packaging. This indicator in decibels is measured. Usually good fans have no less than 40 dB noise level. It is worth noting that such a noise is almost invisible.
  • The second factor is the engine. It can be combined on bearings or on a sleeve. The first option is becoming the best, such a device is more silent and reliable.
  • The following factor notes the performance of the fan. It is determined by air volume. For the correct choice of this value, it is necessary to carry out calculations, namely, calculate the volume (about how to do this a little later).
  • And the last factor is the connection option.

And now we’ll consider the last two factors in more detail.

Selection of the connection fan

  • Connection to the switch. In this case, the fan begins to work when lighting in the room. Accordingly, when it is turned off, the work stops.
  • The following notes the arrangement of a separate circuit breaker for the ventilation system. Thus, you can independently activate the operation of the system, and turn it off.
  • The third option is automatic work. In this case, the system will start working when the humidity level is exceeded, which is measured by a special sensor. The work continues until the microclimate of the room returns to normal.
  • And the latter is the installation of the timer. In this case, the connection is carried out in the same way as in the first, but the timer is additionally installed. Thus, after turning off the light, the device works, depending on the setting, a certain time.

A combination of systems is also possible, thus, the best option is to install with the possibility of independent inclusion, while with additional installation of a humidity sensor. This decision is due to the fact that the ventilation will support the necessary microclimate, and in addition it can be turned on manually, in the presence of unpleasant odors for speedy weathering.

Calculation of the necessary ventilation performance

As mentioned earlier, the selection of system performance is an important factor, which is done through simple calculations. They are performed as follows:

  • We calculate the volume of the room, for which it is necessary to change the length, width and height.
  • After that, the resulting value must be multiplied by the frequency of air exchange. This indicator indicates how many times in an hour a complete circulation of air should be carried out.

The multiplicity indicator depends on several factors:

Thus, by multiplying the volume of the premises by the frequency of air exchange, you will receive the power of the fan. For example, for a room of 2.53 meters at a standard 3M ceiling height, the indicators will be as follows:

Thus, for a small bathroom, a fan with a capacity of slightly more than 20.25 m 3 /h is suitable.

Features of calculating the power of the hood for the bathroom in a private house

Before you purchase and start installing the hood in the bathroom with your own hands, you should decide on the type of ventilation, the fan model and its power.

As for the type of ventilation in the bathroom, it can be exhaust, supply and combined. The most relevant and effective way is to make an hood in the bathroom of the supply and exhaust type. Will the channel or non.Channel system depend on the presence of ventilation ducts. Canal systems are usually used in rooms where ventilation ducts are equipped.

Hood in a bathroom in a private house can be safe. In private houses, one of the walls of the toilet or bathroom is usually the outer. Therefore, the owners of private houses can break through the through hole leading right into the street, and install an extract in it.

By installing the wall valve in the outer wall, you can equip non.Channel exhaust ventilation in the bathroom

If the channel type of ventilation is used in a private house, then you can make an extract with your own hands to the bathroom from sewer pipes.

You can make a calculation of the bathroom fan power in a private house or apartment by the formula:

Numbers indicate the coefficient of the frequency of use of the bathroom.

The performance of devices for ventilation of bathrooms and toilets depends on their size. The hood fans in the bathroom are selected based on the volume of the served rooms.

Exhausting fans in the bathroom are selected based on the volume of the serviced rooms

For example, it is necessary to calculate the power of the hood for the bathroom of a private house, the dimensions of which 4x3x2.5 m (volume of 30 m³). Given that the use of the bathroom will be carried out by one person twice a day, the coefficient is taken by the minimum, equal 5. Then the necessary power of the exhaust installation is 150 units.

Before making hood in the bathroom, make sure that there is a gap between the door and the floor for an air flow. If it is not, you can make a hole in the lower part of the door leaf and insert a ventilation grill into it.

For proper air exchange, ventilation holes are installed in the bathroom door

Clarification of selection criteria

Those who seriously thought about the question of where to buy a bathroom fan should be spent a little time to study the corresponding assortment, as well as reading user reviews on all kinds of specialized sites. This will help to clarify your own priorities and approximately indicate preferences associated with price and quality.

Rules for choosing an exhaust fan

So, if the decision to buy a fan is made, you need to choose the right model in order not to be subsequently disappointed. You need to choose at once in several parameters-performance, safety, noise level and, of course, in terms of quality-value ratio.


This criterion is the main one, because the effectiveness of air exchange depends on it. It is important to choose the right device power relative to the area here, since the same fan gives a different result in a small and large bathroom. According to construction standards, the frequency of air exchange for the bathroom is 6-8 units, that is, in an hour the entire volume of air in the room should be replaced by 6 to 8 times. As a rule, if no more than three people use the bathroom, they choose a multiplicity of 6, if more than three, the multiplicity of 8. Calculations are not difficult to perform: you need to find the volume of the room and multiply it by the frequency of air exchange.

For example: there is a bathroom with a size of 1.9×1.7 m and 2.65 m high, 3 people use it. We calculate the volume of the room. 1.9×1.7×2.65 = 8.56 m. We round to 9 and multiply by the frequency. 9×6 = 54 m3.

It turns out that for such a bathroom, the best choice will be a device with a capacity of 54 m3/hour. Of course, you do not always manage to find a model that is most consistent with the calculation parameters, so you can choose a fan with a small margin of performance.

Air exchange rate for different rooms

Typically, the performance of fans for bathrooms is 95. 100 m3 /hour


Fans with additional protection of electrical contacts from moisture are produced for bathrooms and bathrooms, which must be indicated in the instructions and on the packaging. If you put a regular model, and water will fall into it, this can provoke a short circuit and even a fire, so you can’t take risks in any case.

Now you can find low.Voltage exhaust devices specially designed for bathrooms and saunas. They have moisture and thermal protection, and can work effectively at 100% humidity and high temperatures. True, the cost of such fans is higher, and they cannot be connected to a conventional power supply, which entails additional costs, but the safety of residents is worth it.

Look for fans in stores that are designed specifically for the bathroom

How to Install a Bathroom Fan | Ask This Old House

Noise level

The noise produced by the fan should not exceed 30 dB, otherwise it will act on the household irritating. If you plan to turn on the fan at night, choose a model with a noise level up to 25 dB. The smaller this indicator, the more comfortable you will be in the bathroom when the hood is turned on. This is especially true for those whose fan works continuously.

Noise, which is more than 35 dB, is irritating to the human psyche

As for the quality of the fans, it is better to focus on well.Known trading brands, whose products have already been tested by time. For example, a lot of positive reviews have household fans of the SOLER PALAU trademark (Spain), Vents (Ukraine), Electrolux (Sweden).

Color variety of Electrolux Eafr exhaust fans

These companies value their reputation, so their products are of high quality assembly and durability. The main thing is to buy fans in specialized stores, where the corresponding certificate can be presented for the goods and write out a warranty card. So you will avoid the risk of buying a cheap fake, not branded equipment.

Additional functions of the fans

Photo.Named add. Functions
Hydrostat, or a bathroom fan with a humidity sensor
Motion Sensor
Constant ventilation
Clock on the front panel of the fan
Check valve

Choice by technical parameters

Like any technical device of an exhaust fan in the bathroom must be chosen primarily in technical parameters. It is worth saying that the housings are usually made of plastic, and the case itself is moisture.Proof (the minimum protection class is IP 24). The shape and type of lattice is arbitrary, the color of the case is most often white, but there are also colored.

Hood for the bathroom and toilet in shape can be different

In addition to external signs, select the diameter of the output pipe of the exhaust fan. It is selected depending on the cross.Section of the duct (it is better not to love, since the air exchange will fall).

Air exchange

It is necessary to choose an exhaust fan in the bathroom on the basis of the volume of the ventilated room and the frequency of air exchange (spelled out sanitary norms). For bathrooms, the recommended multiplicity is from 6 to 8 air volumes per hour. For families, they consider 8 multiple exchange, for 1-2 people there are enough 6-7 frequent.

For example, the bathroom has dimensions m. We change all numbers to find out the volume, we get 14.85 m3. We round, we get that the volume of the bathroom is 15 cubic meters. We will count eight.Time exchange: 15 m2 8 = 120 cubic meters/hour. That is, when selecting fan performance, its performance should not be less than 120 cubic meters/hour.

An example of brief technical characteristics of an exhaust fan for the bathroom

Noise level

The second point to which you need to pay attention by choosing an exhaust fan to the bathroom. The level of noise produced. If you work the fan only during the day, the noise produced should be around 30-35 dB. This is not very loud, against the background of other noise does not interfere. If the fan in the hood will work at night, the noise level should be less than 30 dB, and preferably 20-25 dB.

The most silent bathroom fan should be sought among radial models. The axial due to the transmission of vibration from the motor makes more loud sounds, but there are models in which these vibrations are minimized to use special vibration gaskets. Another way is to use rolling bearings. Such axial fans for the bathroom and give out just 22-23 dB, which is very few.

Nameotype Mounting mechanism transfer (performance) power consumption level Schumadop function of rotation price
Ventts 100 mat overhead axial 98 cubic meters. M/h 18 T 34 dB Timer, delayed delay 2300 rpm 30-35
Electrolux EAF-100TH overhead axial 100 cubic meters. M/h 15 W 33 dB moisture sensor without adjustment 30-35
Vents Ifan overhead axial 106 cubic meter. M/h 4.56 watts 31 dB remote control, humidity sensor Step adjustment 75-85
Soler Palau Silent-100 CZ overhead axial 95 cubic meters. M/h 8 T 27 dB Mechanical control without adjustment 25-39
Blauberg Sileo 125 T overhead axial 187 cubic meter. M/h 17 T 32 dB timer, check valve without adjustment 45-50
Systemir CBF 100 overhead radial 110 cubic meters. M/h 45 watts 45 dB Mechanical control without adjustment 65-75
Systemir BF 100 overhead axial 85 cubic meters. M/h 20 W 41 dB Mechanical control 2400 rpm 32-35
Systemir If 100 channel axial 87.1 cubic meter. M/h 14 T 44 dB 2432 rpm 28-35
Marley MP-100s (SV-100) overhead from 10 to 83 m³/h from 1.1 watts to 4.1 watts from 10 dB to 38 dB Electronic control Smooth adjustment 209-225
Ventts Quait 100. (Vents Quiet 100) overhead Silent 97 cubic meter. M/h 7.5 watts 25 dB check valve, rolling bearing 2300 rpm 28-35
Ventts 125 kaite in (125 Quiet B) overhead Silent 185 cubic meter. M/h 17 T 32 dB check valve, rolling bearing 2400 rpm 42-50
VKO DOMMOM 125. Channel axial 185 cubic meter. M/h 16 T 37 dB overheating and moisture protection without adjustment 7-10

Also pay attention to the moment like the material of the air duct. The fan itself can create an insignificant noise, but a metal duct can make noise when air moves along it. Therefore, when installing a ventilation system, it is advisable to use plastic. If there is already a metal box, you can reduce the level of noise by gluing it with soundproofing materials. The second exit is to sew it in the box, and fill the gaps with porous soundproofing material. The best sound insulation from mineral fibers is best suited for this. Mounting foam, of course, is convenient to use, but her soundproof characteristics are very low. Not very good in this regard and polystyrene foam with polystyrene foam.

Power consumption

Another parameter is power consumed. The smaller this parameter, the less you will have to pay for electricity. From this point of view, axial fan fans are more economical for extract in the bathroom. For a set of high efficiency at low electricity costs, they give out significant air exchange. Radial in this regard is less beneficial: with equal performance, they spend 3-4 times more electricity, but the air is transmitted to a greater distance.

It is also worth remembering that the productivity of the fan depends on the power consumption (the movable amount of air per unit of time). This parameter is also affected by the shape of the impeller and other design features (for example, the presence of rolling bearings), but the large volumes of air must be pumped, the more powerful the exhaust fan is required in the bathroom.

How to calculate the consumption of a bore of the bathroom for a bathroom

Touched on issues of minimum cross.Section of cores on copper and flexibility class that affect the price. The more flexion the cable is, the more expensive the thicker there is, the more you have to pay. Select a toilet fan so as not to overpay, it is recommended, focusing on performance. Conditions differ in people.

Some people, without hesitation, put powerful exhaust fans, pumping their own smells to neighbors. There are consumers choosing too weak a model, after installation, the product does not cope with duties. Start choosing an exhaust fan with a simple one: try to understand if the reverse craving is present. For residents of the lower floors, this is irrelevant, with an increase in height, the need for a powerful exhaust fan increases. Check the presence of reverse traction will help A4 paper sheet. It is necessary to cover the ventilation hole with paper, if there is no sticking, the thrust is unsatisfactory. The power of the device is chosen more.

You will need an anemometer. Aliexpress costs 800. The flow rate is determined, then, based on the area of ​​the transverse cut, the air consumption is calculated. The speed of movement along the walls is lower than in the center. According to the ABOK standard-1, the exhaust fan air consumption is:

  • For a bath or toilet room. 25 cubic meters per hour.
  • For a combined bathroom. 50 cubic meters per hour (if it is not used, the frequency of air exchange is 0.5 1/h, it turns out. Once in two hours).
  • For a hotel room for a bathroom:
  • The room is used. 120 cubic meters per hour.
  • The room is not used. 20 cubic meters per hour.
  • For a public toilet at least 75 cubic meters per hour per person.

Bathroom equipped with a fan

We strive to achieve these indicators. First, we examine the ventilation system with an anemometer for ensuring parameters. The flow rate of the cross.Section is heterogeneous. The average speed is in the form of an integral in a section with division by the size of the area. Available to simplify.

Divide (using a ruler) transverse cut into equivalent areas, we measure in each. We try to averaged for the segment (purely visually, according to the indications of anemometer). Then the arithmetic mean of all speeds is calculated. The result will be close, the quality depends on the ability to measure. During the experience, you do not need to overlap part of the section with your hand. It is ideal to hold the anemometer on the steel bar, the body of the device makes an error.

Well, if you can get a remote anemometer. He has a measuring blade on a steel pipe, cord or flexible corrugation. In each case, see that the device minimally overlaps the cross section of the ventilation passage. At home, this is realized. The situation is much easier when the choice of a fan for the toilet has already been made. There is a lattice here, to which we put an anemometer without loss, without blocking the section, we will measure.

It is difficult to calculate the area if the protective grill of a difficult configuration. It is recommended instead of numerical ways to use field. To do this, on paper, a drawing of any color of the protective grate is performed. The free part is cut out and folded. If necessary, each piece is divided into parts. The task is to get a rectangle, by changing the sides of which, we get the desired area. Now it remains to multiply it by the speed issued by the anemometer to obtain the result.

The found number is compared with the standard. If the value is insufficient, a powerful exhaust fan is required. Depending on the data obtained, the issue of the need for constant or temporary operation of the device is resolved. Even whether it is required to put an exhaust fan! After using the bathroom, the metabolic intensity is supposed to increase. Adjust the speed of rotation of the exhaust fan.

Installation and connection

The installation of the fan in the bathroom can be done with your own hands. But this is if there is the necessary knowledge regarding the installation of electrical wiring and household appliances. In all other cases, it is better to use the services of a professional. The cost of installing a fan in the bathroom will be small compared to the price of the device.

And now the main thing: how to install a fan in the bathroom and connect

First of all, it is necessary to provide the ability to connect the device to the electric network. There are several options here. You can stretch the wire from the camshaft on the site, “be burned” from the switch or from the light device itself. In the last two cases, air vents will turn on and turn off simultaneously with the turning on the lighting in the bathroom. This is not entirely convenient. It is better to install a separate switch.

Before carrying out installation work related to electricity, it is necessary to disable power in the apartment. After the electric wire is carried out from the switch to the ventilation grill, you can start working with it.

The grate has a width of 10 cm. If the device pipe is 100 mm, then no problems will arise. If it is larger (125 or 150), then you will have to expand the hole to the corresponding size. There are nuances again here. The pipe is a flexible, soft pipe made of plastic. When installing, it can easily deform and disrupt the operation of the device. Therefore, it is better to insert a segment of a metal pipe.

To accurately determine the diameter of the hole under the fan, lean it with a nozzle against the wall, with a pencil, outline the circle. In order to securely fix the pipe in the pipe, two rubber rings with an interference are put on it. In addition to fixation, these rings are extinguished by the vibration of the device, reduce the noise level. You can simply fix the device with mounting foam, but in this case it will be difficult to then dismantle it for prevention or repair.

An important point. The distance from the ceiling to the ventilation grill should be at least half a meter for normal air circulation.

After the device has been brought into the pipe, the points for dowels or self.Tapping screws are noted with a pencil. The holes in the tiles are performed using a drill and the so.Called “feather”. Then reliably fix the fan on the wall. It is also important not to overdo it with the tightening of dowels, since the plastic case may not withstand much effort. The device can be set in level, or you can navigate along the line of tiles.

To connect an electric cable, you can use the standard hole, or you can make an additional in the housing. The wires are connected in a terminal block, especially for this designed to avoid sparking in wet air.

calculate, power, bathroom

After the installation work in the bathroom, they include power and check the operation of the device and its sensors. He must work quietly, evenly, without sparking, without vibrating.

In order for the device to work not 1 year and copes with its direct task, you still need to choose the right model depending on the area of ​​the bathroom. It is not difficult to install a fan yourself. But, if there are no basic knowledge regarding such work, it is better not to take risks, but to trust a qualified electrician.

Have you ever installed such a device in the bathroom? How did everything go? Write in the Комментарии и мнения владельцев. Share the article on social networks and save it in bookmarks so as not to lose.

In the video you can watch the simplest and fastest way to install an exhaust fan in the bathroom and toilet.

The foreman and the organizer of absolutely all processes related to repair work. I have been repairing for more than 20 years and I am an expert in this area. When writing an article, he tried to make it as useful and understandable to every person.

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