Repair of ventilation in the toilet and bathroom: how to identify and repair the hood in the bathroom yourself

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Alina Zlobina
Last update: December 2019

In the absence of good air exchange, unpleasant odors and excess moisture accumulate in the bathroom. This creates ideal conditions for the development of harmful flora. Mold and fungus that are very harmful to health instantly appear in the bathroom, appliances and furniture can deteriorate, and finishing materials are gradually destroyed.

A properly organized ventilation system helps maintain a healthy indoor climate. But how to prevent possible problems associated with its malfunction, and what to do if the hood stops working?

We will talk about the signs and causes of poor operation of the ventilation system, ways to assess the efficiency of ventilation ducts using simple improvised means. We will also analyze typical malfunctions and explain how to make a ventilation repair in the toilet and bathroom with your own hands.

How is the ventilation system arranged?

To find and eliminate the cause of poor-quality system operation, you need to understand the device and principle of operation ventilation in the bathroom and toilet.

Air circulation in apartments and houses occurs due to two types of ventilation: natural and forced. In the first case, air enters the premises through windows, doors or ventilators and is removed through special channels located in the upper part of the wall in the kitchen and in the bathroom.

Climbing along the vertical duct, the air masses, together with excess moisture, dust and carbon dioxide, go into the ventilation shaft. The whole process is carried out due to the difference between pressure and temperature of internal and external air.

Air exchange rates for the bathroom
For sanitary facilities, where the humidity level is always increased, the problem of effective ventilation is especially relevant. The exhaust air in the bathroom and toilet should be removed at a speed of 25 m³ / h, in the combined bathrooms - 50 m³ / h.These are the minimum standards.

The effectiveness of a standard ventilation system is affected by the degree of tightness of windows and walls, the condition of ventilation ducts, and weather conditions. Therefore, the operation of natural supply and exhaust ducts is often unstable.

If the natural ventilation is not enough, a controlled forced system is equipped in the bathroom. The quality of its work does not depend on external factors, but is determined by the performance of the fan, which increases the intensity of air exchange and speeds up the process of removing exhaust air, forcing it out into the street. Fresh air enters the bathroom from the living rooms.

Diagnosis of problems with the hood in the bathroom

Assess the condition of the ventilation system will help special diagnostics aimed at checking traction. The event is held in several stages with the help of improvised tools or special devices.

It is better to check the operation of natural ventilation in the cold season. Before this, it is recommended to ensure the influx of fresh air: open the window or set the windows to air mode. In sanitary rooms, the door should be ajar.

Flame ventilation test
The easiest way to diagnose at home is by checking it with fire. You need to take a lit match, a lighter or a candle and carefully bring the flame to the grill of the ventilation duct, which removes the exhaust air from the bathroom

The functionality of the ventilation ducts is evaluated by the behavior of the flame brought to the grid:

  • tilts towards the grill - the system works, the thrust is normal;
  • remains unchanged - no traction;
  • deviates towards the room - there is a reverse thrust.

It is worth considering that this technique is unsafe and highly recommended for use by gas service specialists. If there is a leak in the house, gas accumulates in the ventilation shafts. In such circumstances, an open flame may initiate a fire or explosion.

A safer way is testing with a thin sheet of paper. As in the previous case, it is brought to the air vent. The paper is taken at the lower tip and held upright near the grate.

Checking traction with a piece of paper
If the paper is strongly attracted to and held by the grate, ventilation works well. Short sticking or slight deviation towards the hole indicates weak traction. If nothing happens and the sheet remains motionless, the system is faulty. Paper repulsion is a sign of back pull

Outflow of air can also be felt due to tactile sensations. To do this, wet your hand and bring your wet palm to the outlet. The presence of air flow is determined by cooling air.

These diagnostic options will give only a general idea of ​​the operability of ventilation in the bathroom. It is possible to obtain a quantitative assessment of effectiveness and determine whether the state of the system corresponds to standards using special instruments - anemometers.

Checking the air flow rate with an anemometer
Anemometers measure the air flow rate in the ventilation duct. Often they are used by professionals, but simple models are quite suitable for use at home

The device is brought to the ventilation grill at a distance specified in the instructions. After a few seconds, the air flow indicator (V) Having fixed the received figure, it is necessary to calculate the volume of air passed in the system according to the formula:

Q = V x S x 360,


  • S - cross-sectional area of ​​the ventilation duct in m²;
  • V - air flow rate.

The result is compared with regulatory parameters. The optimum value for the bathroom is 25 m³ / h. The norm for combined bathrooms should be twice as much.

We also recommend that you familiarize yourself with validation rules ventilation ducts in the apartment.

Signs and causes of ventilation malfunction

When the ventilation system does not cope with its functions, problems arise. This affects the comfort of residents and can lead to unpleasant health consequences.

The disturbed air exchange in the bathroom can be judged by the following signs:

  • high humidity;
  • heavy condensation settling on the mirrors and walls of the bathroom;
  • unpleasant musty smells;
  • rust formation on metal surfaces;
  • destruction of finishing materials and “swelling” of furniture coatings;
  • the appearance offungus and mold on the ceiling, walls and in corners;
  • hood in the bathroom blowing in the opposite direction;
  • loud noise from the ducts.

Before you troubleshoot, you need to find out the specific cause and understand where the intervention is needed. There may be several reasons for breakdown and ventilation. The main and most common - clogged ventilation shafts. Also, traction problems are caused by insufficient air flow.

Airtight door in the bathroom
Frequent "culprits" of the disturbed air flow are dense doors and high sills in the bathrooms. When using such structures, traction will be present only with the doors open. Unpleasant odors and steam begin to accumulate indoors

This usually happens after installing sealed PVC windows with double-glazed windows and additional sealing contours. They impede the flow of fresh air currents, significantly weakening traction.

Failures in the functioning of ventilation also occur due to damage or deterioration of the exhaust fan mechanisms, clogged filters in the grilles, and corrosion processes. Such factors lead to a deterioration in air quality and increase the resistance of the channels.

Another reason for poor ventilation is repair or refurbishment of the system at the neighbors.

There are several possible scenarios:

  • as a result of modernization of the planning or installation of additional equipment, ventilation ducts are blocked;
  • during repairs on the top floor, the mine becomes clogged with construction waste;
  • the creation of a strong forced inflow from the bottom provokes a reverse draft, preventing air circulation.

Although these actions by the neighbors are not deliberate, they are classified as administrative violations for which a fine is provided.

Exhaust system design
Not only repairs in neighboring apartments, clogging of the duct and excessive sealing of the rooms can contribute to the appearance of a backdraft effect. Of great importance is the correct design of the exhaust system of the house, the installation of channels and additional equipment

Significant deviations from the vertical ducts, unsuccessful roof construction projects, and high heat transfer rates of the external walls, which will help reduce warming.

In addition, the deterioration of air exchange is often associated with the time of year. Most effective ventilation works in the cold period. In summer, due to the almost identical temperature inside and outside, the so-called “air congestion” is created in the room. With increasing external temperature levels, natural traction always weakens.

Ways to fix the ventilation in the bathroom

Having found out the reason, you can begin to work on troubleshooting and optimizing the functioning of the ventilation system. How to do this, give further detailed instructions.

Method # 1 - cleaning the grill and ventilation ducts

In most cases, the ventilation system stops working due to a banal blockage. According to generally accepted rules, residents of high-rise buildings do not have the right to repair and clean engineering communications at home. To do this, it is recommended to call specialists from managers and other organizations with permission for such types of work. But something can be done independently.

First of all, you need to check your segment of the mine, going from the bathroom: remove the grate and look inside, highlighting with a flashlight. In no case should you illuminate the channel with a lighter or a match. If dry garbage ignites, fire will instantly spread throughout the ventilation duct.

Removing the fan tray for later cleaning
Thoroughly clean the ventilation grill and filters, which become very dirty over time. It is better to do this once every few months. The elements are removed, washed under running water and cleaned with a hard bristle brush. Alternatively, blow the net with a compressed air jet.

In the mine can be anything: construction waste, cobwebs, dust, dead birds and rodents. Garbage seen in an accessible visible area should be carefully scrubbed with a spatula, spatula or toilet brush. Then you can vacuum the place near the entrance.

After finishing the canal cleaning, it is advisable to check the ventilation again using one of the listed diagnostic methods. If the problem persists, then the ventilation shaft at home is clogged. To her clean, you must contact the housing authority or the homeowner.

Method # 2 - optimize airflow

The second way to improve the ventilation system is to optimize air flow. Since the natural circulation of air masses is often disturbed due to the tightness of metal-plastic windows, we will start from them.

On the one hand, modern window structures retain heat, and on the other hand, make ventilation more difficult. What to do in this case?

There are several options:

Keeping the windows constantly open is not the best solution in the winter. It is much more reasonable to install a supply valve on a wall or order window constructions with an integrated valve on top.

Installing a supply valve in the wall
The supply valve is fixed in a through hole made in the wall. Outside they put a protective grille, inside - a noise-absorbing box. When installing an angle valve with a flexible channel, the hole is made at an angle to the floor

An additional method of improving the air exchange in the bathroom is the depressurization of doors. If the bathroom is equipped with a high sill, then it is not worth removing it.

Decorative grille for additional airflow
The problem with the tightness of doors is solved by installing door valves, decorative grilles or rings. Lattices are available in various shapes and sizes on the market. You can choose both a small round and a long rectangular design

Alternatively, trim the bottom of the door leaf by about 2 cm. So the door will not fit snugly against the box, which will allow air to freely enter the room.

Method # 3 - arrangement of forced ventilation

Due to the features of the arrangement and increased humidity, the natural ventilation system in the bathrooms does not always give the desired effect. In addition, if neighbors have additional equipment installed in the channels, this often provokes a reverse draft, disrupting air exchange.

In this situation, cleaning and optimizing the flow will not help restore the normal operation of the ventilation system. In the absence of sufficient traction after applying the previous methods, the only way out is fan mounting.

Installing an exhaust fan in the bathroom
Fans with a low-voltage asynchronous motor are most suitable for the bathroom. They are safe, reliable, low noise.

Criteria for choosing a suitable bathroom fan:

  1. Performance.
  2. Noise level.
  3. Power consumption and engine type.
  4. Degree of protection of the case.
  5. Additional options.

The minimum performance for the bathroom is 50 m³ / h. But it is more reliable to calculate the necessary indicator in each case individually according to the formula:

Vvent = V x (6 ... 8),


  • V - volume of the room;
  • (6…8) - the limits of the multiplicity of air exchange recommended for the bathroom.

To calculate the volume of the room, you need to multiply the area by height.

If there is a reverse draft in the ventilation system, you should choose a more powerful fan that can suppress the resistance in the channel.

It is desirable that the noise level of the device does not exceed 40 dB. It is also important to make sure that the equipment is able to work in conditions of high humidity, has protection against water. Optimum enclosure protection for installation in the shower area or over the bathtub - IP25. She is indicated on the box.

The consumed electric power depends on the speed of rotation of the blades and is about 50-200 watts. There are models with several speed modes.

Exhaust Fan with Check Valve
Fans with a non-return valve help prevent odors from entering the bathroom from other rooms. The valve blocks the cross section after turning off the device

Depending on the installation site, there are wall and ceiling fans.

According to the type of construction, there are:

  • axial - easy to install, easy to operate, medium in performance;
  • centrifugal - have high power, noisy.

As additional functions, a timer, humidity and motion sensors can be provided in the device. The timer turns on the device at the same time as lighting and turns off automatically, taking into account the pre-set delay time.

A useful option for the bathroom is a humidity sensor. It turns off the fan in case of excess moisture. In the toilets they put models with motion sensors. They start the device, detecting movements within the range of visibility and viewing angle.

We talked more about the types of fans and the intricacies of choosing the best in next article.

It’s easy to install a fan yourself. It is necessary to supply power, adjust the dimensions of the exhaust outlet, fix the device inside the ventilation pipes or at the outlet of the socket, depending on the type of construction and connect the switch.

Method # 4 - repair the exhaust fan

If the room is equipped with forced ventilation, a sudden deterioration in air exchange may be due to the fact that the exhaust fan in the bathroom for some reason stopped working.

Fan analysis to identify the cause of the malfunction
Untimely elimination of mechanical breakdowns leads to problems with the electrical part. Therefore, having noticed any signs of a malfunction, an urgent need to be checked

Failures of fans are divided into mechanical and electrical.

The characteristic signs of mechanical problems include:

  • extraneous noise during work;
  • reduction of shaft rotation speed - rotation in the off state manually requires considerable effort;
  • shaft stop - rotation in the off state manually is impossible or occurs with considerable effort.

Electrical failures are accompanied by the smell of burned wiring, the operation of circuit breakers when the fan is turned on, interruptions in operation, difficulties in the process of changing modes. The rotation speed may also decrease, but the shaft will rotate freely manually when the device is turned off.

The most common problem is contamination of bearings, insufficient lubrication of moving elements.

In the presence of extraneous noise and a decrease in speed should:

  • disassemble the fan;
  • clean bearings from dust and dirt;
  • grease parts with a few drops of engine oil;
  • assemble the device.

If the grease does not help, noise and beating of the shaft are maintained during operation, most likely the fan will have to be replaced. Also, a replacement is made when any part, for example, an impeller, is destroyed.

Checking the electrics of the device with a multimeter
When the device does not turn on, it is worth checking the serviceability of the switches and the power cord, the voltage on the electric motor, the performance of the capacitor, and irregularities in the power supply circuit. For this you will need a multimeter

A common cause of a fan breakdown is a fuse blow.In this case, users recommend trying to solder the jumper from the copper wire in place of the failed part and wrap it with insulating tape.

Please note that in the absence of knowledge in the field of electrical engineering and a lack of understanding of the features of the fan device, it is better not to repair it yourself. It is more advisable to contact specialized workshops.

In practice, in most cases, more profitable buy a new devicethan repair a broken exhaust fan in the bathroom.

Conclusions and useful video on the topic

How to clean the ventilation duct from dust and dirt with your own hands:

How to eliminate noise and vibration in an exhaust fan: detailed instructions for disassembling the device and lubricating parts:

Analysis of one of the typical fan malfunctions: what to do if a fuse blows:

Faults are easier to prevent than to fix. Therefore, it is worth annually testing the ventilation in the bathroom, maintaining the cleanliness of the ventilation grilles, periodically cleaning the accessible areas at the inlet of the ventilation duct. It is also advisable to apply measures to improve the circulation of air masses - to ventilate the premises, install window or wall valves.

If ventilation does not work, try to determine the cause of the malfunction and use one of the appropriate methods for repairing and optimizing the system. In case of serious breakdowns, contact the specialists of management companies.

Do you want to supplement the above information with useful comments? Or you still have questions on troubleshooting exhaust hoods, ask our experts and other visitors to the site - the feedback form is located below the article.

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