Supply and exhaust fan

Supply and exhaust fan

The availability of ventilation was provided for by building codes more than a hundred years ago, but recently this aspect has received more attention. This is due to the positive impact of quality ventilation systems on the life of building materials. Up to a certain point in the houses only hoods or vents were installed, as they are more commonly called. At the same time, the influx was carried out in a natural way. Such a system was rarely characterized by high productivity, so a more sophisticated supply-and-exhaust system was developed. Its main element is the fan. What are the types of supply and exhaust fans and what is really their advantage? This will be discussed in the article.

General concepts

The supply and exhaust fan can not act as an independent module. In order for it to perform its functions, it will be necessary to install an entire system, which also includes channels for supplying and discharging air from the room. The ventilation process in this case is carried out in a forced mode. Installing a supply and exhaust fan into the system has many advantages, among which:

  • quality removal of moisture;
  • rapid elimination of unpleasant odors;
  • decrease in the amount of fungal spores in the air;
  • reduction in the amount of dust;
  • increase of oxygen content;
  • simplicity of maintaining the microclimate.

The result of the process of breathing humans and animals is the release of steam. It also stands out during cooking and when visiting the bathroom. The temperature of the vapor is higher than that of the surrounding objects and planes. Such a drop leads to a condensation process. Its result is not only the deterioration of building materials, but also the development of various fungi and mold. Forced ventilation system allows the timely removal of steam, preventing the process of condensation. The main role in this is played by the supply and exhaust fan.

On clothes and mucous membranes a person brings home a significant number of viruses and spores of fungi. If there is no ventilation system in the room, they will accumulate, leading to various diseases. The supply and exhaust fan forcibly moves the air masses, bringing clean air from the street. The latter has antiseptic properties, therefore it destroys a significant number of fungi and viruses. Most likely, everyone noticed that with prolonged stay in a closed room there is drowsiness. This is due to the decrease in the amount of oxygen contained in the air. In such conditions, labor productivity is significantly reduced. The supply and exhaust fan solves this problem in a short time, supplying a fresh portion of air.

In addition to the fan itself in the supply and exhaust system, there are also such elements:

  • duct connections;
  • check valve;
  • control module;
  • filters.

The whole system functions precisely due to the blowing fan. The remaining elements are auxiliary. Smaller noise during operation and greater productivity is enjoyed by radial fan designs, but in some cases axial intake and exhaust fans are used. The task of the check valve, which is mounted in the system, is to prevent the reverse air current if the pressure difference is significant.

In order for the air mass to flow continuously, two main channels are provided, as seen in the diagram above. According to one of them, air is supplied from the street, and the second is the discharge of waste mass. The process is fully automated due to the control module. It receives information from various sensors, based on which there are changes in the rate of supply or discharge of air from the room. In some cases, it is also responsible for driving a non-return valve that opens or closes it.

Work algorithm

In the illustration above, you can follow the principle of the supply and exhaust system. The whole cycle is divided into three stages:

  • inflow and purification;
  • fence and transportation;
  • ejection.

Usually, rough filters are installed at the inlet, the purpose of which is to prevent dust and dirt from entering the duct system. After cleaning, due to the pressure blowing by the fan, air masses are supplied from the street to each room where the channels are supplied. Continuously with this process, air is released from the premises. Supply and intake grilles are located at different levels. The discharged air is not cleaned, but a partial exchange of heat energy occurs to reduce heat loss and save on heating.

The pressure, temperature and humidity sensors are connected to the module that controls the intake and exhaust fan. They are located in different zones, so that the readings are with minimal error. Thanks to the information received, the supply and exhaust system goes to a level of operation in which free circulation of cold air through the system and premises is excluded. This ensures a high-quality airing of the house, and not its cooling in the cold season, as it happens with an open window or window.

The downside of the decision to install a supply and exhaust fan is its cost. The total amount should also include the amount that will be spent on installation. The latter should be carried out by professionals. The technique does not do without maintenance, as far as the fan, so regular waste will go to this. But, since you can not buy health, it is better to take preventive measures to preserve it.

Varieties of structures

The supply and exhaust systems differ not only in the installed fan inside, but also in the way of the temperature exchange between the incoming and outgoing masses. This applies to both heating and cooling the air. The following modules are used for the procedure:

  • recuperator;
  • heater;
  • air conditioning.

Some of them can work in pairs.

Fan with recuperator

The use of a heat preservation system in the supply and exhaust ventilation is mandatory so that its efficiency can be considered high. Several variants of heat exchangers were developed, which differ in their efficiency and complexity of the device. These heat exchangers are also called recuperators. Among the main species are:

  • liquid;
  • rotary;
  • lamellar.

Each of their modules has its advantages and disadvantages.


In addition to the fan that performs the air injection into the ventilation system, there is one in the rotary recuperator. It is structurally different from the main one and performs the function of heat exchange. His blades are simultaneously in two chambers and move the air from one to the other, producing a partial mixing of the fresh and worked-up masses. Due to this, heat exchange takes place, and the temperature of the incoming air rises to a suitable one, in order to reduce the cost of heating. Quality products of this type can compensate up to 90% of heat loss.

Adjust the performance of the system with this module is possible not only due to the intensity of rotation of the main fan, but also by varying the speed of the blades of the heat exchanger. The disadvantage of such a supply and exhaust module of the ventilation system is some of its noise, which is eliminated by special pads. Maintenance of such blades also causes certain difficulties and has a short periodicity.


The design and mode of operation of the plate-type exchanger is somewhat simpler than the previous version. A striking difference is the lack of additional rotating parts. The illustration shows that the air masses before the discharge or before entering the room pass through a special block. It is divided into two sealed compartments through which the rows of metal plates pass. It is thanks to them that heat transfer takes place. Advantages can be considered the absence of the effect of mixing, and therefore unpleasant odors do not return to the room. Serving such a component is much simpler than the previous one.

From the minuses of such a module for the supply and exhaust system can be distinguished formation of condensate during the passage of air. Such modules are not recommended for installation with intake and exhaust fans in areas with a cold climate. This can lead to frost formation and complete blockage of the supply and exhaust fan. Overview of the working system of supply and exhaust ventilation is in the video below.

Additional Features

Together with the supply and exhaust fan, a heating module can be installed. Its task is to warm the air to a higher temperature before it is delivered to the premises. This is necessary in those areas where in winter the temperature drops to low values. If there is no additional heating, the conventional recovery module will not cope with the task of saving heat in the room. In the supply and exhaust system, two types of heaters are installed. One of them is a plate heater, which is mounted directly into the channel. The air heats up, passing through it. With respect to such a heater, strict requirements are imposed for the preliminary filtration of air, as well as for the periodicity of maintenance. Another option for the supply and exhaust fan is a liquid heating system. In this case, radiators are installed, through which pipes with circulating liquid are laid. Such a system is more reliable.


In addition to stationary supply and exhaust fans, which were mentioned in the article, there are compact stand-alone fan designs. They perform the same functions as stationary, but are installed separately for each room and do not require a complex isolation of the ventilation ducts.

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