For normal human life in the room, whether it is an apartment or a production workshop, it is necessary to supply clean fresh air. You can, of course, open the window. But in this case, dust, exhaust gases, and other harmful substances will enter the room with air. It is especially hard for people living on the first floors. As for production facilities, the problem of air pollution cannot be solved in them with one ventilation.
To ensure the flow of clean air masses, various ventilation systems are being developed. One of the most common is the supply and exhaust system . We will talk about it in the article.
General information
Supply and exhaust ventilation systems provide clean air to rooms of any size in any building. They provide several levels of filtration. Due to this, dust, unpleasant odors do not penetrate the room.
The supply and exhaust ventilation system , in addition, ensures the elimination of odors formed in the kitchen and in the bathroom: they do not spread throughout the apartment, but are instantly absorbed.
Poor air circulation in the room can lead to serious negative consequences:
- Violation of the central nervous system and the cardiovascular system.
- Decreased performance.
- Increase humidity.
- The development of fungus, other pathogenic microorganisms.
- Increase the amount of harmful substances.
Classification
Supply and exhaust ventilation systems of buildings are divided into several types, depending on:
- The principle of movement of air in the room.
- Direct destination.
- Service areas (local and general).
- Execution principle (channel and non-channel).
Forced air circulation
Such supply and exhaust systems are equipped with automation , various electronic devices, fans, which allow for forced air circulation in the room.
The disadvantage of such systems is the consumption of large amounts of energy.
Natural air exchange
In such supply and exhaust systems, the movement of air flows is provided due to physical phenomena. Among them:
- Temperature differences. The difference between the temperatures of the air outside and inside the room leads to its movement. Warm masses rise up, and cold masses heavy fall down.
- Differential air pressure on the lower and upper floors.
Such systems, as a rule, are low-power. They are used in small rooms. The advantage of such systems is the lack of energy costs.
Structural elements
The supply and exhaust air conditioning system consists of two independent channels for removing and supplying air. In each of them there are separate devices connected to each other by air ducts. As a rule, the main structural elements of the flow-exhaust system are:
- Air intake grilles. They provide airflow from the outside and prevent foreign objects from entering the system.
- Air valves. With their help, the flow rate of air penetrating from the outside is regulated. When the system is shut off, the valves prevent the penetration of cold flows.
- Air filters. These elements are designed to clean the air entering from the outside from various impurities, insects, etc.
- Ducts with fittings. They provide the connection of all elements of the system into one air distribution network.
- Air distributors. They provide movement of flows indoors.
- Electronic devices. With their help, the operation of individual network components is controlled and their basic parameters are monitored.
Additional items
Some supply and exhaust systems also install:
- Coolers.
- Butterfly valves.
- Recuperators.
- Air heaters.
- Humidifiers, etc.
Additional elements provide adjustment of temperature, humidity and other indicators.
Principle of operation
At first glance at the supply and exhaust system, you might think that it is very complex. But in fact, her device is quite simple.
A network of special channels is laid throughout the room. Through them, air enters the room. Through the exhaust ducts, respectively, it is brought out. To ensure the flow of air masses, a fan is installed.
A convector is mounted in the room. Firstly, it purifies the street air. Secondly, depending on the temperature outside and inside, as well as on the time of year, heating or cooling of the flows can occur. The temperature level is set during the setting process.
A powerful fan draws air into the system, which creates a pressure drop. The air available in the room independently enters the exhaust ducts, as a result, the pressure stabilizes.
As a rule, the filtration of flows is carried out using an ultraviolet lamp. However, at the discretion of the owner of the premises, you can install a foam or santonin filter.
Nuance
It is worth saying a few words about the features of the installation of the supply and exhaust system . There are no particular problems in private homes. Owners of low-rise buildings can lay all air channels independently without any restrictions.
Difficulties arise for apartment owners in multi-storey buildings. In the building project, as a rule, a ventilation system is already provided. It provides air exchange throughout the house. An individual system can be installed if it does not affect the supporting structures and does not damage the appearance of the structure.
Preparing for the installation of the supply and exhaust system
It is worth saying right away that a layman can also install equipment. The main difficulties may arise at the preparatory stage.
Before mounting the system, you need to calculate the parameters. For example, for a room volume of 700 m3, to ensure effective circulation, the air supply should be in the range of 300-400 m3 / hour. With a larger indicator, the energy consumption will increase, with a lower indicator, the system will not function fully.
Installation is carried out according to the project. The diagram marks the mounting areas of the sleeves and other elements.
Experts recommend first installing the central air channel, and from it to lay channels in other rooms.
Technical requirements
The ventilation system in the apartment should be:
- Compact.
- As silent as possible.
- Provides effective air filtration.
Of course, the system should be in harmony with the interior. Whenever possible, dimensional elements should be installed outdoors or under the ceiling. Moreover, they must be provided with access to carry out repairs.
A number of requirements are also imposed on the supply and exhaust ventilation system in a private house. First of all, it must be powerful. The system must be designed so that the channels pass through all rooms. It is advisable to provide automatic control. As a rule, it is provided using wi-fi.
Design
As a rule, it begins with a plan of construction. The drawing indicates the area and purpose of each room. Based on the plan, a wiring diagram is created. For calculation, the following parameters are required:
- System performance at which the necessary air circulation will be provided.
- Pressure level created by fans.
- Permissible noise level.
- The speed of the air flow in the ducts and the size of their cross section.
- Heater power for air coming in from the outside.
When designing, one should take into account the existing norms of air exchange in the room. They are set depending on the area and the number of people in them.
For residential premises, the norm is 2-3 m3 / hour per 1 m2 or 20-30 m3 per person. In domestic premises (bathroom, kitchen, etc.), these parameters increase by 2-3 times.
Payment
It is carried out according to several parameters related to each other:
- Operating pressure and air velocity.
- The shape and cross-sectional area of the ducts.
- Noise level.
The operating pressure indicator is affected by the technical characteristics of the fans, in particular, their performance and the total pressure created in the working area, section size and type of pipelines, their length, the presence of transitions, turns and other additional elements in the system.
When calculating, it is necessary to take into account the specific pressure loss in the ducts. They are measured in Pascals per 1 meter (linear) of the pipeline. Specific losses are measured according to a special diagram.
The total pressure created by the fan must be greater than the total loss in the system. Accordingly, the longer and more complicated the configuration of the duct network, the greater should be the fan power.
Flow rate
The system of mechanical supply and exhaust ventilation should provide an air speed of 3-5 m / s. When the indicator is exceeded, the working pressure decreases, strong aerodynamic noises occur, the level of which exceeds the permissible levels in working and residential premises.
The calculation of the cross-sectional area of the ducts is carried out taking into account the required air flow and flow rate according to the diagram. For example, if the air exchange in the living room is 500 m3 / h and the air speed is 5 m / s, the round duct should have a diameter of at least 200 mm and the square cross-sectional area should be at least 160x200 mm.
Air heater power
It depends on the outside temperature and the performance of the entire system. The calculation is carried out according to the formula:
Power (in W) = temperature difference at the inlet and outlet x output / 2.98 (constant coefficient).
For example, if the air exchange in the apartment is 400 m3 / h, the temperature difference is 28 degrees (-10 on the street, +18 indoors), the power will be as follows:
400 * 28 / 2.98 = 3.8 kW (3758 W).
In residential premises, heaters with a power of 1-5 are used, and in office ones - 5-20 kW.
Supply and exhaust ventilation system with recovery
In such a system, the heated air flow is taken in by the air intakes from the rooms in which the humidity level is highest: from the kitchen, bathroom, utility room, etc. It is led out through the air ducts. But before that, the flow passes through a heat exchanger, in which it leaves part of its heat. He subsequently heats the cold air entering from the outside. This flow also passes through the heat exchanger, but in a different direction. Heated air is sent to other rooms: the living room, bedroom, etc. As a result, the room provides constant circulation.
The supply and exhaust system with recovery can have different power and size. Everything will depend on the total volume of premises, their purpose.
A simple design is a set of interconnected components enclosed in a steel case, acoustically and thermally insulated:
- 2 fans.
- Heat exchanger.
- Filters
- Condensate removal system.
In the process, the heat exchanger passes 2 air flows through itself: external and internal. However, they do not mix with each other.
Farsighted home craftsmen install two networks at once: a natural (gravity) network and a forced supply and exhaust system with recovery . The first is emergency. It is used for malfunctions of the forced system and, as a rule, in unheated time.
It must be remembered that during the operation of the forced system, the ducts of the gravitational duct network should be tightly closed, otherwise it will lose its effectiveness.
Lamellar recuperators
The design of the system uses special plates. Supply and exhaust air passes on both sides.
Condensation can accumulate on the plates, so taps for it must be provided in the system. Water gates are installed in the condensate collectors. They prevent the capture of moisture by the fans and its supply to the channel.
Condensation may cause ice to form. Accordingly, there must be a defrosting system.
Recovery can also be controlled using the bypass valve. It controls the flow rate of air passing through the plates.
Rotary devices
In such ventilation systems, heat is transferred by a rotor rotating between the supply and exhaust air channels.
This system is open. Accordingly, odors are likely to enter the supply air from the exhaust stream. This situation can be prevented by the correct placement of fans.
The recovery level is regulated by changing the rotor speed.
In such a system, moving parts are present. The risk of freezing is rather low.
Intermediate heat carrier
As it is used water or a water-glycolic solution. In such systems, the coolant circulates between the heat exchangers. One of them is located in the exhaust, and the second - in the supply channel.
Heating of the heat carrier is carried out by a removed stream. Heat is transferred to the air entering from the outside.
The coolant is circulated in a closed network. Accordingly, the probability of pollution from one stream to another is excluded.
Heat transfer can be adjusted by adjusting the speed of movement of the coolant.
Additionally
Recently, many homeowners have installed modular ventilation systems. They are a complex of components, including:
- Filter element.
- Fan.
- Air heater.
- Auxiliary nodes.
- Automation.
- Silencer
The undoubted advantages of the system are its mobility, the ability to select the components of the necessary power. The downside of this model is the complexity of the design. To create a scheme will require special knowledge.
Another type of supply and exhaust ventilation is a monoblock system. It is made in the form of a block in which all the main components are located. An undoubted advantage of this model is the ease of installation. Installation can be performed even by a layman. However, the cost of such a system is much higher than other types.