For the normal life of a person in a room, whether it be an apartment or a production workshop, a supply of clean fresh air is necessary. You can, of course, open the window. But in this case, dust, exhaust gases, and other harmful substances will enter the room along with the air. It is especially difficult for people living on the first floors. As for industrial premises, air pollution alone cannot solve the problem of air pollution.
Various ventilation systems are being developed to ensure the supply of clean air masses. One of the most common is the supply and exhaust system. We will talk about it in the article.
General information
Systems of supply and exhaust air ventilation provide clean air for rooms of any size in any building. They provide several levels of filtering. Due to this, dust, unpleasant odors do not penetrate into the room.
The supply and exhaust ventilation system, in addition, ensures the elimination of odors generated in the kitchen and in the bathroom: they do not spread throughoutapartment, but are instantly absorbed.
Poor indoor air circulation can lead to serious negative consequences:
- Violation of the activity of the central nervous system and the cardiovascular system.
- Decrease in performance.
- Increase humidity.
- Development of fungus, other pathogenic microorganisms.
- Increasing the amount of harmful substances.
Classification
The supply and exhaust ventilation systems of buildings are divided into several types depending on:
- Principle of indoor air movement.
- Direct destination.
- Service areas (local and general).
- Principle of execution (channel and non-channel).
Forced air circulation
Such supply and exhaust systems are equipped with automation, various electronic devices, fans, allowing 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 by physical phenomena. Among them:
- Temperature changes. The difference between the air temperatures outside and inside the room causes it to move. Warm masses rise to the top, and cold - heavy - fall down.
- Differences in air pressure on the lower and upper floors.
Such systems are usually low power. They are used in small spaces. The advantage of suchsystems are considered to have no energy costs.
Constructive 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 turned off, the valves prevent the penetration of cold streams.
- Air filters. These elements are designed to clean the air coming from outside from various impurities, insects, etc.
- Air ducts with fittings. They provide 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 main parameters are monitored.
Additional items
In some supply and exhaust systems are also installed:
- Coolers.
- Throttle valves.
- Recuperators.
- Air heaters.
- Humidifiers, etc.
Additional elements provide adjustmenttemperature, humidity and other indicators.
Working principle
At first glance at the supply and exhaust system, you might think that it is very complex. But in fact, its device is quite simple.
A network of special channels is laid throughout the premises. They carry air into the room. Through the exhaust channels, respectively, it is brought out. To ensure the flow of air masses, a fan is installed.
A convector is being installed in the room. First of all, it cleans the outdoor air. Secondly, depending on the temperature outside and inside, as well as on the season, heating or cooling of flows can occur. The temperature level is set during setup.
A powerful fan draws air into the system, creating a pressure drop. The air available in the room independently enters the exhaust ducts, as a result, the pressure stabilizes.
As a rule, streams are filtered using an ultraviolet lamp. However, at the discretion of the owner of the premises, a foam or santonin filter can be installed.
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 the air channels themselves without any restrictions.
Difficulties arise for the owners of apartments in high-rise buildings. In a building design, as a rule,a ventilation system is provided. It provides air exchange throughout the house. You can install an individual system if it does not affect the supporting structures and does not damage the appearance of the structure.
Preparation for installation of the supply and exhaust system
It should be said right away that even a non-professional can install the equipment. The main difficulties may arise at the preparatory stage.
Before you mount the system, you need to calculate the parameters. For example, for a room volume of 700 m3, to ensure efficient circulation, the air supply should be in the range of 300-400 m3/hour. If the indicator is higher, the power consumption will increase, if it is lower, the system will not function fully.
Installation is carried out according to the project. The diagram marks the installation sites for sleeves and other elements.
Experts recommend installing the central air duct first, and from it to lay channels to other rooms.
Specifications
The ventilation system in the apartment should be:
- Compact.
- As silent as possible.
- Providing effective air filtration.
Of course, the system must be in harmony with the interior. Dimensional elements, if possible, should be installed outside the room or under the ceiling. At the same time, they must be provided with access for repairs.
There are also a number of requirements for the supply and exhaust ventilation system in a private house. First of all, it must be powerful. The system should be designed in such a wayso that the channels pass through all the premises. It is advisable to provide automatic control. As a rule, it is provided using wi-fi.
Design
As a rule, it begins with the drawing up of a building plan. The drawing indicates the area and purpose of each room. Based on the plan, a wiring diagram is created. The following parameters are required for the calculation:
- The performance of the system, which will provide the necessary air circulation.
- The pressure level created by the fans.
- Acceptable noise level.
- The speed of air flows in the ducts and the size of their section.
- Heater capacity for outside air.
When designing, the existing norms of air exchange in the room should be taken into account. They are installed depending on the area and the number of people in them.
For a dwelling, 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.
Calculation
It is carried out according to several parameters related to each other:
- Working pressure and airflow speed.
- Shape and cross-sectional area of air ducts.
- Noise level.
The operating pressure is influenced by the technical characteristics of the fans, in particular, their performance and the total pressure created in the working area, sizesection 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 air 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 generated by the fan must be greater than the total losses in the system. Accordingly, the longer and more complex in configuration and device the duct network, the greater the fan power should be.
Flow rate
The mechanical supply and exhaust ventilation system should provide an air speed of 3-5 m/s. If the indicator is exceeded, the working pressure decreases, strong aerodynamic noise occurs, the level of which exceeds the permissible levels in working and residential premises.
Calculation of the cross-sectional area of air 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 a residential area is 500 m3/h, and the air velocity is 5 m/s, the round duct must have a diameter of at least 200 mm, and the cross-sectional area of a square duct must be at least 160x200 mm.
Air heater power
It depends on the outside air temperature and the performance of the whole system. The calculation is carried out according to the formula:
Power (in watts)=temperature difference between inlet and outlet x capacity/2.98 (constant factor).
For example, if the air exchange in the apartment is 400 m3/h, the temperature differenceis 28 degrees (-10 outdoors, +18 indoors), the power will be:
40028/2, 98=3.8KW(3758W).
Residential premises use heaters with a power of 1-5, and in offices - 5-20 kW.
Air supply and exhaust ventilation system with heat recovery
In such a system, the heated air flow is taken in by air intakes from rooms where the humidity level is the highest: from the kitchen, bathroom, utility room, etc. It is brought out through the air ducts. But before that, the flow passes through a heat exchanger, in which it leaves part of its heat. They subsequently heat up the cold air coming from outside. This flow also passes through the heat exchanger, but in a different direction. The heated air is directed to other rooms: living room, bedroom, etc. As a result, constant circulation is ensured in the room.
The supply and exhaust system with recuperation can have different power and size. Everything will depend on the total volume of the premises, their purpose.
The simple design is a set of interconnected components encased in an acoustically and thermally insulated steel case:
- 2 fans.
- Heat exchanger.
- Filters.
- Condensate removal system.
During operation, the heat exchanger passes 2 air streams through itself: external and internal. However, they do not mix with each other.
Forward-looking home craftsmen install two networks at once: natural(gravitational) and forced supply and exhaust system with recuperation. The first is emergency. It is used when there is a problem with the forced system and, as a rule, during unheated times.
It must be remembered that during the operation of the forced system, the air ducts of the gravity duct network should be tightly closed, otherwise it will lose its effectiveness.
Plate heat exchangers
Special plates are used in the design of the system. Supply air and exhaust air flow on both sides.
Condensation can accumulate on the plates, so the system must be provided with outlets for it. Water seals are installed in the condensate collectors. They prevent the fans from capturing moisture and feeding it into the duct.
Condensation may cause ice to form. Accordingly, there must be a defrost system.
Recovery can also be controlled with a bypass valve. It controls the flow of air passing through the plates.
Rotor devices
In such ventilation systems, heat is transferred by a rotor rotating between the supply and exhaust air ducts.
This system is open. Accordingly, there is a high probability of odors penetrating into the supply air from the exhaust stream. This situation can be prevented by proper placement of fans.
Recovery level is controlled by changing the rotor speed.
In such a system there are mobileparts. The risk of freezing is quite low.
Intermediate coolant
As it is used water or water-glycol 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.
The heat carrier is heated by the removed flow. The heat is transferred to the outside air.
The coolant is circulated in a closed network. Accordingly, the possibility of contamination from one stream to another is excluded.
Heat transfer can be adjusted by adjusting the speed of movement of the coolant.
Extra
Recently, many homeowners are installing modular ventilation systems. They are a complex of components, including:
- Filter element.
- Fan.
- Air heater.
- Auxiliary knots.
- Automatic.
- Noise silencer.
The undoubted advantages of the system are its mobility, the ability to select components of the required power. The disadvantage of this model is the complexity of the design. Special knowledge is required to create a circuit.
Another type of supply and exhaust ventilation is a monoblock system. It is made in the form of a block, which houses all the main components. The undoubted advantage of this model is the ease of installation. Installation can be performed even by a non-professional. However, the cost of such a system is much higher than other types.
