We calculate the height of the pipe above the roof according to the norms and snips

To create the right microclimate in the house, you need to equip it with an air circulation system. To ensure its efficient operation, it is necessary to correctly calculate the length and diameter of the pipe that removes air from the house. Calculations are performed by various methods, depending on what type of ventilation system is installed in the house.

Incorrect pipe height above the roof contributes to the occurrence of oxygen deficiency in the house and exceeding the permissible humidity. If an error was made in the design of the hood, soot and fungus will appear on the walls and furniture, and the windows will be constantly covered with perspiration.

Ventilation calculation

Ventilation usually consists of round or square ventilation ducts. If special devices are not used to remove air, then the best option would be to install round ducts. Compared to square ones, they are distinguished by higher strength, tightness and better aerodynamic performance. If the room is equipped with forced ventilation, then in this case it is possible to install square pipes.

The volume of incoming air

As a rule, residential buildings are equipped with natural air circulation. The inflow of outside air can be carried out through a window or a special valve. The outflow occurs through the ventilation duct. It can be located inside the wall or designed as an attached. It is impossible to equip the ventilation channel in the outer wall, since in this case condensation may form on the surface, which will lead to damage to the structure. Also, due to cooling, the speed of air movement may decrease.

The values ​​​​for ventilation pipes in residential buildings are determined by the established requirements that are regulated by SNiP. Equally important is the frequency of exchange, reflecting the quality of the ventilation system. So, the volume of air flowing into the room should have the following values:

• in a residential building - 3 m³ per hour per square meter. Moreover, this indicator does not depend on how many people are in the room. Sanitary standards establish that 20 m³ per hour of supply air is sufficient for temporarily staying people in a building, and 60 m³ is required for permanent residents;
• in an auxiliary building (for example, in a garage) - at least 180 m³ of air per hour.

To calculate the diameter of the ventilation pipe, a system is used in which there is only natural air inflow, without installed forced devices. The simplest way to calculate is the ratio of the area of ​​the room to the cross section of the opening of the ventilation channel.

For a living space per square meter, 5.4 m² of duct section is required, and for an auxiliary one - 17.6 m². With a diameter of 15 m², sufficient air circulation will not be ensured. To obtain more accurate figures, complex calculations must be used.

Pipe length

All channels available in the building are connected to the ventilation pipe, through which air moves through the pipe to the street.

To calculate the height of this pipe, you need to know its diameter and have a special table. The cells in the tables contain the values ​​of the duct sections, and the left column indicates the width of the pipes. The top line shows how high the pipe should be at a certain diameter in millimeters.

It is necessary to take into account the following norms of SNiP:

1. When located next to the chimney and ventilation pipes, their height should be the same. If this requirement is not observed, smoke from the heating unit may enter the room.
2. If the air duct is located no more than 1.5 m from the ridge, then its height should not exceed 0.5 m. If the pipe is 1.5-3 m away from the ridge, it should not be located below it.
3. If the roof is flat, then the pipe should be at least half a meter.

When choosing a ventilation pipe and determining its location, it should also be taken into account that it must have sufficient resistance to wind. So, the pipe must withstand a 10-point storm, and for this its weight must be about 50 kg per 1 square meter of surface. The picture shows how the height of the ventilation pipe above the roof is calculated.

Special programs can also be used to determine natural ventilation. In this case, the calculation process is greatly facilitated. To do this, it is necessary to determine the optimal amount of air supplied to a residential or utility room, respectively. The program also defines the following data:

• average temperature outdoors and indoors;
• the shape of the air pipe;
• the degree of roughness of the walls inside the duct;
• the resistance created by the movement of air.

As a result, the program determines how long the vent pipe should be to ensure optimal air movement under given conditions.

When calculating the values ​​for the duct, it is also necessary to take into account the resistance indicators for the movement of air flows. The occurrence of resistance is influenced by grids, gratings and other structural details.

Pipe diameter

To calculate the values ​​of ventilation pipes based on the air exchange rate, the SNiP table is used. The air exchange rate is understood as an indicator that determines how many times the air in the room changes in one hour. Before calculating the diameter of the vent pipe, you must perform the following steps:

• Calculate the volume of each of the available rooms.
• Determine the volume of air required for normal circulation. For this, the formula is used:

Using the above formula, the volume is calculated separately for each room.

• As a rule, for rooms, the rationing of the exhaust or inflow is used. Sometimes in rooms it is necessary to organize not only the flow of air, but also its effective outflow.
• When making calculations, keep in mind that the value of L should be rounded up. After rounding, the resulting value must be divisible by 5.
• After determining the required air volume for the entire area of ​​\u200b\u200bthe dwelling, a special diagram is used to calculate the diameter of the pipe. In this case, you should know that in the central ventilation pipe the speed should be no more than 5 m / s, and in its branches - no more than 3 m / s.

SNiP requirements for air ducts

The requirements of SNiP provide for checking and cleaning the chimney and ventilation pipes:

• before the onset of the heating season;
• at least 1 time in 3 months (for combined and brick channels);
• at least once every 12 months (for asbestos-cement channels and chimneys, as well as for pottery pipes and pipes made of heat-resistant concrete).

During the initial check of ventilation channels and chimneys, the materials from which they were made, the presence of blockages in the channels, the presence of separate smoke and ventilation ducts are checked. The norms of SNiP categorically prohibit the removal of waste combustion products through the ventilation duct.

The homeowner has the right to clean the ventilation ducts only after passing the briefing and with the appropriate document on the briefing passed. When starting the construction of a ventilation pipe, the owner is obliged to notify the operating organization, which is the owner of the house, about this. Upon completion of the work, the same organization must check and give permission to operate the duct.

Building a quality system that allows you to control the level of moisture and provide the best conditions for living is a completely feasible task. To do this, you just need to correctly calculate the parameters of the ventilation pipe.