How to make a hood in a private house: technical requirements and overview of installation rules

Plastic windows and armored doors, on the one hand, maintain the desired temperature in the rooms, but on the other hand, they create problems with air exchange. A well-designed hood in a private home will eliminate the feeling of mustiness and condensation. In most cases, this is the only way to create a healthy microclimate in it.

We suggest that you familiarize yourself with the options for exhaust devices that can improve the microclimate. Together with you, we will analyze the calculations using a specific example. We describe in detail the process of installing a forced version of the hood for those who want to do the installation themselves.

The information provided is based on regulatory requirements. The information is supplemented by illustrations, step-by-step photo guides, diagrams, tables and videos.

Hood options in a private house

Both in public buildings and in private houses, different types of ventilation systems are used. They differ in purpose, in the method of activating air flow and moving air masses. Ventilation system, designed to supply clean air to the house, is called supply air.

The design, the function of which is to remove exhaust air outside the room, is called exhaust. Ventilation with recirculation has a special mission.In this case, part of the air removed from the room is mixed with external cold air masses, with further heating of this mixture to the set temperature and return it to the room.

All points regarding the design of the ventilation system should be thought through at the stage of preparation for building your own home (+)

Air movement occurs as a result of processes that occur naturally due to the displacement of heated air with a lighter weight from the room by cold air, which has a higher volumetric weight.

The flow in such a system moves at low speed, since the weight of the warm and cold mass differs by a small amount. Air duct ventilation with natural impulse is irrational to use if its horizontal length exceeds 8 m.

More effective is a system with artificial activation of air flow, ensured by the operation of fans. The air ducts in this case are longer and can pass through several rooms. System elements are most often placed in the attic. This option is justified for large buildings.

There is a division into ducted and ductless systems. In the first case, the air moves through channels and air ducts, in the second, there is no organized air movement. In this case, you have to open the window transoms and doors. Natural ventilation creates more comfortable conditions for the residents of the house.

Necessary preliminary calculations

The initial parameter for the calculation is the volume of air removed and supplied to the room. There is more than one method, but the most used ones take sanitary standards and room area as a basis.

According to the requirement of the former, it is necessary to start from the fact that the need for air is in m³/h. for one person spending most of the time in the house, it depends on the purpose of the room:

• living room - 40;
• bedroom - 20;
• kitchen - 60;
• bathroom - 25.

Based on the second criterion, we proceed from the following regulatory requirement: per 1 m² of living space there must be 3 m³ replaced air. At calculation of air duct cross-section are guided by the fact that the optimal air speed in the central channel is 5 m/sec, and in the side channel - a maximum of 3 m/sec.

You can independently determine the pipe diameter using the formula:

S = L/3600/v,

where L is productivity measured in m³/h, v - air speed in m/sec.

Data on air consumption depending on the cross-section of the air duct are summarized in the table.

The aerodynamic resistance of an air duct with a circular cross-section is less than with a square one. The square shape is more compact, fits organically into the interior of the room, and has a large range of sizes

Air ducts are made of metal, plastic, aluminum foil, polyester. The last two are flexible systems. Their noise and heat insulation characteristics are good and they are ideally suited for a private home.

Natural air exchange in the house

Natural air exchange is based on the ability of gaseous and some liquid substances with a higher temperature to rise upward. Thus, the exhaust air is naturally removed from the room through a vertically located exhaust duct, drawing in, at the same time, outside air through the supply ducts.

Natural ventilation does not always provide comfort in the house.A mixed version is often used, when in addition to natural air movement, fans are also used (+)

The ineffectiveness of supply ventilation is indicated by excess moisture in the room during cold weather or increased dryness during warm weather. The presence of a large amount of dust and lack of oxygen are also signs of insufficient air flow from the outside.

The consequence of poor exhaust hood is fungus formation under the wallpaper, in the bathroom, soot settling on the kitchen walls, foggy windows.

It is easy to check the operation of the hood. It is enough to bring a sheet of paper to the ventilation grille. With good draft, it will bend towards the ventilation duct, otherwise nothing will happen. It should be concluded that the hood is clogged with something and the channel needs to be cleaned to ensure draft.

To provide a private home with good ventilation, you need to start by calculating the air exchange.Based on its results, the cross-section of the channels, the type of ventilation system are selected and a sketch version of the ventilation scheme is made, where they indicate the locations of the passage of air ducts and the installation of ventilation equipment, the points of intake and output of the air mass.

Private houses are mainly located outside the city, where the air, unlike city air, is cleaner and there is no need for additional purification. Therefore, natural ventilation is preferable for a private home.

A big obstacle to the flow of fresh air are plastic windows, in which there are no cracks, and the glass fits very tightly to the frames.

The output is in the installation of the supply valve. It is placed on the upper frame, so the air coming from the street goes under the ceiling and only after mixing with conventional flows and acquiring room temperature, it goes down.

The location of the exhaust system elements should ensure the passage of air flow covering the entire house in the direction from “clean” rooms to those where the air is most susceptible to pollution.

According to this rule, in rooms with special conditions, which include boiler rooms, kitchens with a gas stove, basements, rooms with fireplaces and speakers, toilets, the presence of a hood is mandatory. Valves are also needed in these rooms.

The design features of the supply valve allow you to ventilate the room without creating drafts or reducing the performance characteristics of the window. In this case, condensation does not form. A slot-type valve, as in the photo, can be installed on an existing window unit

Exist ventilation valves, mounted on the wall.This pipe with a circular cross-section is inserted into a through hole in the wall and covered with gratings both on the inside and on the outside.

As a rule, a wall supply fan can supply 50-100 mᶾ of air per hour into the house. Based on this norm and having performed the appropriate calculation, their optimal quantity is selected

The grille located inside can be adjusted - opened and closed completely or partially. When installing, preference is given to a place near the window. Sometimes the supply valve is mounted behind the radiator and then the incoming air is immediately heated.

Requirements for ventilation of a private house

Sanitary and technical standards put forward a number of requirements for aircraft. When deciding how to make an effective hood in a private home, all points must be taken into account:

1. The inner walls of the channels must be smooth. To ensure this condition, round or rectangular air ducts of constant cross-section are inserted into them.
2. The ventilation riser at the bottom is equipped with an inspection door. It must close tightly.
3. The exhaust duct is installed on the roof with an elevation above it of at least 1.5 m. If the roof has a broken shape, then in order to avoid the occurrence of reverse draft caused by swirling flows, a deflector is installed in the exhaust duct.
4. Ventilation shaft installation. If a ventilation system was not initially provided for in the building, an attached shaft is attached to one of the walls. To improve traction it needs to be insulated.
5. Compliance with ventilation rules. You cannot combine a mechanical kitchen hood with a general air conditioner. A separate channel is arranged for it, otherwise there will be problems with the functioning of natural draft in other rooms of the house.
6. The maximum permissible distance from the ceiling to the top of the ventilation grilles is 150 mm. As this distance increases, zones of stagnant air will appear.

Doors separating adjacent rooms, even when closed, should not impede the flow of air.

The best solution is to purchase a door with a special decorative grille at the bottom. If a solid door is installed, a gap of no less than 2 cm is left between the floor and the door leaf, or a series of holes are drilled at the bottom.

The essence of the basic requirement is that the volume of air to be removed must be equal to the amount of air supplied. If this rule is not followed, then various unpleasant odors will penetrate into the room along with the air. If there is a large imbalance between the volume of incoming air and the exhaust air, drafts will appear.

Combination of ventilation with recirculation

Recirculation is called SW, when the air removed from the room is returned back through the influx with an admixture of fresh air. The disadvantage is that its use is limited by SNiP, and in regions with cold climates it does not work very effectively. Its action is limited to one room.

Recirculation allows you to save on energy consumption due to the fact that power is spent only on heating a small volume of air mass taken from the street

The recirculation system diagram can be turned into an ordinary one supply and exhaust ventilation by closing the recirculation valve and fully opening the supply and exhaust valves. If you do the opposite, the system begins to circulate air in a circle.

When the supply and exhaust valves are only partially opened, fresh outside air will begin to be mixed in.By adjusting the degree of opening, they optimize the flow of elements that ensure comfortable life.

Installation of forced exhaust in a private house

Forced air exchange compares to natural air exchange in many respects:

1. It works regardless of the weather.
2. Cleans the air more effectively.
3. It is possible to adjust the rotation speed and power of the fans.
4. The air flow can be set in motion not only with the help of a duct fan, but also by using monoblocks, which are easy to install.

The main disadvantages are dependence on power supply and the need to periodically replace individual elements. There are several mechanisms for forced ventilation.

This can be a single supply and exhaust unit, a set-up supply system, an exhaust system, or a ducted air conditioner. The supply and exhaust SV is considered the most effective. The design includes a fan, automation, sensors, filters.

The spread of cold air in the room during supply and exhaust ventilation is prevented by a special damper located in the housing

Forced exhaust in the standard version has a single fan and is intended for small rooms. In a kit-type SV, the equipment is the same, but it is placed separately. System power is in the range of 80-7,000 m³/h.

From the practical recommendations of experienced craftsmen, it follows that in a small house consisting of 2 rooms, a hood that processes from 200 to 300 m³ air per hour.

In large buildings it is necessary to install hoods with a capacity of 350 to 500 m³/h.

Kitchen hood installation technology

The hood in the kitchen is usually placed above the stove. It is necessary that the exhaust hood protrudes beyond the stove by 100-150 mm.

Performance is selected based on room parameters using the formula:

P = S x H x 12

Where the first symbol indicates the power of the second - the area of ​​the third - the height of the kitchen.

Depending on the installation method, kitchen hoods can be suspended, wall-mounted, island-mounted, built-in, and based on the type of operation they can be circulation or supply

Air ducts usually follow an indirect path, which can result in reduced exhaust power. To guarantee, 30% is added to the value obtained as a result of the calculation. The installation technology is simple, so once you understand the circuit, you can do all the work yourself.

When there is no built-in aircraft. then first make a hole in the wall, matching in diameter with the cross-section of the exhaust pipe. If you neglect this recommendation, the work will be accompanied by increased noise, and the air will come out at a lower speed.

The structure itself is located at a distance of at least 0.7 m from the surface of the electric stove and 0.8 m from the gas stove.

The next step is marking the fastening. Sometimes the hood kit includes a template, but if you don’t have one, you can use a level and tape measure. Next, fix the exhaust hood, keeping it horizontal.

The structure is connected to the previously made outlet, connected to the electrical network and tested. If the house has a gas water heater, then the ventilation pipe can be led into the chimney of the boiler or heating furnace.

The following photo selection will demonstrate the process of installing a kitchen hood with a masking dome:

Forced exhaust of a bathroom in a private house

In the bathroom for forced ventilation, exhaust fans operating in a humid environment are installed:

1. supply power to the room and install an outlet;
2. a hole is made in the wall corresponding to the cross-section of the fan coupling;
3. the coupling is placed in the hole;
4. drill mounting holes;
5. connect the cable;
6. Having removed the front panel from the fan, attach the latter to the wall;
7. return the removed panel to its place;
8. a grille is attached to the outside.

It is advisable to use such a system in a bathroom located on the second floor. Typically, the air supply of this room with the obligatory presence of a ventilation shaft is included in the project. Air flow is carried out through the gap between the floor and the door, as well as through the vents.

To create forced ventilation in the bathroom, a fan is built into the air exchange system. It pulls exhaust air out of the room, opening the way for a new portion of air to enter from neighboring rooms

Sometimes, as an option to solve the problem of how to make an outlet in the combined bathroom of a private house, something like a drainpipe with a recommended diameter of 110 mm protruding above the roof level is installed along the wall of the building.

In device ventilation of hygienic premises Axial fans are used, which are installed in the standard sequence:

Basement ventilation device

For basement simple and effective ventilation is needed, otherwise it will not meet the demands placed on it. For installation you need 2 pipes with a cross-section from 80 to 150 mm, thermal insulation, protective canopies, grilles.

The supply pipe is mounted at one end into the wall, at a distance of about 0.3 m from the floor. The top of the pipe, approximately 5.5 m long, should run along the outer wall. The draft is provided by the temperature difference in the upper and lower parts of the pipe.

Only the supply and exhaust version of the ventilation system can cope with the ventilation of large basements. Vertical air ducts are placed in the corners, an exhaust duct is placed under the ceiling, and a supply duct is placed at a certain height above the floor surface.

The top of the pipes is protected with visors, which, in addition to their protective function, play an important role in regulating the speed of air passage.

The intensity of the draft also depends on the difference in the lengths of the supply and exhaust pipes. The greater this difference, the more powerful the flow.Normal ventilation should provide 2 air changes within 60 minutes.

Conclusions and useful video on the topic

Video #1. How to implement a ventilation project according to all the rules:

Video #2. Familiarization with the work of natural ventilation:

Numerous factors influence the ventilation efficiency of your own home. When choosing an aircraft type and performing calculations, everything needs to be taken into account. Only if this condition is met will it function flawlessly.

Please write comments in the open block form below the text. We are waiting for your stories about the design and use of exhaust systems. Here you can ask questions and point out any shortcomings if you find them in the information presented for review.