In any apartment building, even during construction, a ventilation system is designed. It is designed for comfortable living of all residents of a multi-storey building. Well-arranged ventilation guarantees an influx of fresh air into each apartment, while it removes the exhaust, rich in carbon dioxide, air, as well as unpleasant odor and dust particles.
During operation of the ventilation system, traction may change, and air from the neighbors may enter the room. To prevent this from happening, you need to mount a check valve, which closes automatically when the direction of air flow changes.
The technique of doing the valve with your own hands is not complicated. It is also not difficult to find the necessary materials and tools for the job. Following the step-by-step instructions and expert advice, all work on the device and installation of the valve can be done independently.
The need to install a check valve
Vent check valve for natural ventilation allows air to flow in one direction. In the event of a change in direction, the sash closes, which is an obstacle to the entry of air masses into the room. A similar phenomenon most often occurs in multi-storey buildings, where there is a complex ventilation system in which several ducts are connected into a common shaft. Therefore, a change in air pressure in any shaft can lead to reverse thrust.
Make a ventilation check valve in the following cases:
- Supply ventilation does not work well (clogged or broken), so the air masses will come from the exhaust shaft.
- The exhaust pipe is not installed correctly, therefore, air may enter from the outside. This phenomenon is especially evident if the house is located in the wind zone.
- If a fan of increased power works in one of the apartments of a multi-storey building, then air movement in other apartments may be disturbed.
- A stove in a private house contributes to the reverse air movement, due to increased combustion traction.
- The simultaneous operation of several fans in the apartment can lead to increased traction in one of the ventilation channels, which can also disrupt the outflow of air masses.
In these cases, a properly mounted do-it-yourself check valve for ventilation can prevent airflow.
Check ventilation
To check the operability of the ventilation system, you need to open the window in any room to create an air flow. Then bring a lighted candle or lighter to the ventilation hole. If the flame bends towards the channel, then the ventilation system is in good condition. Otherwise, you will have to clean the system or produce a ventilation check valve device.
This method is fire hazard, therefore, representatives of the fire and gas services forbid the use of an open flame for testing, especially in houses with a gas main.
There is a safe traction test method. Having opened a window leaf, it is necessary to bring a sheet of thin toilet or tissue paper to ventilation. If the paper sticks to the grate, then the traction is good.
Types of Check Valves
Depending on the design, do-it-yourself check valves for ventilation are divided into the following main types:
- petal;
- membrane;
- butterflies;
- with gravity grating.
Petal valve
Such a vent check valve for natural ventilation is popular due to its compact size. A flap valve is made in the form of a flap located on the axis. In the presence of a direct air flow, the damper opens, and when the air masses move in the opposite direction, the check valve flaps are closed for natural ventilation.
The axis of the flap valve can be located both in the horizontal plane and in the vertical. The normal position of the petal is closed.
Diaphragm valve
The diaphragm valve works on the principle of a flap device, but the sash has a very small thickness and is very sensitive to a small air flow. This type of check valve is most often used in rooms with natural ventilation.
A rather thin membrane allows even a very small flow of air masses to pass in the forward direction, and it fits very tightly to the plane of the hole, closing it with the slightest change in the direction of flow. The most common size of the check valve for ventilation is 100 mm.
Butterfly Check Valve
In many ways, such a valve is similar to a flap device. The presence of two valves located on the axis resemble a butterfly. The principle of operation of the butterfly valve is very simple: with direct air movement, the flaps open, and with a reverse flow, the ventilation hole closes.
Basically, the butterfly system is used in forced ventilation, because the shutters do not compress when the air flow is low.
Gravity Valve
Externally, such a device is a grille with a check valve for ventilation. Such grilles with shutters are installed directly on the wall of the building and do not require additional decorative overlays.
The principle of operation, like all previous types, is to open the valves with a direct air flow, and close them when the fan is off.
Ventilation grille with check valve is mainly used in industrial plants. By the method of arrangement of the blinds, valves with a gravitational grate can be both horizontal and vertical.
The shape of the check valves for ventilation are rectangular and round.
Material for making a check valve
Do-it-yourself check valves for ventilation are made of the following materials:
- Galvanized steel of small thickness. Models with galvanized valves are more commonly used in manufacturing plants or in office buildings. Strength and resistance to aggressive environments of galvanized steel, allows to operate non-return valves for a long time. Also, fire safety requirements at industrial enterprises determine their widespread use. In domestic conditions, metal valves are not practical, since their operation is accompanied by a characteristic knock, and eventually rust traces may appear, which spoils the appearance of the device.
- In apartments, it is better to install the check valve itself, for ventilation made of plastic. Such valves are easy to choose for any style of interior design, as they have an aesthetic appearance. In systems with natural ventilation, plastic valves exhibit good performance, as they are sensitive devices.
- In valves of the combined type, the body is made of galvanized steel, and the sash is made of plastic. The sensitivity of the valve is very high, which leads to their use in systems with natural ventilation.
In addition, the valves are heated and without it. Heated valves are mounted on the outside wall. When the temperature fluctuates, a heated valve prevents icing of the flaps.
The standard sizes of non-return valves for ventilation are 100, 125 or 150 mm.
Check Valve Selection Parameters
If you decide to buy a valve in a distribution network, then you need to familiarize yourself with the main characteristics that must be followed when choosing a device.
The main selection criteria:
- The natural ventilation grill with a non-return valve must match the size of the ventilation duct opening. It’s better to choose the right device than to adjust the channel.
- For natural ventilation, it is necessary to select a check valve with high sensitivity. If the traction is low, it is better to install a fan.
- The valve size must match the fan parameter. If the non-return valve for ventilation is 100 mm, then the fan must correspond to this size.
- It is also necessary to take into account temperature conditions, because some devices have poor performance at low temperatures. Such valves are installed indoors only.
- If the duct has a rectangular shape, then the check valve should be rectangular.
In the case of improper selection of equipment, ventilation in the room may be disrupted or a change in air direction may occur.
Step-by-step valve manufacturing instructions
You can make a non-return valve for ventilation with your own hands by studying similar factory models. Following the instructions, it is not difficult to make a home-made valve of the membrane type, which in its characteristics will not be inferior to industrial models.
Instructions for self-manufacturing valve:
- First, you need to make a plate, which will be the main element of the valve, sashes will be installed on it. The plate is cut in size and shape of the ventilation channel. For the manufacture of the plate, you can use durable plastic or textolite with a thickness of 3 to 5 mm.
- To connect to the fan and fix the plate in the exhaust ventilation channel, holes are drilled along its edges. Holes in the central part are also drilled to allow free passage of air flow. The ability of the system to pass air will depend on the number of holes.
- Further, with the help of a sealing gasket and hermetic means, the plate is fastened in the exhaust pipe. It is recommended to install gaskets made of soft material or rubber in the places of fastening the plate with screws, this will reduce vibration and noise level in the ventilation system.
- The next step will be the manufacture of valves for the check valve. For this, a piece is cut out of a dense film in size and shape corresponding to the size of the plate. The film adheres to the edges of the plate. It is from this film that two valve flaps will be made in the future.
- We cut the film into two equal parts, these will be the valve flaps. The cut must be made even.
- We install a pipe with a plate and a film in the ventilation duct and fix it with dowels.
- We seal the gaps between the exhaust pipe and the walls of the ventilation duct.
The principle of operation of the membrane-type valve is quite simple:
- nothing prevents the air flow in the forward direction, since the wings are open;
- when changing the direction of the draft, the shutters are closed, preventing the penetration of air from the outside, thereby protecting the room from extraneous odors and dust.
Features of the use of valves in the kitchen
In the kitchen, the system additionally arranges an exhaust ventilation system above the stove. This prevents polluted air from spreading over the entire area of the kitchen.
When the fan is on, the system draws smoke from the surface of the stove. But when the fan power is off, odors from neighbors can get into the room. Installing a check valve on the hood is a prerequisite for maintaining clean air in the kitchen.
It should be remembered that in the kitchen there is another hole in the overall ventilation system. Through this channel, contaminated air can flow back into the room. Therefore, it is recommended to install a reverse device on a common shaft. The butterfly valve is mounted on exhaust ventilation from a plate, and on a natural ventilation membrane valve.
It is recommended to install a non-return valve in the bathroom, which will not let cold air into the bathroom from the outside, and will also be able to reduce the humidity of the room if there is an influx of air masses from neighbors.
Tips for installing a non-return valve
Installing a non-return valve in the ventilation system is easy. For this, special tools will not be needed, just a puncher to drill holes in the wall, as well as a screwdriver or a simple screwdriver to tighten the screws.
It is always easier to do quality work, taking into account the advice of specialists on the installation and operation of the valve:
- Self-assembly of the valve should begin with determining the direction of flow of air masses. Only after this action can you proceed directly to the installation of equipment.
- To prevent insects from entering the apartment through the ventilation system, it is recommended to glue a piece of capron or a special fine-mesh plastic mesh before mounting the flaps. Kapron is preferable to use, it is easier to clean or replace.
- The valve will be installed more efficiently if you select a device with a convenient mounting system (flange or clamp).
- For the design installed in the outer wall of the building, it is better to purchase a check valve with electric heating. This will prevent freezing of the flaps at low temperatures.
- In order to avoid jamming of the blades from dust and contamination, it is necessary to periodically clean the leaves from plaque.
Crankcase ventilation
The use of a non-return valve is not limited to the ventilation system of the apartment. For example, we can consider the action of the check valve ventilation of the crankcase, an internal combustion engine.
During engine operation, exhaust gases, as well as vapors of gasoline, oil and water, enter the crankcase. The accumulation of such gases causes the destruction of metal parts of the engine.
The crankcase ventilation system uses the vacuum principle. A valve is needed to adjust the pressure of the crankcase gases. If the vacuum is negligible - the valve is open. With a large vacuum, the valve closes.
Remember that the non-return valve not only protects against the entry of contaminated air and dust into the home, but also maintains an optimal microclimate in the room, preventing cold air from entering the room. Thus, it is possible to ensure comfort and the absence of extraneous odors.