Contents
Residents of apartments in multi-storey buildings are often faced with the fact that smells from neighbors through the ventilation ducts enter their premises. An unpleasant situation that the check valve for ventilation will help to cope with. How it looks, how it is arranged and where to put it, and we will discuss.
Why do you need a non-return valve for ventilation
During normal operation of the exhaust ventilation, air moves from the room to the street. Exhaust openings are located “in dirty or damp” rooms – a bathroom, a kitchen. The task of this part of the ventilation system is to remove odors and excessive moisture to the street. But sometimes a situation arises when air goes in the opposite direction through the exhaust ventilation – it enters the premises. This moment is called thrust overturning and they try to fight this phenomenon.
Why fight backlash? In the case of apartments, this is fraught with odors from neighbors, which is very unpleasant. If we consider private houses, portions of outside air in them reduce the temperature in winter. The second point is more dangerous and unpleasant – with reverse draft, the boiler may go out, combustion products (and carbon monoxide too) can return to the room from the chimney. In any case, the reverse movement of the air flow is an incorrect operation of the ventilation system and this phenomenon must be fought. The check valve for ventilation is just set to block the movement of air in the wrong direction.
The device and the principle of operation
The check valve for ventilation is most often a piece of round or square pipe. In this segment, a piece of material (metal, plastic, mica) of a suitable shape is movably – usually on an axis – installed. This is the valve itself. In the closed state, it completely covers the pipe section, in the open state it should create as little resistance as possible. In order for everything to work correctly, it is necessary to set it so that when a reverse air flow occurs, the valve closes.
They put not only valves in the pipe for ventilation – there are options for a ventilation grill and a fan. In the case of a ventilation grill, a thin plastic or mica membrane can be used that is attached to the grill. There is also a butterfly valve and slats such as blinds. The same type of air return valve can be installed on the exhaust fan.
The principle of operation of this device is simple: during normal air movement, the valve is open and creates a slight resistance to air flow. When a reverse draft occurs, it closes, preventing the entry of foreign odors or cold air from the street into the room.
Troubles that may arise
Everything seems to be clear and logical: extraneous smells in the apartment are very unpleasant. Traction overturning in a private house is no less unpleasant, but also dangerous. In principle, with a properly calculated system, such phenomena should not occur, and the causes of occurrence must be dealt with. But not everyone has the opportunity and resources. It is easier to put a check valve for ventilation. This is true, but there are nuances that are worth knowing.
- A valve installed in the vent prevents natural ventilation. If you want natural exhaust to work, you need to think about the connection so that the valves do not interfere.
- Even the “quiet” valves made of plastic, when closed, slam, sometimes making quite loud sounds. These pops are stronger, the stronger the pull. With a variable wind, they are very annoying. So it will be necessary to think of something to make the valve “quieter”.
This is the quietest valve – an elastic membrane, but not very reliable - Some fans or cooker hoods have a built-in non-return valve. If the regular one does not suit you for some reason, it must be removed. Then you can put a separate one. Two valves on the same channel may not get along. Rather, the exhaust channel is unlikely to work.
- For normal operation, the check valve must be regularly serviced – cleaned, checked, lubricated axles. Given the fact that it is not always easy to get close to him, this is at least inconvenient. So consider the possibility of access for cleaning and revision.
As you can see, putting a check valve on ventilation does not mean solving the problem once and for all. You will have to monitor the state of the system and put up with the shortcomings of this solution.
Types
The check valve for ventilation can be made of metal or plastic. Metal is most often galvanized, less often stainless steel. There is also a small group with a plastic case and a metal damper – most often called the “combined check valve for ventilation”.
How to choose on this basis? Just. Choose the material from which your air duct is made. They can be round or square models. Here again, we choose the same shape as the existing / planned air ducts. Fortunately, the dimensions correspond to standard pipes used for air ducts.
Opening method
Check valves can open in different ways:
- Manual. The dampers are opened or closed manually, for this they have a special lever. This is not very convenient, in addition, due to the design features, they are not tight, so they cannot completely block the penetration of foreign odors.
- Electric. Forced to open simultaneously with turning on the fan or hood. Suitable only for ventilation systems with forced air removal (without natural circulation).
- Mechanical. The most common type. Open and close against air movement. They are placed both in tandem with a fan or extractor hood, and for natural ventilation.
A manual non-return valve can be placed on a forced air vent pipe to the outside. This is sometimes done – they are not taken out into the ventilation duct, but out into the street through the wall. In this case, it is better to have a damper that will open only while the hood is running. You can, of course, put a normally closed valve, but in cold weather it will freeze and stop performing its functions. Therefore, manual opening is more reliable in this case.
The most common are mechanical check valves. They are installed in about 90% of cases. Structurally, they can be of different types. Here we will talk about them in more detail.
Shapes of mechanical valves
Different flaps can be installed in the check valve. The force at which it will move away largely depends on the shape of the damper. If the damper is to be operated with a fan or exhaust hood, it is important that the weakest fan setting can open the damper. They say that the fan should push through the valve. If you want to maintain natural ventilation, it is necessary that the damper can “work” even from a slight movement of air.
The designs and forms of mechanical check valves for ventilation ducts can be as follows:
- With a one-piece butterfly valve on the axis (clapperboard). This is the most common variant. This is a disk or a rectangular piece that is movably fixed on an axle. Sometimes the axis is centered, sometimes it is offset. This is a fairly popular model as it has no springs and can be installed in a natural air circulation system. But there is a problem: when the damper is closed, a pop is heard. The stronger the pull, the louder the pop. This is annoying during the day, and at night it generally interferes with sleep. Because of this feature, this model is often called a “cracker”. Moreover, gaskets made of rubber and foam rubber do not save much. When installed on natural ventilation, the axis is oriented vertically. This is important, since in this position the force for opening is minimal.
Types of flaps on the check valve for ventilation - With two-piece damper (butterfly). This option is found only in round valves. There is also an axle. Two half-discs are fixed on it, which are held in the closed position by means of springs. The springs are weak, even a not too strong flow can open them. But with a weak breath of natural ventilation may not work.
- Membrane. A flexible plastic is used as a damper. This option seems to be the most preferable – the membrane should open more easily. In fact, diaphragm valves work worse than others. At first, they can really react to even a small movement of air. As dust and soot accumulate, they become heavier and, after a while, stick.
Diaphragm valve looks so movable
Choosing a valve for ventilation is really not easy. If you are guided by what the majority uses, you will have to stop at the clapperboard. With all its shortcomings, it works more reliably, opens even with natural ventilation. The most effective way to make the cracker quieter is to take silicone sealant, apply it to the thrust ring on the body (do not apply to the disk, as it will become heavier, which means it will be more difficult to turn). Lubricate the valve disc with soapy water and press it against the sealant ring – until polymerization begins. Then we move the valve aside, we get an o-ring that dampens the pops. The result is an almost silent closure, and almost hermetic.
Valve for ventilation: where and how to put
If the ventilation system is made without the use of fans and hoods with engines, it is called natural. To make everything work, to block the reverse thrust, valves are installed immediately at the outlet of the channels. To maintain normal circulation, it is advisable not to use grids that block the valve. Yes, this option looks better, but ventilation suffers. Most likely, it simply will not work with a small thrust.
If you still want to install a decorative ventilation grill in front of the valve, you will have to put up with poor ventilation, slower removal of odor and excessive moisture. Only the installation of a grate / valve of a larger diameter than calculated can help. In this case, air exchange will not be affected.
In the case of forced ventilation, the check valve can be either before or after the fan. This choice depends on the type of system and fan. Since duct fan models are rarely used in private systems, it usually turns out that the damper is after the fan in the pipe. How far is not important. The main criterion for choosing an installation site is ease of maintenance, since the damper will have to be cleaned and checked periodically.
Installation in a kitchen with a hood
When installing a forced exhaust hood in the kitchen, many people want to maintain natural ventilation as well. To do this, you will need to install a tee at the inlet to the ventilation duct. Connect an exhaust hood with a check valve to one of its inlets, and put only a check valve in the second. As you can see, the system is not too complicated, but it works.
Why does the hood also need to have a non-return valve? Because if it is not there, the reverse air flow can pass through the hood. Yes, it will not happen every time, but with a strong flow, it will.
When installing this unit, try to make sure that the check valve for ventilation is located as high as possible under the ceiling. As a result, the warmest and most humid part of the air will be removed, which is very important for the kitchen.
For bathroom and toilet
Bathroom ventilation can have its own exhaust duct – then everything is easy, simple and understandable. Before entering the ventilation duct, we put a check valve to block the flow of air that will move into the room. But not all apartments can boast of individual shafts for the bathroom and toilet. In some houses of the old layout, there is an exhaust duct only in the toilet. Bathroom ventilation is done by passing the box through the wall. In this case, we put a non-return valve for ventilation not only at the outlet to the ventilation duct, but also in the channel between the bathroom and the toilet. This will prevent bad odors from entering the bathroom.
There is an even sadder situation: when there is only one exhaust duct and it is in the kitchen. Actually, the installation logic does not change – you need to install the devices so that smells from one room do not get into another.
One check valve for ventilation is placed on the outlet to the dome hood (or on the channel that removes air from the kitchen), the second – on the pipe that goes from the bathroom. As you can see, if you understand the logic of work, you can determine the most successful installation location yourself.