Ventilation check valve: purpose, types, installation

Residents of apartments in multi-storey buildings are often faced with the fact that smells from neighbors through ventilation ducts enter their premises. An unpleasant situation that a ventilation check valve will help to cope with. How it looks, how it is arranged and where to put it, and we will discuss.

What is a check 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 wet" rooms - a bathroom, a kitchen. The task of this part of the ventilation system is to bring odors and excess moisture out into the street. But sometimes a situation arises when through the exhaust ventilation the air goes in the opposite direction - it enters the premises. This moment is called the overturning of the thrust and they try to fight this phenomenon.

A check valve for ventilation is needed for the normal operation of the system

Why fight backward thrust? In the case of apartments, this is fraught with odors from neighbors, which is very unpleasant. If we consider private houses, portions of the outside air in them reduce the temperature in winter. The second moment is more dangerous and unpleasant - during reverse draft, the boiler can 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. A check valve for ventilation is just installed to block the movement of air in the wrong direction.

Device and principle of operation

A check valve for ventilation is most often a piece of pipe with a round or square section. In this segment, a piece of material (metal, plastic, mica) of a suitable shape is movably - usually on an axis - mounted. This is the valve itself. In the closed state, it completely covers the cross-section of the pipe, in the open state it should create as little resistance as possible. For everything to work correctly, it is necessary to set it so that when a reverse air flow occurs, the valve closes.

These are check valves on the duct pipe

Not only valves are installed 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 grille. There is also a butterfly valve and louvers. The return air valve on the exhaust fan can be of the same type.

Other options

The principle of operation of this device is simple: during normal air movement, the valve is open and creates little resistance to the air flow. In the event of a reverse draft, 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: odors in the apartment are very unpleasant. Rollover traction in a private house is no less unpleasant, but also dangerous. In principle, with a correctly calculated system, such phenomena should not arise and the causes of their occurrence must be fought. But not everyone has the capabilities and resources. It is easier to install a check valve for ventilation. This is true, but there are nuances worth knowing.

• A valve installed in the ventilation opening interferes with natural ventilation. If you want the natural extraction to work, you need to think over the connection so that the valves do not interfere.
• Even the "quiet" plastic valves, when closed, clap, sometimes making rather loud sounds. These claps are stronger the stronger the pull. They are very annoying in variable winds. So it will be necessary to come up with something to make the valve "quieter".
• 

  It is the quietest valve - 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 one channel may not "get along". Rather, the exhaust duct is unlikely to work.
• For normal operation, the check valve must be regularly serviced - cleaned, checked, lubricated the axles. Considering that it is not always easy to get to him, it is at least inconvenient. So consider the ability to 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 disadvantages of this solution.

Views

The ventilation check valve 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 casing and a metal damper - most often called the "combined check valve for ventilation".

A check valve for ventilation is made of plastic and metal

How to choose on this basis? Simply. Choose the material from which your duct is made. Models can be round or square. Here again we choose the same form as for the existing / planned ones. air ducts... Fortunately, the dimensions correspond to the standard pipes used for air ducts.

Opening method

Check valves can be opened 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 do not differ in tightness, so they cannot completely block the penetration of foreign odors.
• With electric drive... They are forced to open at the same time as the fan or hood is turned on. Suitable only for ventilation systems with forced air removal (no natural circulation).
• Mechanical... The most common type. They open and close against air movement. They are installed both in tandem with a fan or an exhaust hood, as well as for natural ventilation.

In addition to mechanical ones, there are manual opening and electromechanical

The manual non-return valve can be installed on a forced-draft chimney to the outside. This is sometimes done - they are taken out not into the ventilation duct, but into the street through the wall. In this case, it is better to have a flap that will only open while the hood is in operation. 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 safer in this case.

If the hood is brought out through the wall

The most common are mechanical check valves. They are installed in about 90% of cases. Structurally, they can be of different types. Let's talk about them in more detail.

Mechanical valve shapes

Different dampers 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 valve will be operated with a fan or an exhaust hood, it is important that the weakest fan operation can open the damper. They say that the fan must push the valve. If you want to maintain natural ventilation, it is necessary that the damper can “work” even from slight air movement.

The designs and shapes of mechanical check valves for ventilation ducts can be as follows:

• With a one-piece butterfly valve on the axis (cracker). This option is most often found. This is a disc or rectangular piece that is movably fixed on an axis.Sometimes the axis is centered, sometimes 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: a pop is heard when closing the flap. The stronger the pull, the louder the clap. This is annoying during the day, and even interferes with sleep at night. Because of this feature, this model is often called the "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 because the opening force is minimal in this position.
  

  Types of dampers on the check valve for ventilation

• With two-piece damper (butterfly). This variant is found only in round valves. There is also an axis. 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, natural ventilation may not work.
• Membrane. Flexible plastic is used as a shutter. This option seems to be the most preferable - the membrane should open more easily. In fact, diaphragm valves perform worse than others. At first, they can actually react to even small air movement. As dust and soot accumulates, they become heavier and, after a while, stick.
  

  The diaphragm valve looks so mobile

It is really not easy to choose a valve for ventilation. If you are guided by what the majority uses, you will have to stop at the cracker. For all its shortcomings, it works more reliably, it opens even with natural ventilation. The most effective way to make the cracker quieter is to take silicone sealant and apply it to the stop ring on the body (do not apply to the disc, as it will become heavier, which means it will be more difficult to rotate). Lubricate the valve disc with soapy water and press it against the sealant ring - until polymerization begins. Then we move the valve, we get an O-ring that dampens the pops. The result is a virtually silent, almost airtight closure.

Valve for ventilation: where and how to put

If ventilation system made without the use of fans and hoods with motors, it is called natural. For everything to work, valves are installed immediately at the outlet of the channels to close the reverse thrust. To maintain normal circulation, it is advisable not to use grids that block the valve. Yes, this option looks better, but ventilation suffers at the same time. Most likely, it simply will not work with a small traction.

If you still want to install decorative ventilation grill in front of the valve, you will have to put up with a deterioration in ventilation, slower removal of odor and excess moisture. Only the installation of a grate / valve with a larger diameter than calculated can help. In this case, air exchange will not be affected.

Natural ventilation works by temperature and pressure differences

In the case of forced ventilation, the check valve can be placed either in front of or after the fan. This choice depends on the type of system and fan. Since ducted models of fans in private systems are rarely used, it usually turns out that the damper is located after the fan in the pipe. How far away doesn't matter. The main criterion for choosing an installation site is ease of maintenance, since the damper will have to be periodically cleaned and checked.

Installation in a kitchen with hood

When installing a forced draft hood in the kitchen, many want to preserve natural ventilation. To do this, you need to install a tee at the entrance to the ventilation duct. Connect an exhaust hood with a check valve to one of its inputs, put only a check valve in the second. As you can see, the system is not too complicated, but it works.

How to connect an extractor hood so that natural ventilation remains

Why should there also be a check valve on the hood? Because if it is not there, the return 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 ventilation check valve is located as high as possible under the ceiling. As a result, the warmest and wettest part of the air will be removed, which is very important for the kitchen.

For bathroom and toilet

The ventilation of the bathroom can have its own exhaust duct - then everything is easy, simple and clear. Before entering the ventilation duct, we put a check valve to shut off the air flow that will move into the room. But not all apartments can boast of individual bathroom and toilet shafts. In some old-style houses, there is only an exhaust duct in the toilet. Bathroom ventilation is done by passing the box through the wall. In this case, we put a check 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 unpleasant odors from entering the bathroom.

How to put a non-return valve for ventilation in a separate bathroom with one ventilation duct

There is an even more sad situation: when there is only one exhaust duct and it is in the kitchen. Actually, the installation logic does not change - you need to place 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 the work, you can determine the most successful installation place yourself.