How to solve the problem of reverse draft ventilation

Although modern technologies have made significant strides forward, mistakes are often made during construction, which lead to not entirely desired consequences. For example, in many apartment buildings there is a problem with reverse draft in ventilation. There can be many reasons for this. In this article we will look at the most common reasons why backdraft occurs in ventilation. We will also look at ways to fix this problem.

How does ventilation work?

To understand the possible cause and how to fix it, you need to understand the principle on which the ventilation system of a private house works. In most cases, a mechanical ventilation system is used in a private home. The principle of its operation is relatively simple. Holes are made for air inflow and outflow. So, through some openings fresh air enters, and through others, polluted air is squeezed out onto the street.

That is, without a good influx, polluted air will not be removed from the room. Therefore, it is extremely important that this system, the fresh air supply system in a private home, works properly. Very often, fresh air enters through the cracks of windows, doors, floors, etc. However, modern technologies are aimed at completely eliminating the flow of fresh air. For example, metal-plastic windows are installed that do not allow air to pass through. This applies to doors and other surfaces. As a result, natural ventilation stops working completely.

Preventive measures

What needs to be done to prevent backdraft from forming.

Keep the ventilation system in good condition.
Do not install fans or hoods into ventilation ducts. Use a recirculating hood or vent it outside the room to the street: through a wall or window glass.
Install baffles or rotary turbines at the end of the riser.
Organize air flow into the premises by any means.
Install interior doors that block air movement between rooms. Strong drafts are also causes of backflow.
Clean the ventilation system from snow and ice in winter.
Check ventilation periodically.

To create comfortable conditions, a sufficient supply of fresh air is necessary. If the air exchange system does not function properly, reverse draft may occur in the ventilation of a private house, which has a bad effect on its microclimate.

Hood – to be or not to be

Exhaust equipment is installed in almost every apartment or private house. Installation is especially carried out in the kitchen. It is used during cooking. But how can this be related to the backdraft problem? Owners of apartments or private houses can observe the following. When the hood is turned on, air begins to blow through the ventilation hole in the toilet or kitchen. And the presence of a mechanical hood can contribute to this.

The reason may be due to the use of a heavy-duty hood. After all, many people want it to draw out every steam and smell when cooking. However, as practice shows, this is not always justified. A working hood simply pulls all the air out of the room. It is for this reason that reverse draft is formed in the ventilation duct. Windows, doors and other structures do not allow air to pass through. It has nowhere to go, so a reverse draft forms in the ventilation.

That is, the problem boils down to the fact that there is a clear lack of fresh air flow. The worst thing is that the reverse draft of ventilation in the apartment can provoke the appearance of odors in your home from the neighboring apartment and floor. Is it possible to somehow correct the current situation?

Solving this problem is very simple. You simply need to open the door or window while the hood is operating. In this case, the ventilation system of a private house or apartment will work correctly. After all, it is important that there is air circulation. And checking the health of the system is very simple. You can simply place a piece of paper on the ventilation duct. If it sticks, then everything is fine in your case.

Ways to optimize air exchange

Setting up a ventilation system in an apartment will require an integrated approach. It is necessary to ensure free supply circulation of flows. If the apartment has plastic windows with high airtightness, you need to install special air supply devices.

Improving supply ventilation

In order to ensure a constant and productive flow of fresh air, you may find it useful:

Slot-type window ventilators;
Infiltration valves.

Let's determine the advantages and disadvantages of these products.

Slot ventilators are mounted directly into the window frame. This type of supply unit is inconvenient only because it is impossible to install it in a ready-made window. To do this, you will have to completely replace the entire glass unit.

Window supply product

In contrast, an infiltration air valve is installed directly into the wall. Moreover, the place can be chosen arbitrarily. It is best to mount it behind the radiator battery. At the same time, the air entering the apartment will naturally warm up. Such a valve also produces good filtration of incoming flows, thanks to which clean air enters your apartment.

Both of these products are equipped with regulators, with which you can direct circulation and control the intensity of air flow into the room.

Infiltration valve

Forced exhaust ventilation

A fan is a device that can greatly increase the draft of a ventilation duct. The combination of supply devices and an exhaust blower forms a mechanical forced air exchange system.

There are several ways to install a fan:

It can be placed on the wall or ceiling;
The fan can be installed in the exhaust airlock;
If an entire air duct network is deployed in the apartment, the blower is installed either at the entrance to the pipe or inside the air duct (duct version of the product).

Exhaust air blower

In addition, fans have a number of useful functions. Let's look at some of them:

The air blower with a delay timer operates some time after switching off;
By combining the fan terminals with the lighting wires, you will get an ideal hood for the bathroom, in which forced ventilation will be used while visiting the toilet;
A fan with a check valve option does not allow reverse air movement from the exhaust shaft;
Equipped with a hygrostat, the device reacts to the slightest change in the set humidity level, which is also very convenient for a bathroom or a combined toilet.

You can install the device with a motion controller. In this case, the forced pull is triggered when a person appears.

Fan combined with switch

You should approach the choice of an exhaust hood with special responsibility. Its performance can be calculated as follows. The total volume of the ventilated room is multiplied by the air exchange rate (the number of complete cycles of air communication).

The resulting figure will serve as the performance coefficient of the exhaust device.

Possible causes of backdraft

So, there are several reasons why a draft problem occurs in the ventilation in a private house or apartment. Let's look at a few common problems:

The problem may lie in improper installation of the ventilation pipe. That is, the pipe with the exhaust air outlet is located incorrectly in relation to the wind flow. As a result, the wind will blow into the ventilation and the air in it will form a reverse draft.
The reason may also be the formation of a blockage in the ventilation duct. How does this happen? Cold air and steam mix together. As a result, the ventilation process is disrupted.
The reason for the traction failure may be physical blockage of the ventilation system, for example, accumulated dirt, bird nests, etc. Therefore, if reverse thrust is observed, this moment is immediately checked. It is best to periodically check the ventilation duct for blockages. Thanks to this, air exchange will not be disrupted.
If the rooms inside a private house or apartment are too large and there is a draft in them, this can lead to incorrect operation of the ventilation.
Use of modern powerful exhaust systems. They also create an imbalance in the operation of the ventilation system.

Often the problem comes down to the fact that in an old house wooden windows are replaced with plastic ones. This is especially dangerous in situations where ventilation was designed taking into account air penetration through the cracks of wooden windows. Therefore, installing plastic windows can create problems with air exchange. The worst thing is that the formation of a draft problem in an apartment building can result from improper redevelopment by your neighbors.

So, as you can see, there are many reasons for backdraft in a multi-storey building and private building. First of all, you should look for the reasons in your apartment. If you haven’t found them, then you should look for them from the outside. In this case, you will have to use ingenuity and logic to understand the entire ventilation system.

Causes of ventilation malfunction

The causes of the malfunction can be attributed to a large number of factors. The main thing you need to understand is that when there is blowing from the ventilation system in an apartment, it is not the same thing if the same effect appears in a private house. That is, faults in two buildings may be different, because the traction failure in them has different causes.

For example, in an apartment this most often happens due to the installation of a fan or hood in the kitchen, which begins to press through its channel, and the air inside, moving to the riser with pressure, does not have time to pass the entire mass upward. That is, part of it ends up in the adjacent channel of the toilet or bathroom. It is in these rooms that the opposite effect occurs. The same thing happens in the opposite direction, if the fan in the kitchen is turned off and the fan in the toilet is on. This also happens with neighboring apartments located one above the other.

This suggests that you cannot thoughtlessly install additional exhaust devices without calculating their power. And the more powerful the fan, the stronger the reverse draft of the ventilation system in the apartment of a multi-story building.

For this reason, this cannot happen in a private house, because at the design stage today they try to distribute ventilation ducts to all rooms separately. That is, the kitchen has its own riser, and the toilet and bathroom have their own. But sometimes another problem arises in the house. Most often, risers are combined into one or two common channels inside the attic, and then one or two pipes are discharged through the roofing. And here horizontal sections appear in the ventilation system. The main task of the designer is to use as little of this type of air duct as possible, and to minimize the angle of inclination of horizontal sections (the reduction should be minimal). That is, the steeper this section, the better the upward air movement.

And three more reasons:

Lack of thermal insulation. Cold air in winter enters the air ducts, where it freezes, turning into ice. This usually occurs at the mouth of the canal. The consequences are a reduction in the cross section.
Lack of an umbrella (visor), which can lead to rain and reduced traction. This disrupts air exchange.
The ventilation in the house is clogged with debris.

So, in order to remove backdraft, you must first understand why it appears.

Traction is impaired - we make a diagnosis

So, if you suspect that you have reverse draft ventilation in your apartment, then it’s worth making a diagnosis. To do this, certain measures should be taken. For example, it is worth checking regulatory documents. They usually indicate exactly how the ventilation system is installed in your home. Having understood exactly how the ventilation system works, you should figure out whether everything is installed correctly. Sometimes the problem boils down to something trivial - a worker’s mistake during installation. After this, the correct operation of the ventilation system is checked. If there are breakdowns, then everything is recorded and a plan is drawn up on how to fix everything.

Eliminating backdraft

So, it is always possible to revive the ventilation system. It is noteworthy that very often it is enough to open windows and doors from time to time. And sometimes the reason disappears on its own; the atmospheric pressure outside simply changes or the wind direction changes. Everything is banally simple.

To solve a number of reasons, a decision is often made to install a deflector. Thanks to this, the ventilation in a private home is normalized. Air currents begin to move in the right direction.

And most often, the problem disappears if you clean the ventilation ducts. Backdraft disappears by cleaning the ventilation shaft. After all, accumulated garbage can be a problem in residential buildings.

What if the developer made a mistake and there is a constant draft in the room that disrupts the ventilation? In this case, it is necessary to resort to construction and repair work to redevelop the living space. It may be worth installing doors to eliminate drafts, otherwise additional partitions will be installed.

In some cases, an air conditioner or special supply valves are installed. But in this case, it is important to be careful when installing such equipment, because it is necessary to correctly calculate the square footage of the living space, as well as the technical characteristics of the ventilation ducts.