DIY garage ventilation: an overview of the best options for arranging an air exchange system

Inadequate or ineffective garage ventilation contributes to the formation of condensation on the car's units. Exhaust fumes and vapor of working fluids make the garage atmosphere unsafe for the car owner.

To avoid these problems, you need to take care of the normal circulation of air flow. Moreover, the improvement of the microclimate in automobile boxing often does not require special engineering and construction skills and significant financial investments.

We will show you how to calculate and make the natural ventilation of the garage more efficient, and we will also offer alternative methods of inducing air exchange.

Features of garage ventilation

At the dawn of motoring, cars needed a fenced shelter to carry out routine repairs. Cars later became a value requiring protection against theft - a reliable garage with a perimeter protected from penetration.

The experience of previous generations of car owners requires protecting the car, storing it in a garage box.

But a garage is good if it has ventilation. Entering the parking lot after a journey of many kilometers along rainy and snowy tracks, the car brings moisture with it. The room for the car is traditionally small - moisture quickly saturates its atmosphere.

And if the volume of moist air in the garage does not change 6 times per hour (preferably 10 times), then the car will certainly rust.

SNiP 21-02-99 sets the winter storage temperature of the machine in the amount of +5^aboutC, if the box is heated. By the way, this SNiP also allows you not to heat the garage.

Comfortable temperature for the car owner (for example, +15^aboutC) in the winter garage it is “uncomfortable” for the car due to the melting of ice and snow adhering to it. Rationally adhere to regulatory 5^aboutWITH.

The air exchange rate in the garage is set according to ONTP 01-91 in a volume of 150 m³/ h for each parking place. Outwardly, the task is simple - to determine the diameter of the air ducts, put one on the inflow, the second on the hood and the atmosphere is updated.

However, in the cold climate of Russia supply and exhaust system in a closed parking lot, you need to design more closely.

For uniform ventilation of the garage room all year round, a combined system is most suitable. It does not depend on weather and outdoor temperature

Working conditions and calculation of natural ventilation

For self-constructed ventilation in the garage to work, its layout should take into account the volume of air changes, seasonal temperature changes and the wind rose.

Natural ventilation of a car box directly depends on such parameters:

1. Air temperature difference indoors and out. The atmosphere of the garage should be hotter and therefore lighter than the outside air. Then heavy and fresh air will enter the garage through the supply air duct by gravity, trying to replace a less dense volume of the internal atmosphere.
2. Pressure differences between the vertical positions of the inflow and exhaust. A difference of more than 3 m is required between the supply inlet and the exhaust air outlet.
3. Moving air pressure (wind). On the windward side of the garage, increased pressure is set, on the leeward side - reduced. It is necessary to place the supply air duct on the side of the prevailing wind direction.

Ignoring the above conditions will lead to the complete inefficiency of natural extraction. Therefore, in winter, it is necessary to set a higher temperature in the car box in relation to the street and reduce air exchange by adjusting the degree of opening of the air ducts.

In summer you need to open supply and exhaust ducts totally betting on a wind rose.

The location of the supply air intake and exhaust pipe relative to each other must be either along the length of the box, or along its diagonal

The main parameter of air exchange is its multiplicity, i.e. the number of complete changes in the amount of atmosphere in the garage with “street” air.

Knowing the normalized ratio of the supply and exhaust air exchange (6-10 times) and the internal volume of the car box, it is necessary to calculate the air consumption per hour:

L = n • Vg, Where

• L - air consumption per hour, m³/ h;
• n - the numerical value of the standard for the frequency of air exchange;
• Vg - air volume of the garage, m³.

To determine the volume of air contained by the garage, you need to multiply its internal dimensions of width, length and height.

For example, a box with a width of 4 m, a length of 6 and a height of 2.7 m holds Vg = 4 • 6 • 2.7 = 64.8 m³. When choosing, say, seven-fold air exchange per hour, such a garage will need L = 7 • 64.8 = 453.6 m³.

Knowing the air flow rate and its speed, you can find from this diagram the optimal diameter of the round duct for the supply and exhaust system of the garage

For duct section selection inlet and exhaust, the obtained value of L should be rounded up, having achieved its multiplicity of 5.

Therefore, the air flow value obtained in our calculation must be increased to 455 m³because this number is divided by 5 without a remainder - 455: 5 = 91.

Next - we look at the image of the diagram of the diameter of the air ducts and select the appropriate parameter.

Given that air speed in the channels of natural ventilation is about 0.5-1 m / s, for the calculated "approximate" garage, round ducts with a diameter of 500 mm or more are needed. Or profiled, with an internal cross section of 450x500 mm.

To improve air flow, it is possible to install not a pipe-duct, but a lattice air intake at a height of up to half a meter from the garage floor. Moreover, its cross section should be twice or three times larger than that of the exhaust pipe. Ventilation will improve, but in winter the car box will freeze.

It is necessary to equip the intake grille and the hood with movable or removable covers, which make it possible to reduce the intake cross section if necessary.

We draw attention to the sequence of partial overlap of the exhaust and supply openings - first the inlet, then the exhaust.

To select a suitable section of a rectangular duct, it is enough to find the diameter of the round pipe matching it

It is important that the cross section of the exhaust pipe does not turn out to be larger than the cross-section of the supply air intake - the draft will overturn. Therefore, with partial closure of the supply duct, it is imperative to reduce the cross section of the exhaust pipe.

The exhaust duct must be removed strictly vertically and at least 500 mm above the plane of the garage roof.

Above the gable roof, the hood must be raised to a height corresponding to the proximity of the roof ridge to it (see diagram in the image).

If an inspection pit is arranged in the garage for repairs and a cellar for storing food, then for the ventilation of underground rooms, it will be necessary to install separate air ducts for supply and exhaust.

Thus, an independent pipe is required to supply air to the cellar and a second, vertical pipe to the hood.

The simplest option for organizing ventilation in the garage is to install a wall valve, which, in addition to the function of ensuring air exchange, can perform the work of heating and filtering the flow

Ways to Improve Natural Ventilation

Without using mechanical tools to enhance air exchange, there is two ways to achieve a stable atmosphere renewal in the garage: by heating the exhaust pipe and installing a deflector on it.

Exhaust duct heating

Heated air is lighter than cold air masses entering through the supply air intake. Aiming for the highest point, he goes through exhaust ductreplaced by fresh air from the outside - the pressure of the internal (in the garage) and external (on the street) atmospheres should be equal.

When building natural ventilation in autobox, it is enough to follow the recommendations of this scheme

To improve air heating in the upper atmosphere inside a cold garage, you need to paint the exhaust duct black.As a result, the walls of the duct will absorb the maximum amount of solar energy and will heat the air inside the channel, causing it to move upward more intensively.

When planning natural ventilation, taking into account the black color, one should not carry out thermal insulation of the ventilation duct. However, for the method of “warming up with an incandescent lamp”, it is extremely necessary to insulate the exhaust duct.

In the fall, it gets cold in the garage. This is not a problem for a car, but for supply and exhaust ventilation it is very bad.

If the hot engine for the first hour after entering the box still serves as a source of heat for the air, then after a couple of hours in an unheated garage the temperature will be set, almost equal to the street temperature. And natural ventilation will cease to function.

The wind flow blows around the deflector (scheme a), the air from the exhaust channel is divided into several directions (scheme b). In this case, there are multiple zones of low (-) and high (+) pressure

An ordinary 40-watt incandescent lamp will allow maintaining air exchange and preventing icing of the exhaust duct (condensate will accumulate in it).

It is enough to suspend its cartridge under the opening of the vertical exhaust duct and leave it on. The heat generated by the lamp is enough for the movement of air at a speed of 0.2-0.4 m / s.

Moreover, the duct channel must be wrapped with insulating material and make sure that no moisture enters the insulation. There is not much heat from the incandescent lamp, it may not be enough for the full length of the exhaust pipe and the air will cool quickly.

Note that the use of fluorescent or LED lamps does not contribute to the improvement of air exchange - they generate significantly less thermal energy. Only incandescent lamps are suitable.

Installing a ventilation deflector

This device contributes to an increase in exhaust draft up to 20% without the use of any mechanical devices - due to the formation of a low pressure zone at the head of the duct.

Based on the Bernoulli law, deflectors change the movement of air flows due to their design (cross-section).

The parameters of the TsAGI deflector elements are tied to the diameter of the exhaust duct. The numbers on the diagram indicate: hood of the hood (1); diffuser glass (2); outer casing (3); hood stands (4); cap (5) (+)

The wind is forced to bend around the curved body of the deflector, which leads to the formation of miniature zones of relative vacuum, causing the mass of air in the pipe to move up.

Constructively ventilation deflector (on the example of the TsAGI project) consists of the following elements:

1. Diffuser (glass) having the shape of a truncated conical pipe. The narrow side he wears on the exhaust pipe. Helps to establish the difference in air pressure and increase traction.
2. Cap (umbrella) that protects the duct channel from the penetration of volatile debris and precipitation.
3. External housinghaving a cylindrical shape. Creates low pressure zones by dissecting the wind flow.

The TsAGI deflector type is widely used to enhance the natural draft of ventilation pipes in Russia. Along with it, plate-shaped, weather-vane, H-shaped and rotary deflectors.

By the way, domestic natural ventilation hoods are especially often equipped with a Grigorovich deflector.

The efficiency of exhaust deflectors of any design is directly related to atmospheric conditions, namely the presence of wind.

That is, with strong winds, this device develops maximum traction in the natural ventilation system, and with no wind it does not work at all.

The defining moment is the proximity of the roof ridge. The closer it is to the pipe, the higher it should be raised (+)

The deflector is able not only to improve traction, but also to prevent “choking” of the exhaust pipe in strong winds, which low-current natural ventilation cannot overcome.

In addition, the ventilation complex equipped with a deflector device is most protected from tipping over the draft.

We draw attention to the need to raise the headband of the hood, equipped with a deflector, over the roof plane by half a meter or more. The location conditions in terms of the proximity of the roofing ridge, as discussed in the diagram above, also apply.

Combined ventilation of a car box

The advantage of combining natural ventilation with a low-power mechanical system is the guaranteed renewal of the garage atmosphere in any weather.

Neither calmness nor summer heat weaken the performance of such a supply and exhaust complex.

The combined ventilation scheme is completely similar to the natural air exchange system. The same arrangement of the supply and exhaust ducts, the same cross-section of the air pipes and the deflector at the upper end of the exhaust duct are used.

One difference is the installation of an axial or centrifugal fan.

Supply air will not enter the garage cellar with a viewing hole from the general ventilation system - the level is too low. It is required to have a separate inlet and exhaust in this room (+)

The power of the ventilation unit should not exceed 100 W, this is enough. It is required to incorporate a fan into the insulated segment of the duct, otherwise condensate will enter it.

To control the operation of such a fan, an electronic timer is useful, built into the adapter between the power outlet and the power plug of the exhaust device.

Keeping the exhaust fan turned on for a long time is unprofitable due to its energy consumption, and there is no need for this. In addition, in winter, the combined ventilation of the garage will be too effective and will greatly box the box.

An adapter with a timer allows you to set the frequency and duration of the fan for 24 hours and several days in advance.

By placing an electronic timer between the outlet and the fan power plug on the hood, you can control the on / off cycles of the electromechanical element of the exhaust system

Note that when choosing a sufficiently powerful centrifugal installation for ventilation, a larger cross section for the exhaust duct may be required. We remind you that the choice of the cross section of the air-conducting pipe depends on the speed of the air flow.

If the inner diameter is insufficient, the hood will make a loud noise and poorly draw air.

Arrangement of a mechanical ventilation system

Its main advantage is independence from natural factors. There are two main disadvantages: dependence on electricity; quite high cost. Air flow and exhaust air volume removal are performed by centrifugal fans.

The following mechanical ventilation systems are installed in automobile boxes:

• Modular. The supply and exhaust complex is assembled from several independent units that provide for the injection and preparation of supply air, as well as the removal of polluted atmosphere. Such modules work independently, for their joint work control sensors are needed.
• Monoblock. Each such unit is a complete mechanical ventilation device, it is responsible for the intake and exhaust at the same time. Among monoblock ventilation devices, models equipped with recovery plates are considered economical. Recovery allows to minimize energy consumption for heating the supply air.

Monoblock mechanical ventilation is easier to install by preparing a single hole in the wall of the garage. However, the air supply complex, equipped with the necessary modules, is more productive.

The ability to build a complex with the required “air” characteristics is the advantage of a modular supply and exhaust system (+)

Fresh air is filtered before entering the air ducts and, during the cold season, is heated. Its submission to the garage is carried out through the air channels through the holes taken by the grilles, made in the floor or in the walls almost flush with the floor, as well as in the walls of the inspection pit.

The exhaust air is drawn through an exhaust pipe, in the duct of which a fan of sufficient power is installed.

In large autoboxes designed for several cars, it is more efficient to extract the hood through air ducts and using a duct ventilation unit.

Organization of temporary ventilation

If the garage is supposed to carry out repair work with welding and painting metal parts, a serious hood is required, which is not necessary to use constantly.

How to build a system for temporary use? Let's look at one very interesting option:

The technical essence of the original engineering idea will help evaluate the following photo selection:

The solution presented for consideration allows you to repair the car in the winter without opening the gate wide.

The master will be able to work in normal temperature conditions for him, without wearing a warm robe that impedes movement. The hood will remove harmful toxins into the ventilation hole with the doors closed.

Conclusions and useful video on the topic

Effective natural ventilation system in a real basement garage:

How to insulate the exhaust pipe above the garage to stop condensation and freezing:

Mechanical supply and exhaust systems are used in heated garage spaces.For unheated car boxes, a natural ventilation complex is best. It is permissible to ventilate underground garages only by means of mechanical ventilation, by connecting carbon monoxide controllers.

Looking for a way to improve the air exchange in the garage? Or have experience using mechanical ventilation systems? Please leave comments on the article and ask questions. The communication unit is located below.