Inadequate or ineffective ventilation of the garage contributes to the formation of condensation on the vehicle 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 also suggest 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 many kilometers journey 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.
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The ventilation system in the garage is required to create normal conditions for owners, building structures and equipment stored there
Ventilation will eliminate the causes of condensation, loss of it on the hood and other metal surfaces, prevent their rust
Regular air exchange provided by the ventilation system will remove the exhaust air from the garage, which will be replaced by a fresh portion
When arranging multi-level garages, each level of construction must be provided with a ventilation system
Ventilation systems designed for garages are divided according to general principles into natural and mechanical. In natural schemes, the air enters the room itself through ventilation grilles and openings, the exhaust is carried out on the basis of gravity
In mechanical versions, air movement is induced by a fan, which is equipped with either the supply or exhaust parts of the system
The exhaust air, harmful chemical compounds, volatile toxins are removed through the vented pipe
If the supply part of the system is equipped with a fan, then the air is forced into the garage, forcing the spent mass into the exhaust outlet
Ensuring normal conditions in the garage
Ventilation to prevent condensation
Supply of fresh air to the room
Ventilation in multi-level garages
Natural ventilation devices
Exhaust fan
Outdoor exhaust pipe
Duct system
SNiP 21-02-99 sets the winter storage temperature of the machine in the amount of +5aboutC, 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, +15aboutC) 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 5aboutFROM.
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 ducts, put one on the air intake, the second on the hood and the atmosphere is updated.
However, in the cold climate of Russia, the supply and exhaust system in the premises of a closed parking lot needs to be designed 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 a wind rose.
Natural ventilation of a car box directly depends on such parameters:
- 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.
- 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.
- 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 ducts.
In summer, you need to open the supply and exhaust ducts completely, relying 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
To select the cross section of the air ducts of the supply and exhaust ducts, the obtained value of L should be rounded upwards, having achieved its multiplicity of 5.
Therefore, the airflow 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 ducts and select the appropriate parameter.
Given that the air speed in the natural ventilation channels is about 0.5-1 m / s, for the above-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 the 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 choose 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 brought out 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 products, 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 heating and filtering work
Ways to Improve Natural Ventilation
Without using mechanical tools to enhance air exchange, you can achieve a stable atmosphere update in the garage room in two ways - 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 at the highest point, he leaves through the exhaust ventilation duct, being replaced 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, you should not carry out thermal insulation of the ventilation duct. However, for the “incandescent lamp heating” method, 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, multiple zones of low (-) and high (+) pressure arise
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 channel 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: exhaust 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.
Structurally, the ventilation deflector (for example, TsAGI project) consists of the following elements:
- Diffuser (glass) having the shape of a truncated conical pipe. The narrow side he dresses on the chimney. Helps to establish the difference in air pressure and increase traction.
- Cap (umbrella), which protects the duct channel from the penetration of volatile debris and precipitation.
- 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 rotational deflectors are known.
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 “blockage” 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 the vicinity 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 in the cavity of the exhaust duct.
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 inflow 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, which ensure the injection and preparation of the supply air, as well as the removal of the 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 complex (+)
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 intake of exhaust air occurs through an exhaust pipe, in the channel 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 repairs with welding and painting of 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:
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On the exhaust openings, which in the example are two on each side of the gate, we put plastic corner bends. An exhaust mechanical system will be connected to them.
Since it is planned to install a mechanical exhaust system, for the operation of its fan we arrange wiring and bring the power line to a convenient place to connect
At the top, almost under the ceiling, we fasten a piece of the board on which the channel fan is fixed
In fact, we measure the distance of the ducts: from the exhaust hole to the fan and from the fan to the place necessary for work
We lay the corrugated duct to the fan, connect it to the exhaust hole, fix the clamps to the wall
For a movable segment of the duct, which is planned to be cleaned so as not to interfere with movement around the garage, we put a bracket with a metal rod on the ceiling
Based on the connecting part, designed to join the corrugations, we make a wire frame for the exhaust funnel from wire
Foil vapor barrier wrap the frame, fasten the material to the connector with tape
Step 1: Install the corner outlets to the ventilation holes
Step 2: Wiring Device for Connecting a Fan
Step 3: Install the duct fan
Step 4: Preparing the corrugation for ducting
Step 5: Connect part of the duct to the fan
Step 6: Mounting the bracket for the moving part
Step 7: Manufacturing the exhaust funnel frame
Step 8: Wrapping the Funnel with Foil Material
The technical essence of the original engineering idea will help to evaluate the following photo selection:
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Duct system assembled
Fixing the movable part of the duct
Assembled air duct
Preparation for work in the inspection pit
The solution presented for consideration allows you to repair the car in winter without opening the wide open gate.
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.
Effective natural ventilation system in a real garage with a basement:
How to insulate the exhaust pipe over the garage in order 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.