The air in the garage is saturated with the vapors of stored liquids and oils. Additional sources of pollution: car exhaust, moisture, emissions from welding and other repairs. The supply and exhaust ventilation in the garage solves the problem - it reduces the level of humidity and removes harmful fumes, replacing it with clean street air. The task of the motorist is to organize the correct air exchange, guided by our instructions.
Typical Natural Ventilation Scheme
First of all, consider a ventilation device in a garage of the most common type:
- garage - metal or stone without a cellar and a viewing hole;
- mode of use - periodic (on average, the owner stays indoors no more than 1-2 hours per day);
- the structure is used to park the vehicle, store some stock of automotive fluids and perform minor repairs.
We’ll immediately examine the question of whether a forced exhaust and supply system is needed in such a room. The answer is: if the garage is not turned into a workshop, then to extract moisture and gases, a natural exhaust with an influx is quite enough.
When forced ventilation is required:
- In winter, the owner works by welding indoors.
- The owner is constantly engaged in the repair or painting of cars.
- In the garage, fluids with harmful volatile vapors are often used, for example, furniture and rubber glue, acetone, white spirit and so on.
An important nuance. The hood is unable to function without inflow, regardless of traction in the vertical output channel. If you do not provide for air flow from the street, then even a mechanical fan will not be able to throw out water vapor - the impeller will begin to mix the air in one place.
Now we explain how to make ventilation in the garage without a basement with our own hands:
- On the front wall of the garage, on the sides of the gate, punch the calculated supply air inlets. The best option is to lay the sleeves when building the building. The height of the openings above the ground is 20-50 cm (so that less dust is blown out by the wind).
- To correctly select the cross section of pipes and wall holes, calculate the amount of air. The technique is presented in the last section of this guide.
- Install the external grilles in the holes, and from the inside come up with gates or doors. The goal is to limit and regulate air flow during the cold season.
- Seal as much as possible all door narthexes, from where air can leak uncontrollably; in winter, hang from inside the curtain. The exception is sectional doors fitted close to the opening.
- In the ceiling at the opposite wall, drill a hole and bring out a vertical channel from an asbestos-cement or sewer pipe 2 meters high. Cover your head with rain umbrella.
Tip. If, due to objective reasons, it is not possible to raise the pipe cut by 2 m, put a deflector instead of the cap, which increases traction due to wind (shown in the photo).
The scheme works simply: due to the difference in external and internal temperature, as well as the difference in height between the ends of the chimney, a natural draft arises, which carries away the garage air. The pressure inside the room drops, the vacuum provokes the absorption of air mass through the grilles of the supply system.
Air exchange in the inspection pit
The ditch, designed to inspect the bottom of the car, needs to be ventilated. The reason is moisture penetrating from the soil through brick or concrete walls, plus water draining from the machine. If the top of the pit is not covered by boards, the scheme described above will do, you will not have to modify anything:
- Due to its greater density and weight, the cold stream tends to fall down, displacing the warm air masses. Part of the air from the supply holes moves to the bottom of the ditch.
- By mixing with the internal air, the inflow heats up and becomes lighter. The next portion of the cold air mixture pushes it up.
- Getting into the range of the hood, the air is carried away by the draft of the vertical channel and is brought out. The principle of ventilation is illustrated below in the diagram.
In practice, another situation is more often observed: the pit is blocked by boards, moisture is not removed from there and condensate falls on the inside of the shields. The wood rots, the iron corners of the ditch frame sharpen the corrosion.
The correct solution to the problem is laying under the screed of the underground duct of the desired diameter leading from the pit to the street. Practiced 2 versions of the ventilation device in the pit:
- the pipe is connected to the supply wall hole and lowers to a height of 15-20 cm from the bottom of the ditch;
- a separate exhaust duct is laid out from the pit under the floor and rises vertically to the roof.
In the first case, we feed fresh inflow directly into the ditch, in the second, we suck out moist air. The resulting convection current will cause air masses to seep through the gaps between the boards. Both options are equally functional. It is usually more convenient to organize an inflow - the pit always settles closer to the gate and inlet.
Note. It is not easy to lay an additional duct with a screed, it will be necessary to hammer concrete and dig a trench. It is easier to open the pit, and in the summer to dry the wooden shields. But at the stage of building a garage, it is better to develop and implement a project for ventilation systems in advance.
Plastic pipes of the internal sewerage - the most practical solution for the device of natural air exchange in the repair pit. They are cheap and provide minimal aerodynamic flow resistance. An additional convenience is the use of ready-made knees and tees.
We organize the ventilation of the garage cellar
As an example, take a 6 m long garage with a separate basement of 2 x 3 m and an inspection pit. Here it is important to observe one condition: the air of the garage and the ditch should not penetrate into the vegetable store, as some Internet resources suggest.
Recommendation. Install separate ventilation ducts in the cellar that are not connected to other rooms.
How to make an extract from the basement in the garage:
- Through the ceiling, bring into the underground storage 2 vertical ducts - supply and exhaust.
- Lower the inflow pipe to a height of 10–20 cm above the floor; take the other end to the street along the shortest path.
- The exhaust duct begins under the ceiling of the cellar, passes through a car box in transit and rises above the roof (height 1.5-2 m).
Tip. The transit section of the vertical pipe crossing the garage room must be insulated. Otherwise, heated and humid basement air will begin to produce condensation from contact with cold walls. You will not achieve the desired result - the removed moisture drains back to the storage water.
Mount the ducts from the same gray plastic pipes with rubber o-rings in the sockets. An alternative is asbestos cement, but it is more difficult to install because of the decent weight and lack of factory fittings.
The supply air duct is brought into the basement in two ways:
- let the ventilation duct through the basement into the box, turn it with a knee and go outside through the wall (height 200-500 mm from the ground level);
- immediately go through the basement wall, turn up and vertically bring the pipe into the street through the blind area.
The second option will be cheaper if you lay the duct during the construction process when there is no blind area around the building. In a finished garage, it is better to implement the first method - carefully drill a wall with overlapping and install a ventilation duct with your own hands.
About Forced Hood
There is no point in putting a fan on the exhaust pipe of general ventilation for three reasons:
- Effective air sampling and discharge is carried out only when the unit is on;
- in the absence of the owner, the impeller of the switched-off fan covers at least 50% of the cross section of the ventilation duct, moisture removal naturally slows down significantly;
- consumed electricity.
If you converted the garage into a workshop, there is a reason to make a local exhaust device, consisting of a suction umbrella, duct fan and duct with a non-return valve. The cap is made of improvised materials (sheet metal 0.3-0.5 mm), the air channel is made of pipes for sewage Ø110 mm.
The petal valve and the channel type fan are selected for the internal diameter of the ventilation duct - 10 cm. We will give a number of installation tips:
- An umbrella is placed above a source of air pollution (usually a workbench). The cap dimensions are 20 cm larger than the maximum dimensions of the source, the opening angle is not more than 60 °.
- Try to hang the umbrella at a minimum distance from harmful emissions, given the convenience of the work.
- Mark the shortest route for laying the air duct from the workbench to the exterior wall of the building.
- Insert the valve and fan inside the bells, having previously wrapped the sealing material (a suitable option is foam rubber). Drill a hole in the wall of the ventilation duct and insert the power cable there.
- The non-return valve is placed at the outlet of the duct, the fan is within the premises. Outside, protect the duct with a grid with a net in order to block the way for birds and rodents.
Reference. The recommendations are not suitable for a garage converted into a spray booth where the source of air pollution is distributed throughout the box. In such cases, full-fledged forced ventilation with cleaning and heating of the air is arranged, as is done in industrial premises.
Do not forget about the need for inflow - after turning on the fan we completely open the grill for incoming air. Otherwise, the working unit will simply overturn the draft in the nearest exhaust channel.
Chimney as an element of the ventilation system
Since in winter many motorists heat garages with wood and oil stoves, a number of points should be taken into account when organizing air exchange:
- A boiler or furnace requires air used to burn fuel. The heater takes it directly from the room, accordingly, you need to take care of replenishment - to provide an influx from the outside.
- A properly mounted stove chimney is a good exhaust hood that works continuously, even with a flame out in the firebox.
- From the previous paragraph it follows: the chimney easily replaces the ventilation duct, so it makes no sense to assemble a separate exhaust hood. One condition: after extinguishing the furnace and leaving the box, fully open the gate - the draft regulator in order to improve air exchange.
Information for consideration. Often, owners of garages and private homes are biased towards ventilation. Argument: together with the removed air mass, the building loses heat. We answer: the number of losses directly depends on the inflow - how much air the grate will let inside, so much exhaust will give to the street.
Conclusion: adjust the cross section of the inlet doors and gates. The ideal option is to install a supply wall valve.
Calculation of the volume of ventilation air and the cross-section of the channels
The vast majority of motorists are not concerned with calculations - I studied the schemes on the Internet, watched the video and mounted the air pipes from the pipes of the house drainage Ø100 mm. If you want to delve deeper and calculate the parameters of the garage ventilation system, we suggest that you familiarize yourself with the requirements of regulatory documents:
- The air exchange inside the boxes is regulated by the regional document MGSN 5.01-01 "Parking for cars". Clause 3.17 states: the minimum air flow per machine is assumed to be 150 m³ / h, or a two-fold renewal of the air environment is provided.
- Departmental norms BCH 01-89 put forward the following requirement for inspection pits: the ratio of the extraction from the ditch should be 10.
- The norms of air exchange for storing vegetables are prescribed in paragraph 8. 1. 4 of the document NTP-APK 1.10.12.001-02. The volume of inflow and exhaust is equal to 3.5 m³ / h for every 100 kg of potatoes and 7.5 m³ / h for 100 kg of other vegetables.
Reference. The number of air exchange rates shows how many times within 1 hour the inflow updates the air in the box volume.
The calculation process is easiest to show on the example of the garage, presented above in the drawings. Pre-determine the internal volume of the room - 95 m³, ditches (6.6 m³) and the cellar (12 m³). Further calculation is performed as follows:
- According to MGSN 5.01-01, we multiply the value of the box volume by a factor of 2, we obtain an air flow rate of 95 x 2 = 190 m³ / h. The figure meets the minimum requirements for 1 machine of 150 m³ / h.
- The multiplicity of exchange in the pit is 10, the amount of air is 6.6 x 10 = 66 m³ / h.
- Suppose 400 kg of potatoes and 200 kg of other vegetables are stored in the basement. We consider the consumption of ventilation air: 3.5 x 4 + 7.5 x 2 = 29 m³ / h.
Comment. A tenfold exchange in the ditch needs to be laid with the constant maintenance of the bottom of the car (as in a car service). Under normal conditions, a double renewal of the air will suffice: 6.6 x 2 = 13.2 m³ / h.
Knowing the costs in each compartment of the garage, it is easy to find out the cross section of the ducts of the inflow and exhaust according to the formula:
- F - channel cross section in square meters;
- L - inflow volume (flow rate), m³ / h;
- ʋ - air flow rate in pipes and gratings, with natural extraction it is recommended to take 1 m / s.
For a conventional garage, where the ditch is used periodically, we include in the calculation the minimum costs of 150 and 13.2 m³ / h. We summarize these values and determine the cross section of the ventilation duct: F = 163.2 / 3600 x 1 = 0.045 m². Using the circle area formula, we find out the diameter of the air duct - 240 mm. With a slight stretch, two plastic pipes Ø150 mm are allowed.
The figure 0.045 m² also shows the required feed-through (live) cross-section of the supply grille, which is approximately 50% smaller than the actual dimensions of the product. So, we take the cross-sectional area of 0.045 x 2 = 0.09 m² and by selection we find out the dimensions - 0.3 x 0.3 m or 300 x 300 mm. Such a lattice is too big, it is better to make 2 openings in the wall and put two grids with dimensions of at least 150 x 300 mm.
The size of the basement air ducts is considered in the same way: F = 29/3600 x 1 = 0.008 m². The diameter of the pipe will come out 0.1 m or 100 mm. On the nuances of installing ventilation in the garage and the passage of the pipe through the ceiling, see the video:
Conclusion
Examples of the location of the supply and exhaust ventilation ducts indoors are not an axiom. Think carefully about the ventilation of your garage and place pipes in convenient places to minimize the number of turns. It is important to observe the condition: the inflow is directed to the lower zone of the room, and the hood is organized from the upper.