To store vegetables in the basement, you need an appropriate microclimate, temperature - 2 ... 5 ° C, humidity - up to 90% (year-round). Exceeding these indicators leads to the formation of mold, rotting of root crops and fruits. To remove excess moisture and partially adjust the temperature, use the ventilation of the cellar - natural or forced. How to make the ventilation of the underground storage correctly, read on.
Basement air and microclimate
In the basements of private houses, it makes no sense to arrange a forced extractor hood. In most cases, the tasks can be solved by natural ventilation in the cellar. To organize such an air exchange, you need to understand what factors affect the microclimate inside the basement:
- The temperature of the soil at a depth of 1.5-2 m. Depending on the region, this indicator varies from -3 to +10 degrees (in winter). That is, the cellars of the northern and southern regions must be insulated at the construction stage.
- Cold air is denser and heavier than warm, so it always drops to the floor of the room. This flow movement is called convection.
- At the same temperature, wetter air is lighter than dry and rises. That’s why condensation droplets hang from the ceiling, and the walls near the floor hardly sweat.
- Humidity depends on the proximity of groundwater and external waterproofing of the walls. If during the construction of the basement or basement insulation work was not performed, get ready to deal with dampness.
- The temperature of the ventilation air supplied to the cellar from the street.
Reference. The relative mass of air molecules is 29 units, water vapor is only 18. Accordingly, the more moisture 1 cubic meter of air contains, the easier it is. Example: if you open the door to a cold balcony in winter, condensation will immediately appear on the ceiling (see photo above).
Now specifically about the ventilation device in the vegetable cellar. To organize the natural circulation of air flows, we use the phenomenon of convection. Action plan:
- Choose a ventilation scheme. The task is to make the right extract from the upper zone of the basement and, necessarily, to ensure the flow of fresh air.
- We perform the calculation of air exchange, determine the diameters of the exhaust and supply pipes.
- We select pipe material, install ventilation ducts.
A cellar under a residential building or garage, built without a project and external waterproofing, can become very damp in winter. Such stores have to be dried in the summer - we will list the methods at the end of the publication.
Cellar ventilation schemes
To ventilate underground rooms, you can use 1 of 3 schemes:
- classical system with one exhaust pipe;
- scheme with two pipes - inflow and exhaust;
- forced air exchange.
The choice of option depends on the design of the basement, its location and other conditions. The system with 1 duct shown in the picture is applicable for cellars with a separate exit to the street. How does the scheme work in the cold season:
- The underground temperature is always positive (if the basement is correctly built). Warmer and wetter air rises to the upper zone and goes out through the vertical exhaust duct.
- Cold air masses take its place - they seep through the inlet openings in the door (hatch), then descend to the cellar floor.
- As it warms up + humidification, the air begins to lose weight, rises and is again thrown out through the pipe.
An important point. With a one-pipe scheme, the ventilation duct should be installed at a maximum distance from the front door, at the opposite wall. This ensures a complete update of the air environment of the room.
The ventilation system with two pipes is used in cellars without a separate entrance - under private houses, garages and other outbuildings. The natural circulation of air masses is organized similarly, only the second vertical channel, descending to the floor itself, serves as an inflow. Cold outside air is lowered through the supply air duct, replacing the gases leaving the street.
Pipes are located in opposite corners of the storage and are discharged in two ways:
- in the ground outside the building;
- right through the roof, as shown in the ventilation diagram of the garage with a cellar and a viewing hole.
In the first case, the head of the supply pipe is at the base level, it is better to raise the exhaust shaft to a height of 2 m (counting from the intake hole in the basement). If the building is surrounded by other buildings and there is no place to withdraw the second channel, the duct is laid in the second way - on the roof. The end of the exhaust pipe rises above the ridge.
Note. Manufacturers of finished cellars made of plastic or concrete immediately provide for two-pipe ventilation. Channels exit vertically through the ceiling of the store, the hatch closes tightly.
How to calculate duct diameters
In order to equip the ventilation of a home cellar with your own hands, you need to find out the volume of supply air, then determine the cross section of the ventilation ducts. The amount of inflow is calculated by the weight of stored vegetables:
- for every 100 kg of potatoes we feed 3.5 m³ of air in 1 hour;
- 100 kg of carrots, onions and other vegetables - 7.5 m³ / h.
Note. If automobile parts and tires are stored in the basement of the garage, then a single air exchange for 1 hour is enough for ventilation. That is, the flow rate of the air mixture is equal to the volume of the room.
Knowing the amount of supply and exhaust air, we calculate the cross section of the pipe according to the formula:
- F is the cross-sectional area of the duct, expressed in m²;
- L is the volume of air supplied, m³ / h;
- ʋ - the speed of the flow along the channel, with natural ventilation is taken equal to 1 m / s, not more;
- 3600 - conversion factor of time units (seconds / hours).
Calculation example. In the cellar there are 400 kg of potatoes, the remaining vegetables - 200 kg. Then the inflow volume will be 3.5 x 4 + 7.5 x 2 = 29 m³ / h. We determine the cross-section of the pipe: F = 29/3600 x 1 = 0.008 m², using the circle area formula, calculate the diameter - 0.1 m = 100 mm.
Basement Ventilation Pipes
When installing ventilation systems in apartments and private houses, galvanized, enameled and plastic PVC channels are used. But the above options are not suitable for cellars - galvanized air ducts quickly rust out from moisture, and enameled steel and PVC are expensive.
Supply and exhaust shafts in the basements are made of inexpensive and moisture resistant materials:
- from sewer pipes for internal wiring - gray polypropylene;
- the same for external lining - orange polyvinyl chloride;
- asbestos-cement pipelines.
Addition. If the farm has a pipe Ø100-150 mm made of black steel, feel free to use it when arranging an exhaust / inflow. The underground section of the channel should be covered with bituminous mastic, the outer part should be painted 2 times with any resistant paint, for example, PF or NTs brand.
The most profitable and easy to install option is a sewer pipe for ventilation made of gray polypropylene. The material is cheap, lightweight, resistant to any chemical influences. An additional plus is the availability of finished shaped elements connected to straight sections in the socket. The duct is attached to the walls with standard clamps.
Installation of basement ventilation - practical tips
The first recommendation concerns the choice of an air exchange scheme: if possible, try to implement a two-pipe system with an external duct laying out at the base of the building. Causes:
- A single-hood circuit is imperfect, since part of the heated humid air is sent to the upper zone near the front door.You need to make exit openings, otherwise the vapor will condense on the door leaf, drain down and again be carried into the cellar by influx.
- The conclusion of air ducts to the roof is an expensive and inconvenient option. You have to hollow the floors, isolate the roofing, raise the hood of the hood above the ridge. If the basement is already built, it’s easier to dig a hole near the outer wall and drill the foundation.
Note. The single-tube hood works well in storages with an upper hole. Heated air masses gather under an even horizontal ceiling, then they are carried away by the ventilation duct draft.
We offer some specific tips on how to make ventilation with two pipes:
- at the outlet of the supply channel it is better to put a 90 ° elbow, the height above the floor is a maximum of 20 cm;
- protect the air intake port of the inflow with a metal mesh from rodents, install a cap on top;
- height of the supply pipe above the ground - 1 m;
- be sure to warm the overhead section of the exhaust duct, otherwise condensation will form that will flow through the duct back into the cellar;
- the minimum length of the vertical ventilation duct is 2 m from the intake opening;
- close the exhaust pipe end with an umbrella from rainfall.
The height difference between the ends of the ducts does not play a big role. A section of the supply duct rises to a minimum height (up to 1 m), the exhaust pipe is removed from the aerodynamic shadow of the building so that a stable natural draft occurs. If it is impossible to raise the duct, put a deflector - traction amplifier instead of an umbrella.
How to dry a wet cellar in summer
With the advent of warming, climatic conditions change - the street temperature becomes higher, warm light air does not want to fall into the cellar on its own. Accordingly, cold air masses do not leave the room, the natural ventilation of the basement does not work, moisture is not removed.
How to dry a cellar:
- Force the air mass to move forcibly. Through a flexible corrugated pipe, connect a small axial fan to the exhaust duct.
- Option for a cellar with a separate entrance: open the door wide open, inside install a large household fan and direct the flow towards the doorway (hatch).
- Resume the natural circulation of flows by raising the temperature inside the basement. Install a brazier with coals, a diesel heat gun or a homemade wood stove in the room. After 2-3 days of melting, the damp will go away.
- Use moisture-absorbing materials - sawdust, lime, corrugated cardboard. After saturation with moisture, they need to be changed (at least 1 time per day) and dried on the street.
Tip. To prevent fungus from appearing on concrete walls, after drying, treat the surfaces with slaked lime or another antiseptic.
For summer ventilation of the cellar, the owners often use the folk method - they simply open all the hatches and doors to the basement. The method is ineffective, because heavy cold air does not tend to go outside. Such drying will take 1-2 weeks, depending on the humidity inside the room.