In old buildings, leaks in doors and windows served as fans. Over time, chimney and duct systems were created that used the principle of physics that warm air escaping causes the inflow of new, but also cold, air. Currently, mechanical ventilation with heat recovery is increasingly used, but many buildings still use gravity ventilation. How does gravity ventilation work? What is gravity ventilation and what challenges does it pose?
Ventilation in the Onninen wholesaler
How gravity ventilation works
Each of us has had the opportunity to notice what happens to the air in a room when we open a window. It is even more visible when the tenants or users smoke nicotine. The smoke from cigarettes rises upwards, and when the window is ajar, it escapes through the upper part of the window opening. This is due to convention, which is the movement of air caused by the difference in its pressure and density . Warmer air has a lower density, which causes it to rise. It is immediately replaced by heavier air, which in this case is colder.
This simple principle was used to create ventilation systems based on ducts and vents. Of course, in order to For the convention phenomenon to exist at all, a basic condition must be met. The air exchange should take place simultaneously in both directions. A clogged air inlet or outlet is enough and the convention will cease. To clarify, it is worth recalling that the so-called draft is actually a misleading concept. Warm and used air is not sucked out, but pushed out by new, fresh and cool air. To improve the exchange, chimneys are equipped with vertical ventilation ducts . The tightness of the system is also extremely important, so it is good to use proven methods when using the highest quality elements.
The advantage of this solution is that gravity ventilation does not require additional power supply forcing air movement. The disadvantage, however, is the loss associated with the removal of heat resulting from the heating of the premises.
The lack of an electromechanical device that would support gravity ventilation predisposes it to use in places at risk of explosion. An example of such a solution are boiler rooms with boilers in which the combustion chamber is open.
Why might gravity ventilation not work?
The most common reason for disruption of the convention process is the clogging of one of the channels. Remember that gas exchange must take place at the same time. A clogged vent immediately cuts off the outflow and thus blocks the access of further batches of fresh air. Another phenomenon is the so-called reverse draft. It consists in the fact that used air is returned from the ventilation grilles back to the apartment. What causes reverse draft?
The cause is a disturbance in proportions. In other words, there is too little fresh air to be able to displace the used air. This can happen, for example, in the case of too few channels or inlet holes. It is also necessary to check the cleanliness of the grilles, where dust, grease and various types of dirt accumulate. It should be noted that it is necessary to use ventilation grilles with a mat that effectively protects the apartment from airborne impurities entering the interior or the canal.
Another cause of reverse draft is an incorrect temperature difference between the outside and inside of the building. The effect is visible in the summer, when the exhaust duct becomes the supply duct, causing pollutants and unpleasant odours from the kitchen and bathrooms to spread throughout the apartment.
Advantages of gravity ventilation:
Maintenance-free operation;
No power supply to support air exchange;
The ventilation does not emit noise;
Low operating costs.
Unfortunately, the disadvantage is heat loss, which causes increased heating costs.
Ventilation in the Onninen wholesaler
Where to locate the supply and exhaust ducts?
The arrangement of the intake and exhaust ducts of gravity ventilation is as important as its cleanliness. Exhaust ducts should be located in rooms where moisture and unpleasant odors naturally accumulate.
Such places include:
Kitchens;
bathrooms;
Toilets;
Laundry;
Rooms without windows (wardrobes, storage rooms).
Ventilation ducts should be located on each floor (two-level apartments). When using a fireplace, the room in which it is located must be equipped with an intake and exhaust opening. This is to prevent the accumulation of carbon monoxide (CO).
Gravity ventilation is still a widely used solution and it will certainly take a long time before everyone switches to mechanical ventilation with heat recovery. The basis for the effectiveness of this type of ventilation is its cleanliness and the quality of the elements from which it was made. It is good to remember this before starting to renovate and replace old ducts.
It is also worth using professional knowledge , thanks to which not only ventilation, but also the entire house will function without failure for many years. We invite you to read other articles.