Forced ventilation systems are present in almost every apartment or private house. They consist of an air intake device and ducts for drawing, which can be made of various materials.
The plastic version is widely used because of the cheapness, durability and ease of installation, which can be carried out independently.
The content of the article:
- The main parameters of the existing systems
- Rules for choosing the duct
- Types of forms and sample sizes
- Plastic fittings
- Features of the design and installation
- Nuances selection ventilation system geometry
- Check valve and grille
- Fasteners and placing duct
- Ensuring the integrity of the plastic boxes
- Useful videos on the topic
The main parameters of the existing systems
For the normal functioning of the ventilation system with exhaust duct is necessary to calculate the parameters. In most cases, for domestic purposes, you can pick up plastic boxes of standard shapes and sizes.
Rules for choosing the duct
The main parameter of the ventilation ducts is its internal section. From it and drawing power from the speed depends on the channel flow. The cross-section is selected based on the maximum volume air flow capacity. Normative documents regulating the speed of household plastic duct is not, so guided by proven practical way to values equal to 3-7 meters per second.
The cross section duct is taken equal to or slightly greater than the drawing nozzle duct whose size is specified in the device ID. If you do not schedule regular inclusion of a maximum mode, then the permissible proportional decrease in cross-section of ventilation ducts in relation to the size of the outlet.
Thus, if S - area drawing air nozzle section, N - volume at the maximum air flow capacity mode, Device, M - amount of air flow capacity at the intended mode, the required cross-sectional area is calculated by the box formula:
P = S * (M / N)
Insufficient quantity sectional duct leads to significant air velocity, increasing friction force and as a result, the following negative effects:
- growth occurs load on the ventilation hoods mechanisms, which reduces the service life of the device and the additional cost of electricity;
- due to an increase of resistance occurs lowering the maximum productivity, which reduces the air circulation in the room;
- as a result of aerodynamic effects in the duct sound pressure level increases;
- is an increase in air pressure inside of the system elements, as well as the occurrence of vibration, which requires a more reliable fastening and sealing.
If the duct cross-section will be more than necessary, it will not affect the operation of the mechanical ventilation system, however, will lead to unnecessary financial costs. In addition, air ducts and other large assemblies more difficult to install and embed into interior design.
Types of forms and sample sizes
Plastic ducts for ventilation have a circular or rectangular shape. A circle has the minimum perimeter than other geometric shapes for the same area.
Therefore, from the standpoint of minimizing the resistance of the inner surface of the box motion of the air flow generated extractor, preferably a circular shape of the channel.
On sale for domestic purposes, the most common round plastic boxes with the following diameters:
- 80 mm, the sectional area of 50.3 sq. cm;
- 100 mm, sectional area of 78.5 sq. cm;
- 125 mm, sectional area of 122.7 square. cm;
- 150 mm, sectional area of 176.7 square. cm.
Ventilation ducts of rectangular shape is easier to enter the interior of the premises, as well as placed in niches above the kitchen cabinets, above the suspended ceiling, or tension.
The most common boxes in the following sizes:
- 110 x 55 mm, sectional area of 60.5 sq. cm;
- 120 x 60 mm, sectional area of 72 sq. cm;
- 204 x 60 mm, sectional area of 122.4 square. cm.
If necessary, you can find elements of a larger ventilation system. This plastic boxes for household purposes the diameter of a circular shape of 200 mm and a square size of 220 x 90 mm. However, before you opt for a non-standard size, make sure the opportunity to acquire all the elements that allow to build a duct to extract the desired geometry.
Plastic fittings
Ventilation system between the hood and the shaft have a different geometry and topology due to individual approaches regulated kitchens. Therefore, special items are provided for the implementation of almost any configuration of the plastic box.
Ventilation channels are straight duct elements of rectangular or circular shape. Their standard length is 0.35; 0,5; 1; 1.5 and 2 meters, but can be independently with a hacksaw or grinder cut off a segment of the desired size.
If it is necessary to receive the straight portion longer than two meters, it is mounted by means of several standard length fragments using special connectors for plastic channels. When this increase due to the size of the connector portion of length does not occur.
Another essential element is the knee, with which produce air twist angle of 90 or 45 degrees. For rectangular boxes distinguish elements to change direction both horizontally and vertically. To turn on the angles are not multiples of 45 degrees using a so-called raznouglovoe knee. Depending on the desired angle of one of the sides of the connector are cut.
To change the form of boxes with round to rectangular (or vice versa) using special adapters. Their use is generally due to different forms of ventilation ducts with the outlet funnel or opening in the hood bill lattice. They can be both direct and angular shapes. Sales following transition options are most common:
- the diameter of 100 mm to a size of 110 x 55 mm;
- the diameter of 100 mm to a size of 120 x 60 mm;
- the diameter of 125 mm to a size of 204 x 60 mm.
If you want to make the transition to a different size plastic box without changing its form, it is used gearboxes. For round versions there is a special universal adapter that can be used to connect all standard sizes.
For structures with complex topology tees provided by means of which can be done Connect the air flows from a few extracts, for example from the kitchen and the bathroom, in the direction of exit. They can be rectangular, circular, and combined forms.
Fastening element duct to the wall takes place with the use of carriers. Since plastic structures differ from lightweight metal, then installing them is not a difficult task. These parts of the factory production are inexpensive and fit well into the interior of the room, so the use of self-made designs impractical.
Wall brackets or lattice is attached over the hole in the wall leading to the ventilation shaft or the street. Grill, if necessary, may include additional slots for natural ventilation. In this case it is necessary to provide protection from penetration through the holes generated hood airflow back into the room.
To prevent reverse thrust return valve is used for drawing broken. It can be integrated into the plastic duct connector, or its function may perform ventilation grille louvers. In the absence of such a device may enter the room air from outside or from the ventilation shaft.
Features of the design and installation
Installation of plastic boxes for ventilation from the cooker hood can be performed independently without the involvement of specialists. It is necessary to take into account some simple features of the design and installation of such systems.
Installation of plastic system includes a number of conventional steps, which have to go through as an independent master who chooses their own hands to build a box, and hired workers.
Nuances selection ventilation system geometry
A wide variety of structural elements makes it possible to realize almost any geometry of a plastic ventilation duct. However, to preserve the functionality of the air passage system at the appropriate level in the design of the duct must follow these rules:
- If possible, minimize the length of the box. The optimal distance from the nozzle hood to the fan grid is considered distance of less than 3 meters.
- It is desirable not to use a large number of elements that change the direction of air movement. Bends, narrowing and high transitions create additional drag.
- It is necessary to minimize the number of bends to the box is rotated by 90 degrees. They create the greatest resistance to movement of the flow noise is generated and accumulated deposits of oil and dust adhered thereto.
In the case of placing the riser duct near the heating or other heat source is necessary to prevent plastic heating at a temperature above 50 degrees Celsius.
To do this, or to bypass a hot object or lay insulation between it and the air duct. The insulating material easier to use foam, since it has low thermal conductivity, and will not generate noise when vibration duct.
Check valve and grille
An essential element of the ventilation system is a non-return valve. If the box is only on the drawing to the mine, and does not tap into other sources of air intake, the valve mounted at the end of the duct or use a special grating with "venetian blind" preventing return air.
If there are several sources of air intake into the ventilation system of a check valve mounted near the connection of each branch with the main duct and one - near the lattice.
If necessary, support the natural ventilation, there are three solutions at off draw:
- divided outputs for forced and natural ventilation, and they should not go into a ventilation shaft;
- set near the exit tee 'hood - Grille - check valve ";
- use ventilation grid with openings for natural air movement and protection against reverse thrust.
Birds or living in the ventilation shaft rodents sometimes penetrate into the duct. Caught in the bends of the plastic boxes, they can be lost, resulting in the degradation products get into the room. To prevent such a development grille leading to the street or to the mine, it is often provided with special protection, irresistible to animals.
Fasteners and placing duct
Land plastic duct between the hood and the ventilation grille can be fixed in different ways depending on their position relative to the cabinets, walls and ceiling. If any version of the installation is not difficult, and it can hold its own. However it is necessary to approach this procedure is responsible, in order to avoid vibration noise, as well as sagging or other deformation boxes with possible subsequent depressurization.
If the box is inside the cabinet, its fastening to produce a back wall of the cabinet by means of clamps. Also fixed locations passing through the duct wall using foam polystyrene or insertions. These materials do not make noise when in contact with the vibrating elements of the system.
In the case of the location of the duct above the cabinets easiest to perform its fixation to the cabinets using brackets and screws for wood small length. Plastic box in such a position does not create any significant lateral pressure.
When fixing the duct to the wall or ceiling positioning holders recommended by 1 meter. Fixing takes place by means of special clamps, which can be purchased under the form and size of boxes purchased. The weight of the plastic construction is small, so it is quite simple to perform mounting.
If the plastic box is closed tension or ceiling, it is necessary to check the reliability of fixing it at a drawing work at maximum capacity. In other cases, you can easily mount to strengthen after the discovery of weaknesses.
Sometimes during operation of the ventilation system or the sound of rattling can be caused by contact vibrating plastic box elements with a hard object, such as a cabinet, wall, etc. In this case, instead of attaching an additional fairly lay between foam or foam.
Ensuring the integrity of the plastic boxes
The elements in the ventilation system, made of plastic parts, do not have a seal. Dimensions joints fit properly, but after some time, due to the deformation, the density of some of the compounds may be reduced.
In case of leakage at the junctions of structural elements possible penetration of air from the ventilation system to the outside. In this case the spread of odor and humid air on the premises through which extends a duct. Also, sometimes there is considerable noise when the air passes through the gap.
There are two solutions to prevent depressurization of plastic ventilation ducts:
- Fluff joints design special silicone or acrylic sealing compound. His are thin in the edge member before its insertion into the system.
- Roll up the junction with the adhesive tape. Such a method can be applied after the installation of the system in the event of depressurization places.
The first method is more reliable, but may cause serious problems if appropriate parsing ventilation ducts for repair, cleaning or changing its geometry. Over time, the sealant so strongly holds the structural members that in some cases it is necessary to sacrifice one of the parts to start parsing system.
Outer sealing method, by contrast, makes it easy to carry out analysis of the plastic box. However, this method affects the appearance of the structure, so it is hardly used, if it is in plain sight.
Useful videos on the topic
Installation of kitchen boxes. Elimination of cracks in joints of structural components by means of screws, and a silicone sealant. Prevention of vibration using foam:
Installing plastic duct to the hood in the kitchen. Fastening elements together, fixing the ceiling by means of holders:
Operation of the check valve for the operation of the example of the natural ventilation tee "hood - lattice - natural ventilation":
The presented information about the selection of devices and methods of the major components of plastic vents help with their own hands to build a robust box for kitchen ventilation.
