The ventilation device of a private house, basement or garage is rarely dispensed with ducts. In the apartment - and then you need to connect the cooker hood to a vertical shaft laid inside the wall. The range of air ducts sold is quite wide and the user traditionally faces the problem of choosing the right product. The purpose of our review is to consider existing ventilation pipes, outline the scope and identify the shortcomings of various types of ducts.
Varieties of air ducts
All ventilation pipes designed to organize air exchange in rooms or local exhaust, differ in two characteristics - the material of manufacture and the shape of the section. The second moment: when installing ventilation, homeowners often use pipes from other utilities.
We present a complete list of types of used ducts:
- round and rectangular, made of galvanized steel;
- the same from PVC plastic;
- flexible products of two types - aluminum corrugated pipe and insulated round channel on a metal frame;
- fabric air ducts;
- steel - black and stainless;
- double-walled chimneys of the sandwich type, completely made of galvanized steel;
- sections of plastic sewage;
- asbestos-cement pipelines.
Note. In fairness, it is worth mentioning the brick and concrete vertical shafts, arranged in the thickness of the walls of apartment buildings and country houses. Internal channels are laid during the construction phase of the building and are used for exhaust ventilation.
Of the listed ventilation ducts, only the first four varieties are designed to transport air. The remaining products are chimney, water and sewer pipes used by homeowners to reduce the cost of installation.
Galvanized Ventilation Ducts
Thin-walled metal pipes for ventilation made of galvanized steel comply with all regulatory requirements and are definitely recommended for use in any premises - residential, industrial, warehouse and so on. We list the types and main characteristics of galvanized ducts:
- In shape, the channels are divided into 3 varieties - round, rectangular and flat oval.
- According to the manufacturing method, spiral-navivny, longitudinal-seam and seam boxes are distinguished, shown below in the photo.
- According to the norms, there are 2 classes of tightness of air ducts - normal and dense. The latter include spiral-wound pipes, which practically do not allow leaks at the joints.
- Products are manufactured in standard sizes. For example, the diameters of the most "running" round ducts are 100, 125, 160, 180, 200, 225, 250 mm and so on. The thickness of the metal is 0.5-0.6 mm, with a diameter of more than half a meter - 0.7 mm.
- The standard sizes of square and flat oval pipelines are set by a maximum aspect ratio of 6.3.
Explanation of the proportions of the sides of the flat air ducts. According to SNiP, the size of one side of a rectangular pipe cannot exceed the size of the second face more than 6.3 times. Example: the smaller size of the box is 0.03 m, then the maximum size of the second side is 0.03 x 6.3 ≈ 0.19 m = 190 mm.
Consider the advantages of using galvanized ventilation ducts:
- compliance with all sanitary and construction standards;
- rigidity, strength and durability;
- incombustibility, resistance to weak chemical influences;
- scope - any general ventilation systems (excluding aspiration - dust transportation);
- relatively simple installation;
- a wide selection of shaped elements - tees, knees, crosses, transitions;
- Due to standardization of sizes, galvanized ducts are compatible with all fans and air distributors - dampers, valves, deflectors.
Reference. A duct made of galvanized steel can withstand the effects of a strong fire flame for 30 minutes. Special external processing increases the specified fire resistance limit to 2 hours. Rigid construction will not allow the duct to collapse from heating.
The main disadvantage of galvanized ducts is the high price compared to products made from other materials. The question is quite controversial - a lot depends on the region, the volume of the order and the specific manufacturer. As of March 15, 2018, the cost of 1 running meter of an inexpensive air duct Ø100 mm is:
- spiral - 320 rubles. (5.6 cu);
- straight-seam - 180 rubles. (3.15 cu);
- rectangular shape of the corresponding section 10 x 8 cm - 200 rubles (3.5 c.u.).
Note. We additionally indicated prices in arbitrary units, since over time the value in rubles may change.
Other disadvantages of ventilation galvanized pipes also deserve attention:
- At the factory, air ducts look very aesthetically pleasing, but galvanization is difficult to fit into the interior of a private house or apartment. The channels need to be hidden behind the cladding - suspended ceilings, plasterboard cladding.
- Due to the roughness of the metal and zinc coating, the resistance to air flow is quite substantial. The nuance becomes noticeable in extended sections and branched systems where more powerful fans are needed (selected by aerodynamic calculation).
- By weight, the products lose to plastic pipes.
Cognitive video about the production of fittings and spiral ducts:
Plastic ventilation
Plastic pipes for ventilation are also available in rectangular and round sections. But the standard sizes differ from the normal presented above - round ventilation ducts are offered with a diameter of 100, 125, 150, 200 mm and so on. The base material is polyvinyl chloride (PVC), polypropylene (PP) and polyethylene (PE).
Clarification. There are industrial and domestic series of plastic air ducts. The diameters of the first correspond to the standard range, but not all sizes are available to the buyer. For example, Ø14, 16 and 18 cm will have to be ordered separately. The four most “running” diameters of household products we indicated in the previous paragraph.
Advantages of plastic ventilation pipes:
- nice appearance;
- ease and speed of installation;
- light weight;
- long term of operation;
- zero roughness of the inner surface and low resistance to air flow;
- wide range of fittings and connectors;
- resistance to various chemicals.
As it turned out, the price of products can not be attributed to the strength of plastic ducts. The cost depends on the type of plastic used and the type of connection - bell-shaped, flanged or sleeve (nipple). We managed to find relatively cheap PVC pipes for ventilation on the Internet - prices for 1 meter channel Ø100 mm look like this:
- round - 180 rubles. e.);
- flat equivalent section 110 x 55 mm - 188 rubles. (3.3 c.u.);
- rectangular size 12 x 6 cm - 220 rubles. (3.85 c.u.).
Reference. The prices of polypropylene boxes with a wall thickness of up to 3 mm, equipped with a flange or socket, reach 1,100 rubles. / 1 m.
Now, let's tackle the shortcomings of plastic piping for ventilation:
- Due to the mismatch of the diameters of the channels to the standard range of sizes, it is necessary to select a special fan for the air ducts or use adapters.
- Despite its rigidity, plastic remains a brittle material. In addition, over the years, elasticity is lost - after 5-7 years of operation, the pipe may crack from an accidental gentle blow.
- Plastic is flammable and “floats” when heated above 200 ° C.
- Boxes of a light shade quickly turn yellow under certain conditions, for example, in the kitchen or in the bathroom. To restore a presentable appearance, ventilation ducts must be cleaned.
- Polymer pipes are very elongated when heated.
The scope of the plastic ventilation elements is the exhaust ducts of the kitchen and bathroom, the natural air exchange systems of residential buildings, chemical laboratories, but only within the same room.
An important point. A plastic box, laid in transit through several rooms, will quickly burn out in case of fire, and the fire will spread to neighboring rooms through the openings. GKL suspended ceiling - poor protection, plastic will “leak” from high temperature.
Corrugated sleeves
For the arrangement of ventilation, manufacturers offer flexible ducts of three types:
- An aluminum single-wall corrugated pipe is made on a frame of metal wire twisted in a spiral. On top of the "skeleton" of circular cross section is covered with aluminum foil with a sealant made of polyester. A number of sizes are quite saturated: 100, 110, 113, 115, 120, 125, 130 mm, etc.
- Corrugated aluminum sleeve with mineral wool insulation, made on the basis of fiberglass. The design of the pipe is similar - a spiral frame made of wire plus foil and insulation, the outer protective layer is fiberglass. The proposed diameters are 100, 125, 150, 160, 200, 250 mm and so on.
- Industrial flexible corrugations on a wire frame covered with polyester fabric, polyurethane, fiberglass or polyvinyl chloride (PVC). The choice of diameters and sections is very wide, it makes no sense to list all the sizes.
Note. A single-layer aluminum corrugation is sold in a compressed state, a product 620 cm long is stretched by 3 meters. You can buy an air duct of round and rectangular cross-section.
We present the approximate cost of the listed products per 1 meter of flexible hose Ø100 mm:
- single-layer corrugated pipe of the Aluvent type - 50 rubles. (0.9 cu);
- Sonodec DS insulated flexible ducts - 310 rub. (5.5 cu);
- ventilation ducts made of polyester fabric - 408 rubles. (7.15 c.u.);
- the same, from PVC - 335 rubles. (5.9 c.u.);
- polyurethane sleeve - 233 rubles. (4.1 c.u.).
Although flexible ventilation pipes are made of various materials, the set of advantages and disadvantages of this group of products is approximately the same. Positive points:
- light weight;
- simplicity and high speed of installation;
- quick connection to ventilation equipment through clamps;
- the corrugation is easily removed for the purpose of antibacterial cleaning;
- the widest selection of standard diameters;
- lack of fittings and fittings;
- plastic sleeves - abrasion resistance to abrasive particles and chemical attack.
Now about the negative sides of corrugated pipes. All flexible ventilation ducts share a common drawback - low fire resistance. Only aluminum hoses are able to withstand prolonged heating up to 300 ° C, the temperature limit of other polymer products is +125 ° C for polyurethane and +90 degrees for PVC.
An important point. It should be understood that each type of flexible air duct is intended for use in a specific area. For example, polyurethane channels are designed to transport heavily contaminated gases and dust (aspiration).
The second significant drawback of corrugated hoses is their high aerodynamic drag, which makes them increase the fan power. Therefore, the length of a flexible ventilation duct rarely exceeds 10 m. And the last: aluminum corrugations often decrease in diameter (collapse) when a powerful fan is connected to the suction side.
Sewer and other pipes
One way to save on the installation of ventilation is to use asbestos-cement ducts, as shown in the photo ventilation cellar. The positive aspects of this option:
- low price - 100 rubles. per linear meter of the pipeline Ø10 cm (1.75 cu);
- rigidity and structural strength;
- durability;
- material is stainable;
- resistance to high temperatures - products withstand over 1000 ° C.
Reference. Asbestos (chrysotile cement) pipes are made of circular cross-section with a step of sizes 5 cm - 100, 150, 200 mm, etc.
Asbestos-cement pipelines are successfully used as chimneys, cable channels, pillars of columnar foundations and other purposes. Applying them in the ventilation system, you will encounter the following negative nuances:
- Asbestos dust is harmful to health. Sanitary standards explicitly prohibit the use of chrysotile cement pipes as supply air ducts.
- The design is not only rigid, but also heavy, hence the difficulty of installation. Plus there will be difficulties with the connection - the knees and tees do not exist in nature. Need special couplings or adapters.
- The appearance of such a ventilation duct, even painted, is not consistent with residential premises.
The second popular way of budget ventilation device is the laying of air ducts from gray polypropylene pipes intended for internal sewage. The price gain is palpable - a meter of the "hundredth" pipeline will cost 140 rubles (2.45 cu), including 1 o-ring on the socket.
The advantages of the sewer sections are identical to the advantages of the plastic channels, but there are more disadvantages:
- pipe diameters do not match the standard sizes of ventilation ducts: 4, 5 and 11 cm;
- shaped elements are made with a large turning radius;
- sections and fittings are large due to sockets;
- Due to the accumulation of static charge by plastic, a lot of dust settles on the inner walls of the air lines.
Note. High-quality plastic ducts designed for ventilation have a protective antistatic coating.
Iron and stainless pipelines are a dubious option for organizing air exchange in a private house. Price, heavy weight, the problem of tight connections - this is a short list of the disadvantages of metal ducts that are appropriate in industrial buildings. The only way to use it is to use brick exhaust shafts to protect against condensation.
Which duct to choose - recommendations
Having familiarized with the characteristics of the pipes used in the ventilation device, it is not difficult to draw a simple conclusion: each kind of duct must be used for its intended purpose. Then difficulties will not have to be overcome. Therefore, cheapness and economy are far from the main criterion of choice.
What type of pipeline is worth buying in various situations:
- The kitchen hood is connected to the shaft by a plastic or flexible aluminum duct. The first one clearly wins in appearance and ability to fit into the interior (the color of the plastic can be selected). The shape of the cross is a rectangle or square.
- If you need to organize forced ventilation within the same room, also take plastic boxes. Connect to the fan with round pipes.
- For concealed installation, definitely use galvanized ducts. At a price they differ little from plastic, but more reliable in terms of fire resistance.
- Transit air ducts must be fireproof - this is what fire regulations require. Example: an extractor hood going from the bathroom to the garage, where the ventilation duct turns onto the roof. The plot in the garage is made of galvanized steel pipes.
- Sewer sections use in non-residential rooms - pantries, attics, workshops. Appointment - the organization of a natural extract.
- Any corrugations are great for connecting to ventilation equipment. The insulated version of the flexible channel can be laid in a cold attic.
- Use asbestos pipelines and polypropylene sewer sections for air exchange in the cellar, basement or garage.
- It is convenient to install a chimney sandwich outside a private house when thermal insulation of the duct is necessary. If you want to save money, install an ordinary metal pipe and make insulation.
An important point. Any air ducts laid through unheated rooms, or facing the street, must be insulated. Otherwise, in winter you will get a stream of condensate from the exhaust pipe.
Finally, about the diameter of ventilation ducts
The most common size of ventilation pipes in the household series is Ø100 mm. According to the cross-sectional area, it corresponds to a flat duct made of plastic 55 x 110 mm or a similar galvanized one. The indicated diameter is easiest to choose grilles and fans.
When connecting a cooker hood or other ventilation system, refer to the cross section of the equipment outlet. The ventilation pipe must be at least this size. The shape of the box does not play a special role, although from the point of view of aerodynamics, round and oval channels are preferable.