Perhaps among professionals, the most common is the fastening of rectangular air ducts using a stud and a profile, which can be of two main types: Z- and L-shaped. In both cases, fastening to the duct is carried out using self-tapping screws.
Photo 1.1. Fastening by means of a Z-profile and a stud
Photo 1.2. Fastening by means of an L-shaped profile and a stud
There is no fundamental difference between L- and Z-shaped profiles (photo 1.1, 1.2), but usually the Z-profile is used when attaching more massive air ducts, since in this case the additional corner supports the body of the air duct from below, removing part of the load from the screws and giving the structure additional rigidity. In addition, in the places where the profiles are attached to the stud, there must be rubber seals, which compensate for light vibrations of the duct and reduce the noise level.
Photo 1.3. Fastening with a traverse and a stud
Photo 2.1. Fastening with a clamp and a stud
If it is necessary to install a rectangular air duct of impressive dimensions (with a side of more than 600 mm), usually use fastening with pins and a traverse (photo 1.3). With this method of installation, the air duct rests on a cross-beam, and possible lateral movements are limited by pins. Ideally, for a tight fit and better sound insulation, a special rubber profile is placed between the duct and the traverse. Thus, with traverse fastening, the body of the duct is not injured by self-tapping screws, and therefore this method is most preferable when installing heat- and sound-insulated air ducts.
When installing circular air ducts, clamps and studs are most often used (photo 2.1). This method is simple, effective and allows you to install both conventional and heat-insulated air ducts with equal success. The main thing is to have on hand a set of clamps of the required diameter.
Photo 3.1. Fastening with punched tape without a clamp
However, in some cases, both round and rectangular ducts are fastened using punched tape. In the first case, a loop is made, and in the second, the punched tape is hooked to the bolt at the junction of the air ducts with each other (photo 3.1). Such a mount is certainly cheaper (the cost of punched tape does not exceed 11-14 rubles per meter), but it has a number of disadvantages. First of all, it does not provide the proper rigidity, and therefore the air duct often begins to “walk” and vibrate. In addition, when fixing the ducts to punched tape, it is difficult to align them in height. As a result, the noise level sharply increases, and in case of obvious errors in the installation, a violation of the tightness of the route may occur. If we use punched tape during installation, then it is better to use it with clamps (photo 3.2). Experienced installers usually limit the use of punched tape to circular air ducts up to 150-200 mm in diameter, and when laying large air ducts, they prefer to use more reliable types of connections.
The method of attaching air ducts to the ceiling is no less important. Usually high-quality metal anchors are used for this, the fastening mechanism of which is generally similar to how a plastic dowel “clings” to the wall under the influence of a screw (photo 4).
Photo 4. Drop-in anchor
Anchors are inserted into a pre-drilled hole, and with the help of a special chisel, a membrane is knocked out, separating the threaded part from the “flower”. After that, a hairpin is wrapped in the anchor, under the action of which the “flower” opens in the hole and firmly fixes the anchor in the ceiling. Drop-in anchors can withstand very significant loads, therefore it is recommended to use this particular type of fastener. In the case of using something that came to hand, a loosening and loosening of the connection of the hairpin with the ceiling may occur, which will lead to deformation of the duct with all the ensuing consequences.
Photo 3.2. Fastening with punched tape with a clamp
Fig. five. Fastening with a clamp
A separate case is the laying of air ducts in rooms where it is impossible or impractical to attach them to the ceiling. In this case, a metal beam is usually chosen for the installation of the route: an angle, a T-beam or an I-beam. Special clamps are put on the existing profile, to which the hairpin is attached (photo 5, clamp on the profile).