Every residential building and building for any purpose needs to be insulated. Floors, ceilings, foundations and walls can be subjected to this procedure. No home or institution can be operated without ventilation through which heat is leaked. This means that such a system also needs thermal insulation.
What is insulation needed for?
It allows you to solve three main problems. Firstly, you can prevent the formation of condensation. Secondly, reduce the noise level of the equipment. Thirdly, you can reduce heating costs.
The choice of material and its types
To insulate the duct, it is necessary to select the material. It can be cylindrical shells, rolled materials or sheet products. In the latter case, we are talking about an option that is suitable for square and rectangular ducts. But in the case of systems of a different configuration, sheet insulation is rarely used. This is due to the complexity of installation and the increase in the time of work. In addition, many joints have to be made that weaken the structure.
An excellent replacement is roll insulation. The basis is usually mineral wool. Its thickness varies from 40 to 80 mm. The most popular format is 50 mm. Rarely used mineral wool with a thickness of 80 mm. Such solutions for thermal insulation of ventilation ducts are relevant for large-panel housing construction, but not for a private residential building.
Mineral wool and foamed polyethylene
If you use mineral wool with an outer foil layer, you will be able to not only make the structure more efficient, but also protect it mechanically. It is important to consider that the cotton wool is gradually caking, and over time it will begin to crumble, so care must be taken when working with it.
Thermal insulation of ducts is often carried out with foamed polyethylene. Such work is cheaper, since the cost of materials is less. The insulation has a small thickness, so the pipe must be wrapped with polyethylene several times. According to its characteristics, this material is similar to foamed rubber. Among rolled options, mineral wool insulation is considered as a priority.
Insulation shell
The shell can be monolithic (in this case it is strung on a pipe) or a team. The latter option is used for existing operational systems. The shell can help out in those places where the pipe is drawn through the wall. When winding a roll insulation in such cases, complexity can arise. Quite good results can be achieved in outdoor open areas. However, those points where the duct turns cannot be closed with a cylinder. In such conditions, it is recommended to use insulating mats.
The shell may be made of:
- Styrofoam.
- Mineral wool.
- Extruded polystyrene foam.
- Polyethylene.
- Rubber.
In the supply and exhaust ducts during operation there is a lot of noise. As the cross section of the pipe increases, the throughput becomes higher, but the resistance also increases. The interior finish allows you to make the surface as smooth as possible, which slows down the air flow less.
Mufflers and foams
Rarely today, combined insulation solutions are used, because more practical methods are offered on the market. Mufflers can significantly reduce noise. In addition to mineral wool, glass wool, which is coated with reinforced aluminum, can be used for thermal insulation. Inside is fiberglass with impregnation. You can use foam elastomers. They are good because they die out when exposed to fire and do not sustain combustion. Such materials have an additional number of features, they:
- Do not allow mold to develop.
- Absorb moisture.
- They are harmful to microorganisms.
- Pass steam without harming yourself.
Thermal insulation of air ducts is quite often carried out with the following materials:
- Polyisocyanate.
- Polyvinyl chloride.
- Polystyrene.
They are fireproof, like polyethylene and polyurethane. These materials are supplied in the form of tubular sectors, blocks and plates. The main area of ββuse is internal thermal protection. Expanded resins are made on the basis of phenol, which are fireproof and stably tolerate the effects of microbiological substances. For this reason, they are placed in the ducts of industrial refrigerators.
What to look for before starting work
Choosing the right material for thermal protection is quite difficult, so some factors should be taken into account. Firstly, it is important to consider where the pipes are located - in the room or on the street. Secondly, the diameter and thickness of the pipe must be taken into account. Thirdly, you need to pay attention to the main structural material.
If we are talking about household ventilation, it is insulated with foamed polyethylene. Of it, finished shells are made that take the form of a pipe. With their help, you can isolate the system from hypothermia. The advantage of these materials is the absence of harmful substances in the composition. If it is necessary to simultaneously warm the gas pipe and ventilation, it is necessary to use mineral wool.
Technique of work. Step-by-step instruction
When thermal insulation of air ducts, which are located outside the heated rooms, insulation is carried out from the output to the deflector. If the pipe goes through the attic and passes through the roof, it must be insulated throughout the length of the section in the attic. The same requirements apply to the area that goes through an unheated room.
The heated supply system is equipped with appropriate material throughout. The use of boxes is often resorted to in the attics. The thermal insulation in this case has the form of casings and consists of foamed polyethylene. Among the advantages of this approach, one should highlight the affordable cost and the ability to purchase goods in any hardware store. It is recommended to choose a casing taking into account the size of the pipe.
Foamed polyethylene can deteriorate when exposed to ultraviolet light. To exclude a similar effect, it is necessary to cover the structure from the outside with aluminum kitchen foil. When insulating the supply air ducts, it is necessary to measure the diameter and height of the system from the outside. Next, the casing of the desired size is prepared. If an umbrella is installed, it must be removed. The casing is stretched to the base of the pipeline. After this, the umbrella can be returned to its place.
From bottom to top, foil is superimposed on the system. This will increase the life of the structure. With the help of copper or stainless clamps, it is possible to fix the winding. If the work is carried out in the middle zone of Russia, this solution is best suited. If we are talking about a more severe climate, you will need reinforced insulation like mineral wool. It works well on domestic and industrial ventilated channels. If desired, the material can be used inside and out. A typical example is Izover coatings.
Necessary tools
When installing thermal insulation of air ducts, it is necessary to prepare the following tools:
- Putty knife.
- Stapler.
- The square.
- Scotch.
- A sharpened construction knife.
- Ruler.
- Roulette.
- Marker.
The spatula must have a rubber working part. The tape must be aluminum, the strip thickness is 7.5 cm. The marker is necessary for marking.
Expert Advice
Before cutting insulating material, when calculating the required width, it is necessary to start from the diameter of the pipe. Doubled insulation thickness should be added to this value. The amount increases by 3.14 times. This will allow you to get the desired indicator. The roll is unwound and the necessary distance is measured on it. When measuring, it is important to prevent wet cotton. If it rains outside, it is better to postpone preparation than to lose an expensive product.
When you make an incision on the surface, you need to separate the cotton layer from the foil. When the roll is cut, according to the prepared mark, it is necessary to wrap the pipe in it. Every 10 cm, it is necessary to fix the seam with a stapler and glue the connected area with tape.
After this, tape is carried out with a rubber spatula, then the glue will better clutch to the surface. If the work is carried out with pipes that supply the house with air, it is necessary to cover the system at the joints from heat leaks. This problem can be solved quite simply by cutting curved pieces. Their length is selected in accordance with the calculated values. Fragments should be exposed so that they duplicate the problematic bend. Joining places must be covered with aluminum tape, which can be leveled with a spatula.
It is quite simple to work with the shell, as it is applied to the place and latched. Thermal insulation of ventilation ducts can be difficult in the place where air separation occurs. When work is being carried out in industrial plants, materials should be used that can prevent detonation or combustion, but shock sensitivity does not matter. The sections of air ducts that are located outdoors cannot be isolated with foam.
Thickness calculation
The thickness of the duct insulation is directly proportional to the thermal conductivity and inversely proportional to the heat transfer coefficient. The thickness of the layer is set taking into account:
- Differences in air temperature in the system and in the room.
- Duct parameters.
- Temperature and humidity inside the building.
- Thermal conductivity insulation.
Calculation of thermal insulation of air ducts is carried out taking into account the dew point temperature, which depends on humidity and air temperature in the room. It is important to pay attention to the coefficient of thermal conductivity of the material. The thickness will depend on it.
If the coefficient is 0.03, the optimum final thickness value is 1.9 cm.
With a coefficient of 0.032, the thickness should be increased to 2.1 cm.
The thickness increases to 2.3 cm if the thermal conductivity is 0.034.
The thickness will be 3 cm if the coefficient is 0.04.
Self-adhesive thermal insulation for air ducts usually has a coefficient of 0.038. For this value, the material thickness should be 2.8 cm.
Description of self-adhesive thermal insulation
Self-adhesive sheet insulation is made of foamed polyethylene. The degree of firmware reaches 60%. The coating is aluminum reflective foil. The thickness of this layer is 70 ΞΌm. The density of the material is 29 kg / m 3 . The temperature range for operation varies from -60 to + 80 Β° C. The coefficient of thermal conductivity is 0.037. It is measured at a temperature of +40 Λ.
Self-adhesive thermal insulation for air ducts belongs to the first group of fire safety. The material is packaged in a roll, the width and diameter of which are 0.98 and 0.76 m, respectively. Installation of the material is quite simple thanks to a self-adhesive layer of cross-linked polyethylene. The insulation is flexible, so it can be used for radiators without dismantling them.
Conclusion
The calculation of the thickness of the insulation of the duct is an extremely important stage in the work. If this indicator is chosen incorrectly, the system will work with less efficiency. You may experience increased heat loss. Materials for thermal insulation of air ducts are usually selected taking into account the purpose of the premises. A very important factor is the safety of insulation for residential buildings.