Ventilation belongs to the main systems of human life support. Its correct operation ensures clean indoor air. In order for the system to function for a long time, it must be insulated. This is the boundary between cold and warm air and, as a result, the area of condensation. Thermal insulation of air ducts is a common protective procedure, without which no construction takes place.
Benefits and disadvantages
Thermal insulation of air ducts has the following advantages:
- prevention of the formation of condensation on surfaces (external, internal) and all the negative consequences that it entails;
- reduction of heat loss;
- protection against noise arising from the operation of ventilation;
- providing fire resistance in order to avoid the spread of fire if a fire occurs.
The disadvantages include:
- considerable costs;
- in case of improper performance of work on the thermal insulation of the air duct or the use of low-quality materials, mold and mildew may occur, which is dangerous to health;
- the insulation used can emit substances harmful to people.
The thermal insulation of the ventilation ducts accelerates the upward movement of air, thereby improving the quality of the entire system.
The main types of insulation
As a heater for ventilation, different types of materials are used, differing in properties and characteristics:
- Mineral wool. The insulation effectively fulfills its task, providing reliable thermal insulation. Mineral wool does not burn at all, which complies with fire safety regulations. Mold and fungi do not grow in it. With all this, the material has an affordable price.
- Basalt fiber. This is a high-quality type of mineral thermal insulation that is resistant to high temperatures, aggressive environments, and ultraviolet light. Fiber is a non-combustible material. It is produced in the form of slabs, mats, and shells. The main disadvantage is that it absorbs moisture.
- Glass wool. Fiber has much in common with mineral wool (properties, production technology), but also has different characteristics. Due to its fibrous structure, glass wool material is considered an excellent sound insulator. It has high chemical resistance, non-hygroscopic, does not emit toxic substances, and does not contain corrosive agents. The material is non-flammable.
- Foamed polyethylene. Produced in the form of 10 mm sheets, shells, bundles. The former may have a foil coating. Such polyethylene is considered the cheapest insulation material. Among the disadvantages: does not tolerate high temperatures, ultraviolet light, burns. Pros: does not absorb moisture, durable, plastic.
- Polyurethane foam. Such insulation for ventilation pipes is resistant to moisture, strong, durable, but does not tolerate exposure to ultraviolet radiation. Operating temperature range - (-60 - 80 ° С). Polyurethane foam is a good heat insulator with an affordable price.
The main characteristic of thermal insulation for ventilation is thermal conductivity. It must be one of the lowest.
Duct insulation device
Condensation in ventilation systems is considered a serious problem. Water droplets are formed that can damage walls, floor coverings, ceilings. Over time, due to the influence of condensate, the air duct fails.
It is possible to avoid condensation by using an insulation device of the required thickness, which will ensure that the temperature on the outer insulating surface is not lower than in the room. The peculiarity of this design: the presence of a vapor barrier layer that protects the insulation from moisture. For this, foil coatings are often used. Mineral wool, basalt fiber, polyethylene and others are used as the main part of the insulating layer.
The joints of the insulating layer must be carefully glued with foil tape. Additional fixation of roll insulation is done with wire or steel tape.
Fire retardant insulation
Ventilation ducts often connect different types of rooms. Therefore, they must be protected by fire-fighting insulating material. Such measures are required to prevent damage to air ducts by fire in the event of a fire in the building.
For fire insulation equipment, the following are used:
- Mineral wool wired mats and slabs.
- Basalt fiber cylinders.
Mineral wool slabs (square section) during installation are fixed with pins and washers for fixing, screws. Wired mats (round, rectangular) are sewn with wire. The use of foil mats increases the functionality of the insulating layer and also improves the appearance of the duct.
In the case of a significant length of vertical air ducts, fire insulation is additionally attached to the ceiling and other building structures. For this, steel wire or plates are used. Fixation methods are defined by fire and building codes.
Recently, flame retardants have been used to improve fire safety. They are applied to the air ducts with a brush, roller, using a spray gun. In the event of a fire, a fire-resistant barrier is created under the influence of high temperature.
Sound insulation of air ducts
The ventilation system (pipes, hood) can become a source of unwanted noise, from which the premises must be protected. Sound generators are fan blades, valves, dampers and other rotating elements. Some of the noise and vibrations are eliminated due to the properties of the materials from which the air duct is made. This function is performed by sleeves, ventilation ducts.
Most of all, noise propagates through metal air ducts. In this regard, if the requirements for the noise level are high, a noise isolation device is needed. Sometimes the use of duct mufflers helps, but ideally, insulation equipment based on basalt or fiberglass.
Noise reduction is also achieved with specially coated slabs made of fiberglass. They are installed inside the duct, and the joints are covered with a metal profile.
Insulation thickness
When calculating the density of the insulation, it is necessary to take into account two main indicators of the material used to make the insulation:
- Coefficient of thermal conductivity.
- Heat transfer coefficient.
The thickness of the insulation is directly proportional to the first indicator and inversely proportional to the second: if the thermal conductivity of the insulation is low, a thin insulation must be used for finishing.
When calculating the thickness of the thermal insulation layer, the following is taken into account:
- humidity and temperature in the room;
- thermal conductivity of insulation;
- the difference in temperature indicators in the room and the pipe;
- duct parameters (size, shape).
Any material for thermal insulation will absorb some moisture over time, which increases thermal conductivity.
Installation rules
Insulation technologies for ventilation ducts in the building and on the street are almost the same. For the first, there is no need to apply a protective layer, since there is no influence of unfavorable factors of nature. Insulation of ventilation pipes is also required in a cold attic, roof.
Indoors
Insulation is done in the same way as for walls, floors:
- The air duct is covered with a membrane. It serves as a waterproofing barrier.
- Insulation is laid.
- The insulated air duct is completely covered with another membrane or foil (vapor barriers).
If the insulated ventilation pipe is located in a room with high humidity or an aggressive environment, the use of protective layers is mandatory.
On the street
If there is an old insulation, it must be removed, the surface must be cleaned from glue and other materials.
- In the case of using roll or sheet material, the pipe is wrapped several times. An excellent option is self-adhesive thermal insulation for air ducts.
- A reinforcing frame (synthetic, metal) is placed under the polyurethane insulation. It is put on the air duct, and the ends are fastened.
- Insulation is laid on the surface, fastened with clamps, wire.
- The insulated air duct for ventilation is covered with a protective material. Most often, a casing made of tin or aluminum sheets is used.
Insulated ventilation pipes (plastic) in a private house, as a rule, come out through the roof or wall.
It is required to insulate the air duct reliably so that the device is not damaged by wind or precipitation.
Duct insulation materials have different costs and characteristics. Proper insulation should provide overall duct protection to extend the life of the entire monitoring system.
