The device for thermal insulation of pipes of the heating system, including external ones, is an important component of high-quality heating equipment for housing and is carried out without fail. The need for this operation is due to many factors, the degree of influence of which on the efficiency of heating an apartment or house depends on the specific circumstances.

Modern technologies allow heating on the street independently, having studied the characteristics of the heat-insulating materials used and how they are installed.

Functions of thermal insulation of external heating pipes

The purpose of the heat-insulating coating of the pipeline has several components that affect not only the efficiency of the heating system, but also the safety of its operation, the resource of heating equipment. To make the requirements for insulating coatings clearer, let us consider in more detail the functions performed by them.

Reduced heat loss

The efficiency of a residential heating system depends on many factors, including the amount of heat loss. One of the components of the volume of heat loss is the transfer of part of the energy by the coolant to the transit medium when moving from the heat generator to the heat exchanger. Simply put, hot water or steam, moving through pipes from a heating boiler to radiators, partially cools down, giving off heat to the environment (air, wall material, soil, etc.) through the walls of the pipeline. And, the higher the thermal conductivity of the pipe material, the greater the heat loss. Therefore, the pipeline of the heating system needs an additional heat-insulating shell that prevents heat exchange between the coolant and the environment through the pipe material.

Frost protection

In the heating system during the off-season, due to some circumstances, there may be water that will disable the pipeline, freezing in the circuit during the inactivity of the boiler during the first frost. Thermal insulation of the pipeline will significantly slow down this process, keeping the water temperature in the system above zero for several days or even weeks.

Preventing the formation of water condensate

The thermal insulation of the pipeline will prevent the formation of condensate on it during temperature changes in the environment, if the heating system is not free from water, and this will protect the pipes from corrosion from the outside.

Protection against thermal burns in direct contact with the heat conductor

A sheath made of heat-insulating material, by definition, cannot have a high temperature and will exclude the possibility of getting a burn in case of accidental contact of the human body with a hot pipeline.

Neutralization of geometric deformations

If the heating system is routed inside the building structures, the flexible shell of the pipeline will take over the temperature deformations of the pipes and protect the outer wall finish from the effects of cyclic compression-expansion on it from the inside when the heating is turned on and off.

Requirements for thermal insulation materials

Given the importance of the role of thermal insulation for pipelines of heating systems, the need for its high-quality device, due to the listed functions, the following requirements are imposed on thermal insulation materials, enshrined in SNiP 2.04.14-88 "Thermal insulation of equipment and pipelines":

• low value of specific thermal conductivity - the determining condition for the suitability of the material to perform the main task (thermal insulation);
• sufficient heat resistance - the ability of a material to maintain its structure and physical characteristics at high temperatures (in everyday life - 105, in production - up to 700 degrees Celsius) temperatures, without reacting with the contacted substances, without becoming a catalyst for any chemical processes and without releasing harmful substances.
• chemical resistance - the ability of a material to respond stably to organic substances;
• sufficient hydrophobicity - water-repellent properties that prevent the heat-insulating layer from getting wet, since filling the pores of the material with water will make it an excellent conductor of heat, while simultaneously contributing to the destruction of the pipeline under the influence of corrosion;
• vapor permeability - the ability of the insulation to dry quickly in case of direct contact with water;
• airtightness - a characteristic that excludes the filling of the insulating material under the influence of wind with dust particles that increase thermal conductivity (all solid thermal insulation materials meet this requirement, soft ones need additional protection);
• durability - the material must meet all the requirements throughout the entire shelf life specified in the instructions for use.

Types of execution of heat-insulating materials for pipelines

By execution, materials for thermal insulation are divided into the following types:

• roll;
• sheet (in the form of mats);
• casing;
• liquid.

Rolled thermal insulation materials - a strip of thermal insulation rolled into a roll of a certain thickness and width, with or without a foil base.

Rolled thermal insulation is wound on pipes in a spiral or (only in horizontal sections) is laid longitudinally on the pipeline with the edges joined under the pipe and fastened with clamps or wire. If the material is foil, then the thermal insulation is arranged with a layer of foil to the outside, but this does not provide sufficient protection of the material from precipitation, so the question arises of how to isolate the heating pipe on the street from moisture. This problem is solved by installing metal protective covers made of galvanized iron on the pipeline over the foil material.

Sheet materials are used in the same way as roll materials for longitudinal laying, the use of protective covers over them is also due to the need to protect against moisture and mechanical damage.

Casing thermal insulation can be hard or soft.

Solid heat-insulating materials of casing design are a hollow cylinder with a wall of a certain thickness, having longitudinal sections of the lock profile on two or four sides. The diameter of the cylinder cavity is made for a certain dimension of the pipes.

Soft materials for thermal insulation are a flexible casing with a wall of a given thickness, with or without a longitudinal section. A flexible heat-insulating sleeve without a cut is put on the pipe before its installation, and the cut allows you to insulate an existing pipeline.

Liquid materials for thermal insulation of pipelines on the street are divided into:

• spraying;
• coloring.

The first variety is applied using a special spray device, which gradually builds up the thermal insulation layer to the required size.

The second variety is applied in the form of a layer applied with a conventional paint roller or brush.

Each of the listed types of thermal insulation has varieties that differ in the material of manufacture, production technology, physical characteristics, price, etc., as manufacturers are constantly improving the properties of the insulating products produced. The modern market, depending on the operating conditions of the pipeline, allows you to choose the material that best meets the requirements of a particular situation.

Options for the location of the heat pipe on the street

During the construction of private housing, there is a situation where it is necessary not only to install and install a heating system in the premises of the building itself, but also to bring it to nearby residential or outbuildings.

The second situation is that housing is connected to a heating main passing nearby, or an autonomous heating boiler is used, located in a separate building-boiler room.

In such cases, the installation of the pipeline between buildings is carried out in one of the following ways:

• open (aerial);
• underground.

Each option for laying pipelines has both general principles for the production of insulation for all situations, and the nuances of performing work inherent only to it. At the same time, any method of installation and insulation of steel pipelines provides for mandatory preliminary preparation of the pipe surface - cleaning and applying a protective anti-corrosion paint and varnish coating.

Open (aerial) way

An open method of laying a pipeline implies its location on concrete or steel supports of a certain height, installed with a calculated step. Laying pipes directly on the ground is allowed only during the construction of temporary highways.

When choosing a heat-insulating material in this case, it is necessary, in addition to the characteristics of the coolant, to be guided by the pipeline accessibility factor in terms of the likelihood of accidental damage to the insulation. If the pipes are located on supports higher than human height, then they are more protected than a low-mounted pipeline accessible to humans and animals. Therefore, for pipes located at low heights, protective casings should be selected from thicker galvanized metal.

Not in the last place is the aesthetics of the equipped thermal insulation, therefore it is undesirable to use casings made of roofing iron without a zinc coating for protection - they will periodically have to be covered with a protective paint layer.

Important! If foam plastic shells, which are a combustible material, are used as a pipeline insulation, then transverse gaps are arranged in the thermal insulation of the foam plastic, filled with non-combustible material, for example, mineral wool.

Underground way

This technology is divided into two subspecies:

• channel - the mounted pipeline is located underground in a sleeve that takes on the weight of the soil;
• channelless - pipes equipped with thermal insulation are laid directly in a dug trench.

The channel installation method significantly increases the cost of work and is almost never used in private homes.

The laying of the pipeline underground is carried out below the freezing mark of the soil, and permeable materials (mineral wool) are not used to insulate the pipes, which, when flooded, can become saturated with water and lose their insulating properties.

Varieties of heat-insulating materials and methods of their application for insulation of pipes on the street

The range of heat-insulating materials, despite the high requirements for their characteristics, is very wide today, so the budget becomes the guiding criterion when choosing how to insulate the pipes of the heating system on the street.

Foamed polyethylene

Polyethylene foam (PPE) is reasonably considered one of the most effective heat insulators, since its thermal conductivity is only 0.035 W / m2 deg. C is two times lower than that of mineral wool (0.07 W/m2 deg. C). Such polyethylene is offered to the consumer in rolls, in sheets and in the form of sleeves-cases of various sizes.

The elastic bubbly structure of PPE in its rolled version makes it easier to perform insulation on shut-off valves and pipelines of complex configuration, as it allows you to cut the material into strips of the required width and wrap problem nodes with it. Polyethylene is vapor- and water-tight, therefore it is not only warm, but also a waterproofing coating.

The specific density of PPE, depending on the structure, is 32 - 35 kg / m 3, so the heat-insulating shell from it does not create significant loads on the pipeline and supports.

Despite the fact that polyethylene can be set on fire, its combustibility is low (class G-2), and when ignited in the absence of additional sources of fire, PPU quickly goes out, while the substances released by it during combustion are slightly toxic.

For thermal insulation of straight sections of the pipeline, it is more convenient to use PPE sleeves (with or without a side notch), since winding pipes with rolled material with the necessary technological overlap requires additional strengthening of the insulating layer with knitting wire or clamps and does not look aesthetically pleasing.

With many advantages, the price of PES is not high, which determines its high popularity among owners of private houses.

Penofol

This insulation is a type of PES and differs from it by the presence of a foil layer on one side, which is a reflector of thermal waves, which increases the heat-insulating, as well as hydrophobic properties of the shell.

Foam foam insulation - foil PPE is also produced in the form of rolls, sheets and cylindrical shells.

Important! The use of foamed polyethylene and penofol is limited by the upper limit of the application temperature of 85 degrees. This value is sufficient for the use of materials on the pipelines of an autonomous heating system, but a higher temperature of the central heating lines worsens the characteristics of the PPU and makes it unsuitable for use in these conditions.

Mineral wool and products based on it

Insulating external heating pipes with ordinary or foil-coated mineral wool, wrapping the line with a strip of this material with fixation with knitting wire, is the oldest method of thermal insulation. But the popularity of this technology, due to the rather high efficiency of its application and the affordability of costs, is still high - the choice of mineral wool as an insulating material for large volumes of work is quite justified.

Three varieties are produced:

• glass wool;
• stone;
• slag.

The first two varieties meet most of the requirements for thermal insulation - they have low thermal conductivity, are neutral with respect to the insulated surface, are quite elastic, chemically resistant and fireproof. As for the slag variety of this material, the process of its manufacture causes the presence of residual acidity in such wool, which negatively affects steel pipelines - in this regard, pipes have to be coated with special paint, which negates the advantage of slag wool in price.

However, all three varieties of mineral wool are water-permeable and hygroscopic to varying degrees, therefore, insulation from these materials must be protected with galvanized iron casings, which will also be protection against mechanical damage.

Polyurethane foam insulation

Polyurethane foam (PPU) according to the texture is made elastic (foam rubber), rigid and sprayed. Rigid and sprayed polyurethane foam is used as thermal insulation - an effective and functional insulating material, numbering more than 30 grades.

All brands of PPU are united by the following advantages:

• breathability;
• resistance to chemicals (higher than that of polystyrene foam);
• low moisture absorption (good hydrophobicity).

Rigid polyurethane is produced in the form of a prefabricated shell-shell or cylinders with a mounting slot, having certain dimensions, with a foil outer surface. Products are superimposed on the pipe and fixed with clamps, heat-resistant sealant or their own self-adhesive inner surface.

Pipes are also produced, on which thermal insulation has already been made of polyurethane foam with a protective sheath - the so-called pre-insulated pipes, which are interconnected by welding with subsequent insulation of only welded joints.

The sprayed polyurethane foam is applied to the previously prepared surface of the pipeline with a special spray device in layers and, as it hardens, the thickness of the insulating layer is increased to the calculated value. To perform thermal insulation using this technology, special expensive equipment and protective clothing are required, so it is not used in domestic conditions.

foamed rubber

The raw material for this high-quality material is synthetic rubber, the production cost of which is much lower than the cost of natural material, but the quality characteristics are just as high.

Foam rubber properties:

• high elasticity with a large margin of tensile strength;
• low specific density of the material - 40 - 80 kg / m3;
• high thermal insulation characteristics;
• no shrinkage during operation;
• low flammability;
• zero vapor and water tightness;
• chemical inertness.

Rubber thermal insulation is produced in the form of rolled material, sheets of a certain format and tubes-sleeves for standard pipe sizes. When using foamed rubber as insulation for outdoor heating pipes, it is necessary to use protective casings made of galvanized roofing iron, which will protect the material from dust contamination and mechanical damage, including vandalism.

The price range of rubber insulation, depending on the thickness and manufacturer, is quite wide and allows you to choose a material with an objective price / quality ratio.

Conclusion

A huge range of thermal insulation materials indicates the importance of protecting pipelines from heat loss and the demand for funds to achieve this goal.

Important! Most modern materials suitable for domestic use allow you to perform thermal insulation work yourself. And yet, before proceeding with this operation, it is advisable to consult on how to insulate heating pipes on the street from professionals who already have experience with the type of insulation coating you have chosen.