Heating of a private house with cross-linked polyethylene. Plastic pipes for heating specifications. What is so good about polyethylene, which is sewn correctly

The feeling of comfort in the house in any weather conditions outside the window is created thanks to correct work heating system. Its efficiency, quality and service life directly depend on the pipes. Today, the installation of the heating system is increasingly performed using pipes made of cross-linked polyethylene. The properties of this material allow it to surpass other options in many ways. However, when installing such pipes with your own hands, you need to know some of the nuances that will be discussed in this article.

Product characteristics

Pipes made of ordinary polyethylene (PE) are widely used to create heating, water supply, and sewerage systems.

Several of their main features are:

• Frost resistance, allowing the use of polyethylene structures at temperatures up to -20 degrees. This is a great advantage, as it makes it possible to carry out any work with pipes in the winter, including installing new equipment or repairing failed systems.
• Resistant to high temperatures (up to 40 degrees).
• Flexibility that prevents pipes from deforming when bent.
• Plastic. Polyethylene products can expand or contract depending on temperature without losing their shape.

In order to obtain higher strength pipes, a reliable and high-temperature resistant material called "cross-linked polyethylene" (PEX) was created.

Its main feature is the maximum operating temperature - 90 degrees. Sometimes such pipes can withstand temperatures of 100-110 degrees, while maintaining normal functioning for a certain time.

Another important feature of XLPE pipes is high oxygen permeability. When installing such products, it is necessary to remember this property and use aluminum foil or a special polyvinylethylene coating to protect them.

Production methods

The technology of "crosslinking" polyethylene in 1968 was invented by the Swedish chemist Thomas Engel. In 1972, one of the Swedish companies put it on an industrial stream. This technology and is the market leader today.

The meaning of the process of "crosslinking" is the connection of molecules into a three-dimensional network as a result of the formation of cross-links. In its course, polyethylene, the molecule of which contains hydrogen and carbon atoms, loses part of the hydrogen. Therefore, free bonds appear to connect molecular units with each other, as a result of which the molecules are tightly “crosslinked” with each other.

There are different ways to obtain cross-linked polyethylene. Depends on the method specifications finished pipe. The longest, but at the same time the highest quality method is the processing of polyethylene with peroxide. It gives the highest degree of crosslinking (85%). A pipe made of such a material easily withstands low and high temperatures, resists the effects of chemicals, acquires resistance to shock and other mechanical stress, and can restore its original shape.

Another way is to irradiate the material with electrons in an electromagnetic field. Such cross-linking involves electron irradiation of the finished product.

There is also a method of physical crosslinking, which uses X-rays. However, such structures are rigid. They are not resistant to extreme cold and cannot return to their previous form.

The most common is the chemical method of silane crosslinking. It is more effective than physical. At the same time, polyethylene is obtained that is optimal in price and quality, suitable for use in everyday life.

A heat-resistant, strong material, pipes from which are excellent for mounting heating systems of any type, hot and cold water supply systems, floor heating equipment, is obtained as a result of each production method. It's just a matter of choosing the right one desired characteristics, and also remember that the higher the degree of crosslinking, the higher the price of the material.

Advantages

Pipes made of cross-linked polyethylene have a number of advantages, due to which they are most often used for the installation of heating systems.

• Resistance to high temperature (up to 95 degrees). Products made of cross-linked polyethylene are capable of expanding or contracting to certain sizes under the influence of low and high temperatures.
• Excellent mechanical strength due to good molecular memory of the material. It easily restores its original shape after deformation, unlike conventional polyethylene pipes.
• Corrosion resistance. Products made of cross-linked polyethylene are not afraid of corrosion either inside or outside (unlike, for example, copper). This quality allows not to carry out flushing and cleaning of PEX pipes, which is periodically necessary for their metal "brothers" and has a rather high cost.
• Guarantee against the appearance of growths inside the pipes. Unlike steel pipes, which after some time become covered from the inside with growths that slow down the flow rate, the inner walls of PEX pipes have a special Teflon coating and are not subject to the deposition of layers. Due to the smoothness of the inner walls in the heating system, there is always high hydraulics.h

• Light weight material. For example, 1 m of a pipe with a diameter of 16 mm weighs only 90 g. Therefore, they are convenient to transport and easy to install.
• Ease of installation. PEX products can be mounted according to any scheme. They allow you to make loops and any number of bends. This does not require special welding equipment, as the pipes are connected without requiring soldering or gluing. Pipes for heating are sold in 100 and 200 m, which makes it possible to mount large sections of the system without the use of fittings.
• PEX products are environmentally friendly and resistant to the growth of harmful bacteria inside them. The material is included in the group of environmentally friendly, therefore it is widely used for drinking pipelines.

disadvantages

Despite the huge number of advantages, cross-linked polypropylene cannot be called ideal.

It is worth considering its shortcomings.

• Brass fittings used when connecting XLPE pipes for heating are subject to corrosion, so you have to pay close attention to the choice of materials for screed or plaster. It is better not to use materials that cause corrosion of the fitting, otherwise the quality of the heating system will noticeably drop.
• Pipes made of cross-linked polyethylene are "afraid" of ultraviolet radiation. Therefore, they are more suitable for indoor use, in closed systems and communications. To use such products outdoors, a special protective cover is required.
• The price of such pipes, in contrast to the cost of metal-plastic and conventional polyethylene, is quite high.

Therefore, before purchasing pipes made of cross-linked polyethylene, it is necessary to carefully study all the technical characteristics of the heating and water supply system of the room in which they are planned to be installed.

Work process

If the installation of metal pipes requires special knowledge and skills, then this is not required when installing cross-linked polyethylene pipes. To do a good job, you need only certain tools and a little effort.

Pipes made of cross-linked polyethylene are connected with fittings made of various materials: polymers, brass, bronze. It is best to use polymer fittings (for example, Rehau), as they are of high quality, do not corrode and last a long time.

AT in general terms, the process of installing PEX pipes is as follows:

• the end of the connecting structure is expanded with a flaring tool, giving it a larger diameter;
• insert the fitting fitting there;
• using a press, the tension sleeve is pressed in, giving the greatest strength to the connection.

This technology makes pipe connections reliable and durable. The service life of such systems corresponds to the service life of the pipes themselves.

The heating system requires the use of high-quality and wear-resistant materials that are not afraid high pressure and frequent temperature changes. All the above stated characteristics correspond to polyethylene pipes for heating.

In order to give polyethylene flexibility, chemical and mechanical resistance, it is crosslinked by electron flow. There are several different methods for the production of cross-linked polyethylene and, depending on the technology, the technical characteristics of the material change, however, the main advantages and disadvantages are still common.

Advantages of cross-linked polyethylene

Unlike ordinary polyethylene, cross-linked does not soften or deform under the influence of high temperature. It is this property that allows the material to be used for heating and underfloor heating systems. In addition, cross-linked polyethylene (PEX) has the following advantages:

• Complete absence of corrosion;
• Pipes do not overgrow and do not silt;
• Light weight;
• Ease of installation and transportation;
• Resistant to large pressure and temperature fluctuations;
• Does not crack;
• Excellent sound insulation;
• Resistance to negative temperatures;
• Possesses molecular memory;
• It is environmentally safe for humans and any other living organisms;
• Inexpensive cost;
• Strength;
• Long service life (according to manufacturers, it is about 50 years).

The main disadvantages of the material

The positive qualities of cross-linked polyethylene have made it indispensable for heating systems and underfloor heating. However, there are still some disadvantages, among which it is worth highlighting:

• Lack of resistance to ultraviolet rays;

To reduce the destructive effect of ultraviolet radiation on cross-linked polyethylene, pipes are coated with a special protective varnish.

• Possibility of mechanical damage, for example, by rodents;
• No resistance to surfactants;
• Destruction under the influence of oxygen.

When oxygen enters the inner layers of the pipeline, it quickly collapses. It is for this reason that many manufacturers add a protective layer against oxygen exposure, the so-called oxygen barrier. This reduces the risk of damage to the product, but causes an increase in its cost.

Design and production method of PEX pipe

The cross-linked polyethylene pipe is a multilayer structure that consists of five balls. The main layers are as follows:

• XLPE inner ball;
• glue ball;
• Oxygen barrier;
• glue ball;
• External ball of cross-linked polyethylene.

It is this five-layer construction that ensures high heat resistance of the material, because it does not deform even with liquid transfer rates up to 95 ° C. That's why PEX is an excellent choice for heating and underfloor heating.

For the manufacture of the pipeline, the extrusion method is used, which consists in extruding the required shape from molten polyethylene. After that, all pipes are vacuum calibrated. Products are supplied for sale in coils or cuts, depending on the diameter.

Product Specifications

The unique properties of cross-linked polyethylene put it on a par with many solids. The main characteristics of the material include:

• Melting point - 200 degrees;
• The combustion temperature is about 400 degrees;
• Elongation at break - 350 - 800%;
• Density - 940 kg per cubic meter.

Pipeline made of molecularly cross-linked polyethylene is produced in a wide range of diameters. Manufacturers offer sizes from 12 to 250 mm, however, diameters of 16 - 25 mm are the most popular with consumers.

PEX crosslinking methods

There are about 15 ways to crosslink polyethylene, but three of them are the most widely used.

Today, cross-linking methods are in demand:

• Peroxide (PEX-a);
• Silane (PEX-b);
• Radiation method (PEX-c).

More expensive, however, and a better way of cross-linking is peroxide. It is thanks to him that it is possible to bind about 85% of free molecules. This allows the material produced in this way to have increased resistance to mechanical stress and have a higher melting point.

PEX-a - best method production of cross-linked polyethylene, all other options are just an attempt to reduce the cost of the material.

Reinforced pipeline for heating

One of the latest innovations in the market of materials for heating and underfloor heating is a reinforced pipe made of cross-linked polyethylene. It is even more durable and heat resistant than regular PEX. The main difference in the production technology is the introduction of nylon threads into the pipe walls, which occurs at the stage of extrusion of the mold from hot molten polyethylene.

Reinforcement methods can be as follows:

• Kapron thread;
• Kevlar;
• aluminum foil.

The reinforced pipeline can withstand even such loads as a pressure of 30 atmospheres, does not crack during torsion or bending. But the cost of production is higher, because the production requires expensive equipment.

Key XLPE Producers

Cross-linked polyethylene is the most successful material for installing a heating system and underfloor heating. Today, a whole group of foreign and domestic companies is engaged in the production of high-quality and durable products. The key manufacturers are:

• Rehau (Germany);
• Valtec (Italy);
• Uponor (Sweden);
• Tece (Germany);
• Bir Peks (Russia).
• STOUT (Spain)

Rehau is a world leader in the production of XLPE pipes for heating and underfloor heating.

Rehau has taken the leading position in the world market today. It is her products that have excellently proven themselves due to their excellent quality and good performance. The price of the products is not the cheapest, so many developers are looking for more budget options, for example, STOUT brand products.

STOUT is a professional plumbing equipment for the installation of heating and water supply systems. Products are manufactured at the same European factories where other premium segment brands order their goods.

The main items of the STOUT product range are covered by a 5-year warranty. All parts of the system are ideal for each other, easy to install and maintain, adapted to the operating conditions in Russia.

Different manufacturers use different methods of crosslinking polyethylene: PEX-a, PEX-b, PEX-c. the best way cross-linking is today recognized as peroxide (PEX-a), for this reason it is recommended to opt for products trademarks Rehau, Uponor and STOUT, which is produced using this technology.

Low temperature heating lines are becoming very popular. Thanks to modern systems and heating appliances housing can be heated at a coolant temperature of 80 0 C.

Therefore, consumer demand for inexpensive and easy-to-lay XLPE pipes for heating has increased.

These materials are excellent for arranging underfloor heating in rooms. They are comfortable and are produced in bays.

Using polyethylene pipes for heating, the technical characteristics of which make it possible to minimize the number of connection points, it is possible to carry out a very tight pipeline.

These products have a large number of positive characteristics:

1. High fatigue strength. It remains even at an operating temperature of 95C;
2. The ability to maintain a stable shape;
3. Polyethylene pipe resistant to cracking;
4. Excellent impact tolerance, and strength in notched areas. These characteristics are maintained even at very low temperatures of -50 degrees.
5. In polyethylene pipes, strength is perfectly combined with flexibility;
6. Excellent wear resistance to abrasion;
7. Good shrinkage characteristics;
8. Resistance to influence of chemicals;
9. Corrosion resistance;
10. Does not contain halogens and heavy metals.

disadvantages

Watch the video

Polyethylene pipes for heating, the technical characteristics of which have a number of positive points, are still not without some disadvantages:

1. The cross-linked polyethylene pipe is sensitive to ultraviolet light. In the light, its material is quickly destroyed, and the pipe cracks and breaks;
2. It is not recommended to use brass fittings for PE pipes hidden under a screed or plaster;
3. Do not exceed the capacity of these products.

What you need to pay attention to when choosing

Watch the video

When buying pipes made of cross-linked polyethylene, you should pay attention to:

1. stitching method. Such indicators are marked with the letter E when the molecules are crosslinked by reagents or irradiation. The letter P indicates the presence of peroxides, organosilants are denoted by the letter S, and nitrogen by N. The highest degree of crosslinking is in products labeled PEX-P. Most often used for heating lines.
2. The presence of protection against the ingress of oxygen. It is an aluminum layer or a coating of ethylene vinyl alcohol.
3. Pay attention to UV protection. This is labeled - UV (this is partial protection). The UV-1 value indicates complete protection, and the addition of additional stabilizers is indicated by the letters UV-2. For a heating network, it is better to opt for products with the most a high degree protection, the higher it is, the lower the possibility of reproduction of bacteria in water.
4. Diameter. The diameter of the manufactured products can be from 10 to 280 mm, and the wall thickness from 1.7 to 29.9 mm. For the heating system, it is recommended to use products with a diameter of 16 to 20 mm.

Applications

Polyethylene which are ideal for pipelines for various purposes, have proven themselves to be versatile and reliable. Therefore, they are used for:

• Arrangement of the "warm floor" system in residential and industrial buildings;
• Conducting the main cold and hot water supply.

Such pipelines for a long period of operation operate reliably and without accidents.

The main advantages of such water pipes:

• Long runoff service - almost 50 years. Because all parts are made to the highest standards.
• Reliability of connections, due to the fact that fittings do not require auxiliary seals.
• Versatility. Pipes are resistant to high pressure. They tolerate temperature extremes very well. This allows them to be used in private and industrial construction.
• Small pressure loss. The narrowed diameter of this type of pipe rolling is compensated by the expansion at the cut end of the billet.
• Compatibility. If necessary, polyethylene or brass fittings can be used to connect a homogeneous and multilayer product.
• Absolute harmlessness. All elements are made from natural materials.
• New manufacturing technologies. All methods of production of these materials are safe and are aimed at increasing the strength of products. Crosslinking is performed by the action of the electron flow. Therefore, they are better than others for the heating network, for the installation of "warm floors" and for water supply.
• Possibility to hide wiring. The entire highway can be masked with plaster in the wall or in the floor.

Watch the video

Workpieces are being calibrated;

A connecting ring is put on the workpiece;

With the help of a press, a connection is made.

The resulting connection comes out tight and reliable, leaks in it are excluded.

Why cross-linked polyethylene is better than polypropylene and metal-plastic

And it must be said right away that polyethylene pipes, the technical characteristics of which are so multifaceted, are the best solution, because:

• With the help of these pipes, long-lasting communications are created that have been used for more than 50 years;
• It is convenient to create connections with such products and it takes a little time. Laying is carried out using fittings without auxiliary seals;
• These pipes are very convenient in storage, as they do not take up much space;
• They are made in coils that are not difficult to transport;
• Absolute ecological harmlessness.

Pipes made of cross-linked polyethylene for heating have a high rate of reliability and a long period of use. These products meet all quality standards, and are excellent for arranging a heating network, water supply and gas supply.

To date, an established heating system is, first of all, a guarantee that in a house or apartment it will always be cozy and comfortable for all household members, even in the most severe frosts. And fortunately the use modern materials and technology allows you to achieve the longest and most productive operation of any heating system. At the same time, the responsibility for the direct connection between all elements and communications lies with the pipes, the choice of which determines the serviceability and service life of the heating equipment.

Recently, the use of polyethylene pipes has become a very popular solution for arranging water supply and heating systems. They are have a lot of advantages compared to other analogues on the market, but at the same time, certain technical features should definitely be taken into account before proceeding with their direct operation. That is why this article will be devoted to these important issues.

Features of polyethylene pipes

First of all, it should be noted that pipes made of ordinary polyethylene, which are designated by the PE symbol, are intended for water supply and sewerage systems, including drinking water. This is due to the following features of pipes made of similar material:

Due to the incompatibility of this type of pipe with high temperatures, scientific and technological progress did not stand still and contributed to the design of special pipes made of cross-linked polyethylene, which are usually denoted by the abbreviation PEX. They are the ones intended for various systems heating and water supply hot water, whose coolant temperature does not exceed 90 degrees.

XLPE pipes for heating

In order to obtain a more durable polyethylene, this material was subjected to special treatment under high pressure, as a result of which the molecules created between themselves even more strong ties in the form of transverse lines. the so-called "stitching" can be done in several ways, namely:

1. by electron irradiation of polyethylene in a medium electromagnetic fields;
2. by processing polyethylene peroxides;
3. through the use silane gas;
4. by processing polyethylene nitrogen compounds.

The above technological processes contributed to a significant increase in the strength and thermal stability of PEX pipes, which allows them to be used as an element individual and central heating, hot and cold water supply, radiator and panel heating systems, as well as for "warm floor" and "snow melt" systems. Pipes made using peroxides are considered to be of the highest quality.

Pipes made of cross-linked polyethylene are used subject to certain parameters, namely:

1. maximum continuous operating temperature must not exceed 90 degrees, but in force majeure circumstances, the pipes are able to withstand a temperature of 100 degrees for some time;
2. maximum allowable operating pressure in the system must not exceed 10 bar at a temperature of 90 degrees and 25 bar at a temperature of 0 to 25 degrees.

A feature and at the same time a disadvantage of the material from which this type of pipe is made is high oxygen permeability, which makes it impossible to use them in closed heating systems in pure form. That is why they are covered with a special protective layer of polyethylene or can be reinforced with a layer of aluminum foil.

The connection of pipes made of cross-linked polyethylene is carried out using fittings, which can be made from various materials, namely polymer, brass and bronze. Polymer fittings are considered to be the most high-quality and proven ones, which over the years have shown themselves from the best side. The algorithm for connecting such pipes can be written as follows:

1. the end of the connecting pipe is moved apart flaring tool, in order to give it a larger diameter;
2. then in this hole is placed fitting fitting;
3. in order to increase strength, the tension sleeve is attached to the pipe with press.

This technology makes it possible to significantly increase the service life and reliability of such connections, which in terms of quality are fully consistent with long term operation of the pipes themselves made of cross-linked polyethylene.

For private houses, people prefer to use polypropylene pipes:

Advantages and disadvantages of polyethylene pipes

They have many advantages that distinguish them from other types of pipes intended for heating systems, but at the same time, they also have some significant disadvantages, the study of which is mandatory when choosing them. So, to the paramount positive aspects exploitation PEX pipes can be attributed:

Despite the many positive characteristics, the disadvantages of PEX pipes in heating systems also take place. Please note that if using brass fittings direct contact with various plaster and screed materials should be limited, as this will lead to corrosion. and correspondingly poor performance of the system. A disadvantage can also be called vulnerability to ultraviolet rays, which leads to the need to use them in communications of a closed type.

When choosing pipes made of cross-linked polyethylene, it is necessary, first of all, to compare the technical parameters of this heating element with the characteristics of the living space where they will potentially function. If characteristics such as pressure and temperature of the existing heating system exceed the threshold values ​​of PEX pipes, it is better to refuse their use. But, as practice shows, such cases are extremely rare. Therefore, based on the foregoing, we can say with confidence that PEX polyethylene pipes fully comply with modern conditions that are put forward by heating systems operating in the vastness of our country.

In order to decide on the choice of pipes for heating and not make a mistake, it is recommended that you read this article:

How PEX pipes are made

High-quality heating of a house or apartment is a guarantee of comfort and coziness of living. And it depends not least on the quality of the created heating system. Today, for these purposes, manufacturers offer many different materials that greatly simplify installation work and increasing the durability of the created systems.

It is clear that none of the water heating systems can do without quite a large number pipes, and their choice should be approached with the utmost responsibility. Gone are the days when steel pipes VGP were practically no alternative. The modern choice is rich. For example, XLPE pipes for heating are relatively new material which has many advantages over others. However, it also has its own characteristics that should be taken into account. In order not to make mistakes when considering the question of what are suitable, during the installation work and further - already during the operation of the heating system, it is necessary to have an idea about the main characteristics and capabilities of this material.

What is cross-linked polyethylene?

You should not think that the usual polyethylene, familiar to everyone, sold in the form, for example, of films of various densities, is the same material from which they are made for plumbing and heating circuits. For products that will experience considerable operational loads, it is cross-linked polyethylene that is used. And keyword in the name is still "crosslinked". Yes, the basis is the same, and the differences lie in the features of the molecular structure.

We will try to explain the difference intelligibly.

Conventional polyethylene has a linear molecular structure. Long chains of linear molecules are not interconnected. Therefore, the material does not have high resistance - it is easy to break it by mechanical action, and even with not very large heating, it begins to “float”.

Chemists-technologists tried to somewhat change the molecular structure of the material, namely, to try to connect linear molecules with cross-links.

During the manufacture of this material, the molecular chains are “crosslinked”, which creates numerous stable cross-links. In fact, the linear structure turns into a three-dimensional one. It is important that the material not only does not lose all its positive characteristics, but also acquires much greater stability. The more intermolecular bonds created, the higher the degree of crosslinking is considered.

One of the very interesting and useful properties, acquired by polyethylene as a result of cross-linking, is a kind of "memory" of the original shape of the product from this polymer. So, with an increase in pressure, with mechanical or thermal effects on the same pipe, its deformation is quite possible. However, after the loads are normalized, removed or weakened, the material tends to restore the previously given original shape. Agree that this is a very important advantage for the heating system.

Polyethylene pipePE-RT

An innovative development in the production of pipes has become products made of PE-RT polyethylene (polyethylene with increased heat resistance - "Polyethylene of Raised Temperature resistance"). By and large, this type of polyethylene cannot be fully called a crosslinking product. The fact is that already the initial granular raw material from which products are made has stable intermolecular bonds, and even more branched than those of PEX.

The process of creating PE-RT became possible with the development of technology that allows you to control the processes of spatial formation of macromolecules. These developments allow you to create materials whose structure will correspond to precisely specified parameters. This opens up opportunities to focus on a certain property of materials.

The abundance of intermolecular bonds makes the material resistant to internal and external loads, eliminates the appearance of cracks or breaks during strong bends. Despite aggressive influences, PE-RT, unlike PEX, always retains its thermoplasticity. Therefore, the connection of pipes of this type can be made not only with the help of pressure fittings, but also using welding technology. This simplifies and reduces the cost of installation, and high-quality welding ensures the highest reliability of the joints, and hence the heating system as a whole.

Given the advantages of PE-RT, we can conclude that it is confidently replacing the previously widely used PEX products from the market. These advantages include the following qualities:

• The manufacturing technology of PE-RT is much simpler, since it does not require an intermolecular crosslinking cycle. All the necessary properties to achieve the required parameters are already incorporated in the raw semi-finished product. Interestingly, heat-resistant polyethylene waste can be recycled without losing any of the original qualities of the product.
• The durability of PE-RT pipes is estimated at 50 years or more.
• This type of pipe, due to its plasticity and strength, is able to withstand several freezing cycles together with the coolant, without losing its original qualities and depressurizing the heating system.
• PE-RT pipes are repairable, which is impossible for PEX-analogues.
• Due to its structure, the material perfectly absorbs the sound of the coolant flowing through them. In addition, due to plasticity, they do not emit squeaks in the system, which is sometimes the case with PEX pipes.

PE-RT is applied both for production metal-plastic pipes, and made only from this polymer.

Both the metal-plastic version and PE-RT-polyethylene pipes have higher technical and operational characteristics than their PEX counterparts.

Many PE-RT pipes, if they do not have an aluminum layer, are equipped with special oxygen barriers. As this layer, manufacturers use their own developments, such as EVON or OXYDEX.

An example is a table with the main technical and performance characteristics pipes PERT-AL-PERT quite popular production brand COMPIPE:

Name of parameters	Indicators
Outer diameter, mm	16	20	26	32
Wall thickness, mm	2	2	3	3
Coil length, m	200	100	50	50
Pipe weight (g/rm)	113	149	264	331
Pipe cavity volume (l/rm)	0.113	0.201	0.314	0.531
Minimum bending radius, mm	45	60	95	125
Outer layer (material)	PE-RT (high temperature resistant polyethylene)
Inner layer (material)	PE-RT(high temperature resistant polyethylene)
Connection method of aluminum layer	TIG butt welding
Working temperature, ˚С	70
Maximum temperature, ˚С	95
Maximum pressure, bar	10
Linear expansion coefficient, (K⁻¹)	2.3×10⁻⁵

Prices for PE-RT pipes

PE-RT pipes

Methods for connecting polyethylene and metal-plastic pipes

To connect pipes made of cross-linked polyethylene, special fittings are used, and the installation itself is carried out using a compression method (crimping) or using diffuse welding technology. Fittings can be polymer or metal (brass or bronze). Polymer fittings are well combined with pipes made entirely of polyethylene PEX or PE-RT.

Such connections have already proven their high reliability, therefore they are quite suitable for the operating conditions of heating systems. Of course, it is necessary to choose pipes and fittings from the same manufacturer, since only such a combination will guarantee the quality of the installation.

You may be interested in information about what they are

So, there are several ways to connect.

One of the easiest and fastest mounting methods is the compression sleeve option. The whole process consists of three steps:

1 - A crimp sleeve is put on the pipe and shifted from the edge by about 100 mm. Then, the pipe cavity at the edge is slightly flared with a special expander. This is necessary so that the fitting can easily enter into it.

2 - Next, a fitting is inserted into the expanded channel of the pipe until it stops. Since the cross-linked polyethylene will tend to return to its original shape after the expansion process, it will tightly press against the material of the connecting part.

3 - At the final stage, the sleeve put on earlier is shifted, closing the created connection. Thus, the polyethylene will be tightly clamped between the fitting and the sleeve. The shift of the sleeve requires considerable effort, therefore it is done with a special tool.

Another option, already mentioned above, is suitable for connections both for pipes made only from polyethylene and for metal-plastic ones. This method includes approximately the same stages of work, but at the end of the process, the sleeve shifted to the edge of the pipe is crimped with special tongs.

You might be interested in knowing what is

PERT-AL-PERT pipes can be connected using a fitting and a compression nut:

• First, a union nut is put on a metal pipe, then a compression ring.
• Then, after a slight flaring of the edge, a metal fitting is inserted into the pipe until it stops, which often has sealing rubber rings, but may be without them.
• The next step is to move the compression ring to the edge of the pipe, and the nut on top of it.
• The nut is tightly screwed onto the thread of the fitting.

This connection method does not require special tools - it is enough to have a wrench or adjustable wrench on hand. However, according to experts, such pipe fittings are not highly reliable. Leakage may occur immediately after starting the heating circuit or after a short period of time. In any case, it is not recommended to leave such joints without visual control.

Another installation method is diffusion welding, which can only be used to join pipes based on PERT. Of course, special fittings must be available for such installation.

Complicating this work is the need for special welding machine. If it is possible to rent such a device, it is quite possible to install the system yourself. In general, the process is very similar to welding polypropylene pipes and is usually very quickly mastered even by beginners.

You may be interested in information on how to mount

Advantages and disadvantages of XLPE pipes

To summarize the above, it makes sense to highlight the advantages and disadvantages of PEX and PE-RT polyethylene pipes.

So to benefits pipes made of cross-linked polyethylene when used in heating systems include the following factors:

Resistance to high temperatures, and this is especially pronounced for PE-RT pipes.

• Excellent strength characteristics - the pipes are resistant to external mechanical influences and internal pressure loads.
• The elasticity of the material allows the pipes to be used in complex laying patterns with many turns under a small radius.
• Even after serious deformations, the pipe tends to restore its shape.
• Inertness to corrosion, as well as aggressive components of the coolant.
• The ideal smoothness of the inner walls does not create significant hydraulic resistance to the coolant circulating through the pipes. In addition, the possibility of insoluble deposits on the inner walls is almost completely eliminated, even if a low-quality coolant is used.
• The low weight of the pipes and the large length in coils speed up and simplify installation work for laying long circuits.
• High reliability of connections.
• The environmental friendliness of the material allows them to be used for installation in a plumbing system, the water from which is used for drinking and cooking.
• Pipes in open areas do not require periodic painting - they are quite "pretty" in themselves.

However, in order to fully have an idea about pipes made of this material, it is necessary to single out their limitations , since they also exist:

• Both PEX and PE-RT pipes have relatively low UV resistance. Therefore, they are best used in closed areas (the same contours of the "warm floor" or wiring hidden in the walls).
• The cost of quality pipes complete with the necessary press fittings can be quite impressive! In addition, one cannot discount the need for a special installation tool, and the skills to work with it.
• Very great care should be taken when using pipes made of cross-linked polyethylene in a heating system connected to a central one. In any case, it is better to check the permissible operating parameters several times and compare them with the possible modes of operation of the system, about which information must be obtained from local utilities in advance.

You may be interested in information about what is in the heating system

A few words about brands and prices

The issue of the cost of purchased pipes is always important. But it should not be decided solely from the standpoint of maximum cost savings, to the detriment of quality. Therefore, we can advise the main thing - to choose materials from truly reputable manufacturers in order to “bite your elbows” due to problems that began even during installation or, worse, already during the operation of the system.

Pipes manufactured by well-known European companies have earned a good reputation. These include Rehau, Henco, Uponor, Kermi, Oventrop and others. Some domestic firms are also trying to keep up with them, but so far the priority for professionals is still imported products.

The table below shows several pipe options that are well suited for arranging a "warm floor" system. Price indicators are averaged, and in different regions may differ from those shown - this is easy to check on the spot.

Manufacturer and pipe model	Brief specifications	Length in the bay	Price per linear meter
Uponor PEXa evalPEX Q&E 16 x 2.0	Diameter 16 mm. Cross-linked polyethylene PE-Xa, wall 2 mm, t max - up to 95 degrees, (short-term heating up to 110)	50 - 240 m	130 rub.
Uponor PEXa evalPEX Q&E 20 x 2.0,	Diameter 20 mm. Cross-linked polyethylene PE-Xa, wall 2 mm, t max - up to 95 degrees, (short-term heating up to 110)	50 - 120 m	150 rub.
REHAU "Rautitan stabil"	Diameter 16 mm. Metal-layer, PE-Xc/AI/PE wall 2.6 mm	100 m	175 rub.
REHAU "Rautitan stabil"	Diameter 20 mm	100 m	200 rub.
REHAU "Rautitan flex"	Diameter 16 mm. Cross-linked polyethylene RAU-PE-Xa, wall 2.2 mm	100 m	190 rub.
REHAU Rautitan Pink	Diameter 16 mm. Cross-linked polyethylene RAU-PE-Xa, wall 2.2 mm, t max - up to 90 degrees	120 m	150 rub.
Contour PERT D 16 red	Diameter 16 mm. Monolayer pipe PERT of Russian production., t max - up to 90 degrees, pressure - up to 6 bar.	200 m	55 rubles
BioPipe PERT 16x2.0	Diameter 16 mm.	240 m	50 rubles
Thermotech MultiPipe PE-RT II, ​​16*2 mm	Diameter 16 mm. Five-layer PERT pipe with diffuse barrier	240 m	150 rub.

The presented selection deliberately does not show pipes of the lowest price category, as well as products of dubious or completely unknown manufacturers. The reasons are probably understandable - the author simply does not have a moral right to recommend such material for the installation of a heating system, which is created with the expectation of several decades of operation.

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