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 nodes, it is possible to carry out a very tight pipeline.
These products have a large number of positive characteristics:
- High fatigue strength. It remains even at an operating temperature of 95C;
- The ability to maintain a stable shape;
- Polyethylene pipe resistant to cracking;
- Excellent impact tolerance, and strength in notched areas. These characteristics are maintained even at very low temperatures of -50 degrees.
- IN polyethylene pipes oh strength is perfectly combined with flexibility;
- Excellent wear resistance to abrasion;
- Good shrinkage characteristics;
- Resistance to influence of chemicals;
- Corrosion resistance;
- Does not contain halogens and heavy metals.
Flaws
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Polyethylene pipes for heating, the technical characteristics of which are whole line positive aspects, still not without some disadvantages:
- The cross-linked polyethylene pipe is sensitive to ultraviolet light. In the light, its material is quickly destroyed, and the pipe cracks and breaks;
- It is not recommended to use brass fittings for PE pipes hidden under a screed or plaster;
- Do not exceed the capacity of these products.
What you need to pay attention to when choosing
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When buying pipes made of cross-linked polyethylene, you should pay attention to:
- 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.
- The presence of protection against the ingress of oxygen. It is an aluminum layer or a coating of ethylene vinyl alcohol.
- 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 highest degree of protection, the higher it is, the lower the possibility of bacteria breeding in water.
- 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 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. The pipes are resistant to great 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 many-sided, are the most 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.
Is a polyethylene pipe suitable for heating? We will get acquainted with a relatively little-known material - cross-linked polyethylene, analyze its features and the installation methods used.
But first, some general information.
Yes, polyethylene. Yes, heating. No, it won't explode.
About polyethylene
What do we know about this material? Well, it's transparent... and they seem to make bags out of it. This is where the list of well-known information seems to end.
Let's try to expand it.
- Polyethylene has been around for over a century. It was first discovered by accident by engineer Hans von Pechmann in 1899 and was immediately forgotten.
In 1933, the material received a second life in the form of insulation for telephone cable.
Useful: The physical properties of polyethylene, including density and strength, vary depending on polymerization conditions.
Moreover, the lower the pressure during the reaction, the stronger the resulting material. There are polyethylene of low, medium and high density.
- All types of polyethylene soften at 80-120C. Taking into account the fact that the pipe will be under pressure in the water supply system, manufacturers limit the operating mode of polyethylene pipes maximum temperature in… 40 degrees.
Hence the unambiguous and final verdict: polyethylene pipes are not suitable for heating. Dot.
Pipes made of ordinary polyethylene are not intended for hot water.
Useful modification
In its normal state, polyethylene consists of long monomolecular chains. However, there are a number of operations that can change its structure.
Due to heating in the presence of a catalyst, bombardment with electron beams, or simple immersion in water with a catalyst and special additives, the molecules begin to form not only longitudinal, but also transverse connections. Stitch together. The result is a fundamentally different material, which is commonly called cross-linked polyethylene (PE-S, or PE-X).
To understand how its properties have changed, we will give a description of a cross-linked polyethylene pipe for heating, manufactured in Germany under the Gabo Systemtechnik brand.
- The pipe is able to work for the declared 50 years in the 90C / 7 bar or 70C / 11 bar mode.
- Maximum working temperature for it is 95C - the same as manufacturers usually indicate for reinforced polypropylene.
- The pipe remains extremely flexible. The minimum bending radius is only 6 of its diameters. On the practical side, this means that by installing your own heating from cross-linked polyethylene, you can get by with a minimum number of relatively expensive fittings.
Thus, cross-linked polyethylene is suitable for heating systems without any reservations: according to the current SNiP temperature (see. temperature chart heating systems) in internal engineering networks residential buildings should not exceed those very 95C, which, as we have just found out, the pipe can withstand perfectly.
Make no mistake: cross-linked polyethylene can also be melted. But at a fairly high temperature.
Production
Technology
As an example of production technology, let's take information from the website of the dealer of those same Gabo pipes.
The Germans are traditionally famous for their pedantry and in terms of compliance with technological standards, they are certainly ahead of the rest.
- High-density polyethylene in the form of granules is melted and forced through annular hole extruder - a special press that forms a pipe of the desired section.
During the extrusion process, continuous monitoring of the homogeneity of the material is carried out.
Useful: all pipes for the transport of drinking water are mixed with additives during the extrusion process that make it opaque, including for ultraviolet radiation.
- Finally, the finished pipe is crosslinked. The most technologically advanced and cheap methods of production with the use of reagents; electron beam irradiation is slower and more expensive.
The method used is not directly named: the seller's website vaguely states that "irradiation with fast electrons is the most environmentally friendly." From this we draw a cynical conclusion that, most likely, the Germans, like many other manufacturers, use the reaction with a silane and a catalyst.
The finished pipe is shipped to dealers in 200m coils. The retail price of a meter of 16 mm pipe is about 50 rubles.
The extruder in the photo turns the hot amorphous mass into a strong pipe.
Regulations
Pipes made of cross-linked polyethylene fully comply with GOST 52134-2003 "Pressure pipes made of thermoplastics and fittings to them."
What interesting things can we find in the text of this document?
- In the marking, in addition to the material (PE-X), the method of crosslinking must be indicated. Definitely bring to clean water Germans is not difficult at all - just study the pipe.
- In addition, the marking of all thermoplastic pipes includes an indication of the outer diameter, wall thickness and maximum working pressure.
The standard provides a table of pipe sizes. In the column for XLPE, we find a size variation from 10 millimeters of outer diameter with a wall thickness of 1.3 mm to 250 millimeters with walls as much as 3.4 centimeters thick.
Deviations from the given dimensions in terms of the average outer diameter are only allowed upwards and depend on the nominal size: for a diameter of 10 mm, a deviation of 0.3 mm is permissible, for 250 - 2.3 mm.
The wall thickness can also only be exceeded. Downward deviations are not allowed. The variation in deviation values is from 0.4 mm for the thinnest pipes to 3.7 for the thickest ones.
Not in the standard physical properties material, however, this information will be useful.
Application features
We have already found out that cross-linked polyethylene is suitable for heating. Where and how best to use it?
The ideal option is laying pipes as a warm floor. The combination of good thermal conductivity and low coefficient of thermal expansion makes polyethylene pipes more than suitable. The ability to purchase an inextricable pipe up to 200 meters long will also come in handy.
The instruction, in general, differs little from laying any other water-heated floor:
- The pipe is laid out on the subfloor in a spiral or snake and recessed into the screed.
- All connections are above the floor. The reason is clear: a solid pipe leaks extremely rarely. 9 out of 10 leaks are at the connections, and it would be better if they were available.
- Starting the heating for the first time (see heating system with forced circulation) occurs only a month after laying the screed, when the concrete gains strength. Warming it up earlier will not speed up drying, but will cause it to crack.
It is clear that for a warm floor, the maximum operating temperature of cross-linked polyethylene is clearly excessive. Temperatures above 40C will already feel uncomfortably high. Typically, the temperature of the coolant in the pipes of the warm floor does not exceed 30 degrees.
A single pipe is laid in the screed, without joints.
How are XLPE heating pipes connected to brass and plastic fittings?
You will need special equipment. At a minimum - an extender, scissors for cutting will also come in handy.
The connection principle uses the molecular memory of the material: the pipe may change its linear dimensions for a while, but will quickly return to its original dimensions.
- The pipe is cut to size.
- A locking ring is put on it. It should protrude a millimeter beyond the edge of the pipe.
- The head of the extender is inserted into the pipe and, in several movements with a twist between them, stretches the pipe, plunging further and further until the head is completely inside it.
- Then the extender is quickly removed, and the stretched pipe is put on the fitting, where it returns to the original diameter and securely covers it.
Tip: application graphite lubricant reduce tensile stress and prolong tool life.
Sometimes brass rings are also used, which are put on after connecting to the fitting.
Polyethylene pipes for heating: do-it-yourself video installation instructions, features of cross-linked polyethylene, photo
121) Polyethylene pipes for heating: do-it-yourself video installation instructions, features of cross-linked polyethylene, photo
The use of cross-linked polyethylene for heating systems
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.
Cross-linked polyethylene for underfloor 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 polyethylene 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).
Cross-linked polyethylene for heating
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.
- Opportunity mechanical damage, for example, 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.
PEX pipe construction
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:
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.
PEX-c pipes
Reinforcement methods can be as follows:
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 is a world leader in the production of XLPE pipes for heating and underfloor heating.
Rehau cross-linked polyethylene
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.
XLPE pipes
XLPE pipes
Different manufacturers use various ways polyethylene crosslinks: 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.
Features of the installation of the material
Installation of heating and underfloor heating using cross-linked polyethylene can be carried out by two main methods:
- Using compression fittings;
- With press fit fittings.
More simple option installation, which also allows you to repeatedly disassemble the structure at the docking point, if necessary, is installation using compression fittings. To install a warm floor using this technology, you must perform the following steps:
- Put the compression nut on the pipeline.
- Put on the split ring.
- Push the pipe onto the fitting.
- Tighten with a wrench.
Installation of cross-linked polyethylene
Attention! Tighten the compression nut carefully, as excessive force may damage the pipe.
Installation of a warm floor using press fittings creates a one-piece connection. It is necessary to prepare the press for installation in advance and follow the instructions below:
- Put on the clamping sleeve.
- Insert an expander of the appropriate size into the pipe.
- Insert the pipe into the fitting nipple.
- Press the sleeve onto the fitting.
- Wait a few seconds and get a strong and reliable connection. Due to the molecular memory of the material, the pipe cannot be removed from the fitting.
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Why cross-linked polyethylene is better than other pipes for heating
What quality characteristics of cross-linked polyethylene should be paid attention to when choosing pipes for heating, what these pipes consist of and what is the method of their stitching, as well as how to install them correctly
Cross-linked polyethylene pipes for heating: advantages and disadvantages, installation features
Low temperature heating systems are becoming more common. Modern appliances and systems allow you to heat your home with water temperatures up to 80 °C. This has led to consumer demand for inexpensive XLPE pipes for heating. They are easy to install and are great for underfloor heating.
Products are sold in bays, which is very convenient. It should also be noted that it is possible to minimize the number of connection nodes, which makes it possible to obtain a sealed pipeline. The described pipes have a small mass, and they can be used to create water supply and heating systems of increased complexity.
The use of a building hair dryer allows you to save the consumption of materials that would be required for bends during the installation of steel products. If the pipe is heated to a high temperature, it will be able to take any shape, and when cooled, it will retain it. The advantage of these products is that they can be installed without professional assistance, which saves money. And you can choose the connection method that you can afford.
Main advantages
XLPE pipes for heating have many advantages, among them are:
- maintaining a stable form;
- excellent impact tolerance;
- high fatigue strength;
- crack resistance;
- combination of flexibility with high strength;
- excellent shrinkage characteristics;
- high wear resistance to abrasion;
- resistance to corrosion;
- resistance to chemicals;
- the absence of the presence of heavy metals and halogens in the composition.
XLPE pipes for heating are capable of maintaining fatigue strength even when subjected to temperatures up to 95 °C. The products withstand impacts well, and their characteristics are preserved even when exposed to low temperatures down to -50 °C.
Main disadvantages
Pipes made of cross-linked polyethylene for heating have some disadvantages. For example, products are sensitive to ultraviolet light. If pipes are left unprotected after installation, the material at their base will quickly collapse, and the pipe itself may break and become cracked. It is not recommended to use brass fittings for such pipes that are covered with plaster or screed. When purchasing such products, you must remember that it is not recommended to exceed the capabilities of their operation, as this may adversely affect durability and strength.
Mounting features: choice of materials and tools
PEX pipes made of cross-linked polyethylene for heating are products with a marking, the end of which provides for the presence of one of four letters: a, b, c or d. The most common recommended are the first two types - PE-Xa and PE-Xb. In this case, we are talking about stitching methods.
Regardless of which technology is used in the production process, the output is a strong, complex three-dimensional polymer chain of ethylene molecules. Such products can be used for drainage, water supply and as the basis for a floor heating system. A high heat transfer coefficient is good for heating systems. Whereas if such pipes are planned to be used for water supply, then additional thermal insulation is necessary, otherwise the water will cool down on the way to the point of consumption.
Installation does not require highly specialized skills and special tools, but there are some nuances that should be taken into account. When choosing fittings for pipes made of cross-linked polyethylene, you may prefer a compression version of them, which is a compression product. Such a connection will be able to withstand pressure up to 2.5 MPa.
Can also be used for mounting welding machine, with it you can achieve a reliable connection that can withstand up to 12 MPa. In any case, the main tool will be used - a pruner knife. In the first method, you should take care of the presence wrench, in the second case, you will need a hydraulic or hand press, and for welding, a welding machine for XLPE pipes should be prepared. Products have high elasticity, therefore, during installation, they should be held in place, providing fixation with special clips-latches.
Rehau brand pipes and reviews about them
These pipes are manufactured by a world-famous German concern, which sells products with a high threshold of resistance to damage. Specialists keep a high standard of quality, and pipes remain in demand and popular. According to consumers, the Rautitan series is specially designed for heating and water supply systems, because it can withstand high temperatures.
The manufacturing process uses crosslinking at the molecular level. This eliminates leakage, in addition, the pipes gain memory when bent. The outer layer of such products is made of aluminum, which provides additional strength. As buyers emphasize, even if the outer layer is damaged during operation, the inner polymer coating will prevent leakage.
The manufacturer sells pipes with a compression sleeve connection technique. The connection is one-piece, which guarantees long-term tightness. Rubber seals are not used.
When installing Rehau pipes, there is the possibility of optical control. The sliding sleeve is installed according to a certain method. At the first stage, it is necessary to carry out the expansion, and then insert the fitting and push the sleeve. According to consumers, such installation can be done independently. Salt and scale do not form on the surface of the products.
Pipes provide low sound transmission and sound absorption, which is especially true when compared to metal pipes. The systems are environmentally friendly and safe. For a simple and quick connection, cold pressing can be used. If you use pipes with a diameter within 32 mm, then they are bent without using a tool, which, according to home craftsmen, is very convenient for private installation.
Rehau pipes are supplied for sale with a 30-year warranty, which is confirmed by tests. The installation of such pipes, although it is more expensive compared to the installation of metal-plastic products or polypropylene pipes, but you can be sure that such systems will last much longer.
During installation, the human factor is reduced to a minimum. Installation of such products is possible even at low temperatures, when outside the window is -15 ° C. If you are interested in the diameters of XLPE pipes for heating, they are supplied with parameters ranging from 16 to 63 mm.
Pipe cost
Before purchasing, you should be interested in the price of a XLPE pipe. For Stout PEX-a, the cost is 59 rubles. per metre. In this case, we are talking about a product 16 x 2 mm. In a bay of 500 m. When purchasing a Rehau Rautherm S pipe with parameters 14 x 1.5 mm, you will pay 61.96 rubles. per metre. In the bay 120 m.
If the product parameters are increased to 17 x 2 mm, then you will have to pay 63.33 rubles. per metre. Buying a Kalde PEX-b product with an oxygen layer and dimensions 16 x 2 mm, you will pay 65.27 rubles. per metre. In the bay 160m.
Installation of pipes for the underfloor heating system
Cross-linked polyethylene pipes for underfloor heating are laid:
Laying with a snake is considered simpler, but the heating will not be as uniform. A distance of 35 cm should be ensured between the products. One circuit should have an average length of 40 to 60 m, but not more than 120 m. Otherwise, increased heat losses will be noted, and the return coolant will have a low temperature.
Additional layers
When laying a pipe made of cross-linked polyethylene for underfloor heating, a heat-insulating layer is located below. The following materials can serve as it:
- Styrofoam;
- polystyrene sheets;
- reflector based on foamed polyethylene.
Fastening is carried out with clips, brackets or single driven dowels. Some polystyrene boards are made with an applied profile for fixing pipes. Such canvases have markings.
When pouring heating pipes made of cross-linked polyethylene, the reviews of which were presented above, it is necessary to provide expansion joints in the screed to level the linear expansion. The floor can be started after the screed has hardened. The temperature of the heating medium must increase by 5 °C per day before entering the operating mode. If the pipe has anti-diffusion protection, then installation is carried out only after checking the top layer for damage.
Conclusion
When laying XLPE pipes for underfloor heating, you can use compression and pressure fittings. It is easier to carry out the work if you use the first fitting option, while you need a regular nut. The thread should be directed towards the location of the connector.
Press fittings can be used to form permanent connections. Docking is carried out using special equipment. At the first stage, a clamping sleeve is put on, and then an expander is inserted into the pipe, which has the appropriate size.
Cross-linked polyethylene pipes for heating: advantages and disadvantages, installation features
Low temperature heating systems are becoming more common. Modern devices and systems make it possible to heat housing at water temperatures up to 80 °C. This has led to consumer demand for inexpensive XLPE pipes for heating. They are easy to install and are great for underfloor heating.
The heating system requires the use of high-quality and wear-resistant materials that are not afraid of 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 is the best method for the 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 their home, 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. Peroxide (PEX-a) is recognized as the best crosslinking method today, for this reason it is recommended to opt for products of the Rehau, Uponor and STOUT trademarks, which are produced using this technology.
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 have a lot of advantages compared to other analogues on the market, but at the same time certain technical features definitely worth considering 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 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 given material succumbed special treatment under conditions of high pressure, as a result of which the molecules created even stronger bonds between themselves in the form of transverse lines. the so-called "stitching" can be done in several ways, namely:
- by electron irradiation of polyethylene in a medium electromagnetic fields;
- by processing polyethylene peroxides;
- through the use silane gas;
- 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:
- 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;
- 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 systems pure heating. 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. The highest quality and most proven are polymer fittings, which over the years have shown themselves from the very beginning. better side. The algorithm for connecting such pipes can be written as follows:
- the end of the connecting pipe is moved apart flaring tool, in order to give it a larger diameter;
- then in this hole is placed fitting fitting;
- in order to increase strength, the tension sleeve is attached to the pipe with press.
This technology allows you to significantly increase the service life and reliability of such connections, which are fully consistent with the quality of 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 drawbacks, the study of which is mandatory when choosing them. So, to the primary positive aspects of operation 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 brass fittings are used, direct contact with various materials for plaster and screed 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 technical specifications this heating element with the features 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, it can be said with confidence that PEX polyethylene pipes fully comply with modern conditions, which put forward 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
Low temperature heating systems are becoming more common. Modern devices and systems make it possible to heat housing at water temperatures up to 80 °C. This has led to consumer demand for inexpensive XLPE pipes for heating. They are easy to install and are great for underfloor heating.
Products are sold in bays, which is very convenient. It should also be noted that it is possible to minimize the number of connection nodes, which makes it possible to obtain a sealed pipeline. The described pipes have a small mass, and they can be used to create water supply and heating systems of increased complexity.
The use of a building hair dryer allows you to save the consumption of materials that would be required for bends during the installation of steel products. If the pipe is heated to a high temperature, it will be able to take any shape, and when cooled, it will retain it. The advantage of these products is that they can be installed without professional assistance, which saves money. And you can choose the connection method that you can afford.
Main advantages
XLPE pipes for heating have many advantages, among them are:
- maintaining a stable form;
- excellent impact tolerance;
- high fatigue strength;
- crack resistance;
- combination of flexibility with high strength;
- excellent shrinkage characteristics;
- high wear resistance to abrasion;
- resistance to corrosion;
- resistance to chemicals;
- the absence of the presence of heavy metals and halogens in the composition.
XLPE pipes for heating are capable of maintaining fatigue strength even when subjected to temperatures up to 95 °C. The products withstand impacts well, and their characteristics are preserved even when exposed to low temperatures down to -50 °C.
Main disadvantages
Pipes made of cross-linked polyethylene for heating have some disadvantages. For example, products are sensitive to ultraviolet light. If pipes are left unprotected after installation, the material at their base will quickly collapse, and the pipe itself may break and become cracked. It is not recommended to use brass fittings for such pipes that are covered with plaster or screed. When purchasing such products, you must remember that it is not recommended to exceed the capabilities of their operation, as this may adversely affect durability and strength.
Mounting features: choice of materials and tools
PEX pipes made of cross-linked polyethylene for heating are products with a marking, the end of which provides for the presence of one of four letters: a, b, c or d. The most common recommended are the first two types - PE-Xa and PE-Xb. In this case, we are talking about stitching methods.
Regardless of which technology is used in the production process, the output is a strong, complex three-dimensional polymer chain of ethylene molecules. Such products can be used for drainage, water supply and as the basis for a floor heating system. A high heat transfer coefficient is good for heating systems. Whereas if such pipes are planned to be used for water supply, then additional thermal insulation is necessary, otherwise the water will cool down on the way to the point of consumption.
Installation does not require highly specialized skills and special tools, but there are some nuances that should be taken into account. When choosing fittings for pipes made of cross-linked polyethylene, you may prefer a compression version of them, which is a compression product. Such a connection will be able to withstand pressure up to 2.5 MPa.
A welding machine can also be used for installation, with it you can achieve a reliable connection that can withstand up to 12 MPa. In any case, the main tool will be used - a pruner knife. In the first method, you should take care of the presence of a wrench, in the second case you will need a hydraulic or manual press, and for welding, you should prepare a welding machine for pipes made of cross-linked polyethylene. Products have high elasticity, therefore, during installation, they should be held in place, providing fixation with special clips-latches.
Pipes brand "Rehau" and reviews about them
These pipes are manufactured by a world-famous German concern, which sells products with a high threshold of resistance to damage. Specialists keep a high standard of quality, and pipes remain in demand and popular. According to consumers, the Rautitan series is specially designed for heating and water supply systems, because it can withstand high temperatures.
The manufacturing process uses crosslinking at the molecular level. This eliminates leakage, in addition, the pipes gain memory when bent. The outer layer of such products is made of aluminum, which provides additional strength. As buyers emphasize, even if the outer layer is damaged during operation, the inner polymer coating will prevent leakage.
The manufacturer sells pipes with a compression sleeve connection technique. The connection is one-piece, which guarantees long-term tightness. Rubber seals are not used.
When installing Rehau pipes, there is the possibility of optical control. The sliding sleeve is installed according to a certain method. At the first stage, it is necessary to carry out the expansion, and then insert the fitting and push the sleeve. According to consumers, such installation can be done independently. Salt and scale do not form on the surface of the products.
Pipes provide low sound transmission and sound absorption, which is especially true when compared to metal pipes. The systems are environmentally friendly and safe. For a simple and quick connection, cold pressing can be used. If you use pipes with a diameter within 32 mm, then they are bent without using a tool, which, according to home craftsmen, is very convenient for private installation.
Rehau pipes are supplied for sale with a 30-year warranty, which is confirmed by tests. Although the installation of such pipes is more expensive compared to the installation of metal-plastic products or polypropylene pipes, you can be sure that such systems will last much longer.
During installation, the human factor is reduced to a minimum. Installation of such products is possible even at low temperatures, when outside the window is -15 ° C. If you are interested in the diameters of XLPE pipes for heating, they are supplied with parameters ranging from 16 to 63 mm.
Pipe cost
Before purchasing, you should be interested in the price of a XLPE pipe. For Stout PEX-a, the cost is 59 rubles. per metre. In this case, we are talking about a product 16 x 2 mm. In a bay of 500 m. When purchasing a Rehau Rautherm S pipe with parameters 14 x 1.5 mm, you will pay 61.96 rubles. per metre. In the bay 120 m.
If the product parameters are increased to 17 x 2 mm, then you will have to pay 63.33 rubles. per metre. Buying a Kalde PEX-b product with an oxygen layer and dimensions 16 x 2 mm, you will pay 65.27 rubles. per metre. In the bay 160m.
Installation of pipes for the underfloor heating system
Cross-linked polyethylene pipes for underfloor heating are laid:
- snake;
- spiral;
- double snake.
Laying with a snake is considered simpler, but the heating will not be as uniform. A distance of 35 cm should be ensured between the products. One circuit should have an average length of 40 to 60 m, but not more than 120 m. Otherwise, increased heat losses will be noted, and the return coolant will have a low temperature.
Additional layers
When laying a pipe made of cross-linked polyethylene for underfloor heating, a heat-insulating layer is located below. The following materials can serve as it:
- Styrofoam;
- polystyrene sheets;
- reflector based on foamed polyethylene.
Fastening is carried out with clips, brackets or single driven dowels. Some polystyrene boards are made with an applied profile for fixing pipes. Such canvases have markings.
When pouring heating pipes made of cross-linked polyethylene, the reviews of which were presented above, it is necessary to provide expansion joints in the screed to level the linear expansion. The floor can be started after the screed has hardened. The temperature of the heating medium must increase by 5 °C per day before entering the operating mode. If the pipe has anti-diffusion protection, then installation is carried out only after checking the top layer for damage.
Conclusion
When laying XLPE pipes for underfloor heating, you can use compression and pressure fittings. It is easier to carry out the work if you use the first fitting option, while you need a regular nut. The thread should be directed towards the location of the connector.
Press fittings can be used to form permanent connections. Docking is carried out using special equipment. At the first stage, a clamping sleeve is put on, and then an expander is inserted into the pipe, which has the appropriate size.
