Cross-linked polyethylene for underfloor heating: how to equip a heated floor from cross-linked polyethylene

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Antonina Turyeva
Last update: November 2019

The underfloor heating system allows you to significantly increase the level of comfort in the house. The heat generated by the system spreads in a zone comfortable for the owners, does not stimulate the movement of air with dust. If you have certain skills and knowledge, you can make a floor with a pipeline of polyethylene yourself.

We will tell you how to use the most inexpensive material in the arrangement of floor heating. In the article we presented, it is described in detail how to correctly lay sewn polyethylene for a warm floor, with what step and in what pattern to arrange. Our tips will help you build a perfectly functioning system.

Crosslinked Polyethylene: Features and Benefits

Crosslinked polyethylene is a variant of ordinary ethylene, reinforced by chemical, physical or complex exposure. Thanks to this procedure, in addition to the characteristic longitudinal bonds, transverse compounds appear in the polymer structure.

As a result of production manipulations, polyethylene products obtain dimensional stability, acquire increased resistance to deformation, and high temperature. The processing process with the introduction of organic compounds into the polymer is called “crosslinking”.

Depending on the technology, it is carried out either before or after extrusion. Long pipes in stitches made of cross-linked polyethylene are used to equip heating systems because of their high tightness - the risk of leaks is reduced to zero.

Technical characteristics of linear products from cross-linked polyethylene:

  • outer diameter 10-200 mm;
  • wall thickness 2-5 mm;
  • average specific gravity 110 g / linear m;
  • density 940 kg / m3;
  • softening at a temperature of more than + 100ºС, melting + 200ºС, burning + 400ºС;
  • average working pressure of 6 MPa;
  • average thermal conductivity - 0.4 W / mK.

Given that the maximum temperature of the coolant is + 90º C, and the pressure does not exceed 4 bar, we can conclude that pipes of this type are excellent for installing a water heated floor.

The cost of polyethylene underfloor heating
The cost of 1 sq.m. floor heating made of cross-linked polyethylene is 1500-3500 rubles

Compared with steel corrugated or copper pipes, also often used for underfloor heating, these products have the following advantages:

  1. Resistance to corrosion processes. The material is not susceptible to corrosion, aggressive environments, does not deform with increased acidity, alkalinity, and also in contact with organic substances.
  2. Excellent strength characteristics. Resistance to static and dynamic loads, resistance to tearing, bending, stretching, etc. Pipes without damage tolerate the effects of low and high temperatures.
  3. Stable bandwidth. On the walls of the pipeline is not deposited sediment, reducing the inner diameter of the pipes.
  4. Elasticity. Flexible pipes do not burst when bent under any radius.
  5. Environmental Safety. When heated, the product does not emit toxins.

With proper installation and compliance with the recommended thermal regime, a polyethylene warm floor will last at least 50 years. The full cost of creating a system pays for itself in 1-2 years.

Installation of underfloor heating in steps

The technology of the device consists in the phased creation of layers stacked in strict sequence. The total thickness of the system will be 10-20 cm, depending on the characteristics of the screed, insulation used and reinforcement.

The standard process for installing a water floor from polyethylene pipes involves a number of steps:

Preparatory work before construction

It should be borne in mind that the average load created by the “underfloor cake” on the concrete base is 300-350 kg / m2. Therefore, the overlap should be designed for such a weight.

When installing a heated floor using pipes made of cross-linked polyethylene, the following work steps are required:

  1. Choice of pipes. Calculation of the length of the contour. Drawing up the styling scheme.
  2. Foundation preparation. Laying waterproofing and insulation.
  3. Installation of pipe circuits. Hydraulic tests.
  4. Fill screeds and finish laying the selected flooring.
  5. Putting the system into operation.

When buying collectors, it is better to give preference to devices with balancing valves and flow meters, which in the future will simplify the system setup, and in case of a malfunction, they will help to quickly identify the problem circuit.

To construct a heated water floor, you will need the following:

  • water boiler for heating the coolant;
  • expansion tank;
  • circulation pump for forced movement of the coolant;
  • plumbing fittings: fittings, ball valves;
  • cross-linked polyethylene pipe reel;
  • fasteners for insulation boards and PE pipes;
  • distribution manifold assembly;
  • damping tape;
  • insulation and reinforcing mesh;
  • mortar for screed or “dry screed” mixture.

All materials should be prepared in advance, so that in the process of arranging a warm floor, you should not be distracted by shopping and buying additional components that are missing.

Distribution manifold
It is better to entrust the choice of a distribution manifold to professionals or calculate it yourself using special calculator programs

Selection and creation of pipe laying patterns

For residential premises, three laying patterns are used: “snake”, “shell” or “snail” and “twin spiral”. Spiral "snail" is the simplest option, providing a uniform distribution of thermal energy. According to this scheme, most often water heated floors are constructed, because all angles in it are 90º.

Laying according to the “snake” scheme is somewhat more complicated, because it is associated with 180º turns. But it is great for making a system of cross-linked polyethylene, because pipes from this material bend freely, and throughput is practically not reduced in loops.

The choice of laying scheme depends entirely on the characteristics of the room. If we are talking about the arrangement of large-sized areas, installation is carried out according to the “double spiral” scheme. It is also used if it is planned to allocate zones according to the intensity of heating, for example, in the lobby, in front of the entrance group or in front of the voluminous terrace.

Laying pipes in the room with a snail and a snake
"Snail" guarantees uniform floor heating, "Snake" - the maximum temperature at the edge points of the room

For simple spiral and serpentine schemes, the optimal length of the contour is 60-80 m. For rooms where the length is much longer than the width, the length of the contour is 100-120 m, but provided that pipes of larger diameter are used.

The distance between the pipes (pitch) is 10-35 cm. The wider the pitch, the less heat will come from the floor.

At the peak points where the maximum heat loss is observed, the step width should be minimal, for example, near the front door it should be 10-15 cm, increasing as you approach the center of the room.The distance of the pipes from the walls along the perimeter is 30-45 cm.

Rules for constructing a water floor heating
If possible, the collector unit for the warm floor is located in the center of the apartment (floor of a private house). So all points of the heating floor system will be supplied with a coolant of approximately equal temperature. In areas of increased heat loss, near window and door openings, the distance between the pipes is reduced to increase heat transfer

Details of the scheme and installation options for the warm water floor pipeline are described in articlewhich we recommend that you familiarize yourself with.

Choice and calculation of the number of pipes

When choosing pipes from cross-linked PE, it remains to be decided which diameter of the product is best to purchase. As practice shows, the best option for installing a warm floor in your own house or apartment located on the first floor is a 16 mm pipe.

For rooms whose length is several times greater than the width, pipes of 20 or 25 mm can be used. The wall thickness will fit the standard - 2 mm.

To calculate the required number of polyethylene pipes, you can apply the formula:

D = S / M × k


  • D is the estimated pipe length;
  • S is the area of ​​the heated floor;
  • M is the average step selected according to the scheme;
  • k - safety factor (for rooms up to 30 m2 is 1.1, more than 30 m2 – 1,4).

It should be remembered that the maximum length of a cross-linked polyethylene pipe depends on the diameter - the larger the diameter, the longer the heat transfer pipe can be. For products with a diameter of 16 mm - up to 90 m, 20 mm - 120 m, 25 mm - 150 m.

The length and diameter of the pipes is important.
Too long pipes with a small diameter increase the risk of problems with the circulation of the coolant

About how to complete calculation of water floor heating, including determination of heat loss and power of the circulation equipment, you will learn from the article recommended by us.

To build a water heating floor, it is better to buy products from manufacturers with a reputation and a trade name that deserve respect:

All manufacturers in addition to pipes produce fittings and fittings, in order to achieve the highest possible quality of assembly, it is recommended to buy all components of the same brand.

Preparation of the base for pipes

When the calculations of the required number of pipes are completed, you can proceed to the preparation of the base for the contour of a water heated floor.

This step includes the following workflows:

  • removal of old flooring and old screed;
  • laying of an insulating layer;
  • installation of insulation;
  • reinforcing mesh laying;
  • damper sticker.

First you need to align the base so that the differences are not more than 5 degrees (check the building level). For leveling, you can use a sand mixture followed by tamping or self-leveling compounds. The leveled base is removed from dust and debris.

Then lay the waterproofing layer.The simplest form is a plastic film.

If you have financial capabilities, it is better to use high-quality Russian or European waterproofing in the form of a polymer membrane. It not only reliably protects the floor from moisture, but also allows the system to “breathe” the warm floor.

Heater over vapor barrier
To increase the parameters for heat conservation, vapor barrier can be laid on a foil insulation-heat reflector

For waterproofing comes the turn thermal insulation substrate, which can be used as extruded polystyrene foam. This is the cheapest and most effective way to reduce heat loss.

Of the new heaters, the cork heat insulator is considered the most environmentally friendly, but its cost is ten times higher than that of the most expensive expanded polystyrene. Insulation plates with a thickness of 5 cm are attached to wooden guide rails using dowels-nails. Between themselves, the plates are fastened with glue and special brackets.

As for the reinforcing mesh, when using expanded polystyrene plates in its laying is not necessary - the pipeline is laid directly on the insulation. The use of the mesh is justified if another layer of waterproofing is laid on top of the insulation.

If there is no desire to overpay for a heater, then you need to keep in mind that special insulation blocks for installing a warm floor are available, in which channels for pipes are provided. Such blocks significantly increase the cost of creating a warm floor, but it is very convenient to use them.

After the mesh layer, it's time to stick on the compensating damper tape. This is done simply - a foam tape is glued around the perimeter of the room, which compensates for the expansion of the future concrete screed. Instead of damper tape, even pieces of expanded polystyrene can be used.

After preparation of the base, the heating boiler and manifold distribution unit are mounted. The boiler is connected to a water supply and supply system (gas or electricity).

Insulation with clearances for pipes
Special insulation for the underfloor heating system has clearances for pipes and markings for their proper installation

Information about the choice of insulation matsused in the installation of water-heat-insulated floors, the following article conveys in detail, which we advise you to read before planning the installation.

Installation of polyethylene pipes

Laying a warm floor is carried out by contours according to a pre-selected scheme. A circuit is a closed pipe ring that, upon returning to the collector, is connected to it using a fitting.

For small rooms arrange 1-3 circuits. To simplify installation, it is recommended to apply rough markings on the polystyrene foam boards. If there is a marking, it will be easier for you to lay polyethylene pipes and check the step size.

Before start installation of the underfloor heating pipeline It is also necessary to decide how the pipes will be connected and how the polyethylene pipes will be attached to the insulation.

The fact is that pipe jointing can be carried out:

  • by welding;
  • crimp fittings;
  • pressing fittings.

The latter option is the easiest to execute and reliable. To connect the pipes, it is necessary to install a movable sleeve, and then with the expander carefully increase the inner diameter of the pipe to the required size.

To connect a polyethylene heating coil with press fittings, you need to stock up on the tool. For a one-time assembly it is better to rent it, if you plan a large volume, it is advisable to buy:

Tool kit for fitting fittings
The kit for mounting a polyethylene pipeline without welding should have an expander with nozzles of different sizes and press-in pliers with nozzles for crimping - “vice”

Before building a system, a novice in the plumbing industry needs to be trained:

Secure the fitting completely and push the sleeve over it over the pipe. The compression joint withstands prolonged exposure to high temperatures and pressures up to 10 MPa.

As for the method of attaching polyethylene pipes to the insulation, this is true if ordinary polystyrene foam is used.

There are several mounting options:

  • tightening clamps made of polyethylene;
  • steel wire;
  • clamps fixed with a stapler;
  • fixing tracks.

The easiest and most economical method of attachment is with clamps. Consumption is 2 pcs per 1-1.5 m.

Fixing clamps on a site
On straight sections, mounting clamps are installed every 30-50 cm, and bends - 10-20 cm

There are 10 rules for installing cross-linked polyethylene for a warm floor:

  1. When laying bends, sharp creases of the material are not allowed.
  2. Installation works are carried out at a temperature not lower than +18 C.
  3. After bringing the pipe from the cold, you must wait until it warms up to room temperature.
  4. The maximum turning radius for pipes with a diameter of 16 mm should be 10-12 cm.
  5. During installation, it is not advisable to change the selected location of the coolant.
  6. Cutting off the extra length should be carried out immediately before it is connected to the distribution manifold.
  7. Do not step on, put heavy things on, put the tool on pipes.
  8. To move around laid pipes (if necessary), it is recommended to use large sheets of plywood to reduce the load on the coolant.
  9. To increase the rate of heat conservation, pipes coming out from under the floor at the connection point to the collector assembly can be reinforced with thermal insulation.
  10. Pipes should lie flat, without torsion and excessive tension.

After laying the circuit, the pipe returns to the collector and is connected using a fitting that is sized to fit. After that, the system is tested, the purpose of which is to detect defects before the system is hidden under the screed.

For testing, you need a household compressor, which can give a pressure of 4-6 bar. The coolant with the help of the compressor is fed into the pipes and left for 6-12 hours. When shooting the mounting clamps, they must be reapplied 5 cm below the previous mounting location.

Wall collector
The collector is recommended to be equipped near the wall near the floor to reduce heat loss during transportation

Screed device rules

If the hydraulic tests were successful, the depressurization of the pipes did not occur, and the system is completely filled with coolant, then the pipe installation phase is completed. Now you can proceed to the device of the screed and to the finishing.

For screed devices you must use a purchased or self-prepared mortar based on cement grade M300. The minimum screed height that protects the polyethylene pipes is 3 cm above the stacked pipe. This thickness will be optimal for even heat distribution.

In most cases, the screed is continuous without expansion joints. Thermal seams are needed when:

  • the room has an area of ​​more than 33 m2;
  • the length of the room is more than 10 m;
  • the room has a complex configuration.

Damper tape is used to create seams. Thermal seams are treated with sealant.

Do I need to do reinforcement before pouring screed? There is no definite answer to this question. Experience shows that the system functions perfectly without reinforcement, but at the same time, the reinforcing layer gives the screed extra strength. For reinforcing, a mesh of 100x100 mm made of metal or plastic can be used.

Reinforcing will also be useful only if the reinforcing mesh is not just lying on top of the pipe system, but “drowned” in solution, when solidified inside the screed.

The correct reinforcement device complicates the installation of the screed, therefore, when there is no experience or confidence that everything can be done correctly, this step can be skipped. After pouring the screed, the system can be started no earlier than in 25-30 days.

Floor Finishing
Any floor covering can be used as a finishing finish - the top layer of the “pie”

Putting the system into operation

After the final hardening, the cast screed can be fed into the system coolantwhose temperature should not be higher than + 26ºС.

The algorithm for commissioning a warm floor system made of cross-linked polyethylene is as follows:

  • collector connect to the supply and return piping;
  • all circuits are simultaneously opened with taps on the collectors;
  • we install air vent valves in the “open” position;
  • start the circulation pump;
  • set the temperature + 25-26º C;
  • the pressure in the system is raised to the working 1 bar;
  • we close by cranes all contours except the longest;
  • we record all the provisions of flow meters and balancers;
  • open the next contour along the length and with the help of a crane equalize pressure along the first contour.

In this way we connect and balance all the contours of the warm floor. You can evaluate the heating performance only after 2-3 months of operation.

With features and rules for installing underfloor heating on a wooden base will introduce the article, detailing the rules of design and construction of the system.

Conclusions and useful video on the topic

The rules for calculating the heating floor system are given in the video:

After laying the pipe, it is important to test it before performing further installation work. About this in the video:

House craftsmen often make mistakes when assembling a warm floor. The main problems of installing polyethylene pipes are covered in the video clip:

A correctly selected and installed underfloor heating without any special expenses will make the housing warm and comfortable. The technology for installing a floor heating circuit made of PE pipes is simple and can be used not only by professional builders, but also by ordinary people. Subject to all the rules and recommendations, the system will regularly serve you for a long time.

Have you ever had to lay polyethylene pipes when installing a warm floor? Perhaps you know the technological nuances that are not noted in the article? Please write comments, ask questions, post a photo on the topic in the block below.

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Visitors Comments
  1. I want to note that the temperature of the coolant for the warm floor is still not 90 degrees, but a maximum of 45. Otherwise, the heels will simply fry. And this moment makes underfloor heating an excellent heating option when using a heat pump, where just such a temperature is optimal for the system.Due to the large heat transfer area (much more than radiators), this temperature is quite enough to heat the room.

  2. Nikolay

    I did the first warm floor in my own in the zero, then only pipes were offered. Well, after 7 years, they flowed from me. In the morning I got up - a flood in the bathroom.
    When I ordered the installation of the floor for the second time, I wisely approached the issue, studied everything, and polyethylene is really the most suitable material now. Durable, resistant, not clogged, not rust. I don’t know, about 50 years, but 20 will definitely last.