Currently, the number of supporters of this particular method of heating rooms is constantly increasing. More and more owners of private houses and apartments are setting out to create a system of water-based “warm floors” in their properties, appreciating its cost-effectiveness, ease of use and the created comfortable temperature distribution in the premises. Naturally, “our people” always have the desire to do everything or a lot with their own hands. However, you should not rely on the assurances of some online publications that this is a completely simple matter. In order for the system to be efficient, reliable, trouble-free, efficient and economical, it is necessary to take into account many nuances when calculating it, including the parameters and quality of components. And in the series of all the necessary materials, parts and components, one of the key positions is occupied by the heat exchange circuits of the pipes, without the guaranteed quality of which a water “warm floor” is simply impossible. What requirements must a pipe for a heated floor meet, how to choose the right one from a modern assortment - all these questions will be covered in this publication.

Key requirements for underfloor heating pipes

It is necessary to “cool down the ardor” in advance of those home enthusiasts who, fired up by the idea of ​​​​creating a “warm floor” in their home, expect to make do with some leftovers available in the household or any inexpensive pipes, based on considerations of maximizing the cost of the entire project. Most likely, they won’t succeed - such a room heating system requires the use of exclusively high-quality material that meets a number of requirements. No “analogs” will come to the rescue in this situation - it is either simply prohibited, or their use will be akin to a “planted bomb” that will explode unknown when.

Before making a decision and planning a trip to the store for material, you must carefully study all the basic requirements for pipes acceptable for use in “warm floors”. There is nothing you can do - the operating conditions are very specific.

• Even if the owner has a supply of metal VGP pipes, or there is an opportunity to get them at a low cost, this idea should still be rejected immediately. Moreover, it does not matter at all whether these are ordinary steel pipes, galvanized or even made of stainless steel. This categorical prohibition is determined by several factors.

First of all, according to current building codes and regulations, it is not allowed to use pipes made using welded technology (regardless of whether it is a straight seam or a spiral one) in closed floor heating circuits. Well, secondly, such pipes themselves have a very impressive mass. Taken together with the fact that the entire “pie” of a heated floor, taking into account the poured screed, weighs a lot, the use of steel contours will create increased and completely unjustified loads on the floors.

The only option for their use is the main lines from the boiler room to the distribution manifold cabinets. But even in this case, such a solution can be considered “yesterday” - there are simpler and easier to implement options.

• Although there are options for creating water-based “warm floors” using “dry” technology, the overwhelming majority of schemes involve pouring a concrete screed. In this option, the system becomes more efficient, since the monolithic layer of concrete creates an even distribution of heat over the surface and, in addition, becomes a powerful thermal energy storage device, ensuring economical and smooth heating operation.

All this suggests that the possibility of carrying out revisions of laid contours or carrying out minor repairs is completely excluded. Any emergency will lead to extremely large-scale and expensive work to dismantle the concrete pouring and replace the entire circuit as a whole. Therefore, the quality of the pipes must be such that their service life is comparable to the durability of the building structures themselves. The “warm floor” system must be designed for decades to come.

Pipes for “warm floors” must be fully protected from the development of corrosion, from the processes of overgrowing of the internal walls with scale and salt deposits, narrowing the lumen. The manufacturing material must be chemically inert, regardless of the type of coolant used, not subject to aging, and resistant to temperature changes. Ideally, it is recommended to use products that are also equipped with a special “barrier” against oxygen diffusion - such pipes have the highest performance qualities.

• When installing a “warm floor” circuit, any splicing of pipes covered with a screed should be excluded (with some exceptions, which will be mentioned below). Any connection point - be it a fitting or a weld, has always been and remains a vulnerable place, where accidents most often occur when any emergency situations arise.

Any leak is unpleasant, but in an open area, as a rule, eliminating the consequences is not particularly difficult. It’s a different matter if this happens under a layer of concrete pouring - the “resulting” consequences, in the literal sense of the word, can become catastrophic. It may not even be possible to detect a damaged area right away - it can make itself felt by leaking to neighbors or even disrupting the electrical network, which poses an extremely high danger.

And the second argument against connections in circuits. Such nodes are always more vulnerable to the formation of overgrowths or blockages. Cleaning the “warm floor” circuit is incomparably more difficult than an open heating radiator.

Hence the conclusion - the circuit must be made from a single piece of pipe of the required length. In addition, the pipe itself must be sufficiently plastic to allow laying out curved sections with smooth bends, and at the same time maintain its given shape without unnecessary internal stresses in the walls.

It may be argued that on the Internet there are demonstrations of the created contours of “warm floors”, made, for example, from polypropylene pipes, naturally, using welded seams on bends, tees, etc. But, you must admit, not everything that is published on the Internet should become a model for repetition. Please note: against the general background, these are literally isolated cases, the history of whose operation, by the way, is not covered in any way. There are also arguments against such a decision - they will be discussed when considering the characteristics of the pipes.

• The next one logically follows from the previous point - the pipes must be of sufficient length to lay the circuit in a single section. Most products manufactured for this type of application meet this requirement - they are sold by the meter in coils.

In this case, restrictions on the total length of the contour should be taken into account. Excessive length of the pipe can lead to its hydraulic resistance exceeding the capabilities of the circulation pump, and a “locked loop” effect will appear - the coolant will not move along the circuit. There are certain limits that should not be exceeded.

If the area of ​​the room in which the water-heated floor is created is such that longer pipes are required, then it will have to be divided into two or more sections with separate circuits of approximately the same length and connected to a common collector.

• Since the diameter of the pipes was mentioned, we can immediately focus on this characteristic.

Typically, pipes of three sizes are used for underfloor heating circuits - 16.20 and, much less frequently, 25 mm.

For heated floors, pipes with a diameter of 16, 20, less often - 25 mm are usually used

In this matter, it is important to choose the “golden mean” that best suits specific conditions. It is clear that the narrower the pipe lumen, the greater the importance of the hydraulic resistance, and the less heat transfer potential the circuit will have. However, with increasing diameter, the thickness of the screed being poured certainly increases, which leads to a rise in the floor surface, which is not always possible, and to an increase in loads on the floors.

• One of the most important requirements for pipes is high mechanical strength. The walls of the pipe will have to endure considerable loads, both external, from the side of the concrete screed, and internal, caused by the coolant pressure in the circuit. It is clear that critical pressures should not be present here by definition, but still, in order to avoid accidents caused by extreme surges, the pipe must be able to withstand up to 10 bar.
• The pipe material should not be subject to thermal deformation at high temperatures. In “warm floor” circuits, the heating of the coolant usually rarely exceeds 40 ÷ 45 ° C, but to fully guarantee the safety of the pipe, a material is chosen that does not change its characteristics even when reaching 90 ÷ 95 ° C - in case of unforeseen emergency situations on the collector equipment.
• A condition for the effective operation of a “warm floor” is the ideal smoothness of the inner walls of the pipe. This is necessary, firstly, so that the value of hydraulic resistance lies within acceptable limits. Secondly, on a smooth surface there is a significantly lower likelihood of plaque and hard deposits forming. And thirdly, if the surface of the walls is of poor quality, the movement of the coolant through the pipes may be accompanied by noise, which is not to everyone’s liking.

So, the basic requirements for the pipes of the “warm floor” circuits were outlined. Now we can move on to consider the types of material in order to assess the extent to which they correspond to the above parameters, how convenient they are to use, and how economical they are in terms of the cost of the material and installation work.

Which pipes are optimal for heated floors?

Metal pipes

One type of metal pipes has already been briefly discussed above - we are talking about steel VGP. Everything is clear with them - they are categorically unacceptable in the contours of a “warm floor”. But there are other varieties - and they are perfect for these purposes.

Copper pipes

If we consider copper pipes in the light of the requirements stated above, then they are probably close to ideal.

• Copper is an excellent heat conductor, that is, a circuit made of such pipes will provide maximum heat transfer.
• This metal is characterized by the highest resistance to corrosion, that is, the pipes should not cause any doubt about their durability. During the first stages of use, copper will be covered with a thin layer of patina - and after this the process of “aging” practically stops.
• Copper pipes are very flexible and, subject to certain technological techniques, can be bent to a very small radius.
• The walls of copper pipes are characterized by high mechanical strength and are not afraid of sudden pressure surges and temperature changes.
• Many modern manufacturers of copper pipes also use an external polymer film coating - this is another plus for the durability of such circuits, which receive additional protection from the aggressive environment of cement.

Copper pipes have disadvantages, but they can be classified as “indirect” - they do not affect the performance and safety of the heating system:

• Installation of copper pipes is quite a complex matter, requiring special skills and special equipment. This, of course, significantly reduces the possibility of independently creating a “warm floor” system.
• And secondly, the cost of copper pipes is incomparably higher than polymer or composite ones. They are not available to everyone, which is why their popularity is very high.

Corrugated stainless steel pipes

• This type of pipe appeared relatively recently, but immediately proved its advantages over many others.
• The pipes are made of stainless steel, which means that corrosion is completely excluded. In addition, they may have an additional polymer coating.

Corrugated stainless steel pipes are an excellent solution for “warm floors”

• Such pipes have good flexibility, which is extremely important for laying contours of complex configurations, and at the same time stably maintain a given bend. Even an accidental fracture of the pipe when forming a bend is completely eliminated.
• The mechanical strength of the pipes is beyond praise.
• The resistance of the material to a wide variety of influences - temperature, pressure, aggressive pumped media - allows the use of such pipes even in technological industrial installations - and this already speaks for itself.

Corrugated stainless steel pipes are sold in coils up to 30 or 50 meters long. It would seem that this is clearly not enough for the contours of a warm floor. But here too everything is going well.

Such pipes have such a perfect system of connecting fittings that the joints can be placed in the screed without any risk of leakage. This is probably the only exception to the rule mentioned above - such pipes can be joined while laying a long circuit.

What limits the widespread use of such pipes? First of all, this is, of course, the high level of prices for them. However, another reason cannot be ruled out - many potential buyers simply do not have information about the existence of such a reliable option.

Prices for corrugated stainless steel pipes

Corrugated stainless steel pipes

Polymer pipes

In this category, a division can be made into pipes made of polypropylene and into products in which the main material is polyethylene of varying degrees of processing.

Polypropylene pipes

They have already been discussed above, but it is still worth focusing some attention.

Polypropylene pipes are an excellent material for use in water supply systems or when installing heating circuits of the “classic” type - with radiators or heating convectors. They are also quite suitable for ensuring the transportation of coolant from the boiler to the installation site of the distribution manifold unit, both for supply and return. Their installation is simple, and if you have a special welding machine, the necessary skills are acquired literally on the go. The cost of both the pipes themselves and all the necessary elements for installation is very low.

Polypropylene pipes have a lot of advantages, but they are not suitable for a “warm floor” circuit

But for the circuit you will have to look for a different solution.

• The form of release of such pipes is short (on the scale of the lengths of the heated floor contours) sections.
• The pipe has very high plasticity, that is, it is impossible to bend it even under a relatively large radius, not to mention laying the contour loops. That is, in any case, it is impossible to avoid welded joints, the inadmissibility of which has already been mentioned.
• The thermal conductivity of the material is low, that is, proper heat exchange between the coolant and the thin floor will not be ensured, and the overall efficiency of the system will be low.
• Polypropylene pipes stand out from the general background due to the highest rates of linear thermal expansion. Even reinforced ones intended for hot water will require the installation of compensatory loops on long sections. In a warm floor filled with screed, this is impossible to do, and the walls of the pipes will be subject to significant internal stresses, which will certainly affect their durability.

In a word, no matter what anyone says, using such pipes for underfloor heating circuits is a completely unjustified decision from any point of view.

Polyethylene-based pipes

It would probably be appropriate to immediately make a very important reservation. The fact is that if you analyze most of the publications devoted to this problem, you can come to a not entirely correct conclusion. Very often, a gradation of all flexible pipes suitable for a “warm floor” system is made into those made of cross-linked polyethylene and metal-plastic. A strong association involuntarily arises that polyethylene is itself, and some other polymer is used for metal plastic.

In reality, everything is somewhat simpler. All modern flexible pipes for this purpose are made on the basis of so-called cross-linked polyethylene, which, however, may differ in the processing technology of the source material. But the structure of the pipe itself may include a metal reinforcing layer and some other technological layers that increase the performance characteristics of the finished product.

Therefore, in this article we will try to adhere to the same classification - based, first of all, on the original material for making pipes.

To begin with, it’s probably worth getting a certain understanding of what is hidden under the mysterious name “cross-linked polyethylene”

Pipes based on cross-linked polyethylene

The development of a cheap and accessible technology for producing polyethylene in the full sense of the word has revolutionized the life of mankind - this material is found literally at every step, and without it it is difficult to even imagine our life. But with all the advantages of this material - inertness, harmlessness to water and products, plasticity, fairly high overall strength, it also has a number of disadvantages, which are due to the molecular characteristics of the polymer.

Polyethylene molecules are distinct long chains that are not connected or very weakly connected to each other. Under high loads, the material begins to stretch strongly, and under thermal influence, even not so significant, it begins to float and lose its given shape. Naturally, this seriously limited the scope of application of such a polymer in those products that are used under similar conditions.

But if you create cross-links between chains of molecules, the picture immediately changes. The structure turns out to be not linear, but already three-dimensional, and polyethylene, without losing any of its advantages, receives additional qualities - increased strength and stability of its given shape.

The more such connecting “jumpers”, that is, the higher the degree of cross-linking of polyethylene, measured as a percentage, the more stable and better the material is obtained.

There is another remarkable property of cross-linked polyethylene - it is a kind of “memory effect”. If a product, under the influence of any external loads, changes its shape or configuration, then when conditions normalize, it will tend to its given initial position. For the manufacture of pipes this becomes an invaluable advantage.

There is a generally accepted letter designation by which you can immediately determine that the product is made of cross-linked polyethylene - PEX. But usually these letters are followed by another one - this is a symbol that indicates the technology for creating cross-links in the molecular structure of the material. The performance characteristics of the polymer depend quite strongly on the method used, so it is worth dwelling on this nuance.

• RE-Ha - intermolecular cross-linking of polyethylene occurs under the influence of a chemical reagent - peroxide. Of all the technologies adopted today, this is the one that provides the maximum degree of cross-linking - it reaches 85%. In this case, the original polymer does not lose its qualities in any way, but its strength and stability sharply increase, and a particularly pronounced “memory effect” is noted.

The technology is quite complex and expensive, but gives the best results. It is also important that the crosslinking process is completely controllable, that is, the output is a polymer with strictly specified parameters.

• PE-Xb – the creation of cross-links occurs using silanol technology, due to the so-called “grafting” of an active silane molecule and treatment with water vapor. It must be said that this technology was initially conceived as a cheaper replacement for RE-Ha. However, it cannot be said that the stated goal was completely achieved.

Cross-linked PE-Xb polyethylene is inferior in plasticity, that is, bending pipes along a small radius will be much more difficult. The total degree of cross-linking rarely exceeds 65%. Another disadvantage is that the technological process is difficult to control, and the output of products from different batches may differ in their parameters. Moreover, the stitching process, in fact, does not stop in finished products - it simply goes into a sluggish phase. It turns out. That over time the same pipes can become stiffer and shrink. In some countries, such polyethylene is prohibited for use in heating networks precisely for this reason - the connections on the fittings are not the most reliable, and therefore require regular tightening. Well, in metal-plastic pipes based on PE-Xb, delamination of the general structure of the walls has been noted more than once.

• PE-Xs is cross-linked polyethylene, in which cross-links arise due to directed electron radiation. The production of this polymer is quite simple from a technological point of view and inexpensive, but the resulting material itself is significantly inferior to RE-Ha polyethylene.

It, of course, finds its application, for example, it is used for the production of metal-plastic pipes of a low price category. They are quite applicable for water supply networks, but their use in a heated floor circuit can only be done very conditionally.

• PE-Хd - according to this technology, cross-links were formed by treating raw materials with special nitrogenous substances. Currently, this method has completely lost competition to others, and is actually not used, and pipes with this index are not found.

High-quality cross-linked polyethylene pipes are widely used in underfloor heating systems. Moreover, some types are designed exclusively for such functions.

• Metal-plastic pipes that combine the inner and outer layers of cross-linked polyethylene and an internal solid aluminum layer are in great demand among craftsmen. The accepted designation for such pipes is PEX-Al-PEX.

1 – inner layer PEX

2 – outer layer PEX.

3 – a continuous layer of aluminum foil, butt welded.

4 – adhesive layers (adhesive), ensuring the integrity of the wall structure.

Such pipes have quite decent performance qualities, as they combine the advantages of polymer and metal. They lend themselves well to bending (subject to special technological rules), stably retain the given circuit configuration, and have a fairly high heat transfer.

But since we are talking about the contours of a heated floor, then the parameters of the polymer itself used to make the pipe come to the fore - special attention should be paid to this. The fact is that metal-plastic pipes are very similar in appearance, and sometimes unscrupulous sellers try not to educate the buyer about the intricacies, presenting their product as universal, suitable for any operating conditions.

As already mentioned, preference should be given to pipes in which the inner layer (or better, both polymer layers) are made of cross-linked polyethylene PE-Xa. They won't be cheap, of course, but it's worth it.

The building materials market is literally teeming with counterfeits of branded products, and the risk of purchasing a low-quality pipe is quite high. Therefore, you need to “leave all your indecisiveness at home” - be sure to require sellers to have documents confirming the originality of the product and its compliance with standards.

You can find metal-plastic pipes in which the outer layer is made of PE-Xc or even ordinary high-pressure polyethylene - PE-HD. They practically do not differ in appearance, but they should not be used in underfloor heating systems. Any experienced plumber can tell you how many metal-plastic breaks he has encountered in his practice. Over time, the unstable outer layer begins to “tan”, crack, especially in places where hinges turn or bend, and can easily crack. And the thin inner layer and aluminum layer will not be able to withstand the pressure from the inside in such circumstances.

In addition, gradual delamination of the pipe body cannot be ruled out, since the materials still have different linear stretch coefficients with increasing temperature. Therefore, despite a lot of real and apparent advantages, you should still refuse to use this type of pipe in a circuit under a screed. For these purposes, single-layer ones made of cross-linked polyethylene PE-Xa or PE-Xb are more suitable.

Such pipes are sold in coils of large footage. They are very convenient for laying out even the most complex contours, and if the fastening technology is followed, they hold their shape perfectly. The plasticity of the material allows contours to be laid with the smallest pitch between turns - about 100 mm.

It is even better if it is possible to purchase such pipes, supplemented with a special barrier against oxygen diffusion. The penetration of active oxygen into the coolant from the outside causes and activates corrosion processes in metal parts and components of the heating system, and boiler heat exchangers are especially susceptible to such aging. To prevent such a process, special barriers to oxygen diffusion were developed.

1 – inner layer PE-Ha or PE-Xb

2 – EVON anti-oxygen barrier.

3 – connecting layers.

4 – outer layer, respectively, also – PE-Ha or PE-Xb

This barrier itself is usually a layer of a special organic compound, polyethylvinyl alcohol. It is characteristic that all components of such a structure have equal thermal expansion characteristics, so even with significant thermal changes, no delamination threatens the walls.

To all that has been said, it should be added that manufacturers of such pipes made of cross-linked polyethylene necessarily complete their products with convenient connecting elements that will simplify the connection of underfloor heating circuits to the collectors.

To make it easier to choose a pipe, and more difficult for an unscrupulous seller to mislead the buyer, you can try to understand the labeling system. We can look at this with an example - although different manufacturers may have their own particularities in this matter, the general principle still remains the same.

1 – usually the first position indicates the brand and specific product type of pipe.

2 – data on the outer diameter of the pipe and the total thickness of its wall.

3 – codes indicating compliance with accepted international standards for acceptable areas of pipe application. The indicator indicated in this example indicates that the pipe is suitable for pumping drinking water.

4 – control technology used to assess the quality of the product.

5 – the polyethylene cross-linking technology discussed in the article above.

6 – confirmation of pipe compliance with established standards DIN 16892/16893. These standards predetermine the maximum temperature and pressure values ​​of the pumped liquid. On some pipe models, it is practiced to include these indicators in the markings. For example, it might look like this:

« DIN 16892PB 14/60°CPB 11/70°CPB 8/90°C",

which would mean max 14 bar at t=60°C, 11 bar at t=70°C and 8 bar at t=60°C.

These indicators can also be indicated in tabular form in the technical documentation attached to the batch of pipes. In addition, maximum service life under different modes can be given. For example:

7 – parameters of the material batch – information about the date and time of production, production line number, etc.

In addition to this information, the pipes are also marked along their length - this greatly facilitates both control over the acquisition of the required quantity and the laying of the contours itself.

Pipes based on polyethylene with increased heat resistance (PE-RT)

Attempts to modify polyethylene as much as possible led to the creation of a fundamental new material, denoted by the abbreviation PE-RT, from the English name, which literally means polyethylene with increased heat resistance. Now the second generation of this polymer is used in production.

Its main difference is that the material does not require additional technological steps of cross-linking - its molecular structure with numerous and branched bonds is already far from linear. Moreover, this quality is inherent in the source material - the conglomerate entering the extrusion line is already fully a polymer with a stable molecular lattice. Interestingly, no loss of properties is observed even during recycling.

Such polyethylene shows much better results in terms of resistance to high temperatures and pressure. Its service life can be tens of years. The unique molecular structure keeps the material thermoplastic, meaning it can be welded or soldered. This allows in some cases to carry out repair and restoration work without dismantling the damaged fragment and without using fittings, which is completely impossible, for example, with PEX - where the damaged area will have to be removed.

Pipes made of PE-RT are not afraid of negative temperatures - they have the potential to withstand several cycles of complete freezing and thawing without breaking through the walls and without any loss of their performance qualities.

The pipes “behave” well in underfloor heating circuits and are silent even with strong pressure of the pumped coolant.

By analogy with cross-linked polyethylene, PE-RT is also used in the production of both pure polymer pipes (with or without an anti-diffusion layer) and metal-plastic pipes, in various combinations. Since the main load falls on the base inner layer, it is made from heat-resistant polyethylene PE-RT, and the outer protective layer can be made from cross-linked PEX or even PE-HD. But in the highest quality pipes, both the outer and inner layers are made of PE-RT. So when choosing, you should pay special attention to the formula indicated on the label.

It can probably be said with good reason that PE-RT pipes will be the choice that fully meets all the previously listed requirements for underfloor heating circuits and is not beyond reasonable limits in terms of the cost of purchasing material and components.

Prices for PE-RT pipes

PE-RT pipes

How much pipe is needed for a “warm floor”?

It is very difficult to answer this question unequivocally. Everything depends on the step of laying the circuits, and it, in turn, is directly related to the tasks assigned to the floor heating system and the characteristics of a particular room.

To decide on this issue, you will need to carry out thermal calculations for each of the rooms where it is planned to install a “warm floor”. Essentially, it is necessary to calculate the heat loss of the room, which must be compensated by such a heating system. In any case, a “warm floor” will only make sense if measures have been taken to maximize the thermal insulation of the room. Practice has proven that if heat loss is more than 80÷100 W/m², then installing such a home heating system will turn into an absolutely unjustified loss of effort, money and time.

It is also important whether the “warm floor” will be the main source of thermal energy, or whether it is planned only as a means of increasing comfort in individual rooms or even in some limited areas, that is, it will work in “tandem” with radiators.

Typically, the laying step ranges from 100 to 300 mm. Reducing it is impractical, and often simply impossible, since this will not allow the permissible bending radius of the pipe. If the laying step is too large, the heat will be distributed unevenly, and a “zebra effect” will occur - clearly noticeable stripes with different levels of heating of the floor surface.

In areas that require increased heating, the laying of the circuit can be locally compacted, and in areas a vacuum pitch is acceptable, but still within the specified limits.

Thermal calculations, taking into account all the features of the premises, are a rather complex procedure that requires certain knowledge. It deserves a separate detailed publication and will not be considered within the scope of this article. The best way out is to entrust this matter to specialists who will help you decide on the pattern of the contours and the step of its installation, and draw up a diagram. And only then will it be possible to calculate the required amount of pipe for the “warm floor”

You can use the following calculation formula:

l = k × Syh/hyh

l— the length of the contour in a certain area.

Sych- land area.

hych— step of laying pipes on the site.

k— coefficient taking into account pipeline bends.

Coefficient k depends also depends on the laying step and is in the range of 1.1 ÷ 1.3.

To make the task easier for the reader, below is a convenient calculator in which all the relationships are already included. You can calculate the lengths of pipes for each section with a certain laying pitch, then sum them up, and do not forget to add the distance to the insertion point (manifold, plus leave approximately 500 mm at each end for connection.

Nowadays, many people are increasingly installing one type of warm water floors in their apartments or private homes. This creates additional comfort and coziness in homes. Before installing a heated floor, an important question arises: which pipe to choose. With the development of modern technologies, this choice is quite diverse. Therefore, we will consider the main points that should be followed when selecting a pipe.

Pipes for water floors and the main criteria for their selection.

In order to choose the optimal type of pipes, you should clearly understand the conditions in which they will function. In addition, you need to imagine some features:

• The operating temperature of the coolant in heated floors rarely exceeds 50 degrees. Usually it fluctuates between 30-40 degrees. Therefore, the material used in the manufacture of underfloor heating pipes must have very good thermal conductivity (to transfer heat through the cement screed)
• The length of the laid pipe quite often exceeds 100 m (the length depends on the diameter). Therefore, to facilitate the operation of the pump, the inner walls of the pipe should be as smooth as possible.
• When the water floor pipe circuit is heated, it lengthens. Therefore, the pipe material must have a small coefficient of thermal expansion. Or have sufficient elasticity and strength of the shell to prevent deformation and destruction.
• In the event of force majeure, in the event of a collector failure, the material must withstand the water temperature of the central system (70-90 degrees)
• In addition to the above, the material must have the following properties: increased protection against corrosion, complete tightness, ease of installation and the absence of joints. Such careful selection of material can be avoided by choosing.
• Pipes and components must have a reasonable price.

What kind of pipes exist for underfloor heating?

All pipes for installing a warm water floor can be divided into two large groups: metal and polymer.

Types of metal pipes for heated floors

When installing a warm water floor, two types of metal pipes are used: copper and corrugated stainless steel.

Copper pipe for underfloor heating.

For its manufacture, annealed copper with diameters of 15, 18, 22 mm is used. The pipes are sold in coils of 25 m (wall thickness 1 mm). When considering copper pipes for use in heated floors, it is worth noting their following advantages:

One of the highest heat transfer coefficients compared to polymer pipes of any type.

New products have a good coefficient of smoothness of the internal walls.

Thermal expansion ranges from 50-80 mm per 100 m, at a temperature of about 50 degrees.

The working pressure of copper is up to 67 bar.

The maximum temperature withstand is 200 degrees.

They do not allow oxygen to pass through at all.

They corrode very slowly.

Despite their good parameters, copper pipes are rarely used when installing heated floors for several reasons:

High cost (compared to polymers)

Installation problems. Requires special equipment.

The kinks in the formation of contour loops are a weak point. Installation must be performed by a sufficiently experienced person.

Corrugated pipe for underfloor heating made of stainless steel.

In production, annealed stainless steel corrugation is used. Pipes with diameters of 15-20 mm are made. The pipes are connected using special fittings.
Sold in coils from 10 to 50 m. Let's consider the main advantages of corrugated pipes:

Excellent heat dissipation, just like copper.

Working pressure up to 15 bar, at a temperature of 150 degrees

Just like copper, it does not allow oxygen to pass through at all and is practically not subject to corrosion.

Possessing good ductility, it is convenient for installation.

Resistance to mechanical stress

The disadvantages of corrugated pipes include:

High price compared to polymers.

The corrugated structure creates additional hydraulic resistance to the coolant current.

Polymer pipes for floor heating

The most popular and inexpensive type of pipes when installing a warm water floor. It is divided into two types: polypropylene pipes and polyethylene pipes. There are the following markings of polymer pipes for heating:

PP-R and PP-RCT are a random copolymer. A type of polypropylene. Can be reinforced with aluminum, basalt or fiberglass. -RCT marking indicates that the product has a higher temperature resistance

PE-X is cross-linked polyethylene of three types A, B and C. The pipes contain a layer of impermeable polymer that protects them from oxygen penetration.

PE-RT - pipes made of polyethylene. At the same time, they have a barrier to oxygen access.

PE-X; AI; PEX and PE-X; AI; PE - pipes made of 5-layer metal-plastic.

When installing polymer pipes, the following connection options are used:

When installing PP-R, polypropylene fittings are used. The connection occurs by soldering.

Cross-linked polyethylene and heat-resistant are installed using the axial method. The process consists of three stages: flaring the end, installing it on the end of the fitting, and installing the sleeve.

When connecting metal-plastic pipes, two methods are used: compression and pressing.

Warm water floor made of polypropylene pipes.

Looking ahead, it’s worth saying right away that using polypropylene pipes in a warm water floor system will not be a good solution.

Even despite the low cost of polypropylene. To make sure of this, you should pay attention to its characteristics:

Among all polymers, polypropylene has the worst heat transfer.

Complexity. Polypropylene pipes have poor ductility. As a result, when laying the contour it will be impossible to do without joints. And this is unacceptable when laying the contour of a water-heated floor.

When heated to 50 degrees, a polypropylene pipe 100 m long will add 15 cm to the length. As a result, the pipe enclosed in a cement screed may be damaged.

Of course, it is worth noting some advantages of polypropylene:

Low price compared to other polymers.

Acceptable smoothness of internal walls, 0.01 mm.

Working pressure up to 13 bar, at a temperature of 70 degrees.

Chemical resistance. Zero oxygen carrying capacity.

Types of polyethylene pipes used to install heated floors.

Pipe for underfloor heating made of cross-linked polyethylene.

Pipes made of cross-linked polyethylene are produced in two types: 3-layer and 5-layer. In 3-layer cross-linked polyethylene, the anti-diffusion barrier is located on the outside of the pipe. In 5-layer polyethylene it is located inside the wall.

Let's look at the features of cross-linked polyethylene:

The differences between A, B and C lie in the method of cross-linking the molecular lattice. A - under the influence of peroxide. B - under the influence of water vapor and silane molecules. C- under the influence of the directed action of electrons.

More durable and resistant to mechanical stress compared to heat-resistant polyethylene.

Thermal conductivity is 3 times better

e than propylene pipes

Internal smoothness of walls, 0.007 mm.

The maximum temperature at which cross-linked polyethylene will not lose its properties is 90 degrees. Working pressure up to 10 bar.

The disadvantages of cross-linked polyethylene include the following:

Increased permeability to oxygen.

Heat-resistant polyethylene as a material for the manufacture of heated floor pipes.

Heat-resistant polyethylene is made from simple polyethylene. As a result of processing, the molecular lattice of the polymer is modified. The advantages worth noting are the following:

Heat-resistant polymer pipes are cheaper than cross-linked polymer pipes

Possesses thermoplasticity. Repeated heat treatment is possible without loss of properties

Thermal conductivity is also 3 times better than that of propylene pipes

The inner walls are quite smooth, 0.007 mm.

The operating temperature is 80 degrees.

Flaws:

Shorter service life compared to cross-linked polyethylene

Less resistant to mechanical stress compared to cross-linked polyethylene

There is no anti-diffusion barrier in the walls. As a result, the coolant is saturated with oxygen faster.

Which pipes are better for a warm water floor?

When choosing a pipe for a water heated floor, you should consider the entire set of their parameters. Let's consider pipes for heated floors in order of their greatest suitability:

1. Metal-plastic PEX-AL-PEX. Pipes are generally inexpensive and easy to install. They also have a fairly long service life. They have good heat transfer and reduced elongation.
2. Cross-linked polyethylene. It has almost all the advantages of the previous one, except for lower heat transfer and increased thermal expansion.
3. Heat-resistant polyethylene. Lower price compared to other options. The main disadvantage is the increased oxygen permeability. In case of severe overheating, the service life of the product is reduced.
4. Copper pipe. The best option for installing heated floors, if you do not take into account the high cost.
5. Stainless steel corrugation is optimal for short lengths.

Calculation of pipes for heated floors

In most cases, the pitch of laying heated floor coils ranges from 10 to 30 cm. In order to calculate how many meters of heated floor pipes will be required for its installation, you can use the following formula.

L- pipe length in a given section
k— coefficient depending on the laying pitch and pipe bends. Fluctuates between 1.1-1.3
S- area of ​​the area on which the contour is located
H— pipe laying step

What pipe diameter to use for a warm water floor.

Almost always, before starting to install a warm water floor, the question arises about the diameter of the pipes that need to be used.

For laying heated floors, pipes with a diameter of 16 and 20 mm are used.

Almost always the circuit is laid with 16 mm pipes.

Pipe diameter 20 mm. it is necessary to lay in areas more than 100-120 mm.

Pipes with a diameter of 20 mm. are used in cases where the heated floor will be the main source of heat.

Video of pipes for warm water floors

When you have to renovate an apartment or house, opt for a heated water floor design, where the heat source will be hot water. This improves the quality and efficiency of heating and reduces the cost of maintaining housing.

Installing a water floor is difficult, but such work can be done independently, subject to the rules and technological sequence.

Types of warm water floors

When choosing a heating design, take into account the type of installation, room parameters, coating materials, strength of supporting structures and the requirements.

The classic option is concrete technology, when the water floor is installed in a concrete screed with preliminary installation of insulation and moisture insulation.

There are also flooring systems made of wood or polystyrene. There are rack and modular types. To install a rack structure, use edged boards, and for a modular structure, use ready-made sheets (modules).

After laying the base, cover it with sheets of chipboard or plywood and lay a finishing coating of laminate or linoleum.

Water heated floor installation

The liquid moves through the pressure pipeline, is discharged to the heating circuit, and as it passes through it it releases heat to the floor surface.

The cooled water returns back, entering the boiler and heating up again to the desired temperature.

Special limiters are installed in the base that connect the floor temperature with the volume of water in the heating circuit (so that the base is heated, creating an optimal microclimate).

The wooden floor structure consists of the following elements:

• base coat base;
• edged board, OSB, chipboard;
• aluminum distribution plates;
• pipelines for coolant;
• substrate for laying the finishing base;
• prefabricated screed GVLV;
• fine coating.

Wooden structures are used in old, frame and wooden houses, where a concrete screed is not suitable.

For installation, determine the appropriate option:

• modular type consists of ready-made elements;
• rack type is mounted from ready-made boards.

For the modular type, ready-made sheets of chipboard or polystyrene with grooves for installation of pipelines are used. The base is laid on logs, which are mounted in 60 cm increments on the old base or subfloor. The internal space is filled with a heat insulator.

The rack design is based on the use of boards with a thickness of 28 mm, which are laid at a distance of 20 mm from each other (to form grooves into which pipelines are mounted). Modular floors are used less frequently, but are durable and reliable.

The technique for laying a concrete system involves the use of screeds.

Scheme for laying a warm water floor:

• base;
• thermal insulation layer;
• reinforcing mesh;
• heating pipes;
• concrete pouring;
• substrate for the final coating and top layer (laminate, parquet).

Warm water floors are used in two-pipe heating with forced circulation of coolant and manifolds for distribution to equipment.

It includes the following elements:

• Boiler group and boiler. They create a non-stop supply of coolant to the risers (heating supply lines). After passing through the heating devices, the cooled coolant returns through the main line.

The boiler runs on solid or liquid fuel, pellets, from a heat pump, electricity, etc. The boiler room includes a pump, boiler, safety group and expansion tank;

• Radiator manifolds for pipes and heating devices;
• Return and supply lines that feed radiator manifolds, a mixing unit with a heated floor manifold. Cabinets with collectors are installed on each floor.

A suitable option in the heating design is to connect the boiler to the inlet to the pumping system. Due to the fact that the heating of the coolant reaches 35-45 C, a mixing unit is used to reduce this value. A two- or three-way valve is installed.

Advantages when purchasing collectors:

• durable and strong metric connection;
• use in underfloor heating;
• elimination of self-unwinding of parts;
• automatic regulation of thermal conditions on individual branches thanks to an electrothermal head on a thermostatic valve.

Nodal elements undergo quality control and research in accordance with the requirements of regulatory documentation. Product quality is confirmed by ISO9001, ISO9002 certificates and a hygienic certificate of conformity.

Italian products meet the requirements of modern design and are guaranteed for 3 years. The designs are reliable, durable, thought out in detail, economical and safe to use.

Thanks to the flexible control of water floors, drafts and dust are eliminated, comfort and temperature distribution in the room are increased, and the microclimate is normalized.

Under the brand Stal The manufacturer Energy produces bimetallic Stal-350, Stal-500 with a 5-year warranty and free delivery.

Consumers are offered radiator kits with 3-16 sections, the number of which determines the final cost of the product.

– infrared heated floors, which are characterized by a unique design that eliminates detailed consideration of the location of heating zones.

The thermostat reduces power in areas of reduced heat transfer, self-regulation of the system reduces energy consumption. The devices can operate with mild damage.

Capillary, energy-saving rod and cable floor models are available. The cost of the product depends on the configuration.

The Russian-Italian company VALTEC offers a range of products for heat and water supply, adapted to difficult operating conditions.

The product range includes fittings, water shut-off and control valves, membrane tanks, metal-plastic pipes. Raw materials and components are subjected to strength tests and incoming control, testing at the production stages.

The products are manufactured using innovative equipment, therefore they are characterized by the highest quality, which is confirmed by certificates. Each product is subject to careful control and testing, which minimizes the risk of accidents.

Compared to other floors, products from this manufacturer have a long service life.

The manufacturer provides a warranty on fittings, pipes, taps and other devices for a period of 7 years. The conditions apply to defects that appeared due to the fault of the manufacturer.

Any defects that appear are repaired free of charge, defective parts are replaced with new ones, or the manufacturer returns the money paid. Consumers are offered products at average market prices that will not fail.

When calculating heating system options, owners of private homes and apartments these days are increasingly deciding to install a water circuit under the floor covering. This method is economical and versatile: it can be either the main or an additional source of heat, it is used in any room - from the bathroom to the loggia. To achieve the greatest efficiency of such heating, you should find out in advance which pipes are best for heated floors and how to decide on their quantity.

The question of which pipe is best to use for a heated floor should be taken seriously: this is explained by the specific operating conditions of a water heating system. The material must only be new and meet a whole list of technical requirements.

1. Specific gravity, manufacturing technology. Installation of “underground” heating from steel water and gas pipes is not allowed, even if they are made of stainless steel. SNiP (Building Norms and Rules) prohibit the use of welded pipes in closed floor heating systems. The ban applies regardless of the type of seam (straight or spiral).

Another disadvantage of pipes made of steel is their heavy weight. The “pie” of a heated floor, including a concrete screed, already has an impressive weight. The steel contour sharply increases the load on the floor.

2. Resistance to external influences. The durability of the contour poured with concrete depends on it. After hardening, the monolith becomes a powerful heat storage and distributor (options using “dry” screed are less effective). The only negative: diagnostics in case of breakdowns is difficult, replacing a separate section of the pipeline is almost impossible. In the event of a break, the entire system will have to be dismantled.

To avoid such troubles, choose pipes from a chemically inert, heat-resistant material (must withstand 90-95 o C), completely protected from corrosion, with a smooth inner surface that is not prone to the formation of lime deposits. The ideal choice is a pipe with special protection against oxygen diffusion.

3. Durability. The screed presses on the walls from the outside, and the coolant presses from the inside. Although critical pressure readings are unlikely, the pipe should be rated at 10 bar (in case of extreme surges).

4. Sufficient length. The circuit must be solid, since any connections (couplings, fittings, welding) are potential places for leaks. A gust not detected in time leads to flooding of the neighbors below or to a short circuit in the electrical network. Another argument against joints is the high probability of pipes becoming overgrown and clogging the system in these places.

The length of the contour is determined by calculation. Typically, floor heating material is supplied in coils and sold in linear metres. Plasticity allows you to give the pipe a curved shape with bends of the desired radius.

Pipe sizes

The most popular contour diameters are 16 and 20 mm; material ∅ 25 mm is used much less frequently. When deciding which pipe is best for a warm water floor, consider the following:

• the smaller the diameter, the greater the hydraulic resistance and the less heat transfer capacity;
• as the diameter increases, the thickness of the screed has to be increased - as a result, the floor level rises (this is not always possible), and the load on the floor increases.

The maximum contour footage depends on the selected diameter. As the length of the pipe increases, the hydraulic resistance of the liquid increases and can exceed the technical capabilities of the circulation pump. A “locked loop” effect is created: the pumping unit pumps the coolant, but it stands still.

Table 1

If the maximum length of one circuit is not enough, it is recommended to use additional circuits.

Which pipe material is better?

Knowing the basic requirements for pipes, it is easier to assess the advantages and disadvantages of the materials most often used for installing a hydraulic floor.

Cross-linked polyethylene

Unlike conventional polyethylene, in which the bonds between hydrocarbon chains are very weak, its improved analogue is much denser. As a result of pressing under high pressure, cross-linked polyethylene (PEX) is obtained, which has many positive properties:

• resistance to mechanical loads - the polymer does not burst, crack, wear off, and cannot be scratched;
• heat resistance - the product works normally in the range of 0-95 o C, melting begins after 150 o C, combustion - at 400 o C;
• corrosion and biological resistance – cross-linked polyethylene will never develop rust or fungus;
• environmental friendliness - the material is completely safe for health, under no circumstances does it emit harmful compounds.

People often ask: if we compare different pipes for heated floors, which ones are best laid? PEX pipes are considered the most flexible: they bend easily and do not break even after several bends in the same area.

• degree of crosslinking - it must be at least 65-80%, otherwise the material will be fragile;
• a method of linking molecules.

The table below shows the types of cross-linked polyethylene pipes that can be used to make a water floor.

table 2

Pipes of the PEX-a category have the highest quality, but their price is quite high. The PEX-b category, which also has good technical characteristics, is more affordable in terms of cost.

Note: It is worth noting that products made from heat-resistant polyethylene PE-RT have recently appeared on the market, which is of high quality and competes with pipes made of PEX-a.

Metal-plastic

This is an inexpensive and reliable option that is in high demand. The material consists of several layers glued together. The inner side of the walls is perfectly smooth due to the polymer coating. It protects the aluminum base and adhesives from the destructive effects of water.

Advantages of metal-plastic pipes:

• long service life - manufacturers guarantee their performance for 50 years;
• corrosion resistance;
• health safety - polymers are chemically neutral and do not react with substances dissolved in water;
• low specific gravity;
• good soundproofing qualities - the coolant moves along the circuit almost silently.

Polypropylene

The material has obvious advantages: it is durable, environmentally friendly, and affordable. If necessary, the pipes are connected using a soldering iron (welded). The joints are absolutely permanent and durable.

However, there are many significant disadvantages to using this material for a heated floor system. One of them is inconvenience during installation. Polypropylene is quite rigid, so the minimum bending radius corresponds to 8-9 tube diameters (5-6 for cross-linked polyethylene). For example, a 16 mm polypropylene pipe can be laid in increments of at least 128 mm. Sometimes this is not enough to provide the specified thermal output. In addition, polypropylene has low thermal conductivity and a high degree of linear expansion. Another nuance is a strict temperature requirement: in the room where the circuit is installed it must be at least 15 o C.

Copper

This metal successfully competes with synthetic materials. The benefits of copper are:

• high thermal conductivity;
• durability - if all technical requirements for installation and operation are met, the pipes will last at least 50 years;
• plastic;
• thermal and mechanical strength - the copper tube will not burst, crack or melt under any circumstances.

The disadvantages of copper pipes include:

• high cost of material - the cost of copper connections is added to the costs of the pipes themselves;
• the complexity of installation - it is carried out using a pipe bender and a press machine; servicing such equipment requires professional training;
• sensitivity to water quality - if it is alkaline or acidic, corrosion of the pipes begins (the same thing happens when copper comes into contact with steel fittings).

Summing up the comparison of materials, we note that experts recommend choosing polyethylene or metal-plastic.

Calculation of the number of pipes and laying scheme

Having decided which pipes are best to buy for installing heated floors, you should calculate their quantity. For this purpose, draw a laying diagram:

• draw a room plan on a sheet of graph paper to scale;
• large pieces of furniture and household appliances are schematically drawn - it is not recommended to install pipes under them;
• a contour is drawn on the free area according to the chosen scheme.

There are the following main options for floor heating water circuits:

1. "Snake". The pipe is laid first along the perimeter of the room, and then parallel to one of the walls and finally comes to the starting point. This scheme is not difficult to design and implement, but it has a serious drawback. While the coolant sequentially, like a snake, passes through the entire room and returns to the collector, it has time to cool down. The area of ​​the floor close to the insert heats up much more than the area further away.
2. "Snail" or "spiral". The pipe always follows the contours of the perimeter, moving towards the center. After reaching the central point, the pipe returns to the collector. During installation, the circuit is laid at double intervals so that there is room for return. In this option, the heat is distributed more evenly across the floor.

“Snail” suggests only one sharply defined bend - in the middle of the diagram. Therefore, rigid pipes with a large bending radius can be used.

When designing, intermediate measurements are taken so as not to go beyond the maximum length of the circuit, depending on the diameter of the pipe (Table 1). A large room is divided into several sectors, for each of which a separate circuit is developed, connected to a common manifold. In this situation, it may be advisable to use a combined scheme: lay most of the room in a “snail” pattern, and the rest in a “snake” pattern.