How to bend pipes for underfloor heating

How to bend polypropylene pipes for underfloor heating

Polypropylene pipes. the most common material that is often used when installing a heating system. The polypropylene pipe is able to withstand the effects of high temperature heat carriers and well withstands the pressure of several atmospheres inside the pipe.

The disadvantage of PPP pipes is that they are sold straight, and to create complex configurations often need a pipe with a certain bend, which must be done manually.

It’s important! Manufacturers of PPP pipes do not recommend creating bends and changing the configuration of their products. Thus there is a risk to change the properties of materials and make the construction unreliable.

However, experienced repairmen often resort to bending the pipes, and this does not cause problems with deformation or impairment of strength.

During the construction of a complex heating system it is necessary to build structures with complex configurations.

For example, in apartment buildings, where each room has a separate riser and a radiator, the system is very simple. One pipe goes from the riser to the radiator, the other goes back. Sometimes they are connected by a third. In this case, it makes no sense to make a bend. It is enough to put the right connection elements in the number of 4. 6 pieces.

Things are different in a private home, where the heating has to be laid from scratch, starting from the boiler and lead pipes from the basement upstairs to all the rooms. Sometimes it is difficult in this case to build a straight system that will be devoid of turns and changes in the height of laying pipes. You can install two different pipes in all the bends, connected by a special coupling, but this is time consuming, costly and less effective.

Another big application of bent polypropylene pipes is the floor heating system. The fact that in this case the pipes are laid according to a predetermined pattern, reminiscent of the shape of a tubular electric heater in a washing machine or “coil” in the bathroom.

Such a system has many places in the bend of the pipe. In this case, you either need to install connectors at each bend, which is very impractical, or purchase special flexible pipes. The latter can be replaced by bending a polypropylene pipe.

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The procedure solves both technical and economic problems. By bending you can significantly reduce the number of connectors. There is no need to constantly cut and connect pipes, and you can save on unnecessary parts.

In addition the coupling is always a weak point. This is where leaks, corrosion and fractures most often occur. If you replace the socket with a one-piece pipe, there is a chance that the construction will last longer. It is also worth considering that polypropylene pipes are cheaper than pipes made of bendable plastic. By bending a PPP pipe you can save a lot of money on the underfloor heating system.

During the bending process several physical forces act on polypropylene. First of all, it is a mechanical force that gives the necessary bending of the pipe. The material is slightly compressed along the inner axis and stretched along the outer axis. This elastic deformation can easily damage the pipe if the procedure is not performed correctly.

In addition, in most cases hot bending is used. Another factor affecting polypropylene is temperature. Like any type of plastic, PPP is not always able to withstand significant temperature effects. Avoid deformation of the pipe when bending it is possible only by taking precautions.

It is worth heeding the advice of experts concerning:

• Exposure temperature. Remember that polypropylene melts at about 140 ͒С. It becomes flexible and the pipe can be bent. However, if this temperature is significantly exceeded, the pipe can simply melt or break. To avoid this, the temperature of exposure should not exceed 150 ͒С.
• Duration of exposure. The pipe should be heated until pliable, it is important not to miss the point where it becomes pliable. Further exposure will change the material’s properties.
• Uniformity of warming. Regardless of how it is heated, make sure all sides are evenly heated.
• Bending radius. This rule, unlike the previous ones, applies to any method of bending: both hot and cold. It is easy to calculate this parameter, it is worth remembering that the bend radius should exceed the radius of the pipe by no more than 8 times. For example, if the radius of the pipe is 5 cm, then the bend must have a radius that does not exceed 40 cm.

The procedure is quite difficult to perform. With the first time the desired result may not work. In addition, when connecting a bent pipe to the heating system, there is always a risk that it will leak at the bend. To avoid this, it is important to choose the correct method of bending.

There are two varieties of bending procedure: hot and cold. In the first case, the polypropylene is a factor of temperature and mechanical force.

In the second. only mechanical force. Each method has its advantages and disadvantages.

This is important! Under the influence of temperature, the pipe is easier to bend, therefore, less effort is required, which may eventually break the pipe. Cold method is recommended only for experienced craftsmen.

The easiest method of hot bending that can be easily recreated in a house or apartment. heating the pipe with a construction hair dryer. Such a hair dryer can be purchased or rented. In addition, for bending you will need a special spring bender or a bent at a desired angle template.

The bending is performed using a pipe bender in several steps:

• The pipe bender is placed inside the desired section of pipe or put on top.
• Warm gently and evenly with a hair dryer, making rotational motions so as not to overheat any area.
• When the pipe becomes pliable, make the necessary bend and fix the pipe bender in this state it will hold at the desired angle).
• Allow the construction to cool, and then release it from the pipe bender when it is fully cured.

When using a template, the methodology is slightly different. The pipe is first heated to the desired temperature until it becomes pliable, and then placed in the template, where it hardens and cools.

It is important that the inside surface of the template is smooth, otherwise the pipe will repeat all its roughness.

Instead of a construction hairdryer can be used an ordinary burner. However, such a budget option can be expensive, because the temperature of the burner is much higher and it can simply melt the pipe.

There are other hot methods, such as bending with a forming machine, but in the home their use is impractical.

This method does not require any additional devices or materials. Suffice it to take the pipe and bend it in the right place to the required bending angle. To facilitate the task, you can use a pipe bender.

In fact, polypropylene pipes bend even without temperature effects. It is only necessary to apply sufficient force.

It is worth realizing that in this case, instead of stretching on the outer contour and compressing the inner contour, the material may just break in several places. These bends provide ostensible elasticity and make it possible to create a bend, but they can also cause leaking pipes.

Just 5-10 years ago, underfloor heating could safely be called an expensive pleasure. Water heating, which uses underfloor heating, was considered an element of luxury. This method of heating in most cases was installed in the elite housing. Today the situation has changed radically. The water floor is becoming commonplace. and more consumers prefer this type of heating in their homes. The main reason for such popularity of water underfloor heating is their cost effectiveness, affordable price and high efficiency.

Besides in the heating equipment market there are consumables, devices and devices that can independently equip heating floors in your home, saving both money and time. You can always choose materials that meet the technological parameters of the heating system and your personal requirements for this method of heating. If the equipment included in the set of the pump and mixing unit of warm floors, a separate conversation, the pipes deserve special attention.

Despite the fact that today the choice of consumables is quite large, preference is given to the option when the floor heating is made of polypropylene pipes. Why? Let’s go into detail.

To begin with, underfloor heating can be used as the main heating option in a living space or act as an additional source of heat. Depending on the technological characteristics of the residential structure, which heating option to use in the case of underfloor heating, you decide. For an apartment in an apartment building, a warm floor can be an exception. In some cases, residents are trying to improve comfort in the bathroom or other technological rooms with a heated tile surface.

Important! It should be recalled that there is a ban on the installation and installation of warm water floors in residential areas of apartment buildings. The reason for this situation is unpreparedness of the engineering structures of the house for the installation of a complex heating system, which are water floors.

In the situation when it comes to installing a heating system “warm floors” in a private home, there are no prohibitions and obstacles to the project. It is possible to carry out the installation and installation of underfloor heating of any area in various combinations.

For those who have decided to install underfloor heating in their homes, it is important to know about the necessary equipment and supplies. Pipes for any water heating system are the main working element. It is through them circulates prepared water, transferring heat energy to the heating sources. This can be radiators or in the case of water floors, heated concrete screed, a set of wooden floor construction. The transfer of heat energy from the coolant to the floor surface is carried out through the water heating circuits. What material the water loop pipe is made of, depends on the speed of installation of an in-floor pipe and the quality of underfloor heating.

To date, companies. manufacturers are ready to offer consumables for every taste. All depends on the financial capabilities of the consumer. On the practical side for the equipment of a warm floor, you can use the following types of pipes:

• copper;
• corrugated, metal;
• metal-plastic;
• Expendable material made of cross-linked polyethylene;
• polypropylene.

Any option has the right to implement, but here comes into play the factor of cost-effectiveness and technological expediency. Polypropylene pipes in this aspect look preferable in many ways. Why do many consumers today give preference to consumables made of polypropylene.

Polypropylene pipe floor heating is currently the most common option. It’s all about price. When installing large-scale heating systems, when it comes to water floors with a total length of the pipeline of several hundred meters, the economic component comes to the fore. Polypropylene heating circuits in this regard are a successful solution to the task at hand.

The following parameters can be safely attributed to the advantages of such consumable material:

• required mechanical strength and elasticity of polypropylene pipe;
• necessary tightness of joints;
• durability;
• High technological characteristics, which simplify the installation of heating circuits;
• low cost.

Here we should focus on a couple of points. Polypropylene has a high resistance to low temperatures. Freezing of the coolant in the pipeline will not lead to mechanical damage to the heating circuit. Such a pipe is perfectly suited for warm floors, equipped in cottage and country houses, where the heating system works periodically.

The special welding method of polypropylene pipes provides tightness of joints. The pipeline, laid in a concrete screed, can safely function in a normal mode for decades. Following the necessary instructions and the technology of laying, you can make a warm floor in your house, forgetting for a long time about its construction and about the device.

For reference: According to the instructions to the products, polypropylene pipes can withstand the operating temperature of the coolant to 75 0 C at an operating pressure of 7.5 atm. According to the product data sheet, polypropylene pipe can be used for 25-30 years.

After assessing the advantages of this option, you should not forget about the negative sides of polypropylene heating circuits.

Important! Polypropylene in the usual version has a high coefficient of thermal expansion, so in the thickness of the concrete screed must be laid a pipe made of reinforced polypropylene pipe.

The main disadvantages of using consumables based on polymers, are poor quality raw materials and non-compliance with the technology of installation works. In other words, often there are pipes in which as a result of exposure to high temperatures there is a swelling of the upper layer. Bend of the water circuit can be made incorrectly, without taking into account the coefficient of thermal expansion of the material.

Simple polypropylene pipes are usually used for water supply and sewage pipes. For in-floor heating to use a simple polypropylene pipeline is dangerous from the point of view of noncompliance of the product with thermal and hydraulic loads. It is better to create underfloor heating on the basis of reinforced pipes. Such a product has all the necessary characteristics inherent in such a method of heating. The duct is three-layered. Between the inner and outer layer of polypropylene is a reinforcing layer made of aluminum foil or woven synthetic threads (fiberglass).

The picture shows two options for the manufacture of pipes, with an aluminum layer and with fiberglass in the middle.

The presence of a reinforcing layer allows the pipeline embedded in a concrete screed to withstand temperatures up to 95 0 C and water pressure up to 10 atm freely.

In order to avoid mistakes in the process of installation one should get acquainted with existing markings on polypropylene products. Today companies. manufacturers offer the following types of polypropylene pipes on the market:

• PN10, the marking which is on conventional products with a homogeneous polymer structure. These consumables are used for equipment of ordinary water supply systems at operating water temperature of 20 0 C and working pressure up to 10 atm. The diameter of such pipes usually ranges from 20-110 mm.
• PN16, the marking corresponding to a homogeneous product, which can be used for the installation of warm water floors. Permissible temperature of the heat carrier may not exceed 80 0 C. Permissible working pressure. 10 atm. Outer diameters are similar to products of type PN10, but in this case there is an increased wall thickness of the pipe.
• PN20, marking for homogeneous pipe in which hot water up to 95 0 C is allowed to circulate. Here the operating pressure is allowed to be no more than 6 atm. Pipes are available in diameters of 20-110 mm.
• PN20 AL (PN20 GF), the designation for polypropylene, which has a reinforced layer of aluminium or glass fibre. In all other respects, these products correspond to pipes marked PN20. The main difference from other consumables, lower coefficient of thermal expansion (CTE).

To make a water heated floor in your home efficient and workable, you need to make a preliminary calculation of the number of pipes needed to lay. Thermal and hydraulic calculations will help you properly install the water heating circuit and connect all heating equipment in a certain sequence.

Working with polypropylene, it is better to focus on the scheme of laying: snail. Despite the fact that this method of laying a little more complicated in the installation, but later you will feel the undeniable benefits of this scheme.

Please note: the snail pattern provides a complete and even heating of the floor surface due to the fact that both the flow and return pipes are laid next to each other. Due to the elasticity of the material can easily create the necessary curvature of the pipe, because the curvature of the heating circuit is crucial in this scheme.

Polypropylene water loop is laid on the already prepared surface, secured by metal clips or plastic clips. In order to speed up the laying process, you can use another method. A screen with large meshes is placed on the prepared base and the heating pipes are placed in it. Mesh also serves as a reinforcement base for the future concrete screed.

After laying the polypropylene pipe is connected to the distribution equipment. During the test run the connection points are checked for leaks. Only after checking the work of the heating circuit in all operating modes, you can begin to equip a concrete screed or lay a set structure.

There are no difficulties in the installation of polypropylene pipes. the material is so handy and practical that it makes it possible to lay underfloor heating yourself. Here we should be reminded of the subtleties of laying. For a warm floor it is important to comply with the step of laying the pipe. When using underfloor heating as the primary heater, the pipeline must be laid in increments of 12-15 cm. If you want to heat the floor more intensively, the pipe should be laid in a 30 cm pitch.

In case of emergencies caused by a break in the main heating circuit, repair work is carried out. Find the place of bursting a polypropylene pipe can be with the help of a thermal imaging camera, or using the map. the scheme of laying heating floors. Damaged section after the removal of the screed is cut out, and replaced by a new fragment. Tightness of joints is achieved by welding. Polypropylene pipe in this regard is very convenient and practical.

How to bend pipes made of cross-linked polyethylene

Despite the fact that for heating and water supply systems in the construction market pipes made of metal, metal-plastic and polypropylene are presented, in recent years there has appeared another new type of material. cross-linked polyethylene. In this article we will talk about what this material is and what its advantages are. And also the instruction will be given on how to install cross-linked polyethylene with his hands.

What are cross-linked polyethylene pipes?

Dense polyethylene is the main raw material. Making pipes out of it is a complicated technological process. When adding chemical compounds and under the influence of high temperature, pressure, irradiation by electrons formation of dense raw materials with a three-dimensional structure occurs. Subsequently, it is cross-linked in an extruder.

All this allows the creation of a unique material that has properties inaccessible to metal and plastic.

• Perhaps the most important advantage is the molecular mechanical memory. In case of deformation due to fracture, expansion due to freezing of water in them or overlapping. Cross-linked polyethylene pipe fully restores its appearance and all specifications. To do this, it is enough to heat it with a construction hairdryer. At this point, the material takes on the form that was given to it by the extruder. This important property allows you to use them for water supply in the street and not be afraid that in winter they can burst because of poorly drained water.

Tip: Cross-linked polyethylene itself is resistant to expansion from the inside, but the plumbing inevitably consists of metal parts as well. Therefore, it is not a good idea to leave water in the heating system at risk of sub-zero temperatures. But they are a safety net in case of force majeure, such as a heating boiler outage.

• The absence of iron and lime formations inside cross-linked polyethylene pipes is the second advantage. This is important for both heating and plumbing systems. Internal reduction in the diameter of the pipes will lead to reduced efficiency of heating, and in the case of water supply. to constant clogs, bacteria breeding and unpleasant odor. All of this can be avoided by choosing a cross-linked polyethylene pipe.
• When working with pipes do not need additional seals on the connections with fittings. Over time they wear out and depressurization occurs. Soldering density of all fittings is so high that cross-linked polyethylene pipes are used for water heated floors, which are installed in a concrete screed and to replace individual elements will be if not impossible, then very difficult and expensive.
• Low weight. Due to their low weight and flexibility they can be easily transported even in a passenger car.
• Long and safe service life. It is an environmentally friendly material, harmless to humans and the environment. It does not rust and does not react to chemical influences. Guaranteed service life of more than 50 years.

Important: Cross-linked polyethylene pipes have low resistance to direct exposure to UV radiation. That is why they are recommended for concealed installations or in windowless rooms.

Tip: if they are used for repairs, you must first make sure that the pressure and temperature in the heating system of the house correspond to the recommended values that are specified for specific pipes.

Types of cross-linked polyethylene pipes

There are 2 types of cross-linked polyethylene pipes:

• universal, which are equally suitable for the heating system in an apartment or country house, as well as for a warm floor, which is installed in the screed and works from hot water;

Important: pipes designed for heating withstand temperatures up to 95 ° C and pressures up to 10 atmospheres. But in emergency situations, when the pressure can jump up to 20 atmospheres, and the temperature of 100-100 ° C, also cope without losing their technical characteristics.

• For heating in pipes made of cross-linked polyethylene is allowed to use water or antifreeze.
• Most pipes can be used for the country house, but when connected to the central heating system in an apartment, cross-linked polyethylene pipes must have special markings. It means that they have an additional heat insulation jacket.
• Water pipes, no matter universal or specialized, are safe and environmentally friendly. They are allowed to be mounted on drinking water.
• Cross-linked polyethylene pipes have standard diameters, but special solder fittings, threaded connections and gutters for fixing along the wall are used for fixing. These accessories guarantee a solid connection and a beautiful appearance in outdoor wiring.

According to the processing method of the original raw material they are divided into 4 categories with appropriate markings:

• PEXa. the cross-linking of pipes takes place using the peroxide method;
• PEXb. treated with gas;
• PEXc. pipes are irradiated by electrons inside electromagnetic field;
• PEXd. the pipes are exposed to nitrogen compounds.

Major manufacturers of cross-linked polyethylene pipes

• The most well known brand of pipes made of cross-linked polyethylene is REHAU (Germany). It has been manufacturing specialized and universal pipes under the brand name RAUTITAN for many years. The product range has all sizes (from 12 to 250 mm) and 4 types: FLEX, HIS, STABIL, PINK.
• The Finnish concern UPONOR has also established itself as a producer of high-quality pipes under the brand WIRSBO. Product range from 12 mm to 150 mm.

Connection methods of cross-linked polyethylene

There are 3 ways to connect cross-linked polyethylene pipes.

• Electric welding fittings. This is a highly effective way. But to implement it, special equipment and skills are needed, so it belongs to the less common methods.
• Pressed fittings. They are available from manufacturers such as UPONOR, REHAU and Bir Pex. The main advantage. the restorative characteristics of polyethylene. So, when pressing the fitting, the polymers in it fill all the space, and the fixing place turns out to be high-strength.
• Crimp fittings. This is the easiest and most affordable way to connect cross-linked polyethylene pipes, which is available for home use.

Important: the connection method should be chosen based on the pressure that is expected in the pipe in operation. Each of the above methods can withstand the load only within certain limits.

The tool for connecting cross-linked polyethylene pipes with your own hands

• hydraulic press;
• expander;
• set of connecting elements (fittings);
• special scissors;
• flat spigot.

preparatory work

• Manifold outlets, to which the pipes will be connected, must be in good condition and provide absolute tightness.
• Before starting work, the workplace must be cleaned of debris and dust, so that no dirt can get into the joints.
• Lay out the required number of pipes and fittings.
• It is desirable to have a diagram of the layout of the pipes.
• In suburban homes, the water comes directly from the well, so it has a low temperature and condensation is formed in the room on the pipes with cold water. And hot water in them cools down quickly and we have to pass it each time long enough. To avoid this, the pipes made of cross-linked polyethylene in the water supply system is recommended to put on additional insulation, such as corrugated.
• Due to the high plasticity of pipes, before starting work they are attached to the wall on special brackets-holders.

How to work properly with cross-linked polyethylene

• The main key to success in the installation of pipes made of cross-linked polyethylene is a quality cut at an angle of 90 °. It must be made exactly perpendicular to the longitudinal axis.
• To ensure the most durable connection in the fittings, the edge of the cut pipes should be absolutely flat, without burrs, notches and waves. In the presence of the above irregularities during the jointing of the edge of the pipe can suffer even more and violate the tightness. The obviousness of the problem will only become clear during operation.
• For cutting it is recommended to use special pipe cutters. These are scissors that, like a pruning shear, cut even thick pipe evenly without much effort. They come in different price categories and inexpensive models are suitable for home use.

Installation of cross-linked polyethylene pipes using the compression method

Crimping cross-linked polyethylene pipes is equally suitable for water supply with cold water and for heating systems. Can be easily dismantled if necessary.

• Cut the pipe to the required length and thread the nut onto the end of the pipe to the connector.
• Then the split ring is put on. Since it is not tight and has a cut, it is easy to do with their own hands. The ring is placed at a distance of 1 mm from the edge of the pipe.
• Then the press sleeve is pushed into the pipe and the split ring is pushed straight onto the fitting socket.
• They move the nut and start tightening it with wrenches. It should fit snugly, but do not overtighten. Otherwise it is possible to damage the thread on the fitting.

This method is especially good if the question is, what to connect the cross-linked polyethylene without a special press.

Installation of cross-linked polyethylene pipes with your own hands video

Installation of XLPE pipes with press fittings

This non-compression method guarantees a one-piece, high-strength connection. But if necessary, it can not be dismantled.

• A press sleeve in the form of a ring is slipped over the pipe.
• At the end of the pipe insert the expander of the desired diameter, press the handle and increase the diameter until it is freely snapped on the fitting.
• Put fittings on the expanded end of the pipe until it stops.
• On top pull the press sleeve. After expansion, thanks to the molecular memory of cross-linked polyethylene, the pipe will return to its shape after some time by tightly crimping the fitting.

Installation of cross-linked polyethylene pipes by electrofusion

• An electric welding socket is placed over the cut pipe.
• There are special terminals on the fittings for welding. A welding machine is connected to it.
• Before welding cross-linked polyethylene, the inside of the fitting is energized. It heats up the fittings and the end of the pipe to a temperature of 170°C.
• You only need to turn off the welder and wait until the pipe and fittings cool down. The cross-linked polyethylene will return to its original shape. The resulting connection will withstand operating pressure in the pipe up to 12 atmospheres.

That is the end of the installation and only the connection of the cross-linked polyethylene pipes to the collector is necessary.

Hello. Tell me how to bend the cross-linked polyethylene 20, for installation of underfloor heating. In the store advised to heat a hair dryer, this is correct.

By hand without heat. Heating is not necessary, cross-linked polyethylene bends perfectly.

It’s strange, but when you try to bend it 180 degrees with a bend diameter of 200mm, it breaks.

Really strange. And what kind of pipe do you have??

TECE Systems wrote: Strange indeed. What kind of pipe do you have??

Unidelta PEX-b I think that’s what I remember, not next to it. Diameter is 20mm.

You have never dealt with these pipes? Special brackets attached to the tube are used to bend the tubes. Look at the recommendations for laying pipes and do according to! This pipe has a minimum bend radius of 350 mm. A smaller bend radius causes the pipe to break! This has to do with wall thickness and diameter.

The “b” stands for polyethylene cross-linking. If I’m not mistaken (I could mistake the first two), then

a peroxy b silane c electron bombardment (radiation) d nitrogen

The silane method is chemical (the others are physical). There are a number of nuances, I will not bore you, but I personally (I say this subjectively) do not recommend Pex-b. Optimally Pex-c.

And what type of PEX is better to use for cottage heating, if HTW will be supplied to consumers from the boiler? Use only in summer. A piece of pipe in a corrugated tube will be underground. I am reading, trying to understand, but I am confused (((. and tomorrow you have to buy the pipe. In online stores PEX-c not found.

Pex-c is, for example, pipes manufactured by German concern Hewing.

In Moscow there is a company called ZAO Egoplast (www.egopast.When the main heating circuit is broken (for example, in the USA), they order the production of MF-pipes under their brand “Pro Aqua” Hewing (they also have “Pro Aqua” Haka, which is worse and has a thinner aluminum, and is made by another company for Egoplast). There is a c-method of cross-linking (bombardment of polyethylene with electrons from an electron-beam gun)

What’s better, it’s hard to say. But Pro Aqua Hewing is a really good pipe.

I’m not advertising for Egoplast, if anything. Yes, I used to work there, but it has nothing to do. Just on Henco the same a lot of fakes, alas. Rehau (Pex-a) frankly, have not tried to mount, I will not say.

Installation of metal plastic pipes.

Pros:

Ease of installation. You can connect the pipe with press or compression fittings. Fewer connections. Since the pipe is quite easy to bend you can go through the turns, which is very good for underfloor heating.

Price of connecting elements and pressing tools. It is not recommended to make hidden wiring with compression fittings. As over time, the threaded connection can loosen and leakage will appear.

Metal plastic pipes pros and cons.

Pros:

Corrosion and chemical resistance due to the multi-layered complex composition. Elasticity, which allows you to easily bend a metal plastic pipe; Oxygen impermeability due to the aluminum layer; Used for both hot and for cold water supply; Easy and quick installation. Ability to perform the connection of metal-plastic pipes with press fittings, threaded connections or push-fittings; Long service life. The service life of such pipes depends on the pressure and temperature of water, as well as raw materials, according to the manufacturer lifetime reaches fifty years or more. But it all depends on the manufacturer and the raw material it uses.

Disadvantages: Installation of metal plastic pipe is undesirable to produce at low sub-zero temperatures, narrowed passage section of fittings, high cost of quality fittings for metal plastic pipes, poor quality installation, possible bends and leaks in the joints. If the material is of poor quality, over time, the stratification of the pipe. When concealed piping can not be used threaded fittings.

Metal plastic is poorly resistant to UV rays.

The manufacturer does not recommend installing metal-plastic pipe on the central heating. Because metal plastic pipes have a working temperature of 95 ° C. The short-term maximum temperature that this type of pipes withstands 110 ° C, respectively, the service life will be much less.

Installation of cross-linked polyethylene pros and cons.

Pros:

Easy installation. Almost perfect connections. No diameter reduction at joints like metal-plastic pipes. Can’t break the pipe like a metal-plastic pipe. Fewer connections. Since the pipe is quite easy to bend you can go through the turns, which is very good for underfloor heating systems.

Very high price for pipe, connectors and tools. (If you take the quality material)

Cross-linked polyethylene pipes pluses and minuses.

Pros:

Flexible pipe, you can bend within limits, but 90 degrees go to the bend. If you bend more, you can overcompensate. But it is impossible to break. Connections are very strong and do not leak 100% of the time. Withstands minus temperatures, that is, if the water in them freezes you can easily defrost (the pipe expands). And the pipes will not be damaged or leak. If you bend the pipe to scrap and then heat it with an industrial hair dryer, it will take its original shape, that is the memory effect. Many different diameters, from 10 mm to 100 mm. The possibility of installation at subzero temperatures.

You need to be careful when choosing is cross-linked polyethylene for (low-temperature heating). The cost, if you take a meter of polyethylene pipe and compare it with metal-plastic and polypropylene, it is more expensive by at least two times! (Depends on what manufacturer) Expensive fittings and connections. expensive than metal plastic pipes. You need special equipment for crimping and installation, again not cheap. The manufacturer does not recommend installation of cross-linked polyethylene pipes for central heating. Since these pipes have a working temperature of 95 ° C. Short-term maximum temperature that can withstand this type of pipe 110 ° C, respectively, the service life will be much less.

Additional ways of bending

Heating a pipe with a construction hair dryer and filling it with sand can be used as independent or additional methods of bending the pipe. They allow you to speed up the process of bending in the manual method and perform the operation in one approach.

Warming up with a construction hair dryer is done as follows:

Instead of a construction hairdryer for heating you can use an ordinary blowtorch.

bending methods

Owing to the different rigidities of metal plastic pipes, different bending forces are required. If for some products simple manual bending is enough, others are better preheated construction hair dryer or blowtorch. You can check the stiffness by bending a small area of the pipe to test it.

A spring for bending a pipeline

At home, it is convenient to use a metal spring, which will help bend the pipe product without damaging its internal structure. The procedure is as follows

Spring for bending metal plastic pipes

The complexity of this method can be to find the necessary diameter spring. Metal wire is successfully used as a substitute.

The basic methods of bending products of PVC

The use of a pipe bender is necessary only in cases where it is impossible to bend a plastic pipe on their own. This applies to large-diameter products, which are intended for the arrangement of sewers.

Here’s what can happen if you do not act according to the rules: this material can not be used for the pipeline

Modern masters successfully use the method of heating with a hair dryer, using sand, wire and mandrel to create the necessary bends in the design of the pipeline.

Using a hair dryer

The melting temperature of PVC products starts from 140 degrees Celsius, but such rates can completely melt the element, depriving it of integrity and the basic technical characteristics. To avoid this, it is recommended to use a construction hair dryer for gradual heating of the PVC product. Polypropylene pipes are also subject to melting at high temperatures, therefore, they can be bent in a similar way:

• Creating a template for the bend. Before carrying out the responsible procedure, it is recommended to create a template for the bend: it is better to make it from a durable material. You can buy ready-made corners, using them to make bends.
• Filling with loose material. To prevent the section from melting and took the correct shape, masters advise to fill it with salt or river sand beforehand. This can be done using a funnel: for 3 meters of pipe with a diameter of 20 mm will require less than one bucket of sand.
• Heating the area with a hair dryer. To heat the material, use a technical hair dryer. First, the heating section is selected, then the temperature is set on the device and the heating is carried out.
• Bending the product. As soon as the element is heated to a state where it can safely bend. it must be transferred to the template and carefully bend to shape.

heating to a certain temperature makes the material malleable and pliable It is important to avoid strong melting and heating to a temperature of 170 degrees. If you do, the plastic will become melted and unusable. After the pipe has cooled on the template, it is installed in the pipeline.

Using sand to bend the pipe

When using sand, you do not need to use a construction hairdryer. The essence of the technique is to heat salt or river sand on a tray. It is heated to the desired temperature and the compound is poured into the pipe with a ladle. The whole procedure is as follows:

• heated sand is poured into the plastic pipe through a funnel using a scoop;
• A metal plug is placed on the back side so that the heat does not escape;
• The minimum temperature of heating sand or salt in the tray should be at least 140 degrees and no more than 170 degrees.

The use of plugs. a must when bending with sand When the loose substance, heated to the required temperature, placed inside, it begins to affect the rigidity of the plastic. It melts gradually, so it is easy to bend. It is also desirable to use a special template for bending, so that the turn turns out even. If the result is not satisfactory, it cannot be used safely.

Tips from the experts

Do not forget about safety precautions. gloves, and when working with a burner and a tarpaulin suit is mandatory! Watch out for burns.

After cooling, let the polyethylene stand for a few minutes more to release internal stresses in the plastic.

It is not necessary to heat all of it to straighten a long pipe, it is enough to heat only a few sections.

Low-pressure polyethylene is afraid of ultraviolet radiation. it is usually laid underground, in dark basements. Where there is ultraviolet light, use polypropylene pipes or polyvinyl chloride.

If the bending failed. for example, got the wrong angle. the polyethylene can be reheated and bent only after it cools down completely, otherwise the polymer will be brittle.

When installing HDPE pipes no soldering is used. they are assembled with special clamping fittings.

Advantages and disadvantages of cross-linked polyethylene

Cross-linked polyethylene pipes for underfloor heating have a number of advantages:

• Elasticity. It allows you to apply the most optimal level of bending when laying, without the risk of subsequent cracking and kinking. In this regard, products from the company Rehau are considered of particular quality.
• Environmental friendliness. Cross-linked polyethylene contains no harmful components that would be released during heating. This gives a guarantee of safety in laying underfloor heating inside living spaces.
• High combustion temperature. The material begins to melt only after reaching a temperature of 400 degrees. The decomposition of the substance produces water and carbon dioxide, which are completely non-toxic.
• Excellent performance. A cross-linked polyethylene system can cope with rotting, corrosion and chemical attack. All this is the key to long-term and flawless operation of the water heating.
• Frost resistance. Polyethylene products do not become deformed in the event of a significant drop in temperature.
• Sound absorption capacity. This avoids noise from the thermal fluid circulating in the circuit.

As for the weaknesses of polyethylene, they usually point to the need for competent installation work. For example, it is advisable to fix the turning sections securely, i.e.к. this material does not hold the bent configuration given to it very well. In addition, noticed not very good resistance of polyethylene products to direct sunlight. Carry out the laying of the contour should be as carefully as possible, avoiding all damage to the protective layer.

With the help of a spring

Often beginners are interested in how to bend a polypropylene pipe into a ring, using a spring for this purpose. According to experienced craftsmen, to successfully bend the plastic at home, it is necessary to acquire a special device. On the shelves there are springs with an inner and outer diameter. Judging by the reviews, some craftsmen at home are much more convenient to work with outer springs. To do this, it is enough to put it on the bend. Next, the pipe is heated with a construction hairdryer or a gas burner. After a while the polypropylene becomes softer and more pliable. Now it can be bent. When the pipe finally cools down, you can remove the spring from it by turning it clockwise. It is also quite effective method with the inner spring. When choosing this device, experts recommend paying attention to its diameter, namely, the sections of the spring and the polypropylene pipe should coincide.

Bending the product gradually. To at the end of the work is not difficult to extract the spring, it is desirable that the adjoining surface of the pipe should be thoroughly lubricated with oil. For this purpose will suit the used machine oil.

Rating of pipes for underfloor heating

It is difficult to assert which pipe for water flooring is better. Currently, the following types are especially popular:

• Copper is superior to the other types, but it is more appropriate to use in a small room because of the high cost.
• Polymer pipe for underfloor heating is mainly used because of its low cost and practical convenience. It has a high heat output thanks to the aluminum layer and immunity to destruction, but have a large radius of curvature, which affects the level of heating of the concrete screed.
• Stainless corrugated is popular because of its unlimited service life and ease of bending, but the movement of water in it creates a noise background, in addition, corrugated stainless steel is not cheap.

To date, the best manufacturers of pipes for underfloor heating are considered:

Calculation of the pipe for underfloor heating

To calculate the amount of material it is necessary in advance to draw a diagram of the entire system, based on the maximum length of the circuit of not more than 120 meters. Knowing the area of the room, you can determine how to calculate the pipe for underfloor heating. On average 5 linear meters of product are needed per 1m². The length of the step should be 20 cm. You can determine the quantity using a simple formula: L = S/Nx1.1, where: