In radiator and underfloor heating systems, pipelines made of cross-linked and heat-resistant polyethylene, produced by a number of domestic and foreign manufacturers, are widely used. At the same time, Rehau pipes are the standard of quality, well known to both professional installers and the average consumer.
The Rehau company produces several types of high-quality cross-linked polyethylene pipes for use in plumbing and heating systems. Also, for their installation, in addition to a wide range of fittings from various materials, the market offers a number of additional devices in the form of mats, fasteners, and gutters.
Rice. 1 Rehau pipes and their areas of application
A little about Rehau
The Rehau company was founded in 1948 in the Bavarian city of the same name. In addition to its president Helmut Wagner, the staff initially included three employees who serviced one extruder.
Currently, Rehau is the world's largest concern with an annual turnover of 3.4 billion euros. The company has approximately 20,000 employees who work in 41 enterprises, 105 sales offices, 23 administrative and 9 distribution centers.
Rehau is known as a manufacturer of:
- Polymer components and electrical equipment for automobile concerns Porsche, Volkswagen, BMW and Audi.
- Plastic window and door systems from the Rehau metal-plastic profile, well known to the average consumer.
- Garden hoses, sewer and cross-linked polyethylene pipes for water supply and heating networks, the production of which was mastered in 1968. 20 years later, in 1988, the technology of connecting them using sliding (tension) sleeves was introduced.
- Blinds, furniture and about 15,000 components for its assembly.
- Interior heating and cooling systems, solar panels and components for geothermal heat pumps.
Rice. 2 Molecular lattice of ordinary and cross-linked polyethylenes
Installation of cross-linked polyethylene pipe
Materials
Before starting work, prepare the necessary tools and consumables. You will need:
- Vise.
- Fittings: couplings, adapters, elbows, tees, sliding sleeves (when installing a sliding sleeve, you do not need to use rubber gaskets, which increases the reliability of the design).
- Expansion device.
- Roulette.
- Pipe cutting tool.
Rehau pipe - design
Pipe making materials
Rehau pipes are made from polyethylene (PE), cross-linked at high temperatures and pressure using peroxides (substances containing the peroxo group -O-O-, for example, hydrogen peroxide H2O2, sodium peroxide Na2O2). When cross-linking in molecular chains with carbon and hydrogen atoms, the latter are torn off. The resulting free bond is used to connect polyethylene chains of molecules together.
The crosslinking process occurs in the molten polyethylene medium present in the extruder during the formation of the pipe casing. Thanks to this, the percentage of crosslinking is uniform along the entire length and cross-section of the pipe.
It is worth noting that there are other technologies for cross-linking polyethylene - silane PEX-B, nitrogen PEX-D and radiation PEX-C. But it is peroxide PEX-A (PE-Ha) that has the highest degree of cross-linking, which reaches 90%.
In addition to products made only from cross-linked polyethylene, Rehau produces metal-plastic pipes consisting of an internal aluminum layer. Their outer shell is made of ordinary polyethylene (PE), and glue is used to connect all layers.
To combat the high oxygen permeability of cross-linked polyethylene, some types of pipes use an anti-diffusion layer in the form of a thin film of ethyl vinyl alcohol copolymer EVOH (trademark EVALTM), which is also glued to their shell.
Rice. 3 Technical and operational characteristics of PEX pipes of the Rautitan series
Related article:
What is the required flow rate of a heated floor pipe per 1 m2 - calculation and table . In a separate article on our website you can learn in more detail about the technical parameters and nuances when laying pipes for heated floors, as well as the amount of pipe required for a certain floor area.
Types of Rehau fittings
Conventionally, all connections can be divided into three groups: couplings, tees and elbows. Distribution combs and manifolds can be included in a separate category.
Based on the type of installation, there are three main methods:
- compressor;
- compression;
- welded
The Rehau company produces fittings of all types.
Compression (adjustable)
The compression type of installation is also called serviceable, since such a fitting can be dismantled at any time without damaging the parts. This may be necessary, for example, to replace seals.
This fitting consists of:
- couplings;
- collet ring;
- crimp nut;
- seals;
- gaskets
A ring and nut are put on the pipe. The coupling fitting has two o-rings and a gasket. The coupling is then inserted into the pipe and crimped. The coupling has both special ribs to hold the seals and threads to connect to the nut.
The advantages of such a fitting include the fact that for its installation you only need two adjustable wrenches; wrenches can also be used.
Crimping
This fitting consists of only two elements - a coupling and a ferrule. For installation, you will need special equipment - an expander and a tool for axial pressing. The sleeve is placed on the pipe with a chamfer towards the connection. The pipe itself is expanded by an expander to a size that allows the coupling fitting to be inserted into it. The sleeve is then pushed under pressure over the area where the fitting is located. Dismantling of such a fitting is impossible. You will have to cut the sleeve, which is quite difficult. This fitting is mounted very quickly and reliably.
Welded
As an alternative, the electrodiffusion welding method is used, but it is unlikely to be possible to implement it yourself. Firstly, even the company’s instructions do not clearly describe this connection method and specifically stipulate that such work can only be carried out by specialists. Secondly, for this method of fastening you will need quite specific equipment, which is problematic to obtain. In addition, the price of such an instrument is quite high.
According to the technology, the coupling is put on top of the connection. Inside the coupling there is a wire that acts as a heating coil to which current is supplied. The surfaces to be welded are heated to the melting point and subsequent connection occurs.
Main technical characteristics of Rehau pipes
PEX-A cross-linked polyethylene pipes have the following technical and operational parameters:
- They are not subject to corrosion and prevent the formation of various types of deposits on the internal walls.
- They have good wear resistance.
- They have noise-reducing properties.
- They are environmentally friendly and do not produce toxic substances over any period of use.
- Their maximum operating temperature is +95 °C; short-term heating is allowed without destruction and loss of physical and chemical characteristics of the shell up to + 100 °C.
- Maximum operating pressure 10 bar.
Rice. 4 Areas of application for PEX pipes
- Thermal conductivity coefficient: for products with an aluminum layer (PEX/AL/PE) 0.43 W/(m•°K), with an oxygen-impermeable EVOH shell - 0.35 W/(m•°K).
- The coefficient of thermal expansion for metal-plastic is 0.026 mm/(m•°K), for pipe products with EVOH - 0.15 mm/(m•°K).
- Outer diameters of PEX pipes: 10, 14, 16 (16.2), 17, 20, 25, 32, 40, 50, 63 mm.
- They have normal flammability B2 according to the German Standards Institute classification.
- Available in rods and coils up to 25 mm inclusive for metal-plastics and up to 32 mm for products without an aluminum layer.
- The Rehau heating system with PEX pipes can be used for at least 50 years.
- The pipeline is mounted and connected to plumbing fittings and appliances using fittings and tension sleeves. It can be laid in screed and under plaster.
- They have a standard dimensional ratio of the diameter of the PEX pipe to the thickness of its wall - Rautitan SDR 7.4.
- The permissible ambient temperature during installation work is from - 10 to + 50 °C.
Polyethylene pipe pe rt
To solve the problem of the negative effects of ultraviolet radiation and increasing the temperature limit, a new material was developed - PE-RT. During production, octene is used as a monomer. It forms a spatial “branchy” structure. This increases heat resistance and strength.
However, using them for a heat supply system is not recommended for the following reasons:
- Despite the increased heat resistance and water temperature limit up to +110°C, at maximum temperature exposure the destruction process accelerates.
- To maintain performance, the average water temperature should not exceed +60°C.
- Short service life.
Can be used for radiator connections, but provided that the water temperature does not exceed +60°C. This is relevant when it is necessary to openly install a highway, when it is impossible to hide a separate section.
Rehau pipes for heating and water supply
The Rehau company produces pipes from cross-linked polyethylene of the Rautitan series for use in heating systems. This includes products with an aluminum layer of PEX/AI/PE and an oxygen-impermeable sheath of PEX/EVOH. The Rautitan system includes the following brands of pipe products:
- Stabil (Stabil Platinum) - metal-plastic PEX pipes of silver color (white aluminum) with diameters from 16.2 to 40 mm (Stabil Platinum up to 32 mm). Designed for use in drinking water supply systems, radiator heating and heated floors, heating and cooling of various types of surfaces.
- Flex is a universal gray PEX pipe with an oxygen-protective layer with diameters from 16 to 60 mm, designed for use in water supply, heating and underfloor heating systems.
- Pink – pink PEX pipe with an oxygen-protective layer only for heating systems, available in diameters from 16 to 63 mm. Designed for use in underfloor heating and radiator heating systems.
- His – white PEX pipe with a diameter of 16 to 63 mm without an oxygen protective layer. Designed for use in drinking water supply systems.
- S – thin-walled orange PEX pipe with an oxygen-protective layer only for heated floors, available in diameters from 10 to 32 mm. The main difference between the S series pipe products is the different standard sizes of outer diameters of 10, 14, 17 and 20 mm. Also, to increase the diameter of the passage channel, they have a reduced wall thickness of 1.5 mm for 14 mm pipes and 2 mm for 17 and 20 mm pipes.
Rice. 6 Sizes and release forms of Rautitan Pink and Flex
Floor heating systems
TM Rehau pipes can be used to create a floor heating system. The main part of this design is Rauterm-S pipe products, but universal products can also be used to arrange heat supply.
The underfloor heating system heats the room due to radiant heat exchange. Thanks to its large area of application, heated floor coverings evenly distribute air flow throughout the entire volume of the room and thereby provide a comfortable atmosphere.
If desired, the heated floor structure can be equipped with electronic temperature controllers. As a result of the use of these devices, electricity consumption is automated and reduced.
The power source for these devices can be equipment that produces alternative energy - for example, solar panels or heat pumps. Heated floors are installed in premises, both residential and industrial, public buildings, and offices.
Rehau pipes insulated
A distinctive feature of Rehau pipe products is the presence of products built into insulation made of extruded foam polyethylene (PE) with the following characteristics:
- Serves to protect the pipeline from cooling by the environment, prevents the accumulation of condensate and is a sound insulator.
- It has an operational service life equivalent to a PEX pipe, that is, at least 50 years.
- Available in round and rectangular shapes.
- The color of the polyethylene insulation is silver according to RAL 9006 (white aluminum).
- The outside of the insulating shell is covered with polyethylene film.
- Thermal conductivity of polyethylene insulation is 0.040 W/(m•°K).
- Used on Rautitan Stabil, Pink and Fiexe pipes with diameters of 16, 20 and 25 mm (round shell), 16 and 20 mm (square section heat insulator).
- The thickness of the protective layer for square insulation is 9 and 26 mm; for round thermal protection, its wall dimensions are 4, 9 and 13 mm.
Also, to protect pipes from condensation, mechanical damage, and compression when laying in a concrete screed, when the pipeline passes an expansion joint, black corrugation is produced. It is made of low-density polyethylene, capable of withstanding temperatures up to + 105 ° C. Corrugated casing is used on pipe products with diameters of 16 (16.2), 20, 25 and 32 mm.
Rice. 7 Dimensional parameters of thermal insulation of Rautitan Stabil pipes
Related article:
Heating pipes - all types of modern pipes, which is better to choose . When thinking about laying heating pipes from Rehau pipes, it may be interesting to find out what other heating pipes there are, what are their differences, methods of laying and installation.
Assembly tool
The Rehau company made sure that the installation of its pipelines occurred as correctly as possible, and it was for this purpose that it released a special tool, RehauRAUTOOL. The simplest basic tool kit Rehau RAUTOOL M1 consists of several tools necessary for installation:
- Pipe cutting shears 40 RAUTITAN Stabil.
- Manual pipe expander Rehau RAUTOOL RO system.
- A set of replaceable nozzles for expanders of different diameters.
- Manual press for crimping sleeves, called "basic tool M1", with a set of attachments for sleeves of various diameters and mounting pins.
- Lubricant in a tube.
- Brush for cleaning tools.
- Suitcase for transportation.
It should be noted that RAUTITAN Stabil pipes require a special nozzle for the expander, which is green, and for pink and flex pipes a blue nozzle is used. In addition, stabil pipes must be bent using special springs, which may not be included in the tool kit and must be purchased separately.
It should be noted that a set of tools is quite expensive, but on any construction market it can be rented for the duration of the work.
RAUTITAN Stabil
This line is versatile and is used to create heating systems and water supply. The material of the inner layer is cross-linked polyethylene, protected by a layer of aluminum. The self-supporting layer PE-Xs ensures that the performance characteristics are maintained in the event of damage to the aluminum layer.
Pipes in this series retain their shape when bent and can be used for open distribution. Products are tested under a pressure of 16 bar with an operating value of 10 bar. They can operate at a coolant temperature of 95°C.
Accessories
The German company Rehau is a well-known company in the field of development and production of quality parts for water supply and heating systems. To connect products to each other, system parts such as Rehau fittings and related prefabricated parts are needed.
In particular, these are:
- sliding sleeves;
- connecting couplings;
- adapter;
- connecting reinforcing parts;
- fastening elements – fixing diverter devices.
Rexau fittings and kits are manufactured from innovative polymer bases. In the manufacture of fasteners, the company uses cross-linked polyethylene of the combined type RE-X. This type of material is a high-temperature compound with the addition of environmental catalysts.
The proposed pipe connection elements from the German manufacturer are not deformed, they are not affected by aggressive environments, and they take the desired shape. This allows the products to be used in various operating modes. The parts are suitable for both heating and water supply systems.
The most popular type of connecting elements is adapters.
These products differ in type:
- adapter with threads inside and outside;
- adapter with union nut RX;
- adapter with union nut MX.
Adapter RX, MX – combined type of connectors. The fittings are characterized by a distinctive design. The material used to make the products is bronze. Moreover, the MX adapter is also a brass alloy.
Rautitan PX sliding sleeves are needed for products with threaded connections of a similar size. The products are durable, durable, and chemically resistant. Usually needed as a supplement for fastening sliding mounting sleeves of appropriate sizes.
Rautitan tees are made from innovative polyethylene. Products are needed to connect additional branches to the main branch. Types of tees can be different.
Usually chosen in conjunction with the installation method:
- equal passage;
- with a reduced end;
- with reduced side part;
- with reduced end and side parts;
- with a larger side part.
MX series brass tees are available in the following types:
- with internal thread located on the side;
- with internal thread for wall mounting;
- with an enlarged part of the passage.
Corner outlets are suitable for changing the direction of water flows. The company offers users a wide range of products made from various materials. Monolithic angles PX or MX series are produced in versions with angles of 45 and 90 degrees. The threaded connection on the angles can be inside or outside. The products are used for fastening water supply and heating systems in concrete walls and in plasterboard verticals.
If you need to connect two straight pipes in a conventional way, then it is worth considering PX couplings. The combined base used in these products is characterized by increased thickness. The design details of the products are different - equal bore and transitional.
Among other parts and repair kits, it is worth noting such parts as:
- nipples, staples, threaded clamps connecting elements;
- dowels, mounting devices, brackets, busbar blocks;
- fixing channel, cuff, outlet parts.
It is more convenient to study the full range of these products in the company catalogs. Fittings and other accessories, presented in all items, are divided into standard sizes T16 up to 63 mm in the catalog, which simplifies the search for products suitable for your system.
RAUTITAN His
These universal Rehau products allow you to create pipelines for various purposes, and can work to supply cold water or move heated coolant. For production, cross-linked polyethylene is used, which is odorless, tasteless and hygienic. When laying pipelines, a general scheme is used for the entire range of pipes from this manufacturer using the appropriate components and fittings. The operating pressure of the product is 10 bar and the temperature is 70°C. A peak increase in coolant temperature of up to 100°C is allowed.
Tool for installing push-on fittings on plastic pipes
To install water supply and heating systems made of cross-linked polyethylene with slide-on fittings, a special tool is required. These are hydraulic devices - a presser and an expander.
An expander (expander) is a device with replaceable cartridges (each cartridge corresponds to a specific type of pipe - universal, heating, thin-walled, etc.), which are equipped with opening petals. When pressure is applied, the petals open and expand the pipe to install a fitting of the same diameter into it.
The Rehau company offers two types of expanders - manual and battery-hydraulic. The cartridges for pipe expansion are the same and are suitable for all types of expanders.
The second device for installing pipes with push-in fittings is a press fitter. It is a hand-held vice that, using muscle force or hydraulics, pushes the sleeve onto a plastic pipe.
The pressing machine is a working cylinder on which two vise jaws with special U-shaped cutouts for different pipe diameters are mounted.
This tool comes in three different types - manual, mechanical-hydraulic and battery-hydraulic. Manual, by analogy with an expander, is driven by muscular force. The mechanical-hydraulic one consists of a working cylinder with a vice mounted on it, and a foot compressor that supplies working fluid through hoses into the cylinder. This type of presser is convenient because it allows installation in hard-to-reach places where it is inconvenient to straighten a hand tool.
The battery-hydraulic presser has the same advantages as the battery expander - it is autonomous and does not require the manual efforts of the installer. You can make up to 100 connections on one battery charge.
There is also a symbiosis of these two tools - a 2-in-1 battery-hydraulic tool. This device has a rotating head, on which there is an expander on one side and an expander on the other. Only one device can be in operation at a time, and they are changed by turning the head.
