Which pipes are best for radiator heating. Pipes for heating and water supply: main types
Foreword
Content
Starting construction own house, any owner dreams of his home being warm, cozy and beautiful. However, it is impossible to create comfort without high-quality heating pipes - in the absence of heat, all the arrangements will not make any sense. Accordingly, it is necessary to pay special attention to the thermal insulation of the building and the installation of the heating system.
There are many types of pipe heating on the market today. All of them are made from different materials and different specifications.
Copper pipes for heating a private house
Copper for pipe heating in a private house has been used since ancient times. This is not surprising, because copper has a number of positive qualities. These pipes are distinguished by the corrosion resistance of the material; high thermal and electrical conductivity. Another important characteristic of copper pipes for heating is oxidation resistance. They are also plastic, resistant to temperature fluctuations, have bactericidal resistance and resistance to ultraviolet exposure.
An important advantage of this type of pipes for heating is that their inner surface is smoother than steel and plastic pipes. Therefore, we can talk about a greater throughput of products.
To improve the properties of copper pipes for heating, they are often coated with a PVC or polyethylene layer. This is done to reduce heat loss during transportation of the coolant, reduce noise and protect against mechanical damage.
If in winter time the heating system will not be used and the water in the pipes will freeze, copper, due to its plasticity, will only stretch a little, and after thawing the water it will take on its original shape. The service life of copper pipes is about 40 years.
If this type of pipes for heating systems is installed in the house, then ideally, shut-off and control equipment and all connecting elements should be made of copper. In practice, this is difficult to implement, so most often it is enough not to put galvanized steel pipes after copper pipes and not to dock them.
Two types of pipes are used for the heating system:
- soft - segments rolled into coils 25 and 50 m long are used for any sections of the heat pipeline;
- rigid - straight segments from 3 to 5 m long, used for risers and highways.
The diameter of copper pipes is 10-28 mm if the wall thickness is 1 mm, and 35-54 mm with a wall thickness of 1.5 mm.
Steel pipes for heating a private house
Steel pipes for heating are made of mild carbon steel. The material is durable and plastic. Steel pipes have high thermal conductivity and low temperature coefficient of linear expansion. The service life of devices is 30-40 years.
But steel pipes also have disadvantages:
- low corrosion resistance;
- low throughput;
- installation complexity.
There are several types of steel pipes:
- electrowelded straight-seam;
- water and gas black welded or seam;
- seamless seamless.
Depending on the wall thickness, light, ordinary and reinforced pipes can be distinguished.
For the heating system, pipes with a diameter of 15 to 25 mm are usually used, light and ordinary.
Polymer pipes
Metal pipes are being replaced by polymer structures. Their serious drawback is wear and tear. The wear rate depends on the degree of exposure to ultraviolet rays, the temperature of the coolant and the pressure in the system.
In addition, there are a few more disadvantages of polymer pipes: high combustibility of the material, a decrease in strength with increasing temperature, a high coefficient of linear expansion.
In production plastic pipes the following polymers are used:
- polypropylene;
- polyethylene;
- polyvinyl chloride;
- polybutylene.
Characteristics of polypropylene and polyethylene heating pipes
The quality of polypropylene is similar to molecularly crosslinked polyethylene. The main characteristic of polyethylene heating pipes is high rigidity. Products can be welded together, but this requires the help of a qualified craftsman.
Polypropylene pipes are not used for high temperature systems and floor heating.
Modern plastic pipes are most often made from polyethylene. Polyethylene is used to make water pipes with working pressure up to 0.6 MPa and pipes for transportation of natural gas and gas-air mixture.
To improve the physical and technical properties of polyethylene pipes for heating, the technology of molecularly cross-linked polyethylene was developed, which is characterized by increased resistance to ultraviolet rays. Another one important characteristic polyethylene heating pipes - high resistance to high and low temperatures and mechanical stress. At the same time, the material does not lose flexibility.
Pipes with a diameter of up to 32 mm made of cross-linked polyethylene are currently used for radiator and floor heating. You can identify a pipe from this material by marking: it usually contains the letter “X”, which indicates that the polymer has been crosslinked.
Another type of polyethylene is LPE, or linear polyethylene.
Pipes from it have heat resistance and are available in two types:
- with an anti-diffusion protective layer - for radiator and underfloor heating (diameter from 12 to 25 mm);
- without anti-diffusion layer - for internal water supply(diameter from 18 to 23 mm).
Isoplast pipes are also produced. The material belongs to cross-linked polyethylene and has some positive traits: high density, heat resistance, resistance to pressure and mechanical damage, as well as low air permeability.
PVC, polybutylene pipes
Two types of PVC pipes are made: simple (designed for temperatures up to +45 ° C) and from chlorinated polyvinyl chloride (temperature can reach +95 ° C). Both types are UV and chemical resistant, non-flammable and have low coefficient linear thermal expansion.
Polybutylene pipes are in many ways similar to varieties made of cross-linked polyethylene, but have increased heat resistance. Pipes are designed for coolant temperature from 70 to 95 °C. Their service life is 50 years. Polybutylene products are flexible, resistant to sunlight, and at the same time, their wall thickness is less than that of other types of pipes.
Asbestos-cement and metal-polymer heating pipes
Asbestos and concrete pipes have high strength, low thermal conductivity and corrosion resistance. Interestingly, asbestos cement from contact with hot water becomes stronger.
There are two types of pipes:
- reinforced (pressure) - designed for water and gas pipelines;
- non-pressure - used mainly for sewers and drains.
Diameter asbestos-cement pipes is 100-500 mm, and the length reaches 5 m. The disadvantage of pipes is their low fire resistance. Therefore, they cannot be used to remove flue gases from fireplaces and stoves and lay in the area of fire.
Metal-polymer pipes (MPT) are plastic, resistant to corrosion, aggressive environments and chemical attack, have a high throughput, durable, withstand high temperatures and pressures and have gas tightness, like metal products. Metal-polymer pipes can be connected to metal appliances and steel pipes, since they have a reduced coefficient of linear thermal expansion.
There are two types of pipes with aluminum foil between polymer layers:
- the same thickness (such pipes do not withstand low temperatures environment);
- different in thickness (the top layer performs a protective function, and between the layers there is an adhesive layer).
Elements for connecting heating pipes
All heating elements (boiler, heaters, etc.) are connected using pipes. But they also need to be somehow fastened together, because it is impossible to use one piece of pipe to join the entire system. For this, special pipe connection elements are used - fittings.
Fittings for steel pipes. To connect steel pipes, threaded fittings are usually used. The external thread is applied with the help of screw caps, and the internal thread is applied with the help of taps.
The following elements are used to connect steel pipes:
- straight tees, crosses and elbows;
- straight couplings;
- compensating couplings;
- futorki;
- transitional tees, crosses and couplings;
- locknuts, caps and plugs;
- tees and crosses with two transitions.
Fittings for copper pipes. Fittings for copper pipes are made of copper. The amount of impurities in the metal should not exceed 0.1%. Also connecting elements can be made of brass or bronze. Fittings are detachable and one-piece. Flanges and clamp fittings act as detachable connectors. One-piece products are connected by soldering and welding.
Fittings for plastic pipes. Fittings made of polypropylene are used to connect plastic pipes. The welding method can also be used - a heavy-duty connection is obtained. Polypropylene fittings are made, equipped with special brass threaded inserts.
Shutoff and control valves in the heating system
To regulate the operation of the water heating system, it is necessary to use shut-off and control valves:
- radiator fittings - installed next to heating devices;
- boiler piping fittings;
- pipeline fittings - used to regulate the flow of coolant.
Radiator fittings. This type of fitting is installed on the connections to the radiators. Its main purpose is to regulate the flow of coolant and heat transfer from the radiator. Heat transfer is regulated quantitatively (the volume of water entering the radiator changes) and qualitatively (controlling the temperature of the coolant).
The composition of the radiator fittings includes:
- air vents;
- radiator valves;
- thermostatic valves (thermoregulators, thermostats);
- bottom fittings, which make it possible to connect the radiator to the pipes;
- side injection unit, with which the radiator is transferred from side connection on the bottom;
- shut-off and drain valve, through which a separate radiator is turned off without draining water in the entire heating system.
For convenience, devices can be divided into three main groups. Air vents are designed to automatically remove air from the heating system. They can be screwed on or connected with a shut-off valve.
In the latter case, the shut-off valve is screwed into the heating system, followed by the air vent. If the air vent becomes unusable, it can be removed without fear of coolant leakage from the radiator, since the shut-off valve prevents this. The radiator valve is used to control temperature changes and heat transfer. For autonomous heating a radiator valve should be used, and a ball valve is more suitable for a centralized system.
Varieties of cranes
There are two types of cranes:
- normal adjustment;
- with thermal head.
The first is used for manual adjustment. It can be angular and straight. The volume of water supply is regulated by a rod mechanism or a brass ball. Thanks to the adjusting tap during the filling of the radiator with water, the possibility of water hammer is eliminated. In addition, it can be used to replace the radiator without turning off the heating.
The thermostatic tap consists of a fitting, a thermal head and a mechanism for regulating the flow of the coolant. The crane allows you to accurately set temperature regime radiator, which ensures maximum energy efficiency of the entire heating system. Automatic thermostats are equipped with special sensors that react to changes in the air temperature in the room. In a heating system with natural circulation coolant, it is difficult to install an automatic thermostat, since radiators do not respond to the intensity of fuel combustion. This element is valid for two-pipe system heating, especially if a liquid fuel boiler is installed.
An important element of the device is the thermal head. If the temperature in the room changes, the element is filled with the working medium and the stem of the control valve is set in motion. When the temperature reaches the required level, the control valve will prevent the further movement of the coolant.
The thermostat can be liquid and gas-filled.
Connecting radiator fittings include all elements that direct the flow of coolant in the right direction. These are nodes, jumpers, adapters, etc. Modern stores offer an extensive the lineup connecting fittings. Products can be made from polypropylene, metal-plastic, alloys (brass, stainless steel) and metals. In addition, the armature has different specifications- working pressure, thread diameter, etc.
Boiler piping fittings
This group of boiler piping fittings includes the following elements:
- flow and pressure sensors (block the operation of the boiler if the pressure is exceeded or the circulation of the system stops);
- elements responsible for the safety of the boiler (pressure gauge, air vent, safety valve);
- make-up installations that maintain constant pressure in the heat system;
- hydraulic separator (used for linking and hydraulic balancing of heating systems);
- air vents or vents.
Flow regulators include the following elements:
- balancing valves;
- valves;
- shut-off valves;
- passage valves with throttles;
- Ball Valves;
- flow regulators (limit the flow of coolant);
- pressure regulators (maintain a given pressure level).
Balancing valves are used to ensure the necessary distribution of the coolant flow in the heating system. They regulate its flow, measure the temperature, stabilize the hydraulic state of the system and the level of pressure drops.
In addition, the device can act as a drain when draining the coolant from the system.
There are varieties of valves with welded, flanged, socket threaded and combined connections. It is recommended to install the device at the bottom of the measuring inlet. An arrow is usually drawn on the valve body, by which it is possible to determine in which direction the flow should move through the valve.
The gate valve consists of a body and a spindle with gate discs in the lower part. When the spindle is lowered, the shutter prevents the passage of the coolant. The valve is used to turn off individual sections of the heating system.
The shut-off valve is used to shut off the coolant supply. It works due to the movement of the locking element along the rod. Often the valve is used in those sections of the pipeline where it is impossible to install a valve.
There are three types of valves: angle, through passage and straight-through. An angle valve is installed at the turn of the pipeline, and a straight-through or through element is installed at the straight node.
Passage and valves with throttles are mounted on the risers of the heating system, highways and piping. The spindle end of the device is connected to the spool, and this distinguishes it from gate valves. When the spindle is lowered, the movement of the coolant is suspended, since the spool gasket closes the valve opening. Today, choke valves are gaining popularity and are replacing balancing valves.
Ball valves are a body with a ball inside. The ball is equipped with a cylindrical hole and is surrounded by a belt of Teflon rings. The stem is usually made in the form of a butterfly or a lever. The stem gland can be non-separable and collapsible. There are pros and cons for each type of device. The non-separable stuffing box is airtight and therefore reliable. And a crane with a collapsible stuffing box can be repaired at any time on its own.
Ball valves are not mounted on connections to heating appliances, since these devices have only two positions: closed and open.
Probably any person, equipping own house, imagines what it will be like. Beautiful interior design, coziness and comfortable air temperature are the main characteristics of a successful home furnishing.
Now think about whether you will be attracted to the decoration of your house if it is terribly cold and uncomfortable to be in? Most likely, many will resolutely answer this question - no.
Thus, in order to avoid such troubles, you need to think in advance about the installation of heating system equipment, and the insulation of the floor and walls.
And the involvement of specialists in such work will turn out to be only pluses for you: a high-quality heating installation and high speed of work, although it will entail additional costs. The main component of any heating system is pipes, and since there is a huge variety of them, you should understand the types.
The choice depends on the type of heating system
Before starting the selection of pipes, it is necessary to determine exactly the heating system that you are going to install.
The type of installation for heating completely determines the type of pipes required.
You should have a list of data about your system, which will list the following parameters:
- Type of heating system: natural or forced;
- Mounting method: closed (inside the walls) or open;
- Two pressure values in the system: average and maximum;
- Two values of coolant temperature: average and maximum;
- System configuration: complex or simple.
In accordance with these parameters, you will need to familiarize yourself with all types, and select the best option for your heating system.
Steel pipes
Steel
In the old days, only metal pipes were used as pipes for heating systems.
Currently, the choice stops not only on them, however, in some cases, installation of this particular type is an effective and justified solution.
If heating system gravity (natural), then you need a pipeline of wide diameter. Metal pipes will be the best option in such a situation.
Steel pipes have a number of advantages, the main of which is durability. Such structures cannot be damaged by mechanical influences.
Also, due to their structure, they do not deteriorate from too hot coolant, and, by the way, can withstand temperatures up to 1500 degrees Celsius. Resistant pipelines made of metal and high pressure. And if welding was carried out by professional craftsmen, then the probability of coolant leakage is zero.
The disadvantages of pipes made of such material are:
- In the complexity of installation,
- In a decent weight design,
- In appeal to the services of a welder, since during installation one cannot do without special welding equipment.
It is highly recommended to install steel pipes only in rooms where repairs are only planned, since installation will certainly damage your flooring and wall decoration. However, if the living space is ready for your comfortable living, and only there is not enough heating, you should not be too lazy and look for another view.
Do not forget that the metal is susceptible to corrosion, you should not hide such pipes in the walls, otherwise, in the event of an unforeseen leak, you will have to ruin the finish on the wall.
The inner surface is not so prone to rust, because the coolant circulates constantly, and as a result, oxygen gradually evaporates. Thus, no significant impact is observed. Under conditions of proper operation, their service life can be almost half a century.
The operational rules consist in the annual painting of the surface, because under the influence of the high temperature of the coolant, the paint changes color and generally deteriorates appearance.
Such a property metal pipes how thermal conductivity in one case relates to advantages (when the pipeline is located in the house and, therefore, heat will be released indoors), in the other case, to disadvantages (if part of the pipes with hot coolant runs outside the house, significant heat losses are observed).
The cost of the metal, as well as the pipes themselves for the heating system from it, is quite acceptable. You will save twice if you find a welder with inexpensive but high-quality services.
Polypropylene
Polypropylene
Polypropylene pipes are excellent for mounting to heating system structures.
In addition, they have an attractive advantage - an affordable price.
However, when choosing, it is worth paying attention to the possibility of operating such pipelines with a hot coolant, since not all types of polypropylene pipes fit into this category.
Polypropylene has a lot of advantages, in addition to the already mentioned acceptable cost.
These include:
- Ease of construction, as a result of which, after installation, there will be no significant load on the walls of your house;
- Smooth inner surface. Thus, even after many years, they will not have lime accumulations and rust;
- Durability. Life time polypropylene pipes is approximately 20 years, and all their qualities will remain unchanged throughout this period;
- Resistance to low temperature. They are perfect for country houses, because the owners do not live there permanently, but come only for a short period of time, and naturally, in their absence, the heating system will be turned off;
- Relatively better looking. Polypropylene pipes do not need to be painted every year and do not change their color.
- Possibility of installation inside walls. The closed method of pipeline installation will save you from constant observation of pipes with the naked eye. However, it will be necessary to take into account that the linear expansion of a segment 5 m long will be about 4-5 mm. It is also advisable to install compensators to prevent damage to the wallpaper or decoration on the walls.
Nevertheless, despite a sufficient number of advantages, polypropylene also has disadvantages:
- Need for soldering. However, in the case of polypropylene pipes, you do not have to hire a professional welder and pay for his services, unlike the installation of steel pipes. You can install them yourself, and for this you will need a little time to master the soldering technique itself and the soldering machine itself, which can be easily purchased or rented at any specialized store in your city.
- Not elastic material. To make the necessary turns of the pipeline, it will be necessary to purchase special adapters, angles and couplings, and this can lead to various difficulties in cases where the heating system is non-standard. However, there is a plus - the price of fittings is low and accessible to everyone. For cutting pipes, you will have to purchase special scissors for plastic.
- Only in exceptional cases will you be able to repair your pipes. Most often, you will have to completely replace the faulty section of the pipeline with a completely new one.
- Reduced hardness. This is fraught with sagging pipes as a result of prolonged exposure to high coolant temperatures. To fix this problem, you will need to purchase special clips that will be attached directly to the wall.
- Inability to work with high temperatures. The permissible temperature of the coolant in polypropylene pipes is 70 degrees Celsius. An indicator of 90 degrees is possible only for a short time. This is not very convenient, because when the temperature outside is below zero, more heat will be needed to heat residential premises, and the best way out is to increase the temperature indicator, which is unacceptable in this case.
Cross-linked polyethylene (PEX pipes)
Cross-linked polyethylene
The production of pipes of this type takes place on the principle of "crosslinking polyethylene".
During the production process, different layers are superimposed on each other, which leads to the formation of additional bonds between the molecules of materials.
Among the advantages of polyethylene are:
- High material density
- Resistant to high temperatures and high pressure. (Normal working temperature- 90 degrees)
- “Memory effect” - if a pipe made of this material is heated and bent under temperature, after cooling it will retain its shape. For installation, this is especially true.
- Service life of pipes - up to 50 years
- Light weight, which does not create additional loads on the supporting structures.
- When assembling, fittings and various threaded connections you won't need any additional tools or equipment.
- Not subject to corrosion
Watch a video that will show the strength of this type:
Metal-plastic pipes
metal-plastic
Heating pipes of this type in recent times are gaining popularity among developers due to the numerous advantages and ease of use. The combination of metal and plastic gives pipes advantages over other types.
The inner walls are made of a smooth polymer material, which prevents the appearance of sediment from water and protects them from corrosion. The average thickness of this layer is from 0.2 to 0.3 mm. Usually it is highly elastic aluminum foil.
The steel outer layer provides additional protection against mechanical stress. The metal is protected by a layer of polypropylene.
The layers are connected by means of high-strength industrial adhesive with adhesion.
Among the advantages of metal-plastic, the following can be distinguished:
- Resistant paint will not fade in direct sunlight.
- Ease of installation and dismantling - the system is connected through press fittings without the use of special tools.
- The service life under normal operation is up to 50 years.
- The metal-plastic pipe is sold in bays, which eliminates the appearance of scraps during installation. You can "rewind" the desired length and cut as much as required.
- Protection against static electricity.
- Easy to repair - disconnect the fitting and replace the part of the pipe that is not working properly.
- Pipes do not expand under the influence of temperatures - you can safely embed them in the walls without fear of cracks.
There are certainly many benefits. But there are also disadvantages:
- High cost - quality does not come cheap.
- Tapered Fittings
- Not suitable for country summer houses - freezing of the coolant will lead to a rupture of the pipeline.
Copper
If you still wondering- and which pipes for heating are better to take, and the price does not play a special role for you, then you should undoubtedly pay attention to copper pipes.
Among the most important points in the use of copper, only one can be distinguished - they have a very wide range of operating temperatures. A coolant with a temperature exceeding 470 degrees can pass through them, and they are not afraid of frost.
Even if the coolant freezes in the pipes, nothing will happen to them, your system will be intact and will not leak. Copper is also resistant to pneumatic and water hammer.
With your own hands, you hardly install copper heating, because for connection, high-temperature soldering is used using solders containing silver.
Yes, and capillary fittings are used, so it’s better to contact professionals who understand this.
Pipes are resistant to corrosion, and the average service life under normal loads reaches 100 years. Quite a lot, right?
But there is a limitation - it is better not to use them outside the home, because. they have high thermal conductivity and the coolant will cool down quickly in winter.
Stainless steel pipes
stainless steel
Steel has always been the strongest and most durable material.
It has no equal in quality, even in comparison with copper.
Stainless steel heating pipes are not subject to corrosion and various temporary defects. Service life - from 100 years, and at a price - they are almost equivalent to copper ones.
They can be divided into 2 main types:
- Welded;
- Seamless.
Welded is produced by welding a sheet of steel, but this method increases the likelihood of leakage. No, the seams will not come apart even after 10 years, but if this happens, the repair will not be cheap.
In this case, there are seamless pipes, which cost an order of magnitude more expensive than welded ones, but are also much more durable.
Stainless steel pipes are divided into 2 subtypes:
- Thick-walled;
- Thin-walled.
Thick-walled ones are often used in pipeline sections that are subject to heavy loads and are under high pressure. When conducting heating in a private house, they are not used.
Thin-walled ones are used in private houses.
Important: We remind you that the installation of stainless steel pipelines is best done by specialists. Don't try it yourself.
This article will consider pipes for heating and water supply, their main characteristics, and also consider in detail the main varieties of such pipes.
In modern conditions, heating without pipes is difficult to imagine, while pipes made of polymeric materials are most often used, the most popular of which are metal-plastic, polypropylene and polyethylene. Elements for connecting such pipes are made of plastic, bronze and brass.
Pipe heating using such pipes and fittings is reliable and durable, has excellent hydraulic, temperature and hygienic performance and has been used in Europe and the CIS for many years.
Comparison of pipes for heating and water supply
Modern flexible heating pipes used for water supply and heating have a number of advantages over obsolete steel pipes:
- Smaller pipe diameter for heating - the technical characteristics of polymer pipes allow the use of a pipe of a smaller diameter than steel pipe with the same transmission capacity, which makes installation more economical and compact;
- High throughput throughout the entire service life: unlike steel pipes, polymer pipes for heating are resistant to salt deposits and corrosion, overgrowth of which reduces the throughput, as well as the quality of the water passing through the pipe;
- High durability, allowing the pipes to serve for a very long time without even in the case of hidden wiring, for example - using a skirting board for heating pipes;
- Environmental friendliness of the material;
- Cost-effectiveness and ease of installation, provided by the low weight and elasticity of polymer pipes, as well as the connection technology, which is much simpler than in the case of steel pipes. So, with the help of polymer pipes it is much easier to hide heating pipes in the floor without the help of a qualified welder.
Features of polymer pipes
If we compare polymer heating pipes with each other, we can note the following features:
- The aluminum layer in, which provides the greatest resistance to thermal stress and the smallest linear expansion, makes them the most common for heating systems, whether it is a one-, two- or three-pipe system. Such pipes are also easy to bend (the bending radius reaches 5 pipe diameters), and the aluminum layer allows you to keep the shape after bending, facilitating and reducing the cost of installation;
- Polyethylene stainless pipes for heating are characterized by high thermal stability, low hydraulic losses and high strength connections;
Useful: unreinforced polyethylene pipes often used for hidden wiring under skirting boards due to the high coefficient of thermal expansion.
- Polypropylene pipes have less heat resistance than polyethylene and metal-plastic pipes, therefore they are more often used in hot and cold water supply systems. Polypropylene pipes for water supply and heating change shape over time, so they are fixed in 50 cm increments.
When installing systems, to which these shortcomings apply to a lesser extent.
Types of heating pipes
Metal-plastic heating pipes
Stainless metal-plastic pipes for heating have good performance parameters due to the high quality of materials and modern technologies their manufacture.
The design of such pipes includes five layers: plastic-glue-aluminum-glue-plastic. The aluminum layer (thickness - 0.2-0.3 mm) is located between the layers of polyethylene and significantly reduces thermal elongation, therefore, such pipes have a significantly lower coefficient of linear expansion than propylene pipes and slightly higher than that of copper pipes. The service life of such pipes is at least 50 years old.
The connection of such pipes is provided with the help of brass (less often - bronze or plastic) fittings, which have a special fitting with rubber rings inserted into the pipe.
The strength of the connection can be achieved in two ways:
- With the help of a spring collet;
- Pressing the press sleeve.
Let's take a closer look at these two types:
Polyethylene heating pipes
Polyethylene pipes for heating systems are made of high strength PEX polyethylene. To create this modification of PE polyethylene, a special technology is used that creates, along with longitudinal molecular bonds, transverse (“crosslinking”).
Cross-links can significantly increase the heat resistance and strength of "cross-linked polyethylene", which allows the use of such pipes both in water supply systems (hot or cold) and heating (central or autonomous).
The PEX polyethylene heating pipe has the following advantages:
- Increased strength;
- High temperature resistance, allowing the use of pipes at temperatures up to 90 °;
- High chemical resistance;
- Resistance to corrosion;
- Smooth inner surface with a roughness of not more than 0.007 mm;
- Non-susceptibility to biofouling and salt fouling;
- Environmental Safety;
- High service life (at least 50 years).
Polyethylene pipes are connected using brass, polymer and bronze fittings with a special fitting inserted into the pipe. The strength of the connection is provided by a tension sleeve.
The main feature of this connection is that the pipe is expanded (stretched, increasing the diameter) using a special tool, after which a fitting is inserted into the pipe and the sleeve is pulled with a special press with great effort, resulting in high-strength connections. Additionally, special protrusions on the fitting allow to increase the strength.
Such a mount has several advantages:
- The absence of sealing rubber rings increases the durability and reliability of the connection;
Useful: the pipe material itself serves as a seal, so rubber rings and other sealing pads on heating pipes are not required.
- The flare prevents narrowing of the fitting's bore, keeping it low hydraulic resistance.
Polypropylene heating pipes
Polypropylene pipes for the heating system are made of PPR polypropylene, which has the required heat resistance and strength.
Features of polypropylene pipes are:
- High fluidity, due to which the pipes change shape over time, even under their own weight, forming a certain slope. Therefore, they are used for internal wiring or fastened in increments of 50-60 cm;
- The need for a large number of swivel fittings, since these pipes have greater bending rigidity than other pipes made of polymers, and when they are installed, their bends of large radii are allowed.
Due to this, the installation of pipes made of polypropylene is more laborious than in the case of pipes made of metal-plastic or polyethylene.
Important: the service life of polypropylene pipes is also at least 50 years.
These pipes are connected using fittings made of the same material as the pipes themselves using a diffusion temperature around 270 °.
This process is also called soldering, it is performed as follows:
- Using a special soldering iron, the end of the pipe is heated from the outside and the fitting from the inside;
- Insert the heated end of the pipe a few millimeters into the fitting;
- Wait about 30 seconds for the connection to cool down, while not allowing any loads on it;
- The filling of the space with molten material, as well as the reliability and strength of the resulting connection can be judged by the influx of molten material on the fitting and pipe.
The interpenetration of the molten materials of the fitting and the pipe in this method provides a high strength connection, the feature of which is the complete solidity of the structure, which provides a number of advantages:
- The strength of the connection is not inferior to the strength of the pipe itself;
- Simple and reliable connection process;
- The flow area of the fittings, which exceeds the section of the pipe itself, provides low hydraulic resistance;
- The low cost of fittings can significantly reduce the overall cost of the heating system.
Finned tubes
Another type of heating pipes are cast iron ribbed heating pipes manufactured at foundries.
The main feature of such pipes is the presence of rectangular fins and flanges, between which paronite sealing rings are used, which provides two main advantages of finned pipes:
- Increasing the heating surface;
- Reduced heat transfer from the pipe surface.
Ribbed cast iron pipes usually have the following dimensions: the inner diameter is 70 mm, the diameter of round ribs is 175 mm. The working pressure is 6 kgf/cm 2 , and the main disadvantage of such pipes is associated with sanitary and hygienic considerations, since such pipes are rather difficult to clean from dust.
It accumulates between the ribs, from where it is almost impossible to remove it. In addition, the fragility of these ribs, as well as a low heating coefficient, can be attributed to the disadvantages.
Important: precisely for reasons of hygiene, the main scope of application of finned tubes are premises that are not designed for the constant presence of people, such as warehouses, laundries, industrial premises, etc.
A variety of cast-iron finned tubes, also used for residential premises, are cast-iron radiators, interconnected by means of nipples and resistant to high temperatures rubber pads. A radiator capable of withstanding a temperature of 150 ° and a pressure of 0.6 MPa can have no more than 8 sections.
The radiator kit includes plugs with holes (2 pieces) and blind plugs (2 pieces), and the plug for the left side of the radiator is marked with the letter “L”. Ductile iron is used for the manufacture of nipples, threads are made at both ends of the pipe. The surface of the radiators is covered with soil.
Summing up, I would like to say that stainless polymer pipes for heating have pushed traditional steel pipes into the past for a reason, since they have a number of undeniable advantages, and also allow you to more simply, efficiently and reliably install the heating system.