In almost any residential building or in a city apartment, you can always find water heating systems. These are mainly centralized or autonomous heating systems, double-circuit or single-circuit, the difference is in power, in details and in the tasks set. However, one technological aspect remains common to all — this is the liquid type. The main work on the delivery of heat to the heating devices is performed by boiler water or antifreeze.
The coolant circulates along the circuit, which are the “circulatory system” of heating. The patency of the pipelines, the duration of the pipeline’s operation depends on the quality of the pipes and the material of manufacture. Today, new technologies in the field of heating equipment have also touched on consumables, bringing to the fore reinforced polypropylene pipes used for heating systems. This product appeared relatively recently, but has already managed to gain wide popularity among consumers. What is the reason for such success of synthetic products, what are the advantages of polypropylene pipes reinforced with fiberglass or aluminum.
The main article about polypropylene pipes.
Reinforcement of polypropylene pipes — the main goal and objectives
We remember well the metal pipelines in our apartments or in private houses, through which hot water gurgles, supplying home batteries with the desired warmth. It is not necessary to talk about the attractive appearance of such highways, especially since the permeability of metal highways deteriorates significantly over time. Poor quality of the coolant, frequent blockages cause a decrease in the functionality of metal heating circuits. Consequently, over time, the quality of heating of residential premises sharply deteriorates.
In most cases, it was these factors that caused the appearance on the market of consumables for heating synthetic materials. First, metal-plastic pipes appeared, and a little later, polypropylene consumables began to enter the market. High performance, technological parameters and affordable price have made synthetics the most common components for heating systems today. Attempts to improve the technological parameters and characteristics of polypropylene led to the decision to reinforce polypropylene.
Reinforcement is a technology, as a result of which the structure of the base material is supplemented with reinforcing components. Due to the inclusion of an additional inner layer in the polypropylene structure, the linear rigidity of the pipe is significantly increased, the strength and stability of the material are increased. The reinforcing layer plays a key role, significantly reducing the coefficient of thermal expansion of synthetic pipelines. Unlike ordinary polypropylene, the reinforced polypropylene pipe is 5 times less susceptible to thermal elongation, which has a positive effect on the appearance of the pipeline and its functional parameters.
For reference: in a home heating system, the temperature of the coolant in the circuit is 50–700C. In the case of autonomous heating, the temperature of the coolant may periodically rise to a critical level of 950C. The operation of an unreinforced polymer pipe at such temperature indicators has an extremely negative effect on the physical properties of its material of manufacture.
For home heating, when a significant part of the heating circuit lies outside and is clearly visible, the use of a conventional polyethylene pipeline is impractical. You will have to constantly solve the problem of sagging highways by installing additional fasteners and clamps. Which product is better to choose for the heating circuit is the next question, which should be considered in more detail.
Types of reinforcement used in combination with polypropylene
Reinforcement is not a new phenomenon in engineering mechanics. The very fact that reinforcing elements are included in the composition of materials or in complex structures indicates that this technology is aimed at increasing the strength characteristics of a material or a finished product. In thermal structures and systems, reinforcement has been used relatively recently. With the advent of reinforced polypropylene consumables, the technological capabilities of heating equipment have increased significantly. Such channels perfectly interact with high temperatures, are stable, durable and easy to install.
Strengthening in this case can have two versions. Polypropylene pipes reinforced with aluminum or consumables, which include a reinforcing layer of fiberglass.
How to choose the most suitable reinforced polypropylene pipes for your own heating system, with one or another reinforcing layer, depends on a number of aspects. To make it easier to make a choice, you should understand. What is the difference between the two options for reinforcing polypropylene, and what are the technological features of such equipment.
Varieties of reinforced products
In many heating systems, it is customary to use three or five-layer polypropylene products. It is these consumables that are distinguished by the presence of the highest technological characteristics that correspond to the conditions and parameters of operation of heating equipment.
Consider the distinctive parameters of various types of polypropylene products:
- three-layer pipes are products in which there is an inner, middle reinforcing layer. Aluminum or fiberglass are used as a reinforcing component;
- five-layer polypropylene consumables are products that have two, inner and outer layers of polypropylene. In the middle of the material there are two adhesive layers (adhesive), between which there is a reinforcing layer.
Note: two adhesive layers are added so that the material does not delaminate during operation. Three-layer products often suffer from this disadvantage, in which the aluminum reinforcing layer often begins to peel off from the polymer base.
Main article: Underfloor heating from polypropylene pipes.
Both options are used with equal success in practice, forming the basis of heating circuit lines. Three-layer and five-layer polypropylene pipes perfectly cope with high working pressure, work in the mode of exposure to high temperatures of the coolant.
Accordingly, such products have their own distinctive marking, on the basis of which it is possible to draw a conclusion about what material the product is reinforced with.
Fiberglass reinforced products
All polypropylene pipes are marked with the corresponding PP symbols. The addition of a glass fiber reinforced layer is indicated in the material marking with the following symbols PPR-FB-PPR. It is immediately clear that the product has three layers, among which the middle layer performs reinforcing functions. This marking indicates that you have polypropylene fiberglass products in front of you.
Outwardly, such consumables are distinguished by the presence of a colored layer inside. The reinforcing layer can be made in different colors, ranging from red, orange, ending with a green layer. The color does not affect the technological parameters in any way. The main structural data are printed on the outer surface of the pipe, indicating the operating conditions, the diameter of the product.
Glass fiber reinforced consumables offer the following benefits:
- no need to clean and calibrate individual pipe fragments during installation;
- the absence of the effect of delamination of products, achieved as a result of a monolithic structure.
However, the advantages of fiberglass lines in comparison with aluminum-reinforced polypropylene pipes are not so significant. Both options can be used for heating circuit equipment, but the following should be remembered:
Unlike aluminum-reinforced materials, fiberglass products have a higher coefficient of thermal elongation (by 5–6%).
At a price, fiberglass products are slightly cheaper than five-layer consumables. The installation of such pipelines for heating is quick and straightforward. Using special scissors — a cutter and a soldering iron, it is possible to lay a heating circuit throughout the entire residential building within one or two days. As a result of diffuse soldering, the required strength of the joints is achieved.
Products reinforced with aluminum
As in the previous case, aluminum reinforced polypropylene pipes are also often used in practice. Among professionals, there is a conditional division into those who prefer synthetic pipelines reinforced with aluminum and those who prefer fiberglass consumables. Each category of masters has its own arguments in favor of one or another type of consumables. Consider how pipes with a layer of aluminum differ from a technological point of view.
Let’s start with labeling. Products of this kind usually carry the following set of characters, the abbreviation PPR-Al-PPR. As in the previous case, the marking shows how many layers the pipe has and what they consist of.
In turn, such consumables are divided into several subspecies:
- the first option — the products have perforated aluminum in the middle part (a thin layer of aluminum foil with small round holes);
- the second option — the pipe has a middle layer of solid aluminum.
The figures below show the first and second options for aluminum-reinforced consumables.
Both options have a three-layer structure. The third option involves a polypropylene reinforced pipe with five layers. Here, two layers of adhesive base are added to polypropylene and aluminum. Due to the presence of two additional thermal layers, consumables of this type have increased resistance to high temperatures and durability.
Products with aluminum can also have different colors, which do not have a special technological significance.
Sometimes on sale there are products marked with the following designations PEX-Al-PEX. Unlike pipes marked PPR-AL-PPR, in this case we are talking about a different layer structure. The first letters designate the outer layer of cross-linked polyethylene. These consumables have slightly different performance characteristics and deserve a separate discussion. There are no fundamental differences in this case, therefore, both of them can be safely used for the installation of heating pipelines.
Important! In the process of practical use, polypropylene channels with aluminum must be cleaned to ensure the strength and tightness of the connection.
Depending on the manufacturer, the aluminum layer may be located in different ways. In some pipes, the reinforcement layer is in the middle, between two other layers on both sides. There are products in which aluminum foil is located closer to the inner wall of the pipe.
In order to properly lay the pipeline with such consumables, in addition to special scissors and a soldering iron, you will need a shaver. This device is used to clean the edges of aluminum foil on individual pipe fragments. Since aluminum itself cannot be soldered, it is necessary to strip the channel deep by 2–3 mm.
A properly equipped heating circuit using reinforced synthetic materials can last a long time. According to the instructions, such systems are operational for 30–50 years, without loss of basic performance characteristics.
Reinforced pipes are able to withstand high temperatures perfectly. Consumables and accessories in which aluminum is present have the lowest thermal expansion.
Technical parameters for the operation of reinforced polypropylene pipes
Now knowing what reinforced synthetic pipes are, we can draw some conclusions. The advantages of reinforced consumables include:
- the lowest coefficient of thermal expansion among all currently known components of this kind;
- each product is designed for a certain working pressure (indicated on the label);
- wide operating temperature range;
- resistance to corrosion;
- resistance of products to a sharp decrease in temperature (the effect of defrosting does not threaten such pipelines).
The main technological parameters of polypropylene consumables reinforced with aluminum or fiberglass are as follows.
Let’s go back to the coefficient of thermal expansion.
For reference: For an ordinary plastic pipe, the thermal elongation is 10 cm per 1 linear meter of the pipe. Upon contact with a coolant whose temperature is 700FROM.
With polypropylene products, in which there is a reinforcing layer, the situation looks different. At high temperatures, even reaching +950C, thermal elongation is only 1 cm per 1 linear meter of pipeline.
The operating pressure also affects the functionality of the heating circuit and its durability. For clarity, just look at the table, which shows the markings and indicators of different types of polypropylene products used in home heating systems.
Heat carrier temperature ˚С
Nominal coolant pressure MPa
For cold water system
≤ + 20˚С
For low-temperature heating systems (heat-insulated floors)
≤ + 45˚С
For cold and hot water systems
≤ + 60˚С
Only for DHW systems
≤ + 95˚С
PN 25 (reinforced)
For central heating and hot water systems
≤ + 95˚С
Note: consumables and components used in the installation of polypropylene pipelines, reinforced and in the usual version, can be made of practiced, traditional materials: brass, copper, nickel-plated inserts. The type of connection is selected from the point of view of technological necessity.
Polypropylene consumables reinforced with special components today have significantly expanded the performance of heating systems. Due to the affordable price and ease of installation, using such products, it is possible to lay a heating pipeline of almost any length. Restrictions can only be due to the power of the heating devices and the specifics of the heating method. Do not forget that polymer pipes are very convenient and practical to use. With such a pipeline, it is easy to carry out repair work. Separate sections of the pipeline are interchangeable. Thanks to the soldering method, the necessary tightness, strength and stability of the joints are achieved.
In terms of manufacturability, synthetic pipes reinforced with fiberglass have great advantages, therefore, over time, this type of consumables will take a dominant position in the market for thermal equipment.