When preparing a heating system project, the task of choosing a pipeline arises. The parameters of the products used depend on the heat output of the boiler, the branching of communications, the dimensions of the dwelling. Deciding what is better to use - polypropylene or metal-plastic for heating and water supply, will help to study the features of pipes made of these materials.
Criteria for choosing pipes for heating
Before considering the differences between polypropylene and metal-plastic pipes, it is worth listing the factors that determine the characteristics of the purchased products. The preferred wire diameter, materials and construction are determined by a number of parameters:
- openness or closedness of communications;
- power of the heating unit, types of fuel used;
- methods of installation of communications;
- the nature of the circulation (forced or natural);
- dimensions of the heated dwelling.
The temperature of the coolant, its stability and the pressure present in the system are also taken into account. A stable low temperature places much less demand on pipes than conditions in which water hammer and pressure drops often occur. The latter are typical for central heating, so only metal communications are used in it.
For polypropylene
Compared to other plastic pipes, products made of this material are characterized by the greatest rigidity and strength. Due to their low price and good performance, they have become very popular. But when purchasing such pipes, it should be remembered that there are different options for them, differing in their ability to withstand hot temperatures. It makes no sense to use PP-N and PP-V for heating: products of the first type are intended only for cold water supply, PP-V can also be used for warmer water, but its temperature should not exceed 50 degrees.
For heating systems, only PPRC pipes may be used. Such products have a three-layer structure. The middle layer consists of a reinforcing material. It can be fiberglass or aluminum. For heating, they buy products that can withstand water at 90-95 degrees. It is important that the inner walls are smooth and the thermal expansion is as low as possible.
The market is replete with polypropylene pipes with a high expansion rate, which are easily deformed when used in high-temperature conditions, so you need to pay close attention to this.
For metal-plastic
Reinforced plastic pipes include aluminum and plastic components. The main criterion for purchasing a heating system is good tolerance to high temperatures. You should take pipes that are sharpened for long-term operation at a temperature of 95 degrees and can withstand surges up to 110. The diameter and wall thickness are also important - they are selected in accordance with the design features of the system.
Comparison of materials
When choosing metal-plastic pipes or polypropylene for heating, the homeowner must understand the behavior of these materials during operation.You also need to take into account the requirements for the installation of different types of pipes.
Products made of metal-plastic can withstand a hot coolant well, without deforming or bursting. They are able to serve in such conditions for up to 50 years. For polypropylene pipes, such terms are real only for models with a reinforcing layer and a mark of compatibility with boiling water. If at least once you pour hot water into the PP-B or PP-H pipe at a sufficiently high pressure, it will last a maximum of a couple of years after such an incident. These products are originally intended only for laying water pipes with low temperatures.
With regard to frost resistance, the characteristics of pipes made of these materials are identical: in no case should the coolant freeze. Moreover, metal-plastic, showing superiority in most operational parameters, in this case collapses immediately. Polypropylene products are able to withstand the expansion caused by ice for a short time.
With a sharp temperature jump, metal-plastic products are unstuck due to the different expansion rates of the constituent materials. This applies to freezing and sudden dispensing of hotter water. In the first case, the welded seam of the metal part may burst altogether. The polypropylene expands and the pipes sag. If they hit the wall at the same time, the pipeline may collapse. It is important to take this into account during installation: the communication device must include sliding supports.
With a limited budget, the price category often becomes the main one when choosing polypropylene or metal-plastic pipes. The first material wins - the price of products made from it is 2-3 times lower. The accessories are also cheap, which cannot be said about those for metal-plastic: the pipes themselves from it are quite acceptable for the budget, but the mounting parts are very expensive.
The advantages of polypropylene include its elasticity, due to which the communications remain sealed even after the water frozen in them begins to thaw. Reinforced versions are resistant to mechanical stress and have a large wall thickness. The material is not subject to corrosion and does not deteriorate from the low quality of the coolant, it has dielectric properties. It is very lightweight, making it easy to transport and install. On sale you can find fittings of various configurations for laying communications, including those that include pipes from other materials.
The main disadvantage of this plastic in terms of installation is the lack of flexibility. Even to create a small turn of the contour, you need to weld in branch elements or adapters. If some section of the communication is damaged, its complete replacement is required: the welded joint cannot be repaired. When carrying out installation work, this must be taken into account: before and after a potentially problematic assembly (for example, a fitting or a tap), even fragments are left so that you can cut the assembly and insert a new one. Also, with poor-quality welding of joints, there is a risk that with a sharp increase in temperature, the plastic will melt and block the path of the coolant. In the absence of experience in laying such communications, it is better to entrust the work to the masters. Definitely, polypropylene should not be used for centralized heating: the material does not tolerate the sudden changes in temperature and pressure inherent in this system.
Metal-plastic, on the other hand, is flexible and able to keep the shape that has been given to it. However, there will be problems with small radii - trying to bend the pipe in this way can break it. It is better not to do the bending by hand, but to use spring parts or a pipe bender. The latter provides a smooth configuration. Also, the advantages include the smoothness of the inner walls, which creates the best circulation, and the good tolerance of the hot coolant.
The main disadvantage of metal-plastic is unsatisfactory behavior when water is frozen: the walls are easily torn.
Features of pipe installation
When preparing for laying, one must not forget that polypropylene pipes are not used in warm floors and other closed structures (for example, hidden in the thickness of the wall). Due to thermal elongation, conditions are not suitable for them when connection control is impossible. Polypropylene is mounted at an ambient temperature of at least +10 degrees.
Primary requirements
Plastic pipes are connected using fittings and a diffusion welding machine. The use of such a tool will create the tightness of the joints. But handling him requires dexterity and skill: if there is a shortage of them, it is better to invite a master.
A reliable way of connecting metal-plastic pipes is pressure testing, carried out using fittings and a pliers tool. It is recommended for use in closed structures. The collet method of connection with the help of plumbing keys is also used.
Reviews of professionals
Konstantin, heating specialist. Most polypropylene pipes are suitable for cold water supply, and heating will lead to deformation and melting of the material. In a private house, in the absence of pronounced surges in pressure and temperature, wiring is made of reinforced polypropylene with markings indicating suitability for such tasks. But metal-plastic is better.
Andrey, builder. Polypropylene is easily deformed by hot water, and, on the contrary, is more resistant to freezing than metal-plastic. Also, polypropylene has a high coefficient of linear expansion. In terms of flexibility, metalloplast also wins.
In terms of reliability, flexibility, withstanding the deviating parameters of the coolant, metal-plastic products show the best results. If it is impossible to allocate funds for such products, reinforced polypropylene is used if the heating characteristics are suitable for its operation.
