The ease of installation and high performance of polypropylene pipelines in water supply and heating systems is only the tip of the iceberg. For the correct operation of the installed communications, it is not enough to choose the type of polymer pipe and buy the material in the right amount — preliminary design sketches are necessary, and for large objects — serious thermal and hydraulic calculations. For the heating system to be effective, polypropylene pipes for heating must have a diameter confirmed by these calculations.
Let us consider in more detail the significance of the diameter of polypropylene pipes in the construction of pipelines.
Pipe material for communications. What are the parameters of the pipe
The questions of how the water supply should look like, what diameter of the pipes should be in the main supplying heat to heating radiators, are solved at the design stage of life support systems in the house. As a result, the diameter of polypropylene pipes for water supply can often differ from the identical size of the pipeline of the heating system, since these communications have different purposes and are therefore exposed to different factors.
The capacity of heat networks, recommended by professional experts, should ensure the speed of the coolant at least 0.4–0.6 m / s — this determines the amount of thermal energy supplied to heat residential premises.
On a note: if the boiler water supply rate in the pipeline of the heating system is less than 0.2 m / s, then there is a high probability of airing the line, and exceeding the supply rate by 0.2 m / s will lead to an increase in costs — the costs of equipment subjected to heavy loads will increase.
The use of polypropylene products has greatly simplified the work on equipping residential facilities with water heating and water supply systems. However, you need to know exactly which type of polymer pipe material is suitable in a particular case. The types of polypropylene pipes that exist today have different technical characteristics and are designed for a specific area of u200bu200buse.
The most reliable for the installation of water heating pipelines and hot water supply systems (DHW) are products of the PN25 or PN30 brand. It is these brands that are able to withstand pressures up to 25 and 30 atm. respectively at the operating temperature of the coolant 950C. Even short-term operation of such pipes is allowed at a water temperature of 1200C, as a distinctive feature of these products are thick walls.
The main article about polypropylene pipes.
For cold water supply, polypropylene pipes with a homogeneous wall are used. For hot water systems and heating circuits, reinforced products are used, since the inclusion of an aluminum or fiberglass shell in the wall structure of a polypropylene pipe significantly increases the strength of the pipe material and reduces the amount of thermal expansion.
For reference: in reinforced pipelines, thermal expansion is 0.03 mm / m0C, while for channels with a wall of homogeneous polypropylene this value is about 0.15 mm / m0C. Based on this, homogeneous products are suitable for cold water supply, and only reinforced polypropylene is used for heating and hot water systems.
What diameters are produced polypropylene pipe materials
When choosing components for a heating and water supply system, the decisive factors are the temperature of the liquid, its flow rate and pressure. The required cross-sectional area of the water supply system is determined in this case by calculations made in accordance with the scope and operating conditions of the equipment.
Based on the configuration of the pipe section (round ring), its geometric parameters are determined by the outer and inner diameters. The current classification of polypropylene pipes clearly defines the typical dimensions of each type of pipe products used for installation.
To date, both domestic and foreign manufacturers produce components for pipelines in a standard version. Taking into account practical application, standard engineering solutions have been developed that allow determining the optimal passage in products for home heating and other water communications. Based on the data in the table, it is possible to make the right choice of equipment and components for the heat main without resorting to hydraulic calculations.
On a note: the values indicated in the marking on the products should not be considered as the parameter of the internal section. On polypropylene materials, the outer diameter is usually indicated.
As a rule, one of the following outer diameter values is present in the marking:
16, 20.25, 32 and 40mm,
which correspond to the inner diameters of PN25 polypropylene pipes:
10.6; 13.2; 16.6; 21.2; 26.6 mm.
For ease of use, the correspondence between the diameters and wall thicknesses of polypropylene pipes used in heating and water supply systems is summarized in the table:
Reasonable question. Why are external parameters applied to finished products, if the size of the internal passage of the pipeline is so important for functionality. The thing is that the outer diameter indicates the appropriate type of connection.
The potential of using polypropylene pipes of various outer diameters at a coolant velocity in the pipeline of 0.7 m/s:
- a pipe with a diameter of 16 mm is designed to connect one or two heating radiators;
- a value of 20 mm corresponds to the connection of up to 5 radiators with a total power of up to 7000 watts);
- for a larger number of radiators (with a total power of up to 11 kW), propylene polymer pipes with an outer diameter of 25 mm are used;
- polypropylene pipe material with an outer dimension of 32 mm is designed to equip the house as a whole or one floor with a heating system of 10–12 kW of total power (maximum 19 kW);
- products with a diameter of 40 mm are used for laying main pipelines in residential facilities of a large area. Usually these are cottages and country houses, in which the number of heaters reaches 20 pieces, and the total power of all connection points is approximately 30 kilowatts.
Influence of pipe diameter on the performance of the heating system
The coolant supply rate and the amount of transferred thermal energy directly depend on the internal section of polypropylene pipelines. For clarity of this statement, the dependence of providing thermal energy on the intensity of the coolant supply and the values of the pipeline diameters is summarized in the table:
The thermal power is indicated in W, the intensity of the coolant supply in kg / s. The calculated data are based on average temperatures: of the supplied coolant at 800C, return to 600C, room air +200FROM..
For example: at a flow rate of 0.4 m/s, the following amount of heat energy will be transferred in the pipeline:
- for a line with an outer size of 20 (internal section 13.2 mm), the amount of heat is 4.1 kW;
- for propylene products Ø 25 and 16.6, respectively, the amount of heat will be 6.3 kW;
- propylene pipelines with outer and inner diameters of 32 and 21.2, respectively, have a thermal energy supply of 11.5 kW;
- pipe materials of 40 millimeters (internal clearance size 26.6 mm) will provide heat supply in the amount of 17 kW.
With an increase in the fluid flow rate to 0.7 m/s, the intensity of the coolant supply will immediately increase by 70–80%.
Important! The practical purpose of the table above is to recommend, based on the value of the required amount of thermal energy, the required pipe diameter during the selection of pipe materials for a residential heating system.
Let’s look at an illustrative example:
There is a typical house with a usable area of 250 m2. The building is sufficiently insulated and needs heating at the rate of 1 kW per 10 square meters to create normal living conditions. m, that is, to create a comfortable temperature in the house, 25,000 watts of thermal energy (maximum) will be enough.
On a note: the first floor always requires more heat — about 2/3 of the total amount consumed.
Thus, out of 25 kW, heating the first floor will require 15 kW, the second — 10 kW.
The house is equipped with an autonomous heating system based on a double-circuit boiler. The radiators installed in the rooms are connected in parallel. The house has a wiring for two wings, with equal heat output. On the ground floor, the power for each wing is 7500 watts. For the second floor, both wings require 5000 watts each.
The boiler produces 25 kilowatts of thermal energy for heating the house. This means that for the heat main it is necessary to use polypropylene pipes and fittings with an inner diameter of 26.6 mm (at a feed rate of 0.6 m / s). This value corresponds to the outer diameter of the pipe 40 millimeters.
To supply the branches on the ground floor, 1500 watts of heat will be required. Using the data from the table, we get the following:
- at a flow rate of 0.6 m / s, the optimal diameter of the inner lumen of polypropylene pipes will be 21.2 mm — the identical external parameter corresponding to this value, according to the table, is 30 mm;
- for each wing, pipe material with an inner diameter of 16.6 mm is suitable, which corresponds to Ø 25 mm of the outer contour of the section of polypropylene pipes.
Now consider the procedure for connecting heaters.
Water heating radiators have an average power of 2 kilowatts, therefore, theoretically, pipes with a minimum outer diameter of 16 mm (PN16) are suitable for their insertion into the circuit. However, in practice it is recommended to use polypropylene products with an internal section size of 13.2 mm and an outer diameter of 20 mm (PN20), since the use of PN16 polymer pipes is considered inappropriate due to low manufacturability.
The second floor is equipped with a 32 mm pipeline. Pipes and fittings Ø25 mm are used for each wing. With radiators, the picture is the same as on the ground floor — the batteries are connected using PN20 pipes.
Based on the above example, for each section of the pipeline in the heating system, it is possible to select components of the required diameter — including this, the efficiency of the heating equipment will depend.
It should be remembered that the materials for the pipeline in the heating system are selected with the calculation of compliance with the maximum technical characteristics of an autonomous boiler, despite the fact that in most cases the unit will operate in normal mode — in accordance with the specified operating parameters.