What is the best pipe diameter for heating in the house?

The efficiency of the heating main depends on the power of the boiler, radiators, and valve parameters. The suitable diameter of pipes for heating is determined using online programs or self-calculations, as well as technical indicators and material. Knowing all the nuances, the owner of the house can choose high-quality and reliable products.

Difficulties in choosing the diameter of the pipeline

The main difficulty in the selection of the diameter lies in the features of the highway planning. Taken into account:

• external indicator (copper and plastic) - the surface of the reinforcement can give off heat fluxes to the room;
• inner diameter (steel and cast iron) - allows you to calculate the throughput characteristics of an individual section;
• conditional parameters - the rounded value in inches, needed for theoretical calculations.

To determine the cross-section, it is taken into account that 100 W of energy is spent per 1 m2 of the room.

Dependence of the size on the speed of the coolant

The choice of the diameter indicator will determine the throughput of the line, taking into account the recommended speed of 0.4-0.6 m / s. In this case, it is taken into account that at a speed of less than 0.2 m / s, air jams are formed, and at a speed of more than 0.7 m / s, there is a risk of an increase in the pressure of the coolant.

How evenly heat energy is distributed along the circuit and determines the diameter of the nozzles. The smaller it is, the faster the water moves, but the speed indicators have a limitation:

• up to 0.25 m / s - otherwise there are risks of air jams and the impossibility of removing them with drains, heat loss in the room;
• no more than 1.5 m / s - the coolant will make noise during the circulation;
• 0.36-0.7 m / s is the reference value of the coolant velocity.

To control the intensity of circulation without increasing the diameter of the nozzles, a circulation pump is used.

Coolant volume parameters

For systems with natural circulation, it is better to choose fittings with an increased diameter. This will reduce heat loss during friction of the water against the inner surface. When using this technique, it should be borne in mind that with an increase in the volume of water, the energy consumption for heating it increases.

Hydraulic losses

The phenomenon occurs if the pipeline is made of plastic products of different diameters. The reason lies in the pressure difference at the joints and the increase in hydraulic losses.

Formula for calculating the diameter of the line

The correct determination of the diameter of the pipe used for the heating line of an apartment or private house is made on the basis of the table and formula. When working with the table, you need to focus on the green cells - they indicate the optimal speed of the coolant pressure.

The calculation is made according to the formula D = √ (354 * (0.86 * Q / ∆t) / V)where:

• V- fluid velocity in the pipe (m / s);
• Q- the required amount of heat for heating (kW);
• ∆t- the difference between reverse and direct feed (C);
• D - pipe diameter (mm).

As an example, consider a two-story house with four wings (2 per floor), connected to a two-pipe system with a total heat loss of 36 kW, 20 kW of which falls on the heating of the 1st floor, 16 kW - of the second. For communications, polypropylene was used, they operate in 80/60 mode at a temperature of 10 degrees.

Counting Algorithm:

1. The entire volume of water falls on the section where the first branch is connected to the boiler. This is a total heat quantity of 38 kW.
2. In the table, you need to find this line and the corresponding green cells. With these parameters, the required diameter is 40 and 50 mm. The choice is made in favor of less.
3. The fork shows the amount of heat on the first (20 kW) and second (16 kW) floors. The section of pipe fittings according to the table is 32 mm.
4. Since there are 2 wings on each floor, the circuit is divided into two branches. For the first floor 20/2 = 10 kW per wing, for the second - 16/2 = 8 kW per wing.
5. According to the table, the diameter is determined - 25 mm, used until the load drops to 5 kW, then - 20 mm.

Calculations for the return are not needed - pipes with similar parameters are used.

Important technical characteristics of pipes

High-quality heating of the premises is impossible without taking into account the technical characteristics of the equipment. They can be considered using the example of standard products made of polypropylene of the PN 20 and 30 brands.

With a coolant with a speed of 0.4 m / s, it is required to take into account the thermal power of products of various diameters. With external parameters of 20 mm, 4.1 kW is generated, with 25 mm - 6.3 kW, with 32 mm - 11.5 kW, with 40 mm - 17 kW.

The procedure for calculating the heating manifold and mounting sleeves

An apartment or a private house is equipped with a heating collector. The device provides wiring of the coolant along several branches. The calculation of the collector is carried out together with the cross-section of pipes for the outer or inner dimensions on the basis of the principle of "three diameters" - pipes on the route are removed from each other by 6 radii each. The collector diameter is also equal to this value.

The parameters of the sleeves are calculated after establishing the cross-section of the line. Elements are selected taking into account the material of the wall and reinforcement, the degree of expansion when heated. For example, the diameter of a plastic pipe is 20 mm, and a sleeve is 24 mm.

The sequence of calculating the cross-section of heating mains

For communications with circulation pumps, it will be necessary to take into account the volume of the coolant in the system, the total length of the heating main, the reference flow rate, heat transfer of heating, the power of the equipment, the value of resistance and pressure without a pump.

To find out the size of the products, you need to make an allowance for the decrease in efficiency - the resistance of turns, bends and fittings. Calculations can be carried out according to the formula H = λ (L / D) (V2 / 2g)where:

• H - height of zero pressure without pressure in m;
• λ - coefficient of resistance of pipes;
• L - the length of the line;
• D - inner pipe diameter in mm;
• V - flow rate in m / s;
• g - acceleration of gravity equal to 9.81 m / s2.

In the process of calculating the minimum heat loss, it is necessary to check several diameters for minimum resistance.

Characteristics of pipe materials

Manufacturers produce pipelines from several types of materials.

Polymer

Products for which plastic material is used - sewn or regular polyethylene. After calculations, you can establish what diameter of propylene pipes is needed for heating a private house, depending on the type of equipment:

• one or two batteries - 16 mm;
• a radiator or a group of radiators with a capacity of 1-2 kW (standard), up to 5 batteries with a capacity of up to 7 kW - 20 mm;
• dead-end wiring shoulder (wing of the house), radiators up to 8 pcs. with a total power of up to 11 kW - for heating it is better to use propylene pipes with a diameter of 25 mm;
• one floor (up to 12 radiators with a total power of up to 19 kW) - 32 mm;
• line of 20 radiators up to 30 kW with a capacity of 40 mm.

The wall thickness of polymer products is selected according to the pressure parameters in the network and is 1.8-3 mm.

Steel

They differ in strength and good heat dissipation, but are difficult in terms of installation. The surface of stainless steel fittings does not corrode and is characterized by smoothness. Steel heating fittings according to GOST 3262-75 are classified according to the outer diameter, on which the wall thickness depends. The data are shown in the table.

Standard and light modifications are used for the organization of apartment or home heating.

Copper

The material has good thermal conductivity, corrosion resistance, and tensile properties. When the coolant freezes, the system can work while maintaining tightness. Features of the dimensions of copper fittings are shown in the table.

To carry out heating, it is worth using copper fittings with walls of 1.5-2 mm.

If there are 5-8 radiators in an apartment and 2-3 forks in a private house, you can independently calculate the diameter of the pipe for the heating main. For this purpose, it is allowed to work with formulas and tables. The organization of a complex system with several levels involves the use of special online programs.