Diagram of a two-pipe heating system. Two-pipe heating system One-pipe or two-pipe heating system for a private house

Among countless wiring options heating systems The most common is a two-pipe heating system with bottom wiring and forced circulation of coolant. You can assemble it yourself, provided that it is designed and calculated correctly. But not every homeowner understands these issues, and even if it is decided to hire specialists for design and installation, their work must be checked. This is only possible if you understand what it is two-pipe system heating of a private house and how to install it correctly. Our article is just to help such homeowners.

Types of two-pipe heating systems

Our topic is entirely devoted to these systems, since they have a number of advantages over single-pipe systems. There is no point in listing them all; it is worth noting only the main thing: the two-pipe system works in such a way that all radiators receive coolant at almost the same temperature.

The word “almost” means that there are exceptions to this rule; these are circuits assembled from steel, copper and stainless steel corrugated pipes that are not covered with a thermal insulation layer.

The fact is that the heating system of a private house, made with your own hands from uninsulated metal pipes, will transfer heat to the premises not only through radiators. Metal has high thermal conductivity, so the coolant flowing in such a line will cool slightly as it moves away from the boiler. Although the temperature drop compared to single-pipe wiring is insignificant, it still needs to be taken into account.

Note. Many supporters of single-pipe schemes such as “Leningradka” say that they are cheaper, since half as much material will be needed. But at the same time, they forget about the drop in water temperature, as a result of which it is necessary to increase the power of the radiators, that is, add sections. This additional funds, and considerable ones.

Based on the orientation of the risers in space, vertical and horizontal types of systems are distinguished, and they can have upper, lower and combined wiring. In a vertical scheme, the building has one or more risers powered by a heat source located in the basement or first floor. Radiators are connected to vertical risers directly, as shown in the figure:

This is a bottom-distribution scheme, since the main pipelines supply coolant to the risers from below. A vertical system with top filling implies their laying from above, with combined version Only the supply horizontal manifold runs under the ceiling, and the return manifold runs from below. Typically, highways laid on top are placed in attic space, and in its absence - under the ceiling of the last floor. Which is not very good from an aesthetic point of view.

Horizontal systems

This is a closed two-pipe system, in which horizontal branches are laid instead of vertical risers, and a certain number of heating devices are connected to them. As in the previous case, branches can have upper, lower and combined wiring, only now this happens within the same floor, as shown in the diagrams:

As can be seen in the figure, a system with overhead wiring requires laying pipes under the ceiling of the premises or in the attic and will be difficult to fit into the interior, not to mention the consumption of materials. For these reasons, the circuit is used infrequently, for example, for heating basements or when the boiler room is located on the roof of the building. But if chosen correctly circulation pump and the system has been configured, then it is better to run the boiler pipe from the roof downwards, any homeowner will agree with this.

Combined wiring is indispensable when you need to install a two-pipe gravity system, where the coolant moves naturally due to convection. Such schemes are still relevant in areas with unreliable power supply and in houses of small area and number of floors. Its disadvantages are that there are many pipes running through all the rooms large diameter, hiding them is very difficult. Plus the high material consumption of the project.

And finally, horizontal system with bottom wiring. It is no coincidence that it is the most popular, because the scheme combines a lot of advantages and has almost no disadvantages. The lines to the radiators are short, the pipes can always be hidden behind a decorative screen or embedded in the floor screed. At the same time, the consumption of materials is acceptable, and from the point of view of operational efficiency it is difficult to find a better option. Especially when a more advanced passing system is used, shown below in the diagram:

Its main advantage is that the water in the supply and return pipelines travels the same distance and flows in the same direction. Therefore, hydraulically, this is the most stable and reliable scheme, provided that all calculations are carried out correctly and the installation features are taken into account. By the way, the nuances of systems with associated coolant movement lie in the complexity of the design of ring circuits. Often, pipes must cross doorways and other obstacles, which can increase the cost of the project.

Conclusion. For a private home the best option is a two-pipe horizontal heating system with bottom wiring, but only in conjunction with artificial coolant circulation. If you need to provide non-volatile operation thermal equipment and networks, it is recommended to take one of the combined gravity systems - horizontal or vertical. The latter would be appropriate in a house with two floors.

Forced circulation heating system

So, the wiring diagram has been selected, further actions the following:

draw it in the form of a sketch, or even better, a three-dimensional model (axonometry);
calculate and select pipe diameters in all branches and sections;
select all the necessary elements of a two-pipe system: batteries, pump, expansion tank, filter, fittings and other parts of the boiler and radiators;
purchase equipment and materials, perform installation work;
carry out tests, balancing (if necessary) and put the system into operation.

On the sketch in the form of an axonometry, it is necessary to draw the mains, arrange the radiators and shut-off valves, put down elevation marks, taking the screed surface of the first floor as the reference point. Subsequently, having completed the calculation, you will need to indicate the dimensions and cross-sections of the pipes on the drawing. An example of how to install a two-pipe system with forced circulation is shown in the drawing:

Important. The finished sketch will allow you to better understand all the nuances of the future system, down to the number and types of fittings made of polypropylene, metal-plastic or other material. It is especially convenient when a house plan is attached to the three-dimensional image.

Selection of pipe diameter

This calculation consists of determining the coolant flow rate based on the thermal power required to heat the room, and from it the diameter of the pipes for a two-pipe heating system. In simple words, the flow area of the pipe should be sufficient to deliver the required amount of heat along with hot water to each room.

Note. By default, it is assumed that the calculation of the building’s heat losses has already been completed and the amount of heat for all rooms is known.

The selection of pipe diameters begins from the very end of the system, from the last battery. First, calculate the coolant consumption for heating this room using the formula:

G = 3600Q/(c∆t), Where:

G – required hot water consumption per room, kg/h;
Q – amount of heat to heat a given room, kW;
c – heat capacity of water, assumed to be 4.187 kJ/kg ºС;
Δt is the calculated temperature difference in the supply and return manifolds, usually 20 ºС.

For example, to heat a room you need 3 kW of heat. Then the coolant flow will be equal to:

3600 x 3 / 4.187 x 20 = 129 kg/h, in volume it will be 0.127 m3/h.

To balance a two-pipe water heating system initially, you need to select the diameter as accurately as possible. Based on the volumetric flow rate, we find the flow area using the formula:

S = GV / 3600v, Where:

S – cross-sectional area of the pipe, m2;
GV – volumetric coolant flow rate, m3/h;
v – water flow speed, taken in the range from 0.3 to 0.7 m/s.

Note. If the heating system one-story house– gravitational, then the minimum speed should be taken – 0.3 m/s.

In our example, let’s take a speed of 0.5 m/s, find the cross-section and, using the formula for the area of a circle, the diameter, it will be equal to 0.1 m. The polypropylene pipe closest in range has inner size 15 mm, we put it on the drawing. By the way, connecting radiators to a two-pipe system is usually done with just such a pipe - 15 mm. Next, we move on to the next room, count and sum with the previous result, and so on until the boiler itself.

Connecting radiators to a two-pipe system

The installed batteries are connected to the mains during the installation process, correct connection heating radiators with a two-pipe system - this is lateral or diagonal. All existing methods shown in the figure:

The temperature balance achieved by the lower connection of the radiator to a two-pipe system is well illustrated by the following pictures:

Batteries used in a vertical circuit usually have a side connection (method No. 3). In horizontal systems, the diagonal connection diagram is most preferable (method No. 1), thanks to this, maximum heat transfer from the heating device is achieved, as shown in the image below:

Balancing

The point of this operation is to balance all branches of the system and regulate the water flow in each of them. To do this, each branch must be correctly connected to the mains, that is, install special balancing valves. Also control valves or thermostatic valves are installed on the connections to all radiators.

It is not so easy to carry out accurate balancing with your own hands; you need to have the appropriate instruments (at least a pressure gauge to measure the pressure drop across the balance valve) and perform calculations for pressure losses. If there is none of this, then after testing you need to fill the system, bleed the air and turn on the boiler. Next, balancing of the two-pipe system is done by touch, according to the degree of heating of all batteries. Devices located next to the heat generator must be “pressed” so that more heat goes to those further away. The same goes for entire branches of the system.

Conclusion

It is noteworthy that installing a two-pipe heating system is much easier than developing it, calculating it, and then balancing it. So this stage you can go through it yourself, and it is advisable to coordinate everything else with specialists.

According to statistics, over 70% of all residential buildings are heated using water heating. One of its varieties is a two-pipe heating system - this publication is dedicated to it.

The article discusses the advantages and disadvantages, diagrams, drawings and installation recommendations two-pipe wiring with your own hands.

Contents of the article

Differences between a two-pipe heating system and a single-pipe one

Any heating system is a closed circuit through which coolant circulates. However, unlike a one-pipe network, where water is supplied to all radiators in turn through the same pipe, a two-pipe system involves dividing the wiring into two lines - supply and return.

A two-pipe heating system for a private house, in comparison with a single-pipe configuration, has the following advantages:

Minimal coolant losses. In a single-pipe system, radiators are alternately connected to the supply line, as a result of which the coolant passing through the battery loses temperature and enters the next radiator partially cooled. With two-pipe configuration, each battery is connected to the supply pipe with a separate outlet. You get the opportunity to install on each of the radiators, which will allow you to regulate the temperature in different rooms of the house independently of each other.
Low hydraulic losses. When installing a system with forced circulation (necessary in large buildings), a two-pipe system requires the installation of a less efficient circulation pump, which allows for significant savings.
Versatility. A two-pipe heating system can be used in multi-apartment, one or two-story buildings.
Maintainability. Shut-off valves can be installed on each branch of the supply pipeline, which makes it possible to cut off the coolant supply and repair damaged pipes or radiators without stopping the entire system.

Among the disadvantages of this configuration, we note a twofold increase in the length of the pipes used, however, this does not threaten a dramatic increase in financial costs, since the diameter of the pipes and fittings used is smaller than when installing a single-pipe system.

Classification of two-pipe heating

The two-pipe heating system of a private house, depending on its spatial location, is classified into vertical and horizontal. The more common is the horizontal configuration, which involves connecting radiators on a building floor to a single riser, while in vertical systems radiators from different floors are connected to the riser.

The use of vertical systems is justified in a two-story building. Despite the fact that such a configuration is more expensive due to the need to use more pipes, with vertically located risers, the possibility of air pockets forming inside the radiators is eliminated, which increases the reliability of the system as a whole.

Also, a two-pipe heating system is classified according to the direction of movement of the coolant, according to which it can be direct-flow or dead-end. In dead-end systems, liquid circulates through the return and supply pipes in different directions; in direct-flow systems, their movement coincides.

Depending on the method of transporting the coolant, systems are divided into:

with natural circulation;
with forced circulation.

Heating with natural circulation can be used in one-story buildings with up to 150 square meters. It does not include installation additional pumps– the coolant moves due to its own density. A characteristic feature of natural circulation systems is the laying of pipes at an angle to the horizontal plane. Their advantage is independence from the availability of power supply, the disadvantage is the inability to adjust the water supply speed.

In a two-story building, a two-pipe heating system is always performed with forced circulation. In terms of efficiency, this configuration is more effective, since you get the opportunity to regulate the flow and speed of the coolant using a circulation pump, which is installed on the supply pipe leaving the boiler. In heating with forced circulation, pipes of relatively small diameters (up to 20 mm) are used, which are laid without a slope.

Which heating network layout to choose?

Depending on the location of the supply pipeline, two-pipe heating is classified into two types - with upper and lower wiring.

The diagram of a two-pipe heating system with top wiring involves installing an expansion tank and a distribution line at the highest point heating circuit, above the radiators. Such installation cannot be performed in a one-story building with flat roof, since to place communications you will need an insulated attic or a specially designated room on the second floor of a two-story house.

A two-pipe heating system with bottom wiring differs from the top one in that the distribution pipeline in it is located in the basement or in an underground niche, under the radiators. The outermost heating circuit is the return pipe, which is installed 20-30 cm lower than the supply line.

This is a more complex configuration, requiring the connection of an upper air pipe, through which excess air will be removed from the radiators. In the absence basement additional problems may arise due to the need to install the boiler below the level of the radiators.

Both the lower and upper circuits of a two-pipe heating system can be made in a horizontal or vertical configuration. However, vertical networks, as a rule, are made with bottom wiring. With this installation, there is no need to install a powerful pump for forced circulation, since due to the difference between the temperatures in the return and supply pipes, a strong pressure drop is created, which increases the speed of movement of the coolant. If, due to the peculiarities of the building's layout, such installation cannot be done, a highway with overhead routing is installed.

Making a two-pipe system with your own hands (video)

Selecting pipe diameters and rules for installing a two-pipe network

When installing two-pipe heating, it is extremely important to choose the correct pipe diameter, otherwise you may get uneven heating of radiators located far from the boiler. Most boilers for domestic use have a diameter of the supply and return pipes of 25 or 32 mm, which is suitable for a two-pipe configuration. If you have a boiler with 20 mm pipes, it is better to opt for a single-pipe heating system.

The size chart of polymer pipes on the market consists of diameters of 16, 20, 25 and 32 mm. When installing the system yourself, you need to take into account the key rule: the first section of the distribution pipe must match the diameter of the boiler pipes, and each subsequent pipe section after the branch tee to the radiator is one size smaller.

In practice, it looks like this: a diameter of 32 mm comes out of the boiler, a radiator is connected to it through a tee with a 16 mm pipe, then after the tee the diameter of the supply line is reduced to 25 mm, at the next branch to the radiator line 16 mm after the tee the diameter is reduced to 20 mm and so on. If the number of radiators is greater than the standard sizes of pipes, it is necessary to divide the supply line into two arms.

When installing the system yourself, adhere to the following recommendations:

the supply and return lines must be parallel to each other;
each outlet to the radiator must be equipped with a shut-off valve;
distribution tank, if installed in attic when installing a network with top wiring, it is necessary to insulate it;
pipe fastenings on the walls should be placed in increments of no more than 60 cm.

When setting up a system with forced circulation, it is important to correctly select the power of the circulation pump. The specific choice is made based on the size of the building:

for houses with an area of up to 250 m2, a pump with a capacity of 3.5 m3 / hour and a pressure of 0.4 MPa is sufficient;
250-350 m2 – power from 4.5 m3/hour, pressure 0.6 MPa;
over 350 m 2 - power from 11 m 3 / hour, pressure from 0.8 MPa.

Despite the fact that it is more difficult to install two-pipe heating with your own hands than a one-pipe network, such a system, due to its high reliability and efficiency, fully justifies itself during operation.

Owners of private houses often face a choice of what type home heating give preference. There are only two types of heating systems traditionally used in everyday life: one-pipe and two-pipe. Each type has both advantages and disadvantages. The difference between both systems is in different ways delivery of coolant to heating devices. What heating structure for own home It’s better to choose one-pipe or two-pipe directly to the owner of the house, taking into account his own household needs, the expected heated area and the availability of finances.

In the first option, heat is distributed throughout the house through one pipe, sequentially heating each room of the house. In the second case, the complex is equipped with two pipes. One is a direct supply of coolant to the . The other pipe serves to drain the cooled liquid back into the boiler for subsequent heating. A correct assessment of your own financial capabilities, an accurate calculation of the optimal parameters of the coolant in each individual case, will help not only decide on the type of heating system, but also competently.

You can understand and figure out what is best for you, a single-pipe or two-pipe heating system, only after carefully studying the technical nuances.

Single pipe heating system. General views

A single-pipe heating system can work with both a pump and natural coolant circulation. When considering the second type, you should delve a little into the existing laws of physics. It is based on the principle of expansion of a liquid when heated. During operation, the heating boiler heats the coolant, which, due to the temperature difference and the pressure created, rises along the riser to the highest point of the system. The coolant moves upward through one pipe, reaching the expansion tank. Accumulating there hot water already through the downpipe it fills all the batteries connected in series.

Accordingly, the first connection points along the coolant flow will receive maximum heat, while the radiators located further away will already receive partially cooled liquid.

For large, multi-story buildings, such a scheme is extremely ineffective, although in terms of installation costs and maintenance, a single-pipe system looks attractive. For private one-story houses, residential buildings with two floors, a similar principle of heat distribution is acceptable. Heating of residential premises using a single-pipe circuit in one-story house quite effective. With a small heated area, the temperature in the radiators is almost the same. The use of a pump in longer systems also has a positive effect on the uniformity of heat distribution.

Heating quality and installation cost in in this case May depend on connection type. Diagonal connection of radiators provides greater heat transfer, but is used less frequently due to the larger number of pipes required to connect all heating devices in residential areas.

The scheme with bottom connection of radiators looks more economical due to lower consumption of materials. From an aesthetic point of view, this type of connection looks preferable.

Advantages of a single-pipe heating system and its disadvantages

For owners of small residential buildings a single-pipe heating system looks tempting, especially if you pay attention to its following advantages:

has stable hydrodynamics;
convenience and ease of design and installation;
low costs for equipment and materials.

The indirect advantages of a single-pipe system include the safety of the supply of coolant, which disperses through the pipeline through natural circulation.

To the most common problems that owners of a single-pipe heating system have to face include the following aspects:

technical difficulties in eliminating miscalculations in the work made during the design;
close relationship of all elements;
high hydrodynamic resistance of the system;
technological limitations associated with the inability to independently regulate coolant flow.

Despite the listed disadvantages of this type of heating, a well-designed heating system will allow you to avoid many difficulties even at the installation stage. In view of the listed advantages and economic component, single-pipe schemes have become quite widespread. Real benefits They have both a single-pipe and another type, a two-pipe heating system. What can you win and what can you lose by choosing one of the types for your home?

Technology for connecting and positioning a single-pipe heating system

Single-pipe systems are divided into vertical and horizontal. In most cases, for multi-storey buildings it is used vertical wiring. In this case, all radiators are connected in series from top to bottom. With horizontal wiring, the batteries are connected one after another horizontally. The main disadvantage of both options is frequent air jams, due to air accumulation in the radiators. The proposed diagram makes it possible to get an idea of some wiring options.

Connection methods in this case are chosen at the discretion of the owner. Heating radiators can be connected via lateral, diagonal or bottom connection. The figure shows similar connection options.

Always for the owner of the house important aspect What remains is the economic feasibility of the equipment installed in the house and the resulting effect. Do not underestimate the option of a single-pipe heating system. Today in practice there are quite a few effective measures to improve heating circuits of this type.

For example: There is a technical solution that allows you to independently regulate the heating of individual radiators connected to the same line. For this purpose, bypasses are created in the system - a section of pipe that creates a bypass movement of the coolant from the direct pipe to the return, bypassing the circuit of a certain battery.

Valves and flaps are installed on the bypasses to block the flow of coolant. You can install thermostats on radiators that allow you to regulate the heating temperature in each radiator or throughout the system as a whole. A competent specialist will be able to calculate and install bypasses to achieve maximum efficiency. In the diagram you can see the principle of operation of bypasses.

Two-pipe heating system. Operating principle

Having become familiar with the first type of heating system, single-pipe, it’s time to understand the features and operating principle of a two-pipe heating system. Thorough analysis of technological and technical parameters heating of this type allows consumers to make independent choice- which heating is more effective in a particular case, single-pipe or two-pipe.

The basic principle is the presence of two circuits through which the coolant disperses throughout the system. One pipe supplies coolant to the heating radiators. The second branch is designed to ensure that the already cooled coolant, after passing through the radiator, returns again to the boiler. And so constantly, in a circle, while the heating is on. At first glance, the very presence of two pipelines in the scheme may repel consumers. The large length of highways and the complexity of wiring are factors that often scare away owners of private houses from a two-pipe heating system.

This is at first glance. Like single-pipe systems, two-pipe systems are divided into closed and open. The difference in this case lies in the design of the expansion tank.

Closed with a membrane expansion tank are the most practical, convenient and safe to use. This is confirmed by obvious advantages:

even at the design stage, it is possible to equip heating devices with thermostats;
parallel, independent connection of radiators;
technical possibility of adding heating devices after installation is completed;
ease of use of a hidden gasket;
the ability to turn off individual radiators or branches;
ease of system adjustment.

Based on the above, one clear conclusion can be drawn. A two-pipe heating system is much more flexible and technologically advanced than a single-pipe one.

For comparison, the following diagram is presented:

The Two-Pipe System is very convenient for use in a house in which it is planned to increase the living space; extension options are possible, both upward and along the perimeter of the building. Already at the work stage, technical errors made during the design can be easily eliminated. This scheme is more stable and reliable than a single-pipe one.

With all the obvious advantages, before choosing this type of heating, it is appropriate to recall the disadvantages of the two-pipe system.

Important to know! The system is characterized by higher complexity and installation costs and rather cumbersome connection options.

If you have a competent specialist on hand and have carried out the necessary technical calculations, then the listed disadvantages are easily compensated by the advantages of a two-pipe heating circuit.

As in the case of a single-pipe system, the two-pipe option involves the use of a vertical or horizontal pipeline arrangement. Vertical system - radiators are connected to a vertical riser. This type is suitable for two-story private houses and cottages. Air jams are not a problem for you. In the case of the horizontal option, the radiators in each room or room are connected to a pipeline located horizontally. Double pipe horizontal diagrams heating systems are mainly designed for heating one-story buildings and large residential buildings with the need for floor-by-floor adjustment. Air jams that arise can be easily eliminated by installing Mayevsky valves on radiators.

The figure shows a vertical two-pipe heating system. Below you can see what a horizontal two-pipe system looks like.

Traditionally, radiators can be connected using bottom and top wiring. Depending on technical specifications and the project - the choice of wiring option depends on the owner of the house. Top wiring is more convenient. All lines can be hidden in the attic space. The system creates the circulation necessary for good distribution of coolant. The main disadvantage of a two-pipe heating scheme with an upper wiring option is the need to install membrane tank outside heated rooms. The upper wiring does not allow the intake of technical water for domestic needs, as well as connecting the expansion tank with a tank for hot water used in everyday life. This scheme is not suitable for residential properties with a flat roof.

Resume

The selected type of heating for a private home should provide all residents of the residential building with the necessary comfort. There is no point in saving on heating. By installing a heating system in your home that does not meet the parameters of the residential property and household needs, you risk spending a lot of money on refurbishment in the future.

Two-pipe or single-pipe heating system - the choice should always be justified, both from a technical and economic point of view.

When abandoning ineffective centralized heating in favor of an individual system, it can be difficult for an apartment owner to decide which is better: a single-pipe or two-pipe heating system. Let's find out what type of system is best to choose for installation, what is the difference between these connection diagrams and how significant it is.

Advantages and disadvantages of single-pipe and two-pipe heating systems

The main difference between the two heating schemes is that the two-pipe connection system is more efficient in operation due to the parallel arrangement of two pipes, one of which supplies the heated coolant to the radiator, and the other removes the cooled liquid.

The single-pipe system circuit is a sequential type wiring, and therefore the first connected radiator receives maximum quantity thermal energy, and each subsequent one heats up less and less.

However, efficiency is an important, but not the only criterion that you need to rely on when deciding to choose one scheme or another. Let's consider all the pros and cons of both options.

Advantages:

ease of design and installation;
savings in materials due to the installation of only one line;
natural circulation of coolant, possible due to high pressure.

Flaws:

complex calculation of thermal and hydraulic parameters of the network;
the difficulty of eliminating errors made during design;
all network elements are interdependent; if one section of the network malfunctions, the entire circuit stops working;
the number of radiators on one riser is limited;
it is impossible to regulate the flow of coolant into a separate battery;
high heat loss coefficient.

Two-pipe heating system

Advantages:

possibility of installing a thermostat on each radiator;
independence of operation of network elements;
the ability to insert additional batteries into an already assembled line;
ease of eliminating errors made at the design stage;
to increase the volume of coolant in heating devices, there is no need to add additional sections;
no restrictions on the length of the contour;
coolant with the required temperature is supplied throughout the entire pipeline ring, regardless of the heating parameters.

Flaws:

complex connection diagram compared to a single-pipe;
higher consumption of materials;
installation requires a lot of time and labor.

Thus, a two-pipe heating system is preferable in all respects. Why do the owners of apartments and houses refuse it in favor of a single-pipe scheme? Most likely, this is due to the high cost of installation and the high consumption of materials required to lay two highways at once. However, one should take into account the fact that a two-pipe system involves the use of pipes of a smaller diameter, which are cheaper, so the total cost of installing a two-pipe option will not be much more than a single-pipe one.

Owners of apartments in new buildings are lucky: in new buildings, unlike residential buildings of Soviet construction, a more efficient two-pipe heating system is increasingly used.

Types of two-pipe systems

Two-pipe systems are divided into types depending on:

circuit type (open and closed);
method and direction of water flow (flowing and dead-end);
method of moving coolant (with natural and forced circulation).

Open and closed loop systems

Two-pipe system open type it did not take root in city apartments due to the peculiarity associated with the upper pipe distribution, which requires the use of an expansion tank. This device makes it possible to control and replenish the heating system with water, but there is not always space in the apartment to install such a large device.

Flow-through and dead-end

In a flow-through system, the direction of water flow in the supply and discharge pipes does not change. With a dead-end circuit, the coolant in the supply and return pipes moves in opposite directions. In such a network, bypasses are installed, and radiators are located in closed areas, which makes it possible to turn off any of them without disrupting the operation of the heating.

With natural and forced circulation

For natural circulation of water, pipes are laid with a mandatory slope, and an expansion tank is installed at the highest point of the system. Forced circulation carried out by a pump installed in the return pipe. Such a system requires air vent valves or Mayevsky taps.

Components of a two-pipe individual heating system

A two-pipe diagram of an apartment’s individual heating network includes the following elements:

heating boiler;
thermostatic valves for radiators;
automatic air vent valve;
balancing device;
pipes and fittings;
radiators;
valves and taps;
expansion tank;
filter;
temperature manometer;
circulation pump (if necessary);
safety valves.

Installation of a two-pipe heating system with upper and lower wiring

The two-pipe system has variations according to the installation scheme. The most commonly used are top and bottom wiring types.

Upper wiring

Laying the top wiring involves installation work to secure the heating system under the ceiling of the room. To batteries installed in places where cold air accumulates (window openings, balcony doors), branches coming from the main pipeline are supplied. Liquid enters the lower part of the pipeline, which is a drain, and has time to cool during circulation. This system is suitable for large premises, in one-room or two-room apartments installation of heating with overhead wiring is not recommended, since this is unprofitable for the owner from an economic and design point of view.

Installation of a heating circuit with upper horizontal wiring is carried out according to the following scheme:

The corner fitting required to connect the upward pipe is mounted to the boiler outlet.
Using tees and corners they produce horizontal installation top line: tees are installed above the battery, corners on the sides.
The final stage of installation of the upper horizontal is the installation of tees with branch pipes on the battery, supplemented with a shut-off valve.
On the lower branch, the outlet ends are connected to the common return line, on the section of which a discharge line is installed pumping station(circulation pump).

Bottom wiring

In a network with bottom wiring, outlet channels and supply heat-conducting pipes are installed. Superiority bottom diagram installation is expressed as follows:

The heating pipes are located in the lower, inconspicuous part of the room, which provides more opportunities for the implementation of various design projects.
Minimum pipe consumption: all installation work is carried out almost at the same level. The wiring point and radiator pipes are located at a short distance from each other.
Due to the simplicity of the circuit, installation of such a system will be possible even for a non-professional.

Important! The lower wiring is installed only if the circulation of the coolant will be forced, otherwise the water will not move through the heating pipes. This scheme is applicable exclusively in city apartments or one-story buildings.

One of the disadvantages of the scheme is the complexity of adjustment and balancing, but the ease of installation and reliability in operation covers these disadvantages.

Installation work begins with the outlet from the boiler pipes using an angle fitting in a downward direction.
The wiring is carried out at floor level along the wall using two pipes of equal diameter. One of them connects the boiler pipe to the entrance to the battery, the other is connected to the receiving pipeline.
Connections between radiators and pipes are made using tees.
The expansion tank is located at the highest point of the supply pipe.
The end of the outlet pipe is connected to the circulation pump; the pump itself is located at the entrance to the heating tank.

Most of the heating systems of apartment buildings and private buildings are built precisely according to this scheme. What are its advantages and are there any disadvantages?

Can a two-pipe heating system be installed with your own hands?

The difference between a two-pipe heating system and a single-pipe one

Let's first define what kind of beast this is - a two-pipe heating system. It’s easy to guess from the name that it uses exactly two pipes; but where do they lead and why are they needed?

The fact is that to heat a heating device with any coolant, it needs circulation. This can be achieved in one of two ways:

Single-pipe circuit (so-called barracks type)
Two-pipe heating.

In the first case, the entire heating system is one large ring. It can be opened by heating devices, or, which is much more reasonable, they can be placed parallel to the pipe; the main thing is that there is no separate supply and return pipeline passing through the heated room.

Or rather, in this case these functions are combined by the same pipe.

What do we gain and what do we lose in this case?

Dignity: minimum costs materials.
Disadvantage: large variation in coolant temperature between the radiators at the beginning and end of the ring.

The second scheme - two-pipe heating - is a little more complicated and more expensive. There are two pipelines running through the entire room (in the case of a multi-storey building - at least on one floor or in the basement) - supply and return.

First, the hot coolant (most often ordinary process water) goes to the heating devices to give them heat, and returns in the second direction.

Each heating device (or a riser with several heating devices) is placed in the gap between the supply and return.

There are two main consequences of this connection scheme:

Disadvantage: the pipe consumption is much higher for two pipelines instead of one.
Advantage: the ability to supply coolant to ALL heating devices at approximately the same temperature.

Advice: in case of a large room, it is necessary to install a control throttle on each heating device.

This will allow you to equalize the temperature more accurately, making sure that the flow of water from the supply to the return on nearby radiators will not “sag” those more distant from the boiler or elevator.

Features of two-pipe heating systems in apartment buildings

In case apartment buildings, of course, no one installs throttles on separate risers and constantly regulates water flow; equalizing the coolant temperature to at different distances from the elevator is reached in a different way: the supply and return pipelines running through the basement (the so-called heating pipeline) have a much larger diameter than the heating risers.

Alas, in new houses built after the collapse Soviet Union and the disappearance of strict state control over construction organizations, it began to be practiced to use pipes of approximately the same diameter on risers and benches, as well as thin-walled pipes installed for welding valves and other nice signs of the new social system.

The consequence of such savings is cold radiators in apartments located at the maximum distance from the elevator unit; By a funny coincidence, these apartments are usually corner and have common wall with the street. Quite a cold wall.

However, we have deviated from the topic. Two-pipe heating system in apartment building has one more feature: for its normal functioning, water must circulate through the risers, rising and falling up and down. If something interferes with it, the riser with all the batteries remains cold.

What to do if the heating system at home is running, but the radiators are at room temperature?

Make sure the riser valves are open.
If all the flags and switches are in the “open” position, close one of the paired risers (we are, of course, talking about a house with, where both beds are in the basement) and open the vent located next to it.
If the water flows with normal pressure, there are no obstacles to the normal circulation of the riser, except for the air at its upper points. Tip: drain more water until, after a long snorting of the air-water mixture, a powerful and stable stream of hot water flows. Perhaps in this case you will not need to go up to the top floor and bleed the air there - circulation will be restored after startup.
If the water does not flow, try to bypass the riser in the opposite direction: perhaps a piece of scale or slag is stuck somewhere. The countercurrent can carry it out.
If all attempts have no effect and the riser does not drain, most likely you will have to search for a room in which repairs were made and heating appliances were changed. Here you can expect any trick: a removed and plugged radiator without a jumper, a completely cut off riser with plugs at both ends, a throttle closed for general reasons - again in the absence of a jumper... Human stupidity truly gives an idea of infinity.

Features of the top filling system

Another way to install a two-pipe heating system is the so-called top filling. What's the difference? The only problem is that the supply pipeline migrates to the attic or upper floor. Vertical pipe connects the filling bottling with the elevator.

Circulation from top to bottom; the path of water from supply to return with the same building height is half as long; all the air ends up not in the jumpers of the risers in apartments, but in a special expansion tank at the top of the supply pipeline.

Starting up such a heating system is immeasurably simpler: after all, for full operation of all heating risers, you do not need to get into each room for top floor and vent the air there.

It is more problematic to turn off the risers when repairs are necessary: after all, you need to both go down to the basement and go up to the attic. Shut-off valves located both here and there.

However, the above two-pipe heating systems are still more typical for apartment buildings. What about private owners?

It’s worth starting with the fact that in private houses the 2-pipe heating system used can be radial and sequential in the type of connection of heating devices.

Radial: from the collector to each heating device there is its own supply and its own return.
Sequential: radiators are powered by all heating devices from a common pair of pipelines.

The advantages of the first connection scheme boil down mainly to the fact that with such a connection there is no need to balance a two-pipe heating system - there is no need to adjust the flow of the throttles of the radiators located closer to the boiler. The temperature will be the same everywhere (of course, with at least approximately the same length of the rays).

Its main disadvantage is the highest pipe consumption among all possible schemes. In addition, it will simply be impossible to extend the lines to most of the radiators along the walls while maintaining any decent appearance: They will have to be hidden under the screed during construction.

You can, of course, drag it through the basement, but remember: in private houses there are often no basements of sufficient height with free access there. In addition, the beam scheme is in any way convenient to use only when building a one-story house.

What do we have in the second case?

Of course, we have gotten away from the main disadvantage of single-pipe heating. The coolant temperature in all heating devices can theoretically be the same. The key word is theoretically.

Setting up the heating system

In order for everything to work exactly the way we want, we will need to configure a two-pipe heating system.

The setup procedure itself is extremely simple: you need to turn the throttles on the radiators, starting with those closest to the boiler, reducing the flow of water through them. The goal is to make sure that a decrease in water flow through nearby heating devices increases water consumption at distant ones.

The algorithm is simple: slightly tighten the valve and measure the temperature on the distant heating device. With a thermometer or by touch - in this case it doesn’t matter: the human hand perfectly feels a difference of five degrees, and we don’t need greater accuracy.

Alas, it is impossible to give a more accurate recipe other than “tighten and measure”: calculating the exact permeability for each throttle at each coolant temperature, and then adjusting it to achieve the required numbers is an unrealistic task.

Two points to consider when adjusting a two-pipe heating system:

It takes a long time simply because after each change in the dynamics of the coolant, the temperature distribution takes a long time to stabilize.
The heating adjustment of a two-pipe system must be carried out BEFORE the onset of cold weather. This will prevent you from defrosting your home heating system if you miss the settings.

Advice: with a small volume of coolant, you can use non-freezing coolants - the same as antifreeze or oil. It’s more expensive, but you can leave your house without heating in winter without worrying about the pipes and radiators.

Horizontal wiring system

With the horizontal arrangement of the supply and return pipelines, it has recently begun to penetrate from its patrimony - private and low-rise houses - into multi-storey new buildings.

Apparently, this is mostly due to the fact that studio apartments have begun to gain popularity: with a large room area without internal partitions it is simply unprofitable to pull risers through the ceilings, as a 2-pipe vertical heating system implies; It is much easier to do the wiring horizontally.

Typical two-pipe horizontal heating system modern house it looks like this: the risers from the basement run along the entrance. On each floor, taps are made into the risers, which supply coolant to the apartment through valves and discharge waste water into the return pipeline.

Everything else is exactly like in a private house: two pipes, batteries and chokes on each of them. By the way, a horizontal heating system - two-pipe or one-pipe - is easier to repair: to dismantle and replace a section of pipe, there is no need to violate the integrity of the ceiling; This is undoubtedly worth recording as an advantage of such a scheme.

The horizontal two-pipe heating system has one feature that follows from its design and leaves its mark on the start of heating. In order for the heating device to transfer maximum heat from the coolant to the air in the room, it must be completely filled.

This means that each such heating device, typically located above the supply and return pipelines, must be equipped with a Mayevsky valve or any other vent in the upper part.

Advice: Mayevsky taps are very compact and aesthetically pleasing, but they are not the most convenient device to remove air from the radiator.

Where aesthetics are not important (for example, when heating devices are covered with decorative grilles), it would be more convenient to install a water tap with the spout up or a ball valve.

We will not add this feature to the list of disadvantages: going around the radiators in one apartment once a year is not a big deal.

As you might easily guess, a two-pipe horizontal heating system is not only a solution strictly for one-story buildings or for apartment buildings with studio apartments. For example, two-story house with separate rooms can also be heated in the same way; you just have to make the wiring identical on both floors and connect pipelines from the boiler to both systems.

Of course, balancing such a heating system will have to take a little more time; but this is a one-time event, and it is not difficult to experience it once in a few years.

Finally, a few definitions and simply useful tips.

Depending on the direction of water flow in the pipelines, a 2-pipe heating system can be dead-end or direct-flow.

A two-pipe dead-end heating system is a system in which the coolant moves through the supply and return pipelines in opposite directions.
In a direct-flow two-pipe heating system, the direction of the current in both pipelines coincides.

In private houses, two-pipe heating systems with both forced and natural circulation can be used.

Forced circulation of the coolant is provided by a circulation pump; This quiet and low-power device is supplied, in particular, in the same housing with many electric boilers.
Natural circulation is used in small-volume heating systems; the principle of its operation is based on the fact that hot water has a lower density and rushes upward.

Two-pipe closed system heating, that is, a system with constant pressure and without both water supply and external coolant supply, it is the most popular solution for private houses with electric boilers.

In order to transfer heat to distant rooms from solid fuel boiler or stoves, an open one-pipe or two-pipe system is also quite suitable.

The design of a two-pipe heating system can include radiators of any type, registers and convectors as heating devices; warm floor implies a different connection method.

In order to install the heating of a two-pipe system, it is certainly better to involve specialists in the work. However, the abundance of materials on this topic on the Internet and the ease of assembling modern plumbing and heating systems with the help of fittings and machines make it possible for an amateur to do this work - if only he wanted to.

If you are installing a two-pipe heating system for a two-story house, when balancing the system it is worth taking into account the peculiarity of communicating floors in terms of heat distribution: all other things being equal, it will always be warmer on the second floor.