One-pipe heating system of a private house: schemes + an overview of the advantages and disadvantages

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Tatyana Lavrova
Last update: March 2019

Have you thought about arranging water heating in the house? It is not surprising, because the one-pipe heating system of a private house can be traditional and completely non-volatile or, conversely, very modern and fully automatic.

But you still have doubts about the reliability of this option - you don’t know which scheme to choose and which “pitfalls” await you? We will help clarify these issues - the article discusses the layout of a single-pipe system, the pros and cons of the owner of a house with a similar heating system.

The material of the article is equipped with detailed diagrams and visual photos depicting individual elements used in the assembly of heating. In addition, a video was selected with an analysis of the nuances of installing a single-pipe system with warm floors.

The principle of operation of water heating

In low-rise construction, the simplest, most reliable and economical construction with one highway has gained the greatest popularity. The one-pipe system remains the most popular way of organizing individual heat supply. It functions due to the continuous circulation of the heat transfer fluid.

Moving through pipes from a source of thermal energy (boiler) to heating elements and vice versa, he gives up his thermal energy and heats the building.

The coolant may be air, steam, water or antifreeze, which is used in houses of periodic residence. Most common water heating schemes.

Traditional heating is based on the phenomena and laws of physics - the thermal expansion of water, convection and gravity. When heated from the boiler, the coolant expands and creates pressure in the pipeline.

In addition, it becomes less dense and, accordingly, light. Pushed from below by heavier and denser cold water, it rises upward, so the pipeline leaving the boiler is always directed upward.

Under the influence of the created pressure, convection and gravity forces, the water goes to the radiators, heats them, and it cools itself.

Thus, the coolant gives off thermal energy, heating the room. Water returns to the boiler already cold, and the cycle begins anew.

Gas heating boiler
Modern equipment that provides heat to the house can be very compact. To install it, you do not even need to allocate a special room

The system heating with natural circulation also called gravity and gravity. To ensure the movement of the liquid, it is necessary to observe the slope of the horizontal branches of the pipeline, which should be equal to 2 - 3 mm per linear meter.

When heated, the volume of the coolant increases, creating hydraulic pressure in the line. However, since water is not compressed, even a slight excess will lead to the destruction of heating structures.

Therefore, in any heating system, a compensating device is installed - an expansion tank.

Classical gravity heating circuit
In a gravitational heating system, the boiler is mounted at the lowest point of the line, and the expansion tank at the highest. All pipelines are made downhill so that the liquid coolant can by gravity move from one system element to another

The difference between single-pipe and double-pipe systems

Water heating systems are divided into two main types - one-pipe and two-pipe. The differences between these schemes lies in the method of connecting the heat transfer batteries to the line.

The single-pipe heating main is a closed ring circuit.The pipeline is laid from the heating unit, radiators are connected to it in series, and lead back to the boiler.

Heating with one main is simply mounted and does not have a large number of components, therefore, it allows to significantly save on installation.

Natural circulation single pipe system diagram
Single-pipe heating circuits with natural coolant movement are arranged only with the upper wiring. A characteristic feature - in the schemes there are risers of the supply line, but there are no risers for return

Coolant movement double pipe heating carried on two highways. The first serves to deliver hot coolant from the heating device to the heat transfer circuits, the second - to drain the cooled water to the boiler.

The heating batteries are connected in parallel - the heated liquid enters each of them directly from the supply circuit, therefore it has almost the same temperature.

In the radiator, the coolant gives off energy and then cools off into the discharge circuit - the “return”. Such a scheme requires a double number of fittings, pipes and fittings, however, it allows you to arrange complex branched structures and reduce heating costs due to the individual adjustment of radiators.

The two-pipe system effectively heats large areas and multi-story buildings. In low-rise (1-2 floors) houses with an area of ​​less than 150 m² it is more advisable to arrange a one-pipe heat supply both from an aesthetic and economic point of view.

Connection of radiators in single-pipe and two-pipe heating systems
The two-pipe radiator connection scheme is not widely used in the individual heat supply device of private houses, since it is more difficult to install and maintain. In addition, twice the number of pipes looks unaesthetic

Single pipe heating options

Elements of any heating system:

  • heat source - boiler (solid fuel, electric, gas boiler;)
  • heat transfer devices - radiators, contours of underfloor heating;
  • coolant circulation device - special booster section of the highway, water pump;
  • device that compensates for excess coolant pressure in the lineopen expansion tank or closed type;
  • pipes, fittings and associated plumbing fittings.

Depending on the type of devices used, the heat supply scheme will also depend.

Natural and forced circulation systems

The circulation of the coolant in the heating system can be carried out naturally - under the influence of physical phenomena, or forced - through a circulation pump.

In the first case, the heating movement in the system is spontaneous and is called natural, in the second - forced or artificial.

Single-pipe heating system options
With a focus on design features, single-tube heating schemes are divided into two types. The first is an obsolete but simple flow diagram, the second is an advanced bypass circuit

To ensure fluid motion in the gravitational system, an acceleration section is necessary.This is a vertical pipe outgoing from the boiler, along which the heated coolant rises.

At the upper point, the pipeline smoothly turns down, so the water rushes along the highway with acceleration.

For the heating circuit with the upper wiring, as well as for two-story houses, this section is the supply pipe, since it rises to a sufficient level.

For heating a one-story building with a lower horizontal wiring, an accelerating collector is arranged, the height of which should not be less than 1.5 m from the level of the first radiator.

The booster section is a device that circulates the coolant in a gravity-fed heating system. The pipe bore diameter of this section of the trunk should be larger than its main part.

For example, with a pipe diameter of the trunk 25-32 mm, for a booster manifold, a pipe with a diameter of 40 mm is selected.

Booster manifold options
The upper point of the booster manifold is arranged in a convenient place near the boiler. Lower the manifold pipe in such a way as to ensure a sufficient height difference between the lower branch of the booster manifold and the lower point of the pipeline to maintain a constant slope of the pipeline

The main advantages of the gravitational system are complete non-volatility (in combination with a solid fuel boiler), simplicity and the absence of complex devices.

The disadvantages are quite a lot:

  • To minimize hydraulic resistance, pipe diameters should be large enough.
  • Each built-in device and device creates obstacles to the movement of fluid, therefore, the system has a minimum number of shutoff valves. This creates difficulties during repair, as it requires a complete shutdown of the system and drain of the coolant from the main.
  • For reliable operation, the gravity system must be carefully calculated and balanced, choosing the optimal pipe diameters and the number of sections of radiators. Extreme radiators in the system should be larger than those into which the coolant enters after exiting the boiler.

Installing a circulation pump in the system neutralizes almost all of its shortcomings. The device gives the coolant an additional impulse, allowing it to overcome the hydraulic resistance of the pipeline elements.

Forced single pipe heating schemes are implemented in private homes most often.

The device of a one-pipe heating system - two types of circuit
Thanks to the modernization of the flow system by installing bypasses, the coolant with the operating temperature almost simultaneously arrives at all devices

The pump can be mounted anywhere in the line. But it is worth considering that hot water reduces its operational life by acting on rubber parts (gaskets and seals).

Therefore, it is advisable to install the unit on the return pipe, where the cooled coolant circulates. Before it, it is mandatory to include a coarse filter to protect it from possible contaminants.

It is desirable to connect all devices and devices of heating systems through shutoff valves and bypasses.

Such installation will allow repair and maintenance of individual elements without the need to stop the entire system and completely drain the water.

Bypass connection for pump and radiator
Bypass can be unregulated and adjustable. In the first case, it is a simple pipe connecting the supply and outlet piping. In the second, it is equipped with shutoff three-way valves

Advantages of a forced circulation heating system:

  • You can implement more complex and branched circuits, increase the length of the contours;
  • There is no need for increased pipe diameters - the pump creates a pressure in the line that is sufficient for movement and uniform distribution of fluid;
  • The circulation is carried out at a given speed and does not depend on the degree of heating of the coolant and the presence of the acceleration section;
  • It is not necessary to observe the inclination angles when laying the pipeline, ascoolant movement is stimulated by the pump.

In addition, it is possible to install control devices on each radiator and maintain an optimal heating mode, reducing energy and heating costs.

There are only three drawbacks of single-pipe forced heating:

  • dependence on power supply;
  • noise - some buzz that produces a working pump;
  • cost - higher in comparison with the gravitational scheme the cost of the device.

It is quite simple to neutralize them. The energy dependence is solved by installing an autonomous electric generator or by the possibility of switching the system to a mode with natural circulation.

To make the pump work almost inaudible, it is enough to mount it in a non-residential premise - a bathroom, a toilet, a boiler room.

Diagram of a heating system with artificial circulation
At the upper points of the line, especially with forced heating with a closed expansion tank, it is necessary to provide for the possibility of bleeding the air released from the water. For radiators, these are automatic air vents or Mayevsky taps, for a pipeline - an air separator

Open or closed heating system?

To avoid excessive increase in hydraulic pressure in the system and its jumps, an expansion tank is installed. It takes excess water during expansion, and then returns it to the main line when cooling, restoring the balance of the system.

There are two fundamentally different designs, which determine the appearance of the entire system.

An open expansion tank is a partially or fully open tank that is connected to the main at its highest point, immediately after the boiler.

To prevent overflow of liquid over the edges at a certain level, a drain is provided, through which excess water will drain into the sewer or into the street.

In one-story houses, the compensating capacity is often displayed in the attic - in this case it must be insulated.

Open expansion tank diagram
In order not to constantly monitor the level of the coolant, a water pipe is brought to the expansion tank and a simple float valve is installed

A heating system with such a compensating device is called open. It is used in the arrangement of non-volatile or combined heat supply.

It assumes direct contact of the hot heat carrier with air, as a result of which its natural evaporation and oxygen saturation take place.

Based on this, an open heat supply scheme is characterized by the following disadvantages:

  1. When installing the pipeline of gravity systems, it is imperative that the slopes are observed - in this case, the air released in the system will be blown into the tank and atmosphere.
  2. It is necessary to regularly monitor and replenish the volume of water in the tank in time, preventing its excessive evaporation.
  3. You can not use antifreeze as a coolant, since toxic substances are released during its evaporation.

Oxygen contained in the circulating liquid causes corrosion damage in the steel parts of the radiators, reducing their service life.

However, it has pluses:

  • There is no need for constant monitoring of pressure in the line;
  • Even with small leaks, the system will regularly heat the house, as long as there is a sufficient amount of liquid in the main;
  • You can even replenish the coolant in the system with a bucket - just pour the expansion tank into the water to the required level.

The closed expansion tank is a robust sealed housing, the internal volume of which is divided into two parts by the membrane. One cavity is filled with air, the second is connected to the highway.

When heated, the coolant, increasing in volume, pushes the membrane towards the air chamber, which plays the role of a damper.As the water cools, the hydraulic pressure decreases and the compressed air balances the system, squeezing the excess water back into the pipeline.

The device of the expansion tank membrane type
All closed tanks are equipped with an air valve. In emergency mode, when the pressure in the air chamber exceeds the allowable limit, it vents gas and protects the device from destruction

A system with a membrane expansion tank is called closed. This is a completely devoid of air access closed hydraulic line.

Compensating capacity can be built in anywhere in the system, however, most often it is installed on the return pipe near the boiler - to increase ease of maintenance.

A closed heating system is characterized by a slight overpressure. Therefore, a mandatory element of the highway becomes security group.

The assembly consists of an air vent, a pressure gauge and a safety valve for dumping the coolant in emergency mode. It is mounted with shut-off valves on the supply pipe for the possibility of shutdown in case of repair.

If there is a rise in the pipeline, then it is placed at its upper point.

Efficient single pipe system

When designing heating, many factors are taken into account - the availability of stable power supply and a separate room for equipment (boiler room, boiler room), the number of floors and layout, the aesthetics of the future design, etc.

In each case, the location of the equipment and how to connect it will differ.

For a very small room - a country house - the simplest self-flowing scheme for sequentially connecting batteries directly into the main pipeline will become most effective.

When installing two or three radiators, it is not necessary to install a large number of shutoff valves - in this case it is easier to drain the water from the system if necessary.

In buildings with a larger area, the heat supply system is a complex, sometimes branched, structure. In this case, the best option is forced heating according to the Leningradka scheme with diagonal connection of heat transfer batteries and adjustable bypass.

Scheme Leningrad
Such a scheme guarantees maximum heating of the radiator area and the ability to adjust and adjust the operating mode. To disconnect any of the elements of the system, it is not necessary to drain water from the entire line

Ways to connect the radiator to the highway

Heat dissipation of radiators depends on how they are connected to the line.

There are three main types of connection:

  • Diagonal;
  • Lateral;
  • Lower.

Consider the features of each of these methods in more detail.

Diagonal or Cross Connection

Diagonal, or cross, connection is most effective. The maximum heating of the battery over the area is achieved, and there is practically no heat loss.

According to this scheme, the supply pipe is led to the upper pipe of the radiator, and the discharge pipe is connected to the lower pipe located on the opposite side of the device.For devices with a large number of sections, only the diagonal type of connection is used.

Lateral or one-way connection

Lateral, or one-way, connection allows to achieve uniform heating of all sections of the device.

To connect, the supply and outlet pipelines are let down on one side. Most often, such a connection is used with a heating device with an upper wiring.

Distribution of the heat carrier along the radiator with lateral connection
The heat dissipation of heating with a lateral connection of radiators, with a flow from top to bottom is equal to 97%. With the reverse movement of the coolant - from the bottom up - this figure is 78%

Lower radiator to pipe connection

The bottom connection is not the most efficient heating scheme. However, it is arranged quite often, especially when the main pipeline is hidden under the floor.

The inlet and outlet pipes are led to the lower nozzles located on different sides of the radiator.

Distribution of the heat carrier along the radiator at the bottom connection
The heat transfer rate at the lower connection of radiators is 88%

Advantages and disadvantages of a single pipe system

Single-pipe heating has gained wide popularity in the field of private construction.

The main reasons are the relatively low cost of the structure and the ability to mount it on its own, without the involvement of specialists.

But a one-pipe heating system has other advantages:

  • Hydraulic stability - the heat transfer of other elements of the system does not change when individual circuits are disconnected, radiators are replaced, or sections are built up;
  • The device of the line costs a minimum number of pipes;
  • It is characterized by low inertia and warm-up time due to less than in the two-pipe, the amount of coolant in the main;
  • It looks aesthetically pleasing and does not spoil the interior of the room, especially if the trunk pipe is hidden;
  • Installation of valves of the latest generation - for example, automatic and manual temperature regulators - allows you to fine-tune the operation mode of the entire structure, as well as its individual elements;
  • Simple and reliable design;
  • Simple installation, maintenance and operation.

When connecting control and monitoring devices to the heating system, it can be transferred to a fully automatic mode of operation.

Possible integration with Smart Home system - in this case, you can set the program of optimal heating modes, depending on the time of day, season and other decisive factors.

Concealed radiators in the interior
The single-pipe heating line can be completely hidden by the finish. Such a device not only does not spoil the appearance of the room, but also becomes its detail - an item of interior

The main disadvantage of single-tube heat supply is the imbalance in the heating of heat-transferring batteries along the length of the line.

The coolant cools as it moves along the circuit. Because of this, radiators installed far from the boiler heat up less than closely located ones. Therefore, it is recommended to install slowly cooling cast-iron appliances.

The installation of a circulation pump allows the coolant to heat the heating circuits more evenly, however, with a sufficient length of the pipeline, its substantial cooling is observed.

Reduce the negative effect of this phenomenon in two ways:

  1. In radiators remote from the boiler, the number of sections is increased. This increases their heat-conducting area and the amount of heat given off, allowing the rooms to be heated evenly.
  2. They draw up a project with a rational arrangement of heat-releasing devices in rooms - the most powerful are installed in children's rooms, bedrooms, and “cold” (northern, corner) rooms. As the coolant cools down, the living room and kitchen go, they end up with non-residential and utility rooms.

Such measures minimize the disadvantages of a single-pipe system, especially for single- and two-story buildings with an area of ​​up to 150 m². For such houses, single-pipe heating is the most profitable.

Conclusions and useful video on the topic

Not only radiators, but also the contours of underfloor heating are connected to the single-pipe heating line. The video shows how to carry out such an installation.

Single pipe heating is a simple and reliable system. However, for effective heating, it is necessary to carefully select its individual elements. To do this, it is advisable to seek the advice of a specialist, where they will help you perform the estimated calculation.

Do you disagree with the schemes given in our article? Or do you have practical experience in arranging one-pipe heating in a private house? Your experience will be useful to our readers. Feel free to share your knowledge in the comments below.

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Visitors Comments
  1. Valera

    In my house, which my grandfather was still building, a one-pipe system. I can confirm that it is simple and high-quality. It has been working “with a bang” for about fifty years, and nothing has been done to it, the house is warm in the most severe frost. Extremely successful system. If I were building a new house, I would also make a one-pipe one, only I would put the radiators on time, and not cast-iron, as in the old house.

  2. Alexander

    I installed heating in a private house, I gave preference to a one-pipe system, since, in fact, it allows us to significantly save on materials. The most important thing is to observe the slope so that there is a natural flow of water. It was easier for me to do it - the boiler itself was located in the basement. This arrangement was a big plus, because I did not have to buy a powerful pump. During operation, I noticed minus - the water in the distant devices of the system is already warm, because it gives up most of the energy in the beginning.

  3. Alexei

    Can the return flow be carried out in the same way as the feed? Or necessarily around the perimeter of the house?

    • Expert
      Alexey Dedyulin

      I understand that you want to implement a two-pipe heating system? You do not have to route the return line around the perimeter, there are different options for how to do this. If there is a one-pipe system, then in this case it is definitely not necessary to lay along the perimeter. I attach an approximate scheme.

      Attached photos:
      • Ravshan

        If you hold pipes along the upper entrances to the batteries under the type of one-pipe system - will it work? Example in the photo.

        Attached photos:
  4. Kirill

    It is possible, but only so that the return does not bask in the feed if there is natural circulation, it is not necessary to steam with the forced option. But you need an alternative source of email. energy if the boiler is tv. fuel, gas stands protection.

  5. Dmitry

    I want to make three batteries for the fireplace stove, but I will not be able to tilt. I want to connect the batteries in series from one to another. The return will go the same way, not around the perimeter. There will be a pump. The return will flow from the last battery directly into the fireplace. Can you do that?

    • Expert
      Alexey Dedyulin

      I do not see any problems to implement such a wiring for the heating system. But I would highly recommend using an expansion tank in the system. I think that there is no need to explain how such an implementation will be more practical than without an expansion tank. I am applying an approximate wiring diagram for your case.

      Attached photos:
  6. Dmitry

    The single pipe system is the perfect solution for small spaces. Simple installation and operation. Thanks for the info.