Let's figure it out together: which is more efficient than a one-pipe or two-pipe heating system? Diagram of a two-pipe heating system Pros and cons of a two-pipe heating system.

Two-pipe heating system

There are only two types of heating systems: one-pipe and two-pipe. In private homes, they try to install the most efficient heating system. It is very important not to sell too cheap, trying to reduce the cost of buying and installing a heating system. Providing a house with heat is a lot of work, and so that the system does not have to be installed anew, it is better to understand thoroughly, and make "reasonable" savings. And in order to draw a conclusion about which of the systems is better, it is necessary to understand the principle of operation of each of them. Having studied the advantages and disadvantages of both systems, both from the technical side and from the material, it becomes clear how to make the best choice.

One-pipe heating system

It works according to the principle: along one main pipe (riser), the coolant rises to the upper floor of the house (in the case of a multi-storey building); all heating devices are connected in series to the downstream. In this case, all the upper floors will be heated more intensively than the lower ones. It is a very common practice in Soviet-built multi-storey buildings, when it is very hot on the upper floors and cold on the lower ones. Private houses most often have 2-3 floors, so one-pipe heating does not threaten with a large contrast of temperatures on different floors. In a one-story building, heating is almost uniform.

Advantages of a one-pipe heating system: hydrodynamic stability, ease of design and installation, low costs of materials and funds, since it is required to install only one line for the coolant. The increased water pressure will ensure normal natural circulation. The use of antifreeze increases the efficiency of the system. And, although this is not the best example of a heating system, it has become very widespread in our country due to the high savings in material.

Disadvantages of a one-pipe heating system: complex thermal and hydraulic calculation of the network;
- it is difficult to eliminate errors in the calculations of heating devices;
- the interdependence of the work of all network elements;
- high hydrodynamic resistance;
- a limited number of heating devices on one riser;
- the inability to regulate the flow of the coolant into individual heating devices;
- high heat loss.

Improvement of one-pipe heating systems
A technical solution has been developed to regulate the operation of individual heating devices connected to one pipe. Special closing sections - bypasses - are connected to the network. The bypass is a jumper in the form of a pipe segment that connects the direct pipe of the heating radiator and the return pipe. It is equipped with taps or valves. The bypass makes it possible to connect automatic thermostats to the radiator. This allows you to regulate the temperature of each battery and, if necessary, shut off the supply of coolant to any individual heating device. Thanks to this, individual devices can be repaired and replaced without completely shutting down the entire heating system. Correct connection of the bypass makes it possible to redirect the flow of the coolant through the riser, bypassing the element being replaced or repaired. For a high-quality installation of such devices, it is better to invite a specialist.


Vertical and horizontal riser diagram
According to the installation scheme, one-pipe heating is horizontal and vertical. A vertical riser is the connection of all heating devices in series from top to bottom. If the batteries are connected in series with each other throughout the floor, this is a horizontal riser. The disadvantage of both connections is the trapped air in radiators and pipes.


The heating system with one main riser is equipped with heating devices with increased reliability characteristics. All devices in a one-pipe system are designed for high temperatures and must withstand high pressures.

Installation technology of one-pipe heating system
1. Installing the boiler at the selected location. It is better to use the services of a specialist from the service center if the boiler is under warranty.
2. Installation of the main pipeline. If an improved system is being installed, then the obligatory installation of tees at the points of connection of radiators and bypasses. For heating systems with natural circulation when installing pipes
create a slope of 3 - 5o per meter of length, for a system with forced circulation of the coolant - 1 cm per meter of length.
3. Installation of a circulation pump. The circulation pump is designed for temperatures up to 60 ° C, therefore it is installed in that part of the system where the lowest temperature is, that is, at the inlet of the return pipe to the boiler. The pump is running on the power supply.
4. Installation of the expansion tank. An open expansion tank is installed at the highest point of the system, a closed one - more often next to the boiler.
5. Installation of radiators. They make a markup of places for installing radiators, fix the latter with brackets. At the same time, they comply with the recommendations of the manufacturers of devices for observing the distances from walls, window sills, floors.
6. Connect the radiators according to the selected scheme, installing Mayevsky taps (for airing out the radiators), overlapping taps, plugs.
7. The system is pressurized (air or water is supplied to the system under pressure to check the connection quality of all system elements). Only after that, the coolant is poured into the heating system and a test run of the system is carried out, the adjustment elements are adjusted.

Two-pipe heating system

In a two-pipe heating system, the heated coolant circulates from the heater to the radiators and vice versa. This system is distinguished by the presence of two pipeline branches. One branch is used to transport and distribute the hot coolant, and along the second, the cooled liquid from the radiator returns to the boiler.

Two-pipe heating systems, like single-pipe ones, are divided into open and closed depending on the type of expansion tank. In modern two-pipe closed heating systems, membrane-type expansion tanks are used. The systems are officially recognized as the most environmentally friendly and safe.

According to the method of connecting elements in a two-pipe heating system, they are distinguished: vertical and horizontal systems.

In a vertical system all radiators are connected to a vertical riser. Such a system allows each floor to be connected separately to the riser in a multi-storey building. With this connection, there are no air pockets during operation. But the cost of this connection is slightly higher.


Two-pipe horizontal the heating system is mainly used in single-storey houses with a large area. In this system, the heating devices are connected to a horizontal pipeline. Risers for wiring the connection of heating elements are best installed on the staircase or in the corridor. Air locks are vented by Mayevsky's taps.

Horizontal heating system is with bottom and top wiring... If the wiring is lower, then the "hot" pipeline runs in the lower part of the building: under the floor, in the basement. In this case, the return line is laid even lower. To improve the circulation of the coolant, the boiler is deepened so that all the radiators are above it. The return line is located even lower. The upper air line, which must be included in the circuit, serves to remove air from the network. If the routing is top, then the "hot" piping runs along the top of the building. The place for laying the pipeline is usually an insulated attic. With good insulation of pipes, heat loss is minimal. With a flat roof, this design is unacceptable.

Advantages of a two-pipe heating system:
- even at the design stage, it is envisaged to install automatic thermostats for heating radiators and, therefore, the possibility of regulating the temperature in each room;
- pipes in the premises are routed according to a special collector system, which ensures the independence of the operation of the circuit devices;
- in other words, the circuit elements in a two-pipe system are connected in parallel, in contrast to a single-pipe system, where the connection is sequential;
- batteries can be embedded in this system even after assembling the main line, which is impossible with a one-pipe system;
- the two-pipe heating system can be easily extended vertically and horizontally (if you have to finish building the house, then the heating system does not need to be changed).


For this system, it is not necessary to increase the number of sections in radiators in order to increase the volume of coolants. Errors made at the design stage are easily eliminated. The system is less vulnerable to defrosting.

Disadvantages of a two-pipe heating system:
- a more complex connection diagram;
- higher project cost (much more pipes are required);
- more laborious installation.
But these disadvantages are very well compensated for in winter, when the maximum accumulation of heat occurs in the house.

Installation of a two-pipe heating system
I. Installation of a heating system with an upper horizontal wiring
1. An angle fitting is mounted to the branch pipe leaving the boiler, which turns the pipe upward.
2. Using tees and angles, mount the top line. Moreover, the tees are attached above the batteries.
3. When the upper line is installed, the tees are connected to the upper branch pipe of the battery, a shut-off valve is installed at the junction point.
4. Then the lower branch of the outlet pipeline is mounted. It goes around the perimeter of the house and collects all the pipes coming from the lowest point of the batteries. Usually this branch is mounted at the basement level.
5. Install the free end of the outlet pipe in the receiving branch pipe of the boiler; if necessary, install a circulation pump in front of the inlet.

In a similar way, a closed system with a constant pressure maintained by a pressure pump and an open heating system with an open expansion tank at the highest point are installed.

The main disadvantage of a two-pipe heating system with top wiring is the installation of an expansion tank outside a warm room on the ceiling. The heating system with top wiring also does not allow taking hot water for technical needs, as well as combining the expansion tank with the supply tank of the water supply system at home.

II. Installation of a heating system with lower horizontal piping
The system with bottom piping replaced the two-pipe heating system with top piping. This made it possible to place an open-type expansion tank in a warm room and in an easily accessible place. Also, some saving of pipes became possible, the combination of an expansion tank and a supply tank of the water supply system at home. The compatibility of the two tanks eliminated the need to control the coolant level, made it possible, if necessary, to use hot water directly from the heating system.
In such a scheme, the discharge line remains at the same level, and the supply line is lowered to the level of the discharge line. This improves aesthetics and reduces pipe consumption. But it works only in systems with forced circulation.

Installation sequence:
1. Mount downward-facing corner fittings on the boiler nozzles.
2. At floor level, two pipe lines are installed along the walls. One line is connected to the supply outlet of the boiler, and the second - to the receiving one.
3. Tees are installed under each battery to connect the batteries to the pipeline.
4. An expansion tank is installed at the top of the supply pipe.
5. As with the top piping, the free end of the discharge pipe is connected to the circulation pump and the pump to the inlet of the heating tank.

Maintenance of a two-pipe heating system
For high-quality maintenance of the heating system, it is necessary to implement a whole range of measures, including adjusting, balancing and adjusting the two-pipe heating system. To adjust and balance the system, special pipes are used, located at the highest and lowest point of the heat pipe. Air is released through the upper branch pipe, and water is supplied or drained through the lower branch pipe. With the help of special taps, excess air in the batteries is vented. To regulate the pressure in the system, a special container is used, into which air is pumped using a conventional pump. Special regulators, reducing the pressure in a specific battery, adjust the two-pipe heating system. The consequence of the redistribution of the pressure is the equalization of temperatures between the first and last batteries.

Almost all heating systems currently available in any buildings and structures can be attributed to one of the two classes mentioned in the heading of this article.

The answer to the question of what is better is a one-pipe or two-pipe heating system, you can only carefully understand the advantages and disadvantages of each of the options considered.

Characteristics of a one-pipe home heating system

Which heating system is more efficient, one-pipe or two-pipe? It is impossible to answer this question unequivocally.

One-pipe CO has all the basic elements inherent in any heating system. The main ones are:

• A heating boiler that runs on any type of fuel that is most available at the location of the heated building. It can be a gas, solid fuel or liquid fuel boiler. The type of fuel used by the boiler has no effect on the heating scheme;
• Pipes through which the coolant circulates;
• Locking equipment for various purposes (latches, valves);
• Heating devices and thermometers;
• Air bleed valves. Placed on radiators (Mayevsky taps) and at the top point of the CO;
• Drain valve (at the lowest point of the CO);
• Expansion tank, open or closed.

Benefits of using one-pipe systems

The difference between a one-pipe heating system and a two-pipe heating system is that the first is by far the simplest and most effective way to heat buildings with an area of ​​up to 150 m2.

The installation of a circulation pump and the use of modern technical solutions make it possible to guarantee the required temperature parameters in the heated rooms. Therefore, answering the question, which one-pipe or two-pipe heating system to choose, among the indisputable advantages of the first system, it should be noted:

Installation versatility. Such a system can be installed in a building of any configuration, and a closed loop guarantees the movement of the coolant along the entire perimeter of the heated premises.
Unlike two-pipe, one-pipe CO can be mounted in such a way that the heating of the premises starts from the coldest side of the building (northern), regardless of the place where the boiler is installed, or from the most important premises (nursery, bedroom, etc.).

The installation of the system requires a minimum number of pipes and shut-off and control equipment, the complete installation of CO is performed in a much shorter time than CO with two pipes. All this allows you to get serious savings in funds allocated to pay for construction work.

The system allows installation of the pipe directly on the floor or under it, which makes it possible to implement any design solutions in the premises.

The scheme provides for serial and parallel connection of heating devices, which allows you to control the temperature in them and adjust it;

Subject to certain installation requirements, the system can be made in a non-volatile version. In the event that the pump stops when there is a power failure, the coolant supply line switches to a parallel laid branch. In this case, CO, from the option with forced (PC) circulation, goes over to natural circulation (EC).

Disadvantages inherent in the specified CO option

A two-pipe or one-pipe heating system for a private house? Evaluating the pros and cons, it should be borne in mind that the main disadvantage of a single-pipe CO is the fact that the heating devices are connected in series. And this, during operation, excludes the possibility of effective temperature control in one of them, without that it does not affect the rest of the radiators.

A factor influencing the choice whether a two-pipe or one-pipe heating system of a private house will be mounted at your facility, do not forget about such a disadvantage of the latter as the increased pressure in the system compared to the two-pipe version. This can be achieved by increasing the power of the circulation pump installed in the system, which entails an increase in operating costs and increases the likelihood of leaks, and also requires more frequent addition of coolant to the system.

The system requires vertical filling. And this automatically determines the location of the expansion tank in the attic and, accordingly, the solution to the issue with its insulation.

If such a system is installed in a two-story building, then another problem arises. The temperature of the water supplied to the first floor may differ from that initially supplied to the second floor by almost 50%. To avoid this, installation of additional jumpers is required on each floor, and the number of sections of heating devices on the first floor should significantly exceed that installed on the second.

Which heating system is more efficient, one-pipe or two-pipe? We have already covered the first one. Let's consider the second one.

Such a system a priori implies the presence of 2 pipelines placed along the perimeter of the heated room. Radiators cut in between them, which dampen pressure drops and create hydraulic bridges. However, the problems created by this can be leveled out due to the correct configuration of the CO.

• Two-pipe systems can be vertical and horizontal, depending on the location of the supply and return (parallel to the slabs or perpendicular to them). However, it should be understood that the circuit installed in apartment buildings is inherently a horizontal two-pipe CO.

  A two-pipe vertical will turn out when the radiators are installed not in the breaks of the risers (as in the above case), but between the supply and return.

• Passing and dead-end COs. The first type includes systems in which hot water, passing through the radiator, moves in the same direction along the return line. If the direction of movement of the heating medium changes after the heater, the system is classified as dead-end.

  The required option is selected taking into account the presence of doorways on the CO pipe-laying line, which is quite difficult to bypass, it is easier to return the water in the direction it came from.

• With bottom and top filling.
• With natural (EC) and forced (PC) circulation.

Advantages and disadvantages of the system

One-pipe and two-pipe heating systems are compared according to their inherent advantages and disadvantages. The advantages of the second system are:

1. The flow into all heating devices of the heat carrier with the same temperature, which allows you to set your own value for the required temperature for a specific room;
2. Less pressure losses in the lines, which allows using a pump of lower power (saving money on operation);
3. The system allows installation in buildings of any size and number of storeys;
4. The presence of shut-off valves allows for preventive maintenance and repairs without stopping the entire CO.

The most popular, despite the presence of innovative technologies, remains the "classic" heating system. That is, with water heating (or some other liquid heat carrier) in the boiler room and its further transfer through the system of laid pipelines through the premises for heat exchange. The type of heat generator can be different (electric, solid or liquid fuel, or even a furnace with a water circuit), but the general principle of operation remains the same.

It is distinguished by a fairly high efficiency, the ability to create the most comfortable microclimate, is simple and understandable to operate, and with proper design and installation, it lends itself very well to adjustments.

But with all the external similarity of the applied water systems, they can differ quite significantly structurally, use different principles of transporting the coolant through the radiators installed in the premises. The subject of our today's consideration is a two-pipe heating system of a private house, which, given the existing shortcomings, can still be considered the best option.

What is a two-pipe system and why is it considered optimal?

If we outline the principle of operation of any "water" heating system, so to speak, in a nutshell, then it is as follows.

• In the boiler, due to one or another external energy source, water or other heat carrier is heated to a certain temperature level.
• Any system is a closed loop of pipes through which the coolant is transferred to heat exchange devices (radiators or convectors), and returns back to the boiler room. Thus, the water gives off heat to the premises, gradually cooling down at the same time.
• The cooled coolant enters the boiler room again, heats up - and so the cycle repeats further and further while the boiler is operating. In a well-debugged autonomous system, by the way, the boiler does not heat constantly - when the required heating level in the premises is reached, its operation is suspended automatically, and the reverse switching on will occur when the temperature drops to some predetermined threshold.

This principle of operation is the same for all such systems. The closedness of the general circuit ensures constant water circulation and heat transfer. But the closed loop itself can be organized in different ways, which is the main difference between the systems.

The easiest way, of course, is to connect the supply and return pipes of the boiler (or the collector, if we are talking about some dedicated section of the system) with one pipe, on which all the necessary heating radiators are located, as if "stringing" them onto this loop closed by a loop. Exactly (in one variation or another) a one-pipe system is arranged.

Indeed, it is very simple, but let's take a look at the diagram - and its main drawback will seem quite obvious.

Even unfamiliar with the laws warmly technology, the reader should absolutely understand that the coolant, which is successively passing from one heat exchange device to the next, loses significantly in temperature. This is understandable: what is a "return" for the previous radiator, for the next already becomes a supply. On the scale of not even the largest heating system, this difference becomes very significant. That is, as the distance from the boiler room increases, the heating of the batteries is less and less.

In such a primitive form, as shown above, the one-pipe system, of course, is practically not used - it would be a completely mediocre performance. More often they use more advanced schemes, which nevertheless allow them to somehow regulate their work.

An example is the popular one-pipe system known by the characteristic name "Leningrad". And although the temperature differences on the batteries are no longer so pronounced in it, it is not possible to completely get rid of it - all the same, a constant admixture of the cooled coolant on each of the radiators goes into the supply pipe.

The Leningradka heating system - advantages and disadvantages

Such a scheme for organizing the contours has won wide popularity for its economy in terms of material consumption, ease of installation. What it is, according to what principles it is created and debugged - read in a special publication of our portal.

There are certainly many ways to minimize this negative phenomenon. So, for example, as the distance from the boiler room increases, the number of radiator sections is gradually increased, special thermostatic devices are installed, and the diameters of pipes in different sections of the circuit are varied. Nevertheless, it is impossible to completely get rid of the "temperature gradient" from radiator to radiator. All the same, the dependence of subsequent heating devices on the previous ones can be traced.

That is why a two-pipe heating system becomes the optimal solution. It excludes such a phenomenon.

Each heat exchange device is necessarily connected to two pipes - one is supplied with a hot coolant coming from the boiler room, the other is used to remove the cooled one, "sharing" its heat with the air in the room.

Gas boiler prices

gas boiler

Please note that nowhere along the entire length of the supply pipe is the cooled coolant added to it. That you can talk that "temperature parity" is maintained at the entrance to any of the radiators. If there is a difference, then it is connected only with the fact that slight temperature losses are possible due to heat transfer from the pipe body itself. But this moment cannot be considered essential, especially since pipes with hidden wiring are very often enclosed in thermal insulation.

In a word, the supply pipe turns into a kind of collector, from which heat exchange devices are already being distributed. And the second collector pipe is responsible for collecting and transporting the cooled coolant to the boiler room. AND no significant dependence of the functioning of any of taken separately from the work of others - not traced.

What kind Benefits typical for such a system?

• First of all, the uniform temperature distribution at the radiator inlets allows very flexible control of the heating system as a whole. For each of the batteries maybe to choose your own thermal mode of operation, for example, by installing thermostatic regulators - depending on the type of heated room and its real need for heat flow. This does not in any way affect the work of other sections of the general contour.

• Unlike a one-pipe system, there are minimal pressure losses in the circuit. This simplifies the balancing of all sections of the circuit, it becomes possible to use a less powerful, that is, less expensive and more economical circulation pump.
• There are no restrictions either on the length of the contours (within reasonable limits, of course), or on the number of storeys in the building, or on the complexity of the wiring. That is, the system can be integrated into a private house of any layout and area.
• If necessary, take any of the radiators out of service - turn them off if there is no need to heat a specific room, or even dismantle them for certain preventive or repair work. This does not affect the overall performance of the system.

As you can see, the advantages already listed above are quite enough to understand all the benefits of installing a two-pipe heating system. But perhaps she has serious limitations ?

• Yes, of course, and these include, in the first place, the higher cost of the initial investment. The reason is trivial, and lies in the name itself - much more pipes are required for such a system.
• The second drawback is inextricably linked with the first - since there are more pipes, it means that the installation work during the creation of the system is larger and more complicated.

True, a reservation can be made here as well. The fact is that the specificity of a two-pipe heating system often makes it possible to get by with pipes of a small diameter. So the total costs, in comparison with a single-pipe distribution with the same heat transfer rates, may not differ so frighteningly. And this - with a whole set of clear advantages!

Another disadvantage can be considered a more significant volume of the coolant circulating through the pipes. This, of course, is not essential if ordinary water is used in this capacity. But in the case when the system is supposed to be filled with a special coolant-antifreeze, the difference can be felt. However, it is also not so essential as to neglect the advantages of the two-pipe system because of this.

What are two-pipe heating systems?

The principle of supplying the coolant to the radiators and its removal through two different pipes is common to the whole variety of such systems. But according to other parameters, they can differ quite seriously.

Open and closed systems

As mentioned above, any system is a closed loop. But a prerequisite for its normal functioning is the presence of an expansion tank. The explanation is simple - any liquid increases in volume when heated. Therefore, some kind of capacity is needed that is capable of "taking in" these volume fluctuations.

An expansion tank is included in all systems. And the difference is whether it is open, communicating with the atmosphere, or sealed.

Open type system

Open-type heating systems once "ruled alone" - there were simply no other options available to the owner of the house. And today, even with the possibility of other solutions, they are still very popular.

The main feature of such systems is the presence of a tank installed at the highest point of the pipe distribution. A prerequisite is that the tank is maintained at normal atmospheric pressure, that is, it does not close hermetically.

Let's go through the main elements of the system:

1 - a boiler providing heating of the coolant circulating through the kennels.

2 - riser (pipe) supply.

3 - open expansion tank.

4 - heat exchange devices installed in the premises (radiators or).

5 - "return" line.

6 - pump with appropriate piping, which circulates the coolant along the circuit.

What is an open expansion tank? It should be understood correctly - from the name it does not at all follow that it is really completely open, that is, it is not equipped with any cover. Of course, in order to protect the container from dust or debris, and in order to at least to some extent reduce the effect of liquid evaporation, as a rule, a lid is provided on it. But it does not in any way limit the direct contact of its volume with the atmosphere, that is, it is leaky.

An open-type expansion tank can be purchased ready-made, but very often home craftsmen make it on their own. For this, any container of the required capacity can be used (preferably made of a material that is resistant to corrosion).

At the bottom of the tank there is a branch pipe for connecting it to the heating circuit. There may (optionally) be provided for connections to the make-up system and to the overflow pipe - if the volume of expanded water goes beyond the established limits, the excess is discharged into the drain.

The determining condition is the location of the tank at the highest point of the system. This is due to two circumstances:

It is simply impossible to install a leaky tank lower - otherwise, according to the law of communicating vessels, the coolant will pour out of it.

The open expansion tank in this position does an excellent job of the function air vent... All air bubbles or gases formed as a result of possible chemical reactions go up and from the tank are released into the atmosphere.

By the way, the location of the expansion tank shown in the diagram is not at all a dogma, although it is most often practiced. But other options are also possible:

a- the most common Option: the tank is located directly in the upper part of the vertical "booster" section of the supply line.

Prices for aluminum radiators

aluminum radiators

b- the connection to the expansion tank comes from the "return" line, for which a long vertical pipe is used. Sometimes the features of the system itself, or even the specifics of the structure, are forced to such an arrangement. True, in this case, the functionality of the tank as a gas outlet practically disappears. And you have to install additional devices on the circuit itself in the upper part and on

v - the tank is installed at the top of the remote supply drain. In principle, this can be any section of the upper feed loop - the main thing is that the container stands at the highest point.

G- let's say right away, an atypical location of the tank, similar to "a", but with the pumping unit of the immediate field of it.

Merits open-type systems are ease of installation, no need for additional complex assemblies. The risk of dangerously high pressure in the system is completely eliminated.

But also disadvantages she has a lot:

• The highest point where such an expansion tank can be installed, in most cases in private housing construction, falls on the attic. And this means that either the attic must be warm, or the tank itself will require high-quality thermal insulation. Otherwise, in extreme cold, the water in it may freeze - and this is one step before a serious accident. Moreover, one cannot dump from the accounts and considerable unproductive heat leakage from the system.

On the Internet, you can find many examples when an open expansion tank is trying to be installed indoors under the ceiling. The option is certainly possible, but not always. With the upper location of the supply pipe, the space under the ceiling may not be enough, because the volume of the tank is recommended to withstand at least 10% of the volume of the entire coolant in the heating system. And such an addition, you see, will not decorate the interior of the room. It will be easier to purchase a closed membrane tank.

• The second obvious disadvantage is liquid evaporation, which, of course, can be minimized, but cannot be completely excluded. Even in the case of water, this will require additional trouble - monitoring its level or using special automatic make-up devices. Otherwise, you can miss the moment, and the system will be "airy".

In addition, an open tank is incompatible with systems that use special coolants, antifreeze. Firstly, it is wasteful, and secondly, the vapors of many "non-freezing systems" are by no means harmless to the human body.

An open tank is not recommended for use even if an electrode heating boiler is installed in the system. Due to the peculiarities of the heating principle, the efficiency of the boiler operation directly depends on the balanced chemical composition of the coolant. Naturally, with constant evaporation, it will be extremely difficult to maintain an optimal composition.

One more nuance. Some heat exchange devices, for example, heating radiators, reveal their advantages only at rather high values ​​of the coolant pressure in the system. And in the case of an open tank, this is simply impossible to achieve, since the pressure is balanced by the external atmospheric pressure. This should also be borne in mind.

Closed heating system

An expansion tank is also included in the general scheme of such a heating system, but it already has a completely different design. To put it simply, this is a sealed container, divided into two parts by an elastic partition - a membrane. One part of the tank is filled with air, with the creation of a certain excess pressure, the second is communicated through the pipe with the heating circuit. An example diagram is shown in the illustration below:

1 - metal tank body.

2 - branch pipe for connection to the heating system circuit.

3 - a membrane that plays the role of an elastic partition between the two chambers of the tank.

4 - a chamber filled with a coolant.

5 - air chamber.

6 - nipple device for preliminary pumping of the air chamber.

The heating system is completely sealed. While it is not working, the previously created pressure in the air chamber keeps the diaphragm in the lower position. As the coolant heats up, according to the laws of thermodynamics, the pressure rises in the system, the liquid tries to expand in volume. The only possibility for this is precisely the expansion tank. Under the influence of increasing pressure, the coolant begins to squeeze the membrane upward, thereby increasing the volume of the water chamber of the tank and, accordingly, reducing the volume of the air. This also increases the pressure in the air chamber.

If everything is calculated correctly, and the operating characteristics of the expansion tank correspond to the parameters of the system, then there is an approximate parity of pressure in the chambers. When measuring the level of heating in the system, the membrane will simply take a slightly different position in one direction or another, and the equilibrium will not be disturbed. With the heating completely turned off, as the coolant cools down, the membrane will return to its original lower position.

Here is approximately the same simplified diagram that we used above, but only for a closed heating system:

The numbering of the main elements and nodes of the system has been retained, only two new items have been added.

7 - membrane expansion tank.

8 - "security group".

Everything is very simple and very effective. Of course, you will have to buy a tank - making it yourself is hardly reasonable. (There is a nuance - some modern models of heating boilers, especially wall-mounted ones, are already equipped with them, as they say "by default"). But these additional costs look not burdensome, and in return there are many benefits.

• In principle, there are no restrictions at all on the installation site of the diaphragm expansion vessel. Most often, it is mounted on the return line not far from the boiler and the pumping unit, but this is not at all a mandatory rule.

• A closed heating system allows you to carry out any kind of piping, if, of course, it uses the principle of forced circulation (this will be discussed below).
• The owner is free to use any of the possible heat carriers.
• The system can maintain the optimal value of the pressure (head) of the water in the circuits.
• The coolant does not come into contact with air, that is, it is not saturated with it, which means that corrosion processes on the metal parts of the circuit will not become more active.

A few words about disadvantages, since there are very few of them:

• If the boiler is not initially equipped with an expansion tank, you will have to purchase it yourself. However, with an open tank, the situation is about the same.
• The closed system must be completely sealed, the coolant does not come into contact with air, but the processes of gas formation in the boiler, pipes and radiators cannot be completely ruled out. And there is no way out, as in an open system, for gases. That is, you will have to install gas vents at the highest points of the system and on radiators.
• The tightness of the system requires monitoring. The situations are different, and sometimes failure of any level of protection can lead to a dangerous increase in pressure in the circuits. This is fraught with leaks at the connections, and even an explosive situation.

In order to combat these negative features, in a closed system, it is necessary to install the so-called "security group".

Prices for bimetallic radiators

bimetallic radiators

1 - control and measuring device. This is either just a pressure gauge showing the level of pressure of the coolant in the system, or even a combined device that also shows the heating temperature at the same time.

2 - automatic air vent self-relieving the accumulated gases.

3 - safety valve with a preset level of operation. That is, in the event that the pressure reaches a possible "ceiling", the valve will release excess fluid, preventing the creation of a dangerous situation.

Very often, a safety group is installed directly in the boiler room - it is easier to track the pressure gauge readings this way. Often, heating boilers already have a similar safety node. True, this does not relieve the owner of the need to install air vent valves and at the top points of the heating system.

The selection of the required expansion tank model is subject to certain rules and is carried out on the basis of calculations. This will certainly be discussed in a series of publications specially dedicated to calculationsall basic elements of a two-pipe heating system.

Differences in the principle of organizing the circulation of the coolant.

For normal heat exchange, the coolant should not be static - it constantly moves along the heating circuit. And this necessary circulation can be achieved in different ways.

Two-pipe system with natural circulation of the coolant.

Not so long ago, such a system in private houses was considered almost the only possible one - it was very difficult to acquire pumping equipment. Nothing, as they say, was completely dispensed with. Many do not abandon it to this day - for its reliability and complete energy independence.

The movement of the coolant flow in this system is due to the effect of natural gravitational forces arising from the difference in the density of the heated and cooled coolant. In addition, the special arrangement of the individual elements of the heating circuit contributes to the same.

The diagram below will help you understand the principle more easily:

First, let's look at the top of the diagram. The numbers on it indicate the following:

1 - heating boiler.

2 - supply pipe, and, in particular, its vertical so-called accelerating section of large diameter, usually installed directly from the boiler.

3 - heat exchange device - radiator. The diagram shows the lowest radiator in the system. It must be located with an excess relative to the boiler. This height difference is shown by the letter h.

4 - "return" pipe.

When the coolant in the boiler is heated, the density of the liquid changes - hot water always has a density (Pror), which is less than that of cooled water (Rohl). Naturally, this already gives the flow an upward direction, along the acceleration section. From the top point, all pipes are laid with a slight downward slope (depending on the diameter - from 5 to 10 mm per meter of pipe length). This is the second factor promoting natural flow.

And finally, we look at the bottom. Let's discard the upper "red" section - we will leave only the "return" from the last radiator to the boiler. There is already no difference in density - the water has given up its heat on the last radiator, and with approximately the same temperature level it flows towards the boiler room. But that same excess in height, which was mentioned above, does its job. Before us is nothing more than ordinary communicating vessels. It is quite understandable that any hydraulic system with a fluid of equal density and temperature will tend to equilibrium. That is, in this case - to the equality of levels in both "vessels". It turns out that such an arrangement, even if a slope is not provided (and it is still usually set even in this section), a directed flow of the coolant is created towards the boiler. The more significant this excess " h”, The greater the naturally generated head. True, this height, even in the largest system, should still not exceed 3 meters.

The consolidated action of all these interrelated factors creates a stable circulation in the heating circuit.

Dignity systems with natural circulation of the coolant are as follows:

• Reliability and reliability - no complex mechanism or assemblies are assumed, and the durability of the entire system, in principle, depends solely on the condition of the circuit pipes and radiators.
• Complete independence from power supply. Naturally, no costs for consumed electricity are assumed.
• The absence of pumping equipment is also the silent operation of the system.
• The natural circulation system has a very useful self-regulation quality. What does this mean? Let's say the temperature in the premises of the house is close to optimal. Heat transfer on radiators is not so intense, the coolant cools less, therefore, and the difference in density becomes less noticeable. This tends to "calm" the flow. It got colder. The water in the batteries cools more, the difference in the density of the hot and cooled coolant grows, and therefore the intensity of its circulation spontaneously increases. Thus, the system itself is constantly striving for the optimal temperature balance. This property greatly simplifies the regulation of the system, so that often it is not necessary to install additional thermostatic devices in the premises.
• If desires appear, then any system with natural circulation can be equipped with a pumping unit without much difficulty.

All this is wonderful, but also very serious disadvantages for such a system, it is decent.

• Considerable difficulties are expected with the installation of the contours. Firstly, pipes of a rather large diameter must be used, which makes the entire structure heavier and more expensive. And pipe sizes must be varied correctly in different areas. Secondly, the slope of the pipes must be respected, and sometimes this becomes, due to the peculiarities of the premises, a considerable problem. Thirdly, the system will work correctly only with the upper supply of the coolant to the radiators, that is, you will have to forget about the hidden piping.

• There are restrictions on the remoteness of radiators from the boiler room, if viewed in plan. Otherwise, the hydraulic resistance of pipelines and fittings may exceed the created natural head of the coolant, and the circulation will freeze in remote areas.
• Low pressure indicators in pipes almost completely make it impossible to use modern thermostatic devices for precise temperature control on radiators. The system of "warm floors" with natural circulation is impossible in principle.
• The system turns out to be rather inert. In order for it to work in the "normal mode", the primary operation of the boiler at high power will be required, otherwise the circulation will not work.
• The energy efficiency of such a system is not the best. Part of the generated energy is spent precisely on creating conditions for ensuring circulation. This makes it undesirable to use natural circulation circuits if an electric boiler is installed - the losses will be too expensive.

But, nevertheless, a system with natural circulation is quite viable, and is used quite often. It was said above that it is not designed for large houses. It should be correctly understood that here we mean the “spread” of the building in the plan - the distance between the radiators and the boiler in the horizontal projection cannot be more than 25, maximum - 30 meters. And try to keep the slope at such a considerable distance!

But for a compact house, even with two floors, the system is quite suitable. Practice has proven that natural circulation, without the use of any pumping equipment, will cope with the height of the booster section up to 10 meters. And this, you see, is a lot. For example, if you "give" a floor of 3 meters in height, and taking into account the location of the boiler room below the level of the radiators (for example, in a semi-basement or basement), then there will be enough opportunities for a two-story house, even with a margin.

An example of an open two-pipe natural circulation heating system for a two-story house is shown in the illustration below:

The boiler is located at the lowest point of the heating system (item 1). As already mentioned, it should be below the radiators of the first floor by an amount h. In the immediate vicinity of the boiler, a water supply pipe (item 2) is cut into the "return" line, which provides the initial filling of the system or its recharge as needed - with gradual evaporation of the coolant.

Upward from the boiler is a large-diameter "booster" pipe. It is laid up to an open expansion tank installed in the vodka room (pos. 3). The tank in this case is made of a large volume and is located approximately in the center of the building. The fact is that in the diagram shown, it performs another interesting function - it becomes a semblance of a collector from which feed risers diverge in different directions. Radiators (pos. 4) of both the second and the first floors are connected to these drains, from which, in turn, the "return" pipes descend, closing on the return manifold leading to the boiler. On each of the radiators, valves are installed (pos. 5), which allow both to close this section (for example, to carry out preventive and repair work), and to fairly accurately regulate the heat transfer of the battery.

It was already mentioned above that the correct selection of pipe diameters for each section of the system is very important. Ideally, this requires special calculations, although many experienced craftsmen easily select the required diameters, based on the practice of many years of work.

In this diagram, diameters are indicated by letters of the Latin alphabet. Pipe sections with diameters shown are limited to the tapping points of branches (tees) or radiators.

a- DN 65 mm

b- DN 50 mm

c- DN 32 mm

d- DN 25 mm

e - DN 20 mm

(ДУ - nominal diameter of the pipe).

Forced circulation heating system

With this system, detailed explanations are probably not required. The circulation of the coolant in it is ensured by the installation of a pumping unit (one or even several, if the system is highly branched and requires different pressure values ​​in its individual sections).

The installation of pumping equipment immediately gives a lot of important advantages :

• The restrictions for heating systems, caused by both the number of storeys of the building and its size, disappear. It all depends on the parameters of the installed pump.
• It becomes possible to use pipes with a significantly smaller diameter for the installation of circuits - and this is both easier to assemble and cheaper. There are no requirements for mandatory compliance with the slope of the pipes.
• Forced circulation allows the system to be put into operation smoothly, without "peak" heating at the beginning of work. And during operation, the temperature of the coolant in the circuit can be maintained in a very wide range. That is, even at low heating levels, the circulation will not stop, which is quite likely in a system with a natural fluid flow. This opens up wide possibilities for precise adjustment of both the entire system as a whole and its individual sections.
• Based on the foregoing, there is no big difference in temperatures at the "return" and boiler feed pipe. And this leads to less wear of heat exchangers, prolongs the "active life" of the equipment.
• The system does not impose any restrictions either on the method of pipe laying, or on the connected heat exchange devices. That is, it is quite possible to use hidden gaskets, any radiators or "warm floors" or thermal curtains.
• Stable pressure indicators of the coolant in the supply pipes allow the use of any modern thermostatic heating controllers on radiators or convectors.

There is limitations , which also need to be remembered.

Convector prices

convectors

• Building a system, especially if it is different ramification and diversity used heat exchange devices will require careful calculations for each of the sections. It is necessary to achieve complete "harmony" of the work of all circuits. This is usually achieved by installing a hydraulic switch.

What is a water gun in a heating system?

A heating system is a complex "organism" that requires consistency in the work of all its sections. Achieve such "harmony" allows a simple, but very effective device - which is described in detail in a separate publication of our portal.

However, it is difficult to call this a disadvantage, since any heating system should be created based on preliminary calculations.

• The main disadvantage is pronounced volatility. That is, in case of power outages, the system will paralyze. If in a settlement where construction is underway, such phenomena happen quite often, you will have to think about purchasing an uninterruptible power supply.

Very often they resort to another method. The system is made "hybrid", that is, with the ability to work with both forced circulation of the coolant and natural. In this case, the pump is connected according to a special scheme using a bypass jumper. The owner has the ability, if necessary, to switch the direction of flow using the valves - through the pump or directly through the "return" pipe.

In some pumping units, an automatic valve is even provided, which will independently open the passage through a straight section if the pump has stopped for any reason.

Useful information on circulation pumps.

In order for the heating system to work correctly and as efficiently as possible, the choice of the optimal pump model should be approached wisely. More details about the device, about the variety of models, about calculating the required characteristics - in a special article on our portal.

Differences between two-pipe systems according to wiring diagrams

Possible differences in vertical layout

Let's start with the "vertical". If the house is planned on several levels, then either a riser system or floor wiring can be applied.

• The riser system was clearly demonstrated in the diagram above. There, however, the top feed from an open-type expansion tank is shown. But these are particulars. Even if the circulation is provided by pumping equipment, this does not change anything in principle. On the contrary, it becomes possible to apply a scheme with a lower supply of the coolant to the risers, which at the same time become a kind of vertical collectors.

With a small number of storeys (just for a private house, where there are rarely more than two floors), such a system shows high efficiency. The contours extending upward from the main collector (laid, for example, in the basement or along the floor of the first floor), do not differ in great length and ramification, that is, their hydraulic calculation and adjustment on heating devices will also be easy.

It makes sense to resort to such schemes when the rooms on the first and second (or more) floors are symmetrically located, that is, the radiators will be installed exactly one above the other. Otherwise, it doesn't make much sense.

A clear drawback is that for each group of risers, you will have to punch a passage in the interfloor overlap. These are unnecessary worries, including for insulation, waterproofing and decorative finishing, and weakening of the structure. And one more obvious "minus" - vertical risers are almost impossible to place discreetly. For many owners, this factor is critical.

• Therefore, it is very often done in this way. There is only one vertical pair of risers (supply and "return"). Removing it from your eyes is not a difficult task. But on each of the floors, its own horizontal piping is performed along

Differences in horizontal layouts by floor

Now - about horizontal wiring diagrams for one-story construction, or within one single floor.

• First of all, the scheme may differ in the location of the supply pipe.

It can be located on top (usually under the ceiling), and in this case the coolant is supplied to the heating radiators only from above.

Unfortunately, this approach may be the only one possible when equipping a heating system with natural circulation of the coolant. As we saw earlier, the general "direction" of the fluid flow must be observed from top to bottom. That is, it will not work to arrange the flow below the radiator - full circulation through it may not happen. Alas, these are the costs of this system.

There are no words, such an arrangement of the pipe capitally spoils the overall interior, since it is not an easy task to disguise it in the area of ​​the ceiling, and there is also nowhere to get away from the vertical section laid from it directly to the radiator.

In this regard, it is much more profitable bottom feed circuit for which there are no restrictions if a circulation pump is installed in the circuit. It will not be difficult to place such a layout secretly. For example, it can be hidden under a decorative floor covering, and sometimes even pipes are completely filled with a screed.

In a word, it is this principle of the arrangement of the supply and return pipes that seems to be optimal.

• Very serious differences can be in the organization of the direction of the circulation flow of the coolant.

The diagram below shows a diagram in which, on the conditional three floors, three possible options for laying circuits to heating radiators are shown.

• Let's start with the conditional "first floor". Here, a dead-end wiring scheme is used, or, as it is also called, with a counter flow of the coolant. With this approach, all heat exchange devices are divided into branches - their number may differ (two are shown for example). In each of these branches, the supply pipe is laid up to the final radiator (dead end), and the flow of the cooled coolant moves towards it through the "return" pipe.

The dead-end scheme is very popular, since it requires a minimum number of pipes and is not so difficult to install. But she also has very serious drawbacks. So, within the limits of even one small dead-end branch with several radiators, it is necessary to use pipes of various diameters (with its gradual decrease to a dead-end battery). In addition, balancing of this dedicated circuit with the help of special valves is imperative in order to prevent the flow from closing through the radiator closest to the collector.

• On the "second floor" a diagram with a passing movement of the coolant is shown. It has another name - Tichelman's loop. For such a wiring, pipes of the same diameter are used. It is argued that this arrangement provides equal pressure at the inlet to each of the radiators, which greatly simplifies balancing this circuit. It becomes possible to very accurately set the temperature regimes on each battery. True, the consumption of pipes during the installation of such a scheme, of course, increases.

True, many experienced craftsmen are not at all delighted with the advantages of a system with a passing movement of the coolant. Moreover, theoretical layouts are given that some of the advantages are seriously exaggerated, and the calculations show a far from cloudless picture.

What is the conclusion from this comparison? The tips are as follows:

With small dimensions of the contour along the perimeter (if it does not exceed 30 ÷ 35 meters), the Tichelman loop will indeed become the optimal solution. That is, its advantages will be shown only on a closed loop, which is very limited in total length.

It is also quite suitable for large circuits, but only if a very "budgetary" system is planned, for which there is no opportunity to purchase thermostatic devices for precise temperature control in each of the rooms. Indeed, the pressure spread at the points of entry into the batteries is small. But the hydraulic resistance will already be very significant, pipes of an increased diameter will be required, that is, there is no longer any advantage over the dead-end system in this regard. On the contrary, the complexity of the installation and the large consumption of pipes makes the associated wiring seriously losing.

If the perimeter of the building (floor) exceeds 35 meters, then it will be much more profitable to split the system into several (two or more) dead-end branches. Yes, a hydraulic calculation will be required for each of them. But this will be justified by both lower costs and lower heat losses during the transportation of the coolant. Well, for regulation, in any case, you cannot do without thermostatic valves.

• On the conditional "third floor" - a collector or beam wiring diagram. From the common manifold unit (which is usually tried to be placed closer to the geometric center of the floor), a separate "dead-end line" is laid to each of the radiators - the supply and return pipes.

Such a scheme allows the use of pipes with a minimum diameter, however, their consumption can be very significant. In the illustration, the routing is shown along the walls, but in practice, the routing of individual contours is often carried out along the shortest distance, using hidden routing under the floor surface.

The control accuracy of each individual radiator is maximized here. True, the complexity of installation with the need for subsequent finishing and the high consumption of materials still limit the widespread use of such an approach to the layout of the system.

The first steps in the calculations are to determine the total power of the heating system and the required heat transfer from radiators

Any heating system is a very complex "organism", and each of its elements must function in close connection with others. This "unison" is ensured by carrying out accurate calculations of each of the sections.

On the scale of one publication, it is simply impossible to consider all the subtleties of the calculations. It probably makes sense to collect a whole series of articles devoted to the design of a particular section or unit of two-pipe systems of various types. And this will be in the nearest plans of the editorial office.

But you still need to start somewhere. And this beginning will be a preliminary calculation of the total power of the heating system and the required heat transfer from radiators for each of the rooms.

Prices for popular heating radiators

What is the calculation based on?

Why are these two parameters listed above together? Everything is explained simply.

It would be more correct to start planning a heating system with an estimate of the amount of heat that must be supplied to each of the premises of a house under construction or an existing one. This will allow you to immediately outline the number and characteristics of heat exchange devices, that is, virtually arrange them in the rooms.

The total amount of heat energy required on the scale of the house (that is, the sum of all values ​​calculated for individual rooms) will show the required power of the boiler equipment.

Having a preliminary plan for the arrangement of radiators, you can decide on the choice of the preferred scheme of the heating system, with the features of piping around the premises. This creates the basis for hydraulic calculations, determination of pipe diameters, coolant flow rate, pump characteristics, performance of manifold units, etc. And so on until the very end. But the beginning, as you can see, comes precisely from the needs of each of the premises.

There is quite widespread the practice is to take the required heat output for heating the room, equal to 100 W / 1 m² of area. Alas, this approach does not differ in accuracy, since it does not take into account the forecast of possible heat losses, which will require compensation at the expense of the heating system. Therefore, we propose a different, much more detailed algorithm, which takes into account many nuances.

There is no need to be afraid in advance - with our online calculator, you will not expect any difficulties in performing the calculation.

Moreover, the calculator will help the reader to assess in advance the advantages of a particular scheme for connecting radiators to pipes, placing them on the wall. And if you plan to purchase and install collapsible batteries, then you can immediately calculate the required number of sections.

We are getting acquainted with the calculator, and below there will be a number of explanations on how to work with it.

All existing heating systems can be conditionally divided into two groups:

• one-pipe;
• two-pipe.

To answer the question: which heating system is better than one-pipe or two-pipe, it is necessary to understand on what principle each of them works.

This will clearly indicate the advantages and disadvantages of each of them, and will also help to make the most optimal choice, both technically and in terms of the necessary means, in order to understand a one-pipe or two-pipe heating system is more suitable.

Videos about the types of heating systems can be easily found on the World Wide Web.

Advantages of a one-pipe heating system

• fewer materials and funds;
• hydrodynamic stability;
• less laboriousness of design and installation;
• no special requirements for infrastructure.

But with all these advantages, we can say with complete confidence that a one-pipe system is far from the best scheme according to which heating can be realized. Still, the main reason why the one-pipe system has become widespread in our country is the indisputable saving of material.

One-pipe heating system: how it works

Such a system has one riser (main pipe). Through it, heated water (or any other coolant) rises to the upper floors of the building (if it is a multi-storey building).

All heating devices (units for heat transfer - batteries or radiators) are connected in series to the downstream.

Modernization of one-pipe heating systems

A technical solution that makes it possible to regulate the operation of each individual heater has been developed.

It consists in connecting special closing sections (bypasses), which make it possible to integrate automatic radiator thermostats into the heating. What other benefits are possible with bypass installations? Let's talk about this in more detail later.

The main advantage of such modernization is that in this case it becomes possible to regulate the heating temperature of each battery or radiator. In addition, you can completely shut off the coolant supply to the device.

Thanks to this, such a heater is repaired or replaced without shutting down the entire system.

The bypass is a bypass pipe fitted with valves or taps. With the correct connection of such fittings to the system, it will allow to redirect the flow of water through the riser, bypassing the repaired or replaced heater.

It is not difficult to understand that the task of installing such devices into the system with your own hands is hardly possible to solve, even if detailed instructions are available. In this case, you cannot do without the participation of a specialist.

A heating system with one main riser must be completed with heating devices that have increased characteristics in terms of reliability. Any devices in a one-pipe system must withstand increased pressure and high temperature.

Vertical and horizontal riser diagram

According to the implementation scheme itself, single-column heating is of two types:

• vertical;
• horizontal.

If the heating devices are connected from the upper floor to the lower one, this is a vertical riser. If the batteries are connected in series with each other throughout all rooms of a building floor, this is a horizontal riser.

Disadvantages of a one-pipe heating system

• the complexity of the thermal and hydraulic calculation of the network;
• the difficulty of eliminating errors in the calculations of heating devices;
• the interdependence of the characteristics of the operation of all devices in the network;
• increased hydrodynamic resistance;
• limiting the number of heating devices on one riser;
• impossibility of regulating batteries and radiators with regulators (pictured below)

Important!
If more than ten heating devices (for example, eleven) are connected to the vertical riser, then the water temperature on the first radiator in the network will be about 105 ° C, and on the last - 45 ° C.

Single-column heating in individual construction

If heating with one main riser is mounted in a one-story building, then it will be possible to get rid of at least one significant drawback of such a scheme - uneven heating.

If such heating is implemented in a multi-storey building, then the upper floors will be heated much more intensively than the lower floors. This will lead to a situation where it is cold on the ground floors of the house and hot on the upper floors.

A private house (mansion, cottage) is rarely more than two or three floors high. Therefore, the installation of heating, the scheme of which was described above, does not threaten that the temperature on the upper floors will be much higher than on the lower floors.

Two-pipe heating system: advantages and disadvantages

Advantages of the two-pipe manifold system

• It becomes possible to install automatic thermostats for radiators or radiators. In this case, such devices are provided at the stage of system design;
• Pipes according to this scheme are routed through the premises through a special collector system. If one of the elements in the system breaks down or starts to work unstably, this does not affect the operation of the other devices in the circuit in any way;
• In other words, with a two-pipe system, the elements of the thermal circuit have a parallel connection, as opposed to a serial one - with a one-pipe system.

The main disadvantages of a two-pipe heating system

• heating becomes more complex according to the connection diagram;
• the price of the project requires more funds;
• installation of the circuit is more time consuming.

Where are two-pipe heating systems used:

• for individual housing construction;
• in projects of the so-called "elite" housing;
• high-rise buildings (with top wiring)

Important!
When designing buildings with more than 9-10 storeys, it is better to use either a one-pipe system with a horizontal floor wiring, or a two-pipe system with an upper vertical wiring.
This will provide better circulation.

Advantages of two-pipe collector heating

• reduced hydrodynamic resistance;
• the ability to independently adjust the temperature in each room.

The collector heating system requires careful preliminary adjustment before starting. Adequate infrastructure is required for the correct installation, installation and operation of a two-pipe system.

Wiring options for a two-pipe system

Top routing

The top-wired system is suitable for natural circulation (without the use of pumps) (). It has a lower flow resistance. In this case, the upper supply pipe is partially cooled. Due to this, additional pressure is generated for the circulation of the coolant.

Bottom wiring

In a bottom-wired system, the supply and return pipes are side by side.

There are such modifications of the lower wiring:

So, one-pipe heating system or two-pipe? In each case, it is necessary to have preliminary calculations and a project (see), on the basis of which both heating devices and the main pipes themselves (see) will be selected. The final decision is only yours.

Several heating systems are known today. They are conventionally divided into two types: one-pipe and two-pipe. Determining the best heating system requires a good understanding of how they work. With this, it will be easy to make the choice of the most suitable heating system, taking into account all the positive and negative qualities. In addition to technical characteristics, when selecting, you must also take into account your financial capabilities. Still, is a one-pipe or two-pipe heating system better and more efficient?

All the details that are installed in each system are present here. The most important are:

Positive and negative properties of a one-pipe system

It consists of one horizontal collector and several heating batteries connected to the collector with two connections. Part of the coolant moving along the main pipe enters the radiator. Here, heat is released, the room is heated and the fluid is returned back to the collector. Liquid gets into the next battery at a slightly lower temperature. This continues until the last radiator is filled with coolant.

The main distinguishing feature of a one-pipe system is the absence of two pipelines: return and supply. This is the main advantage.

No need to lay two lines. You will need a lot fewer pipes, and installation will be easier. No need to punch through walls and make additional fixings. It would seem that the cost of such a scheme is much lower. Unfortunately, this is not always the case.

Modern fittings allow automatic adjustment of the heat transfer of each individual battery. To do this, it is necessary to install special thermostats with a large flow area.

However, they will not help get rid of the main disadvantage associated with the cooling of the coolant after it enters the next battery. Because of this, the heat transfer of the radiator, included in the common circuit, decreases. To keep warm, it is necessary to increase the capacity of the battery by building up additional sections. Such work increases the cost of the heating system.

If you make the connection of the device and the line from pipes of the same diameter, the flow will split into two parts. But this is unacceptable, since the coolant will begin to cool quickly when it enters the first radiator. In order for the battery to fill at least a third of the coolant flow, it is necessary to increase the overall collector size by about 2 times.

What if the collector is installed in a large two-story house, the area of ​​which exceeds 100 m2? For the normal passage of the coolant, pipes with a diameter of 32 mm must be laid along the entire circle. To mount such a system, large financial investments are required.

To create water circulation in a private one-story house, you need to equip the one-pipe heating system with an accelerating vertical collector, the height of which must exceed 2 meters. It is installed after the boiler. There is only one exception, this is a pumping system equipped with a wall-mounted boiler, which is suspended at the desired height. The pump and all additional elements also increase the cost of one-pipe heating.

Individual construction and one-pipe heating

The installation of such a heating, which has a single main riser in a one-story building, eliminates the serious disadvantage of this scheme, uneven heating. If something similar is done in a multi-storey building, the heating of the upper floors will be noticeably stronger than the heating of the lower floors. As a result, an unpleasant situation will arise: it is very hot upstairs, and cold downstairs. A private cottage usually has 2 floors, so the installation of such a heating scheme will evenly heat the whole house. It won't be cold anywhere.

Two-pipe heating system

The operation of such a system is somewhat different from the above-described scheme. The coolant moves along the riser, entering each device through the branch pipes. Then, through the return pipe, it returns to the main pipeline, and from there it is transported to the heating boiler.

To ensure the operability of such a scheme, two pipes are supplied to the radiator: through one, the main supply of the coolant is carried out, and through the other, it is returned to the common line. That is why they began to call it two-pipe.

The pipes are installed along the entire perimeter of the heated building. Radiators are installed between pipes to absorb pressure surges and form hydraulic bridges. Such work creates additional complications, but they can be reduced by creating the correct scheme.

Two-pipe systems are divided into types:

Main advantages

What are the positive qualities of such systems? Installation of such a heating system makes it possible to achieve uniform heating of each battery. The temperature in the building will be the same on all floors.

If you attach a special thermostat to the radiator, you can adjust the desired temperature in the building yourself. These devices have no effect on the heat dissipation of the battery.

Double-pipe piping makes it possible to maintain the pressure value during the movement of the coolant. It does not require the installation of an additional high power hydraulic pump. The circulation of water occurs due to gravitational force, in other words, by gravity. With a poor head, you can use a low-power pumping unit that does not require special maintenance and is quite economical.

If you use shut-off equipment, various valves and boypasses, then it will be possible to mount such systems in which it becomes possible to repair only one radiator without turning off the heating of the whole house.

Another advantage of two-pipe piping is the possibility of using any direction of hot water.

The principle of operation of the passing scheme

In this case, the movement of water along the return and main pipes occurs along the same path. In a dead-end scheme - in different directions. When the water in the system has a passing direction, and the radiators have the same power, excellent hydraulic balancing is obtained. This eliminates the use of battery preset valves.

With different power radiators, it becomes necessary to calculate the heat loss of each individual radiator. To normalize the operation of heating devices, it will be necessary to install thermostatic valves. It is difficult to do it yourself without specific knowledge.

Hydraulic gravity is used when installing a long-distance pipeline. In short systems, a dead-end circuit for the circulation of the coolant is created.

How is the maintenance of the two-pipe system

For the service to be of high quality and professional, it is necessary to perform a whole range of operations:

• adjustment;
• balancing;
• customization.

To adjust and balance the system, special branch pipes are used. They are installed at the very top of the system and at its lowest point. Air is discharged after opening the upper pipe, and the lower outlet is used to drain the water.

Excess air accumulated in the batteries is vented using special taps.

To adjust the pressure of the system, a special container is installed. Air is pumped into it with a conventional pump.

Using special regulators that help reduce the water pressure in a particular radiator, a two-pipe heating system is adjusted. After the redistribution of the pressure, the temperature in all radiators is equalized.

How can you make a two-pipe from a one-pipe

Since the main difference between these systems is the decoupling of streams, it is quite easy to perform this rework. It is necessary to lay another pipeline parallel to the existing pipeline. Its diameter should be one size smaller. Next to the last device, the end of the old collector is cut off and tightly closed. The remaining section is connected directly in front of the boiler to a new pipeline.

An associated water circulation pattern is formed. The outgoing heating medium must be routed through a new pipeline. For this purpose, the inlet pipes of all radiators must be reconnected. That is, disconnect from the old collector and connect to the new one, according to the diagram:

The rework process can present additional difficulties. For example, there will be no room for laying a second line, or it is very difficult to break through the floor.

That is why, before embarking on such a reconstruction, you need to think over all the details of future work. It may be possible to adjust the one-pipe system without making any alterations.