Among the countless options for wiring heating systems, the most common is the diagram of a two-pipe heating system with bottom wiring and forced circulation coolant. You can assemble it yourself, provided that it is designed and calculated correctly. But not every homeowner understands these issues, and even if it is decided to hire specialists for design and installation, their work must be checked. This is only possible if you understand what a two-pipe heating system in a private home is and how to install it correctly. Our article is just to help such homeowners.
Types of two-pipe heating systems
Our topic is entirely devoted to these systems, since they have a number of advantages over single-pipe ones. There is no point in listing them all; it is worth noting only the main thing: the two-pipe system works in such a way that all radiators receive coolant at almost the same temperature.
The word “almost” means that there are exceptions to this rule, these are circuits assembled from steel, copper and stainless steel corrugated pipes, not covered with a thermal insulation layer.
The fact is that the heating system of a private house, made with your own hands from uninsulated metal pipes, will transfer heat to the premises not only through radiators. Metal has high thermal conductivity, so the coolant flowing in such a line will cool slightly as it moves away from the boiler. Although the temperature drop compared to single-pipe wiring is insignificant, it still needs to be taken into account.
Note. Many supporters of single-pipe schemes such as “Leningradka” say that they are cheaper, since half as much material will be needed. But at the same time, they forget about the drop in water temperature, as a result of which it is necessary to increase the power of the radiators, that is, add sections. This additional funds, and considerable ones.
According to the orientation of the risers in space, vertical and horizontal views systems, and they can have upper, lower and combined wiring. In a vertical scheme, the building has one or more risers powered by a heat source located in the basement or first floor. Radiators are connected to vertical risers directly, as shown in the figure:
This is a bottom-distribution scheme, since the main pipelines supply coolant to the risers from below. A vertical system with top filling implies their laying from above, with combined version Only the supply horizontal manifold runs under the ceiling, and the return manifold runs from below. Typically, lines laid from above are placed in the attic space, and if there is no space, under the ceiling of the top floor. Which is not very good from an aesthetic point of view.
Horizontal systems
This is a closed two-pipe system in which, instead of vertical risers, horizontal branches are laid, and a certain number of heating devices are connected to them. As in the previous case, branches can have upper, lower and combined wiring, only now this happens within the same floor, as shown in the diagrams:
As can be seen in the figure, a system with overhead wiring requires laying pipes under the ceiling of the premises or in the attic and will be difficult to fit into the interior, not to mention the consumption of materials. For these reasons, the circuit is used infrequently, for example, for heating basements or when the boiler room is located on the roof of the building. But if chosen correctly circulation pump and the system has been configured, then it is better to run the boiler pipe from the roof downwards, any homeowner will agree with this.
Combined wiring is indispensable when you need to install a two-pipe gravity system, where the coolant moves naturally due to convection. Such schemes are still relevant in areas with unreliable power supply and in houses of small area and number of floors. Its disadvantages are that there are many pipes running through all the rooms large diameter, hiding them is very difficult. Plus the high material consumption of the project.
And finally, horizontal system with bottom wiring. It is no coincidence that it is the most popular, because the scheme combines a lot of advantages and has almost no disadvantages. The lines to the radiators are short, the pipes can always be hidden behind a decorative screen or embedded in the floor screed. At the same time, the consumption of materials is acceptable, and from the point of view of operational efficiency it is difficult to find a better option. Especially when a more advanced passing system is used, shown below in the diagram:
Its main advantage is that the water in the supply and return pipelines travels the same distance and flows in the same direction. Therefore, hydraulically, this is the most stable and reliable scheme, provided that all calculations are carried out correctly and the installation features are taken into account. By the way, the nuances of systems with associated coolant movement lie in the complexity of the design of ring circuits. Often pipes must cross doorways and other obstacles, which can increase the cost of the project.
Conclusion. For a private home the best option is a two-pipe horizontal heating system with bottom wiring, but only in conjunction with artificial coolant circulation. If you need to provide non-volatile operation thermal equipment and networks, it is recommended to take one of the combined gravity systems - horizontal or vertical. The latter would be appropriate in a house with two floors.
Forced circulation heating system
So, the wiring diagram has been selected, further actions the following:
- draw it in the form of a sketch, or even better, a three-dimensional model (axonometry);
- calculate and select pipe diameters in all branches and sections;
- select all the necessary elements of a two-pipe system: batteries, pump, expansion tank, filter, fittings and other parts of the boiler and radiators;
- purchase equipment and materials, perform installation work;
- carry out tests, balancing (if necessary) and put the system into operation.
On the sketch in the form of an axonometry, it is necessary to draw the mains, arrange the radiators and shut-off valves, put down elevation marks, taking the screed surface of the first floor as the reference point. Subsequently, having completed the calculation, you will need to indicate the dimensions and cross-sections of the pipes on the drawing. An example of how to install a two-pipe system with forced circulation is shown in the drawing:
Important. The finished sketch will allow you to better understand all the nuances of the future system, down to the number and types of fittings made of polypropylene, metal-plastic or other material. It is especially convenient when a house plan is attached to the three-dimensional image.
Selection of pipe diameter
This calculation consists of determining the coolant flow rate based on the thermal power required to heat the room, and from it the diameter of the pipes for a two-pipe heating system. In simple words, the pipe flow area should be sufficient for delivery to each room required quantity heat along with hot water.
Note. By default, it is assumed that the calculation of the building’s heat losses has already been completed and the amount of heat for all rooms is known.
The selection of pipe diameters begins from the very end of the system, from the last battery. First, calculate the coolant consumption for heating this room using the formula:
G = 3600Q/(c∆t), Where:
- G – required hot water consumption per room, kg/h;
- Q – amount of heat to heat a given room, kW;
- c – heat capacity of water, assumed to be 4.187 kJ/kg ºС;
- Δt is the calculated temperature difference in the supply and return manifolds, usually 20 ºС.
For example, to heat a room you need 3 kW of heat. Then the coolant flow will be equal to:
3600 x 3 / 4.187 x 20 = 129 kg/h, in volume it will be 0.127 m3/h.
To balance a two-pipe water heating system initially, you need to select the diameter as accurately as possible. Based on the volumetric flow rate, we find the flow area using the formula:
S = GV / 3600v, Where:
- S – cross-sectional area of the pipe, m2;
- GV – volumetric coolant flow rate, m3/h;
- v – water flow speed, taken in the range from 0.3 to 0.7 m/s.
Note. If the heating system one-story house– gravitational, then the minimum speed should be taken – 0.3 m/s.
In our example, let’s take a speed of 0.5 m/s, find the cross-section and, using the formula for the area of a circle, the diameter, it will be equal to 0.1 m. The polypropylene pipe closest in range has inner size 15 mm, we put it on the drawing. By the way, connecting radiators to a two-pipe system is usually done with just such a pipe - 15 mm. Next, we move on to the next room, count and sum with the previous result, and so on until the boiler itself.
Connecting radiators to a two-pipe system
The installed batteries are connected to the mains during the installation process, correct connection heating radiators with a two-pipe system - this is lateral or diagonal. All existing methods shown in the figure:
What temperature balance does it lead to? bottom connection radiator to a two-pipe system, are well illustrated by the following pictures:
Batteries used in a vertical circuit usually have a side connection (method No. 3). In horizontal systems, the diagonal connection diagram is most preferable (method No. 1), thanks to this, maximum heat transfer from the heating device is achieved, as shown in the image below:
Balancing
The point of this operation is to balance all branches of the system and regulate the water flow in each of them. To do this, each branch must be correctly connected to the mains, that is, install special balancing valves. Also control valves or thermostatic valves are installed on the connections to all radiators.
It is not so easy to carry out accurate balancing with your own hands; you need to have the appropriate instruments (at least a pressure gauge to measure the pressure drop across the balance valve) and perform calculations for pressure losses. If there is none of this, then after testing you need to fill the system, bleed the air and turn on the boiler. Next, balancing the two-pipe system is done by touch, according to the degree of heating of all batteries. Devices located next to the heat generator must be “pressed” so that more heat goes to those further away. The same goes for entire branches of the system.
Conclusion
It is noteworthy that installing a two-pipe heating system is much easier than developing it, calculating it, and then balancing it. So this stage you can go through it yourself, and it is advisable to coordinate everything else with specialists.
The heating system is divided into two types: single-pipe and double-pipe. Obviously, it is most profitable to install a more efficient one that will not only cope with its functions, but will also serve you for many years. In order not to be left “in the fool” and not to make a mistake with the choice heating system.
You need to thoroughly understand which heating system is best for you and why.
Thus, you will know which system is better from a technical point of view and how to choose it, taking into account your budget.
High water pressure ensures a natural cycle, and antifreeze makes the system more economical.
Disadvantages of a one-pipe system - a very complex thermal and hydraulic calculation of the network, since if you make an error in the calculations of devices, it is very difficult to eliminate it.
Also, this is a very high hydrodynamic resistance and an involuntary number of heating devices on one line.
The coolant flows into everything at once and is not subject to separate adjustment.
In addition, there are very high heat losses.
In order to be able to regulate the operation of individual devices connected to one riser, bypasses (closing sections) are connected to the network - this is a jumper in the form of a piece of pipe connected by the forward and return radiator pipes, with taps and valves.
To be able to regulate the temperature of each separately, the bypass allows you to connect auto-thermostats to the radiator.
In addition, this also makes it possible, in the event of a breakdown, to replace or repair individual devices without turning off the entire heating system.
Single-pipe heating is divided into vertical and horizontal:
- vertical – this is connecting all batteries in series from top to bottom.
- horizontal - This serial connection all heating devices on all floors.
Due to the accumulation of air in the batteries and pipes, so-called traffic jams occur, which is a disadvantage of both systems.
Installation of a one-pipe system
The connection is made according to the diagram, using taps to vent the radiators, which close the taps and plugs.
System pressure testing - after which coolant is poured into the battery and the system is directly adjusted.
Two-pipe heating system
The advantage of a two-pipe heating system – this is the installation of automatic thermostats, which gives full control of the temperature in individual rooms.
This also includes the independence of operation of circuit devices, which is ensured by a special collector system.
The difference between a two-pipe system and a one-pipe system is that additional batteries can be connected to the first after connecting the main ones, as well as the possibility of extension in vertical and horizontal directions.
Unlike the single-pipe system, it is also possible to easily correct errors.
Disadvantages of this system are minimal if you have enough material resources and have the opportunity to call a specialist.
Installation of a heating system with lower horizontal piping
This system allows the tank to be positioned open type in a comfortable warm place. Also, it is possible to combine expansion and supply tanks, allowing you to use hot water directly from the heating system itself.
In systems with forced circulation, to reduce pipe consumption, the outlet and supply risers are located at the level of the first.
According to statistics, over 70% of all residential buildings are heated using water heating. One of its varieties is a two-pipe heating system - this publication is dedicated to it.
The article discusses the advantages and disadvantages, diagrams, drawings and recommendations for installing two-pipe wiring with your own hands.
Contents of the article
Differences between a two-pipe heating system and a single-pipe one
Any heating system is a closed circuit through which coolant circulates. However, unlike a one-pipe network, where water is supplied to all radiators in turn through the same pipe, a two-pipe system involves dividing the wiring into two lines - supply and return.
A two-pipe heating system for a private house, in comparison with a single-pipe configuration, has the following advantages:
- Minimal coolant losses. In a single-pipe system, radiators are alternately connected to the supply line, as a result of which the coolant passing through the battery loses temperature and enters the next radiator partially cooled. With two-pipe configuration, each battery is connected to the supply pipe with a separate outlet. You get the opportunity to install on each of the radiators, which will allow you to regulate the temperature in different rooms houses independently of each other.
- Low hydraulic losses. When installing a system with forced circulation (necessary in large buildings), a two-pipe system requires the installation of a less efficient circulation pump, which allows for significant savings.
- Versatility. A two-pipe heating system can be used in multi-apartment, one or two-story buildings.
- Maintainability. Shut-off valves can be installed on each branch of the supply pipeline, which makes it possible to cut off the coolant supply and repair damaged pipes or radiators without stopping the entire system.
Among the disadvantages of this configuration, we note a twofold increase in the length of the pipes used, however, this does not threaten a dramatic increase in financial costs, since the diameter of the pipes and fittings used is smaller than when installing a single-pipe system.
Classification of two-pipe heating
The two-pipe heating system of a private house, depending on its spatial location, is classified into vertical and horizontal. The more common is the horizontal configuration, which involves connecting radiators on the floor of the building to a single riser, whereas in vertical systems ah, radiators of different floors are connected to the riser.
The use of vertical systems is justified in a two-story building. Despite the fact that such a configuration is more expensive due to the need to use a larger number of pipes, with vertical risers, the possibility of air pockets forming inside the radiators is eliminated, which increases the reliability of the system as a whole.
Also, a two-pipe heating system is classified according to the direction of movement of the coolant, according to which it can be direct-flow or dead-end. In dead-end systems, liquid circulates through the return and supply pipes in different directions; in direct-flow systems, their movement coincides.
Depending on the method of transporting the coolant, systems are divided into:
- with natural circulation;
- with forced circulation.
Heating with natural circulation can be used in one-story buildings with up to 150 square meters. It does not include installation additional pumps– the coolant moves due to its own density. Characteristic feature systems with natural circulation is laying pipes at an angle to the horizontal plane. Their advantage is independence from the availability of power supply, the disadvantage is the inability to adjust the water supply speed.
In a two-story building, a two-pipe heating system is always performed with forced circulation. In terms of efficiency, this configuration is more effective, since you get the opportunity to regulate the flow and speed of the coolant using a circulation pump, which is installed on the supply pipe leaving the boiler. In heating with forced circulation, pipes of relatively small diameters (up to 20 mm) are used, which are laid without a slope.
Which heating network layout to choose?
Depending on the location of the supply pipeline, two-pipe heating is classified into two types - with upper and lower wiring.
The diagram of a two-pipe heating system with top wiring involves installing an expansion tank and a distribution line at the highest point of the heating circuit, above the radiators. This installation cannot be done in a one-story building with a flat roof, since to accommodate communications you will need an insulated attic or a specially designated room on the second floor of a two-story building.
A two-pipe heating system with bottom wiring differs from the top one in that the distribution pipeline in it is located in the basement or in an underground niche, under the radiators. The outermost heating circuit is the return pipe, which is installed 20-30 cm lower than the supply line.
This is a more complex configuration, requiring the connection of an upper air pipe, through which excess air will be removed from the radiators. In the absence basement additional problems may arise due to the need to install the boiler below the level of the radiators.
Both the lower and upper circuits of a two-pipe heating system can be made in a horizontal or vertical configuration. However, vertical networks, as a rule, are made with bottom wiring. With this installation, there is no need to install a powerful pump for forced circulation, since due to the difference between the temperatures in the return and supply pipes, a strong pressure drop is created, increasing the speed of movement of the coolant. If, due to the peculiarities of the building's layout, such installation cannot be done, a highway with overhead routing is installed.
Making a two-pipe system with your own hands (video)
Selecting pipe diameters and rules for installing a two-pipe network
When installing two-pipe heating, it is extremely important to choose the correct diameter of the pipes, otherwise you may get uneven heating of radiators remote from the boiler. Most boilers for domestic use have a diameter of the supply and return pipes of 25 or 32 mm, which is suitable for a two-pipe configuration. If you have a boiler with 20 mm pipes, it is better to opt for a single-pipe heating system.
Size chart available on the market polymer pipes consists of diameters 16, 20, 25 and 32 mm. When installing the system yourself, you need to take into account the key rule: the first section of the distribution pipe must match the diameter of the boiler pipes, and each subsequent pipe section after the branch tee to the radiator is one size smaller.
In practice, it looks like this: a diameter of 32 mm comes out of the boiler, a radiator is connected to it through a tee with a 16 mm pipe, then after the tee the diameter of the supply line is reduced to 25 mm, at the next branch to the radiator line 16 mm after the tee the diameter is reduced to 20 mm and so on. If the number of radiators is greater than the standard sizes of pipes, it is necessary to divide the supply line into two arms.
When installing the system yourself, adhere to the following recommendations:
- the supply and return lines must be parallel to each other;
- each outlet to the radiator must be equipped with a shut-off valve;
- distribution tank, if installed in attic when installing a network with top wiring, it is necessary to insulate it;
- pipe fastenings on the walls should be placed in increments of no more than 60 cm.
When setting up a system with forced circulation, it is important to correctly select the power of the circulation pump. The specific choice is made based on the size of the building:
- for houses with an area of up to 250 m2, a pump with a capacity of 3.5 m3/hour and a pressure of 0.4 MPa is sufficient;
- 250-350 m2 – power from 4.5 m3/hour, pressure 0.6 MPa;
- over 350 m 2 - power from 11 m 3 / hour, pressure from 0.8 MPa.
Despite the fact that it is more difficult to install two-pipe heating with your own hands than a one-pipe network, such a system, due to its high reliability and efficiency, fully justifies itself during operation.
Most of the heating systems of apartment buildings and private buildings are built precisely according to this scheme. What are its advantages and are there any disadvantages?
Can a two-pipe heating system be installed with your own hands?
The difference between a two-pipe heating system and a single-pipe one
Let's first define what kind of beast this is - a two-pipe heating system. It’s easy to guess from the name that it uses exactly two pipes; but where do they lead and why are they needed?
The fact is that to heat a heating device with any coolant, it needs circulation. This can be achieved in one of two ways:
- Single-pipe circuit (so-called barracks type)
- Two-pipe heating.
In the first case, the entire heating system is one large ring. It can be opened by heating devices, or, which is much more reasonable, they can be placed parallel to the pipe; the main thing is that there is no separate supply and return pipeline passing through the heated room.
Or rather, in this case these functions are combined by the same pipe.
What do we gain and what do we lose in this case?
- Dignity: minimum costs materials.
- Disadvantage: large variation in coolant temperature between the radiators at the beginning and end of the ring.
The second scheme - two-pipe heating - is a little more complicated and more expensive. Through the entire room (in case multi-storey building- on at least one of its floors or in the basement) there are two pipelines - supply and return.
First, the hot coolant (most often ordinary process water) goes to the heating devices to give them heat, and returns in the second direction.
Each heating device (or a riser with several heating devices) is placed in the gap between the supply and return.
There are two main consequences of this connection scheme:
- Disadvantage: the pipe consumption is much higher for two pipelines instead of one.
- Advantage: the ability to supply coolant to ALL heating devices at approximately the same temperature.
Advice: in case of a large room, it is necessary to install a control throttle on each heating device.
This will allow you to equalize the temperature more accurately, making sure that the flow of water from the supply to the return on nearby radiators will not “sag” those more distant from the boiler or elevator.
Features of two-pipe heating systems in apartment buildings
In case apartment buildings, of course, no one installs throttles on separate risers and constantly regulates water flow; equalizing the coolant temperature to at different distances from the elevator is reached in a different way: the supply and return pipelines running through the basement (the so-called heating pipeline) have a much larger diameter than the heating risers.
Alas, in new houses built after the collapse Soviet Union and the disappearance of strict state control over construction organizations, it began to be practiced to use pipes of approximately the same diameter on risers and benches, as well as thin-walled pipes installed for welding valves and other nice signs of the new social system.
The consequence of such savings is cold radiators in apartments located at the maximum distance from the elevator unit; By a funny coincidence, these apartments are usually corner and have common wall with the street. Quite a cold wall.
However, we have deviated from the topic. A two-pipe heating system in an apartment building has one more feature: for its normal functioning, water must circulate through the risers, rising and falling up and down. If something interferes with it, the riser with all the batteries remains cold.
What to do if the heating system at home is running, but the radiators are at room temperature?
- Make sure the riser valves are open.
- If all the flags and switches are in the “open” position, close one of the paired risers (we are, of course, talking about a house with, where both beds are in the basement) and open the vent located next to it.
If the water flows with normal pressure, there are no obstacles to the normal circulation of the riser, except for the air at its upper points. Tip: drain more water until, after a long snorting of the air-water mixture, a powerful and stable stream of hot water flows. Perhaps in this case you will not need to go up to the top floor and bleed the air there - circulation will be restored after startup. - If the water does not flow, try to bypass the riser in the opposite direction: perhaps a piece of scale or slag is stuck somewhere. The countercurrent can carry it out.
- If all attempts have no effect and the riser does not drain, most likely you will have to search for a room in which repairs were made and heating appliances were changed. Here you can expect any trick: a removed and plugged radiator without a jumper, a completely cut off riser with plugs at both ends, a throttle closed for general reasons - again in the absence of a jumper... Human stupidity truly gives an idea of infinity.
Features of the top filling system
Another way to install a two-pipe heating system is the so-called top filling. What's the difference? The only problem is that the supply pipeline migrates to the attic or upper floor. A vertical pipe connects the filling feed to the elevator.
Circulation from top to bottom; the path of water from supply to return with the same building height is half as long; all the air ends up not in the jumpers of the risers in apartments, but in a special expansion tank at the top of the supply pipeline.
Starting up such a heating system is immeasurably simpler: after all, for full operation of all heating risers, you do not need to get into each room for top floor and vent the air there.
It is more problematic to turn off the risers when repairs are necessary: after all, you need to both go down to the basement and go up to the attic. Shut-off valves located both here and there.
However, the above two-pipe heating systems are still more typical for apartment buildings. What about private owners?
It’s worth starting with the fact that in private houses the 2-pipe heating system used can be radial and sequential in the type of connection of heating devices.
- Radial: from collector to everyone heating device there is its own supply and its own return.
- Sequential: radiators are powered by all heating devices from a common pair of pipelines.
The advantages of the first connection scheme boil down mainly to the fact that with such a connection there is no need to balance a two-pipe heating system - there is no need to adjust the flow of the throttles of the radiators located closer to the boiler. The temperature will be the same everywhere (of course, with at least approximately the same length of the rays).
Its main disadvantage is the highest pipe consumption among all possible schemes. In addition, it will simply be impossible to extend the lines to most of the radiators along the walls while maintaining any decent appearance: They will have to be hidden under the screed during construction.
You can, of course, drag it through the basement, but remember: in private houses there are often no basements of sufficient height with free access there. Besides, ray diagram It is in any way convenient to use only when building a one-story house.
What do we have in the second case?
Of course, we have gotten away from the main disadvantage of single-pipe heating. The coolant temperature in all heating devices can theoretically be the same. The key word is theoretically.
Setting up the heating system
In order for everything to work exactly the way we want, we will need to configure a two-pipe heating system.
The setup procedure itself is extremely simple: you need to turn the throttles on the radiators, starting with those closest to the boiler, reducing the flow of water through them. The goal is to make sure that a decrease in water flow through nearby heating devices increases water consumption at distant ones.
The algorithm is simple: slightly tighten the valve and measure the temperature on the distant heating device. With a thermometer or by touch - in in this case all the same: the human hand perfectly feels a difference of five degrees, and we don’t need greater accuracy.
Alas, it is impossible to give a more accurate recipe other than “tighten and measure”: calculating the exact permeability for each throttle at each coolant temperature, and then adjusting it to achieve the required numbers is an unrealistic task.
Two points to consider when adjusting a two-pipe heating system:
- It takes a long time simply because after each change in the dynamics of the coolant, the temperature distribution takes a long time to stabilize.
- The heating adjustment of a two-pipe system must be carried out BEFORE the onset of cold weather. This will prevent you from defrosting your home heating system if you miss the settings.
Advice: with a small volume of coolant, you can use non-freezing coolants - the same as antifreeze or oil. It’s more expensive, but you can leave your house without heating in winter without worrying about the pipes and radiators.
Horizontal wiring system
With the horizontal arrangement of the supply and return pipelines, it has recently begun to penetrate from its patrimony - private and low-rise houses - into multi-storey new buildings.
Apparently, this is mostly due to the fact that studio apartments have begun to gain popularity: with a large room area without internal partitions it is simply unprofitable to pull risers through the ceilings, as a 2-pipe vertical heating system implies; It is much easier to do the wiring horizontally.
Typical two-pipe horizontal heating system modern house it looks like this: the risers from the basement run along the entrance. On each floor, taps are made into the risers, which supply coolant to the apartment through valves and discharge waste water into the return pipeline.
Everything else is exactly like in a private house: two pipes, batteries and chokes on each of them. By the way, a horizontal heating system - two-pipe or one-pipe - is easier to repair: to dismantle and replace a section of pipe, there is no need to violate the integrity of the ceiling; This is undoubtedly worth recording as an advantage of such a scheme.
The horizontal two-pipe heating system has one feature that follows from its design and leaves its mark on the start of heating. In order for the heating device to transfer maximum heat from the coolant to the air in the room, it must be completely filled.
This means that each such heating device, typically located above the supply and return pipelines, must be equipped with a Mayevsky valve or any other vent in the upper part.
Advice: Mayevsky taps are very compact and aesthetically pleasing, but they are not the most convenient device to remove air from the radiator.
Where aesthetics are not important (for example, when heating devices are covered with decorative grilles), it would be more convenient to install a water tap with the spout up or a ball valve.
We will not add this feature to the list of disadvantages: going around the radiators in one apartment once a year is not a big deal.
As you might easily guess, a two-pipe horizontal heating system is not only a solution strictly for one-story buildings or for apartment buildings with studio apartments. For example, two-story house with separate rooms can also be heated in the same way; you just have to make the wiring identical on both floors and connect pipelines from the boiler to both systems.
Of course, balancing such a heating system will have to take a little more time; but this is a one-time event, and it is not difficult to experience it once in a few years.
Finally, a few definitions and simply useful tips.
Depending on the direction of water flow in the pipelines, a 2-pipe heating system can be dead-end or direct-flow.
- A two-pipe dead-end heating system is a system in which the coolant moves through the supply and return pipelines in opposite directions.
- In a direct-flow two-pipe heating system, the direction of the current in both pipelines coincides.
In private houses, two-pipe heating systems with both forced and natural circulation can be used.
- Forced circulation of the coolant is provided by a circulation pump; This quiet and low-power device is supplied, in particular, in the same housing with many electric boilers.
- Natural circulation is used in small-volume heating systems; the principle of its operation is based on the fact that hot water has less density and rushes upward.
Two-pipe closed heating system, that is, a system with constant pressure and without both water supply and external coolant supply, it is the most popular solution for private houses with electric boilers.
In order to transfer heat to distant rooms from solid fuel boiler or stoves, an open one-pipe or two-pipe system is also quite suitable.
The design of a two-pipe heating system can include radiators of any type, registers and convectors as heating devices; warm floor implies a different connection method.
In order to install the heating of a two-pipe system, it is certainly better to involve specialists in the work. However, the abundance of materials on this topic on the Internet and the ease of assembling modern plumbing and heating systems with the help of fittings and machines make it possible for an amateur to do this work - if only he wanted to.
If you are installing a two-pipe heating system for a two-story house, when balancing the system it is worth taking into account the peculiarity of communicating floors in terms of heat distribution: all other things being equal, it will always be warmer on the second floor.
When developing a heating system for our home, we certainly think about the layout of pipes and connecting radiators. Most often, when creating projects, common schemes with two pipes laid through heated rooms are used. A two-pipe heating system is more difficult to install, but it has many undeniable advantages - this is what we will talk about in our review. We will also look at:
- Structural features of two-pipe heating systems;
- Their main disadvantages are;
- Varieties of two-pipe systems.
At the very end we will talk about the most effective ways connecting batteries to heating systems.
Features of two-pipe heating systems
A two-pipe heating system is the most common scheme for laying heating pipes and connecting radiators. It involves the use of two pipes - one supplies hot coolant, and the second carries it to the heating boiler. This scheme different high efficiency and ensures uniform heat distribution throughout all heated rooms.
Single-pipe heating systems, unlike two-pipe ones, have a number of disadvantages:
The difference in the operation of one-pipe and two-pipe heating systems is well illustrated by this picture.
- More limited contour length;
- Uneven distribution of heat throughout heated rooms - the very last rooms suffer;
- It is difficult to heat multi-story buildings;
- Increased hydrodynamic resistance in the heating system;
- Lack of separate adjustment of heating temperature in different rooms;
- Difficulties in repair - it is impossible to remove a faulty battery without stopping the entire system.
Some of the above-mentioned problems are partially solved with the help of the “Leningradka” scheme, but this is not a complete solution to the situation.
A two-pipe heating system involves laying two parallel pipes to which radiators are connected. The coolant from the supply pipe enters the heating devices, after which it is sent to the return pipe (return). Despite the more impressive financial and labor costs, the finished system is more functional to operate and easier to repair.
Two-pipe heating is actively used to heat rooms and buildings. for various purposes. These include one-story private houses and cottages, multi-story apartment buildings, as well as industrial and administrative buildings. In other words, the scope of its application is distinguished by its breadth.
Advantages and disadvantages of two-pipe heating systems
Two-pipe heating is distinguished by its versatility. It works equally well in both small buildings and multi-story buildings, including high-rise residential buildings. Let's look at the main advantages of two-pipe systems:
When using two-pipe heating, even the most distant radiators in the house will be able to provide heat at an acceptable level.
- Increased length of one line (circuit) - this is important when heating elongated buildings, for example, hospital or hotel buildings;
- Uniform supply of heat to the rooms - unlike single-pipe systems, there will be heat even in the rooms furthest from the boiler;
- Two-pipe heating makes it easy to organize separate temperature control in separate rooms and spaces - for this, thermostatic heads are installed on each radiator;
- The ability to dismantle radiators and convectors without stopping the entire heating system is an important advantage that manifests itself in large buildings;
- Two-pipe heating is ideally suited for heating large buildings - for a more uniform distribution of heat, certain pipe layouts and connection of heating devices are used.
Unfortunately, it was not without certain disadvantages:
- High costs for purchasing equipment - compared to single-pipe heating systems, double-pipe heating systems require an increased number of pipes;
- Difficulty in installation - due to an increase in the number of units and the need for optimal distribution of coolant throughout the heated rooms.
Nevertheless, the advantages completely outweigh the above disadvantages.
Types of two-pipe heating systems
We have already become familiar with the advantages and disadvantages of two-pipe heating systems, as well as their distinctive features. It remains to talk about their varieties.
Forced or natural circulation
Natural circulation of the coolant involves the absence of a circulation pump. Heated water circulates through the pipes independently, obeying the forces of gravity. True, this requires pipes of increased diameter - two-pipe heating with thin plastic pipes will not be able to ensure independent circulation, which is associated with high hydrostatic pressure in the system. Heating with natural circulation is simple and cheap, but you must remember the limited length of the circuit - it is not recommended to make it longer than 30 meters.
The scheme of a two-pipe heating system with forced circulation involves the use of a circulation pump. It is installed next to heating boiler and ensures rapid passage of coolant through the pipes. Thanks to this, the warm-up time is reduced, the length of the heating circuit is increased, and the distribution of thermal energy is noticeably improved. Two-pipe scheme heating with forced circulation allows you to heat buildings of any number of floors - you just need to choose a productive pump.
Disadvantages of two-pipe heating systems with circulation pumps:
- Increased installation costs - a good pump is expensive, while buying a cheap one does not make sense due to its reduced service life;
- Possible noise - cheap pumps sooner or later begin to vibrate, the sounds from their operation travel through the pipes even to the farthest rooms. The higher the rotation speed of the pump shaft, the louder the noise;
- The energy dependence of the heating system - when the power is turned off, the circulation of the coolant stops.
For correct operation of a two-pipe heating system with a circulation pump, it is necessary to provide backup source power supply, otherwise the heating boiler may break down.
It should be noted that cheap circulation pumps are noisy even at the very beginning of operation. Increased noise levels are most noticeable in heating systems with metal pipes. And if any section of the pipe gets into resonance, the sound will only intensify.
You should also pay attention to the method of laying pipes - in two-pipe heating systems with natural circulation, a slope is provided, which ensures normal movement coolant. In circuits with forced circulation, no slopes are needed. For the same reason, pipes can be bent as many times as desired, avoiding obstacles - in circuits with natural coolant movement, pipes should be as straight as possible so as not to create excessive hydrodynamic resistance.
Open and closed circuits
The open-type two-pipe heating scheme involves the use of a traditional expansion tank, which is mounted at the highest point of the circuit. The pressure here is minimal, the coolant is in contact with the atmosphere. In case of excessive expansion, the water goes into a special pipe extending from the tank. An undoubted advantage of open circuits is the ease of air removal - it exits through the expansion tank on its own. However, along with the escape of air, evaporation of the coolant is observed, so its level must be constantly monitored.
If there is insufficient water in open two-pipe heating systems, gurgling of water can be heard in the radiators.
Closed heating systems include sealed expansion tanks membrane type. The coolant here circulates in a confined space, so there is nowhere for it to evaporate. If necessary, you can add non-freezing ethylene glycol here. In order to prevent airing of the circuit, air vents are installed in it - automatic or manual.
IN closed systems In heating systems, a circulation pump must be installed, while in open ones its presence is not mandatory.
Vertical and horizontal two-pipe heating systems
A two-pipe horizontal heating system is relevant in one-story houses. Two pipes are laid throughout the premises, parallel to which radiators are connected. If a household or building includes 2-3 floors, then a separate horizontal circuit is created on each floor, connected to vertical risers. This connection diagram ensures uniform distribution of coolant across all floors and rooms.
Vertical systems are most often installed in apartment buildings. Two are mounted here vertical pipes from the top to the bottom floor. Hot coolant is supplied through one, and through the other it descends back to the boiler room. Radiators are connected to both pipes. Most often, the scheme looks like this: separate risers serve all radiators in kitchens, others - in bedrooms, halls and other rooms.
Mixed systems are also installed in buildings, which include both vertical and horizontal sections.
Upper and lower wiring
There are two-pipe heating systems with upper and lower pipe distribution. Upper wiring implies that the coolant first rises to the highest point of the circuit, and from there it is distributed among individual vertical sections. Two-pipe heating with bottom wiring provides that both pipes pass below (near the floor or under it), and branches extend from them upward, to radiators and separate cascades of radiators.
The upper wiring is aimed at creating two-pipe heating systems with independent movement of the coolant. The pipe from the boiler rises to the top point of the system, where it begins horizontal section- it is done on an incline. A similar slope is made in the return pipe so that the coolant flows independently towards the boiler, obeying the pressure in the circuit and gravity.
The second scheme (bottom) is optimal where you need to hide all the pipes. In this case, a two-pipe heating system with bottom wiring made of polypropylene is hidden in the floors or behind the ceilings; only radiators and convectors are visible in the rooms.
Connecting radiators
We introduced you to the main types of two-pipe heating systems. Now you know that the coolant here is supplied through one pipe and removed through another. This ensures even heat distribution even in the largest buildings. Let's see how we can best connect heating batteries. There are three possible connection schemes:
- Lateral connection - the supply and return pipes approach the heater from the side. Accordingly, areas located only on one edge will be the warmest;
- Bottom connection - supply and return pipes fit to the lower edges of radiators and convectors. Heat losses in such a scheme will be maximum, since the coolant tends to pass through the internal volume “right through”, along the straightest section;
- Diagonal is the most optimal connection scheme, ensuring uniform heat distribution throughout the internal volume of the radiators. For example, the inlet pipe goes to the upper left entrance, and the outlet pipe goes to the lower right (or vice versa). In this case, the coolant will heat the entire area of the heating devices as evenly as possible.
The choice of a suitable scheme depends on the design of the heating system and the number of sections in the radiators. When creating two-pipe heating, we recommend choosing a diagonal and lateral connection.
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