Increasingly, a two-pipe heating system is used for heating private houses. It has many advantages and can be implemented in many different ways. Choosing the right option, it is worth getting to know the possible and explore the distinctive features of each.
Read in the article
- 1 How a two-pipe heating system works: basic principles
- 2 Varieties of the system with two pipes
- 2.1 Open and closed two-pipe heating system
- 2.2 Vertical and horizontal two-pipe heating system
- 2.3 Two-pipe heating system with bottom and top wiring
- 2.4 Dead-end and associated two-pipe heating system
- 2.5 With natural and forced circulation
- 2.6 Two-pipe heating system for two wings
- 3 Advantages and disadvantages of a two-pipe heating system
- 4 Which scheme is better: tips for choosing
- 5 Features of design and calculation
- 6 Installation of a two-pipe heating system in a private house
- 6.1 What you need to work: basic elements
- 6.2 Installing the boiler and circulation pump
- 6.3 Lining of pipelines
- 6.4 Connecting radiators: basic diagrams
- 6.5 Equipment pressure testing
- 7 Operation and maintenance of a two-pipe heating system
How a two-pipe heating system works: basic principles
The principle of operation of a two-pipe heating system is based on the use of two circuits: direct and reverse. The first is used to supply a hot coolant, which can be water or antifreeze, To radiators and other elements of a two-pipe heating system. After passing through the radiators and giving off heat, the liquid enters the return circuit, and then returns to the boiler. Then this cycle is repeated again so that the radiators can warm up the air in the room to the set temperature.
Varieties of the system with two pipes
The two-pipe heating system is available in various variations. The division is made according to various criteria, each of which is worth getting to know separately.
Open and closed two-pipe heating system
Open heating system - a closed circuit, which includes an expansion tank, allowing to compensate for changes in internal pressure and allowing contact of the coolant with atmosphere. This leads to the fact that part of the liquid evaporates and it is necessary to periodically monitor its level.
This is a budget option that creates certain difficulties in the operation. You have to constantly top up the coolant in order to prevent the boiler from failing. Also, in winter, water cools down quickly, due to contact with air.
A comment
Sergey Kharitonov
Leading engineer for heating, ventilation and air conditioning of LLC "GK" Spetsstroy "
"An open two-pipe heating system does not allow the use of antifreeze as a heat carrier."
The closed circulation system includes an expansion tank that does not allow the coolant to come into contact with the atmosphere. This greatly simplifies the maintenance of the system. Compensation of pressure surges occurs by choosing a membrane-type expansion vessel. Its design makes it possible to prevent equipment breakdown due to sudden overloads.
A closed system is more efficient and economical compared to an open one. She is not afraid of freezing, as it allows the use of antifreeze.
Vertical and horizontal two-pipe heating system
In a vertical arrangement, the radiators are connected to vertically arranged risers. Due to this, it is possible to provide heating for buildings with several floors. Moreover, each floor is connected to the riser separately. Due to the vertical arrangement of the line, it is possible to prevent the appearance of air jams.
With a horizontal scheme, heating devices are connected to a horizontal line. The number of vertical pipes with this arrangement is minimal. This option is relevant for large one-story buildings. Risers are located in utility rooms or are taken out into the corridor.
Considering the arrangement of the system elements, installation is greatly simplified and the cost is reduced. The supply and return pipes can be located under the floor. However, there is a risk of airing, which necessitates the installation of Mayevsky's cranes. In addition, with a hidden gasket, the installation of a circulation pump is mandatory.
Attention! Horizontal systems are cheaper than vertical systems.
Two-pipe heating system with bottom and top wiring
Top-wired systems involve laying the supply pipe from the top, and the return pipe from the bottom. Due to the difference in the height of the supply and return branches, it is possible to ensure a high pressure in the line. As a result, it becomes possible to use pipes with a smaller cross-section, even when it comes to natural circulation.
When installing such systems, some difficulties arise, since the expansion tank must be located at the highest point. If the house has an unheated attic, some difficulties may arise during operation. Sometimes the problem is solved by arranging the tank inside the ceiling. At the same time, the lower part is inside the heated room, and the upper part is in the attic.
If the aesthetic side is not particularly worried about, the flow line should be placed above the windows. In this case, the expansion tank can be located directly under the ceiling, if the height of the latter allows for a sufficient speed of movement of the coolant. The return flow with this scheme should be located at the floor level or below it.
A comment
Sergey Kharitonov
Leading engineer for heating, ventilation and air conditioning of LLC "GK" Spetsstroy "
"With the upper wiring, part of the heat goes up, which somewhat reduces the efficiency of the system, but the coolant moves quickly, and there is no airing of the line."
A heating circuit with a bottom wiring assumes that the supply and return are mounted below the batteries. In this case, the coolant, having reached the radiator, rises up the pipes, and then, after passing the battery, goes down. It can include several contours. Such systems allow the arrangement of dead-end wiring, as well as the implementation of a scheme with a passing movement.
This option significantly reduces the level of heat loss, but it has the main problem - airing. To combat this drawback, Mayevsky cranes are used, which are provided on each battery. In addition, the system has a relatively low pressure, which slows down the speed of movement of the coolant.
Dead-end and associated two-pipe heating system
The dead-end system got its name due to the presence in the supply and outlet pipes of a coolant with oncoming traffic. This is due to the fact that the branches of the path are not looped back. They lead to a "dead end". The circulation of the coolant is provided mainly by installing a pump. The routing is done horizontally. Air bleeding is provided by Mayevsky taps. Pressure surges are leveled by installing membrane tanks.
A passing scheme is sometimes called the Tichelman ring after its creator. In contrast to the dead-end system, in this case all the contours are closed in a ring. In this case, the first radiator on the supply line is the last for the return. In both pipes, the coolant moves in the same direction.
The device of such a two-pipe heating system is made using a horizontal lower wiring, which is most often hidden under the floor. It achieves an almost perfect hydraulic balance.
With natural and forced circulation
With natural circulation, the movement of the coolant is carried out due to physical processes. When heated, the liquid expands, which leads to a decrease in its density. As a result, the warmer liquid begins to gradually displace the colder one. Having reached the highest point, it gradually cools down and moves by gravity along the radiators. When installing the line, a sufficient slope is additionally provided to move the coolant under the influence of gravity.
Considering that the movement of fluid along the line is carried out exclusively due to physical phenomena, the speed is relatively low. As a result, the radiators warm up much more slowly, and all the air displaced by the water is displaced to the top point of the system. Due to this, it is not difficult to get rid of excessive airing.
Attention! The absence of moving parts and additional equipment significantly increases the service life of the natural circulation system.
In the case of forced circulation, a circulation pump is introduced into the system. Thanks to its presence, it is possible to ensure the movement of the coolant at a certain speed. As a result, the liquid moves much faster, providing quick warming up of the batteries and the room as a whole. All elements of the system are warmed up evenly.
In this case, the pipes can be positioned arbitrarily, which greatly simplifies the installation work. Their cross-sectional size can be kept to a minimum without losing the efficiency of the heating circuit. Taking into account that the liquid is supplied under pressure, it is possible to avoid the airing of the pipes.
The main disadvantage of a forced circulation heating system is their volatility - in the event of a power outage, it turns off. In order to prevent pipes from thawing in winter, uninterruptible power supplies are provided, which contributes to an increase in the cost of installation work.
Two-pipe heating system for two wings
For heating a private house, a dead-end scheme is chosen, since with a small length of the circuit, it makes it possible to better balance the heat transfer. If the length of the contour is large, choose the option for two wings. In this case, pipelines with a smaller cross-sectional size are installed. Valves are installed on each branch, with the help of which the intensity of movement of the working medium is regulated.
Advantages and disadvantages of a two-pipe heating system
The advantages of a two-pipe heating system include the ability to:
- providing all radiators with the same heating agent in terms of the degree of heating. This allows you to get rid of the problem typical for a one-pipe system, in which the battery farthest from the boiler does not provide a sufficient level of heating of the room;
- manual adjustment of the degree of heating of heating radiators in a particular room. When heating is turned off in one room, the rest continue to receive heat in the required volume;
- organization of heating in buildings of any level of complexity. The two-pipe system will allow equally efficient heating of a one- and two-story building;
- the use of pipes, all types of fittings and fittings with a smaller cross-sectional size;
- repair work without shutting down the heating system. For dismantling and subsequent installation of the radiator, it is enough to block a certain branch.
Among the disadvantages compared to the one-pipe version, it should be noted:
- higher cost. Due to the need to use a double number of pipes, fittings and valves, costs almost double;
- the complexity of the installation work. We have to lay two pipelines instead of one;
- longer installation due to increased technical requirements.
Which scheme is better: tips for choosing
When choosing a suitable circuit, they are guided by the characteristics of the boiler to which it will be connected. If the choice is inclined in favor of a non-volatile model, it is worth giving preference to a system with natural circulation, top wiring. The layout must be horizontal. The expansion tank is open.
If the equipment is volatile, there are no restrictions on the choice of the appropriate option. However, most often, preference is given to a closed circuit with a circulation pump.
Features of design and calculation
For the system to work effectively, it is necessary to correctly perform the hydraulic calculation in order to determine the required amount of liquid and its speed for uniform heating of all radiators in the house.
Advice! To perform the calculation, use specialized programs or the help of specialists.
Installation of a two-pipe heating system in a private house
In order to correctly perform the installation work, you should first understand the sequence of actions. The final result and the efficiency of the heating circuit directly depend on this.
What you need to work: basic elements
The list of required equipment depends on the chosen scheme. You must have in stock:
- boiler;
- circulation pump when choosing the appropriate scheme;
- pipes;
- fittings and valves;
- radiators;
- Mayevsky cranes.
Installing the boiler and circulation pump
Work begins with the installation of boiler equipment. If the choice is made in favor of an electric unit or a gas model with a closed chamber, the place for installation is chosen in any room. In all other cases, a separate boiler room should be envisaged and installation carried out in compliance with the manufacturer's requirements and safety standards.
An expansion tank is installed. The place is chosen taking into account the chosen scheme. A pump is mounted on the drain pipe next to the boiler. Place it in accordance with the manufacturer's recommendations.
Lining of pipelines
After installing the equipment, the line is mounted. The order of work depends on the material from which the pipes are made. The choice can be made in favor of:
- metal;
- metal-plastic;
- PVC, PP or XLPE.
Connecting radiators: basic diagrams
After supplying the pipelines, they begin to connect the radiators, choosing the appropriate scheme. Connection possible:
- lateral. In this case, the supply and return pipes are connected to the radiators from the side. At the same time, the radiator warms up unevenly: from the side of the supply pipe, the battery turns out to be warmer;
- bottom. Pipes are fed from below. With this option, the greatest heat losses, since the coolant tends to pass along a straight section, and not along the entire volume of the heating battery;
- diagonal. The best option for uniform heating of radiators. The inlet pipe is located on one side of the battery at the bottom, and the outlet pipe is located on the opposite side at the top.
When choosing a place for installation, take into account that they are located at a distance of at least 5 cm from the wall and floor. Leave at least 5 - 10 cm to the edge of the window sill. The brackets on which the batteries will be mounted are selected taking into account the weight of the latter.
Equipment pressure testing
After completion of installation, shut off all shut-off valves. Then the coolant is supplied, gradually filling the supply circuit. The liquid must expel all the air inside. After filling the system in front of the first radiator, open the feed valve and Mayevsky's valve, gradually filling the battery. Do the same with all radiators in a two-pipe heating system. Having checked the tightness of the system under pressure, they begin to balance it using special taps.
Operation and maintenance of a two-pipe heating system
In the process of servicing a two-pipe heating circuit, a whole range of measures is carried out, including adjustment, balancing and tuning, which are carried out using special nozzles and cranes. With their help, it is possible to dump excess air.
Share in the comments which version of the two-pipe heating system you prefer and why.