The efficient operation of autonomous water heating systems is one of the most important conditions for comfortable living in private households. The availability of installation, ease of operation, economy and efficiency make such complexes quite popular among owners of private houses. Almost today, up to 70% of private households in cities and towns of our country are heated in this way. Of the existing options, in the first place is the two-pipe heating system of a private house — the most practical and affordable for autonomous heating of housing.
What is a two-pipe heating system
In everyday life, you can find various schemes for heating a private house, however, it is up to the inhabitants of the residential building to choose which option for supplying heat is better. Many factors influence the choice of the structure of the heating system. Preference for one or another scheme is given based on the availability of funds from the owners of the house, the expected effect and design features of the residential building. The two-pipe system is used more often in practice due to its high efficiency, reliability and ease of adjustment.
Two-pipe autonomous heating systems are also called double-circuit systems. In other words, the circulation of the coolant from the boiler to the radiators is carried out along two circuits. The first pipe directly supplies heat from the boiler to the radiators, while the second pipe is designed to transport the cooled coolant back. Despite certain technical difficulties associated with the installation of the pipeline, the wiring diagram of this type of heating circuit is simple and understandable. For comparison, you can look at the diagram of a single-pipe and two-pipe heating structure in order to understand the fundamental differences and the principle of operation.
A single-pipe system is one circuit with a coolant. The two-pipe heating structure of a one-story house, in contrast to the one-pipe one, where the pipe with the heat carrier is one single circuit, is more flexible and technologically convenient. The batteries in this case are connected in parallel, which plays an important role in the operation process. Depending on household needs, each radiator can be removed from a single system at any time by closing the corresponding valve.
Read also about the heating scheme of a one-story house with forced circulation!
Advantages and disadvantages of a two-pipe system
Among the advantages of a two-pipe heating scheme, the following stand out:
- the same coolant temperature in all batteries, regardless of their location in relation to the boiler;
- the ability to turn off the heat supply to a single radiator;
- the ability to install a thermostat on each battery;
- technical capabilities to connect a large number of radiators.
Parallel connection provides the possibility of individual temperature setting for each heater, allowing residents to independently regulate the level of heating in each room separately.
Having certain advantages over other heating systems used in private homes, the two-pipe heating scheme has one drawback — the increased length of the pipes. Often this aspect affects the increase in the cost of the system. It is appropriate to recall the aesthetic side of the issue. Two pipes laid in residential areas are more difficult to hide.
Two-pipe heating system, varieties
There are two types of two-pipe heating scheme:
- with forced circulation;
- with natural circulation of the coolant.
The efficiency of the heating system depends on the type of circulation. Which scheme should be installed in the house, with vertical or horizontal wiring, with top or bottom connection of radiators, all these issues are decided based on the heated area, configuration and number of storeys of the house.
The method with natural circulation is focused on changing the density of the coolant during the heating process. The heated coolant with a lower density rises, and then fills the radiators by gravity, gives off heat and returns to the boiler due to the slope of the return pipeline.
Due to the difference in the height of the boiler, expansion tank and heaters, a certain working pressure is created in the pipeline. The higher the open storage tank, the greater the pressure and the more intense the forward flow of the coolant in the pipeline.
Important! We can say that an open heating system with natural circulation is completely autonomous. There is no pressure pump, and therefore no need for electricity.
Basically, today a two-pipe closed heating circuit is used, in which the pump is turned on. It provides more intensive circulation of the coolant and greater heating efficiency. Heating with forced circulation has great technological capabilities. The only drawback is that a power outage completely stops the system.
Unlike the scheme with forced circulation, the length of the system with gravity flow of the coolant has significant limitations, no more than 30 meters. That is, such a heating system is suitable only for small rooms (dachas, saunas, country houses).
Important! When installing a natural circulation system, pipes with a diameter of at least 1¾ inches must be used. The slope of the pipe for the direct supply of the heat carrier and the return pipe should not be less than 3-40.
In order to get an idea of the existing connection options, how a two-pipe heating system with a lower wiring differs from a top-connected option, what is the difference between a horizontal and a vertical type, it is enough to get acquainted with the video.
Types of wiring of the heating system
Pipes can be mounted vertically or horizontally. Vertical heating systems have a number of advantages, among which it is worth highlighting the uniformity of pipes and the large difference in pressure of the coolant at the inlet and outlet, respectively.
A vertical two-pipe heating system with an upper wiring option is more convenient and easier to install. The laying of the pipeline does not depend on the layout of the building. Most of the pipes of the heating system can be hidden in the attic space, hidden by suspended ceilings. A similar arrangement of heating pipes is often used in multi-storey buildings where it is necessary to ensure good forward flow in the pipeline, with a large number of radiators. In this case, the intensity of circulation of the coolant in the pipeline depends on the height of the riser.
According to the location of the pipelines, two-pipe heating systems are vertical and horizontal, with top, bottom or combined wiring. The option with the top connection is more expensive. In each heated room, two pipes will have to be led out throughout the wall panels, direct heat supply and return. There is little aesthetics in this, the length of the pipeline increases significantly.
A two-pipe heating system with a lower wiring looks preferable, despite the greater number of pipe bends, connection points and stretched communications.
Radiators with horizontal installation with a bottom connection option can be easily hidden behind decorative screens. In this case, your home can be appropriately decorated using a variety of design elements. The pipeline with the lower wiring is easy to hide in wall panels or floor screed.
What does the optimal heating system for a private house look like?
It is necessary to provide for all the technical nuances and technological parameters of autonomous heating at the project stage. Giving preference to one or another scheme, it is important that the future heating meets the relevant parameters and household needs.
There is no good or bad wiring. In each individual case, the heating efficiency depends on the correct connection and a well-designed project. In practice, often the owners of residential buildings are faced with a situation where, as a result of the development of the project and the subsequent installation of the pipeline, a dead-end heating system arises. In them, the coolant entering the radiator is forced to collide with a cooled, oncoming flow of spent coolant. This type of connection is used for two-pipe systems with a horizontal pipeline. It is impossible to say that such heating is not profitable and inefficient. The most popular is a two-pipe horizontal heating scheme with a lower wiring with a passing movement of the coolant.
There are two types of coolant flow patterns: associated and dead-end. In the proposed table, you can see the comparative parameters of both options for the movement of the coolant
|Criteria for evaluation||Scheme of movement of the coolant|
|Hydraulics and balancing:
thermal output / standard sizes of heating devices are the same
|1. Hydraulic calculation of pressure reduction in any circuit
2. The system has hydraulic balancing without the use of additional valves
|1. Hydraulic calculation of pressure reduction in each circuit
2. The need to link the circuit with each other, using the configured thermostatic valves on the heaters
|thermal power of the system / standard sizes of shaped elements and heating devices are different||1. Hydraulic calculation of pressure reduction in each circuit
2. The need to link the circuit with each other, using the configured thermostatic valves on the heaters
|II. Piping length||Big||Minimum|
The sizes of the fittings are different, the diameters of the same sections are different
All diameters, standard sizes of shaped sections are the same
|IV. Points of «equal pressure»||present||missing|
Be sure to read: which is more efficient, a single-pipe or two-pipe heating system?
Important! The two-pipe horizontal heating scheme is convenient, practical in operation. Moreover, during the installation process, there is a real opportunity to divide the heating circuit into two wings, providing heat for almost the entire living area of the house.
The installation of a two-pipe horizontal type heating system is mainly used to heat one-story residential buildings, when the task is to connect a large number of radiators. Connecting batteries involves two options:
The option with a beam connection of heating devices is also called radial. For serial connection, a conventional pair of pipelines is used. Both the first and second connection types have their advantages. In a radial connection, there is no need to install chokes that control the operation of radiators located close to the boiler. The temperature in all radiators is the same. This type is very convenient for private, one-story houses.
Good heating system with serial connection. Significantly saves consumables.
The good work of heating in a private house depends on many factors, starting with a competent choice of the type and type of heating, ending with a properly drawn up project. Hydraulic calculations, which are an integral part of the project, are the work of a qualified specialist. Adjustment of the two-pipe heating system is carried out before the start of the heating season, when there is time to eliminate technical problems and inconsistencies.