Connection of heating systems to the heating network. Dependent and independent heating system - differences in schemes, pros and cons

Hi all! What is a dependent heating system, what are its features, why is it called that and how is it fundamentally different from an independent heating system? A dependent heating scheme is such a scheme in which the coolant flows from the main heating network directly into the internal heating system of buildings. That is, the "internal" heating of the house depends directly on the external heating system.

According to this scheme, the heating of the vast majority of buildings in our country has been installed. That is, water from a heat source (boiler house, CHPP) either immediately directly or through a mixing (elevator or pump) unit is supplied to the consumer. The connection of the local internal heating system from the main heating network occurs through an individual, or heating unit, in other words.

Such a heating unit is a must in every building.

The fundamental difference between an independent scheme and a dependent one is that the connection of the internal heating system of the building with an independent scheme occurs through an additional heat exchanger installed in the heating point of the building. That is, two circuits are obtained, the heating circuit is from an external heating network, which heats the coolant in the second circuit - heated. And already the second circuit is the internal heating system of the house.

Both dependent and independent heating systems have their advantages and disadvantages. Let's consider them. The main advantage of the dependent circuit is its simplicity of design, there is the very minimum of equipment necessary for operation and adjustment. Such a system is relatively easy to maintain, does not require additional equipment in the form of heat exchangers. The cost of installing such a heating system is less than for an independent system.

However, there are also very significant drawbacks. In particular, just the dependence on the parameters in the main heating system. Well, for example, a pressure surge from an external heating network, say through the return line. Of course, on the return pipeline in the heating unit is safety valve from such cases, but still there is no one hundred percent guarantee. The same can be said about the dependence of such a system on the consumption of network water in the supply and return of external heating networks. Entirely and completely the consumer depends here on the normal operation of the heat source (boiler house, CHP).

What are the advantages of an independent system versus a dependent one? This is primarily the possibility of precise control of the amount of heat during internal system home heating, its higher reliability. In addition, with such a scheme, it becomes possible to significantly improve the quality of water in the internal heating circuit, namely, to reduce the amount of sand, scale, and mineral salts to a minimum. In general, the advantages of this heating scheme are many.

There is, however, a very significant drawback - the monetary cost of implementing such a scheme. And it is an order of magnitude higher than that of the dependent scheme. Nevertheless, the advantages of an independent scheme outweigh its main disadvantage, and such a scheme is more promising for the consumer.

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It happens that private houses located within the city are located next to the laid district heating networks, and some are even connected to them. Of course, at the present time, the priority is individual heating, and centralized heating is gradually becoming a thing of the past. But if the house is already connected to the network or there are problems with the autonomous system, then you need to use what is available. For joint operation of the heat source with consumers, a dependent and independent heating system is used. What they are, as well as the pros and cons of both schemes will be outlined in this material.

Dependent (open) heat supply system

The main feature of the dependent system is that the coolant flowing through the main networks directly enters the house. It is called open because the coolant is taken from the supply pipeline to provide the house hot water. Most often, such a scheme is used when connecting multi-apartment buildings to heating networks. residential buildings, administrative and other buildings common use. The operation of the scheme of the dependent heating system is shown in the figure:

When the temperature of the coolant in the supply pipe is up to 95 ºС, it can be directed directly to the heating devices. If the temperature is higher and reaches 105 ºС, then a mixing elevator unit is installed at the entrance to the house, whose task is to mix the water coming from the radiators into the hot coolant in order to lower its temperature.

For reference. The centralized dependent heating system has a calculated and real temperature chart. The calculated graph characterizes the maximum water temperature and in open system sometimes 105/70 ºС or 95/70 ºС. Actual schedule depends on weather conditions and can change daily, it is maintained at the central heating point. When there is no street severe frosts, the coolant temperature is much lower than the calculated one.

The scheme was very popular during the Soviet era, when few people cared about energy consumption. The point is that the dependent connection with elevator nodes mixing works quite reliably and practically does not require supervision, and installation work and material costs are quite cheap. Again, no need to pad additional pipes for supplying hot water to houses when it can be successfully taken from the heating main.

But this is where the positive aspects of the dependent scheme end. And there are many more negative ones:

dirt, scale and rust from the main pipelines safely enters all consumer batteries. old cast iron radiators and steel convectors didn’t care about such trifles, but modern aluminum and other heating devices definitely didn’t care;
due to reduced water intake, repair work and other reasons, there is often a pressure drop in the dependent heating system, and even water hammer. This threatens with consequences for modern batteries and polymer pipelines;
the quality of the coolant leaves much to be desired, but it goes directly to the water supply. And, although the water in the boiler room goes through all the stages of purification and desalination, kilometers of old rusty highways make themselves felt;
it is not easy to regulate the temperature in the rooms. Even full bore thermostatic valves fail quickly due to Bad quality coolant.

Independent (closed) heating system

At present, when installing new boiler houses, an independent scheme for connecting the heating system has become more often used. It has a main and an additional circulation circuit, hydraulically separated by a heat exchanger. That is, the coolant from the boiler house or CHP goes to the central heating point, where it enters the heat exchanger, this is the main circuit. An additional circuit is a house heating system, the coolant in it circulates through the same heat exchanger, receiving heat from the network water from the boiler room. The scheme of operation of an independent system is shown in the figure:

For reference. Previously, bulky shell-and-tube heat exchangers were installed in such systems, which took up a lot of space. This was the main difficulty, but with the advent of high-speed plate heat exchangers this problem ceased to exist.

But what about the centralized supply of hot water, because now it is impossible to take it from the main, the temperature is too high there (from 105 to 150 ºС)? It's simple: an independent connection scheme allows the installation of any number of plate heat exchangers connected to the main pipelines. One will provide heat for the heating system at home, and the second can prepare water for household needs. How this is implemented is shown below:

To ensure that hot water always arrives at the same temperature, the DHW circuit is closed with the organization of automatic make-up in the return pipeline. IN apartment buildings the DHW circulation return line can be seen in the bathroom, heated towel rails are connected to it.

Obviously, the operation of an independent heating system has a lot of advantages:

the home heating circuit does not depend on the quality of the external coolant, the condition of the main networks and pressure drops. The entire load falls on the plate heat exchanger;
it is possible to regulate the temperature in the rooms with the help of thermostatic valves;
the coolant in a small circuit can be filtered and cleaned of salts, the main thing is that the pipes are in good condition;
in DHW system there will be water drinking quality entering the house through the water main.

However, due to the dirty low-quality coolant in the central network, periodic flushing of an independent heating system, or rather, a plate heat exchanger, will be required. Fortunately, this is not so difficult to do. Another disadvantage is the higher costs for the purchase of equipment, namely: heat exchangers, circulation pumps and shut-off and control valves. But closed system more reliable and safer than open, it meets modern requirements more and is better adapted to new equipment.

Conclusion

If, for some reason, you happen to choose a connection scheme for centralized networks, then an independent heating system of a private house is preferable. Even if the temperature in the line is low, you still should not supply this water to your system, it is better to hydraulically separate it from the central one. Provided that such an opportunity exists in the material plane, and if not, you will have to crash directly, according to a dependent scheme.

To understand how a dependent and independent heating system differs, it is necessary to give a clear definition of these concepts in order to avoid confusion in the future:

Independence implies isolation from the external heating main public purpose. It can be said that a two-circuit network is being implemented in order to avoid mixing the coolants of the first and second stages. Heat is transferred in a special device called a heat exchanger.

The dependence lies in the inability to independently adjust the temperature of the coolant, start and stop the system according to an individual schedule according to the climatic situation. Hard anchor to item district heating, which adjusts network settings as you see fit.

Each of the two heating options has both individual advantages and disadvantages, which follow from the design features and the principle of operation.

Independent heating system and its types

An independent heating system is divided, in turn, into two subspecies according to the implementation of the method of circulating an energy carrier in pipelines:

Gravitational, otherwise called non-volatile. The liquid moves through the pipes due to the different densities of cold and heated substances. Therefore, the heated carrier coming from the heat exchanger tends upward due to the lower specific gravity, cold, on the contrary, settles at the lowest points of the heating main. This feature imposes several strict requirements for the possibility of full functioning:

A heat exchange device or a water boiler, if the heating is autonomous, must be placed at the lowest point of the building. If radiators are also installed on this floor, then a pit below the floor level will have to be equipped.
All horizontally laid pipelines should be fixed at a slope of two to three degrees in the direction of movement of the coolant in the pipe. That is, the feed will have a positive angle relative to the common vector, and the return will have a negative angle.
To minimize negative impact hydraulic resistance, the passage diameter of the pipes must be large. For two-storey cottage with five to seven heated rooms, a diameter of 35 millimeters will suffice. The more-better principle is fully at work here.

Circulating or volatile. Heat carriers centralized system the supply and heat distribution hydraulics do not have physical contact with each other. The transfer of heat from one to the other occurs in the so-called heat exchanger, which is a tank in which tubes with liquid circulating through them are located. That is, an independent connection of the heating system realizes the possibility of flexible adjustment temperature regime heated structures, simplify network modification and expansion, and save on heating costs. There are also features:

The cost of construction significantly exceeds the cost of the first method.
Increased requirements are imposed on the quality of secondary circuit coolants.
Almost always there is a need for a continuous power supply to ensure the circulation process.

Safety and efficiency of independent heating systems

To be able to save money on heating, several conditions must be met:

Develop and approve the project in the licensing authorities. Without the approved GUI and agreed with all project authorities, all modifications will be illegal. Therefore, the results cannot be used.
Perform installation or reconstruction of existing equipment according to the design solution.
Install a heat energy meter. This will allow you to pay for the received thermal energy exactly in the amount in which it was consumed.
Provide the necessary level of automation or manual control. CHPPs do not react very quickly to temperature changes in weather conditions and can continue to fire their boilers to the fullest. And through the heat exchange tank, unclaimed energy will be transferred to the networks of consumers who open windows and vents from excessive heat.

Installation and connection of an independent heating system

Installation work in its complexity is not much more complicated than the gravity route. Of the additional measures, it is worth noting the need to organize an uninterruptible power supply. This will make it possible not to be left without heat during a power outage and is implemented by automatically switching on an uninterruptible power supply or a liquid fuel electric generator.

In addition, the existing routes of a centralized type are also subject to modernization by separating heat carriers by a heat exchange tank, installing a pump forced circulation and an uninterruptible power supply. Replacement or dismantling of pipelines with radiators is not required.

Due to the fact that a certain set of documents is required, it is recommended to start with obtaining a design solution. This sequence avoids wasting time and wasting money on materials.

First, let's figure out what an independent heating system means. First of all, it should be clear that this system heating is able to work without providing it with electricity. The difference between an independent heating system and other types is that it is not connected to a heat pipeline.

dependent system completely subordinated to the source of its energy supply. It is presented in the form of a boiler, pipes and radiators, interconnected into a single whole. Hot water circulates continuously. In a dependent system, it is not possible to independently regulate the temperature of the supplied water and early shutdown of heating during warming. The dependent heating system is tightly tied to the heating main as the main source of heat carrier.

Features of an independent heating system

An independent scheme for connecting the heating system does not depend on energy sources. There is a negative side of such a heating system - the high cost of its installation. In an independent system, it is possible to use technical water for external needs. As you can see, the dependent heating system is more accessible in terms of installation at the facility. It is mounted without much knowledge. It is important to study in detail the scheme of upcoming work.

Individual heating in a private house allows you to save money by reducing fuel consumption. It can be customized according to personal desires, creating comfortable conditions residence. Dependent heating system is full process water. It leaves behind sand and salt, which eventually clog the pipes, disrupting the normal process of water circulation. As for an independent heating system, you can use purified water when installing it. This approach will extend the life of the equipment.

But there is another important point - the dependence on electricity. An independent scheme for connecting the heating system allows you to do without electricity.

You can purchase a boiler that will run on solid fuels. The boiler is presented in the form of a steel tank, a thermostat and mechanical regulators. This will allow you not to be tied to the gas pipeline. But there is also a not very pleasant moment. It is required to periodically load fuel into the blower. To simplify the task, we advise you to make a bunker and a conveyor for supplying fuel. Sawdust and firewood can be used as an energy carrier. You will need electricity to run the transporter.

Heating boilers

The pyrolysis boiler works in two stages. First, the firewood is heated when oxygen is supplied until gas is formed, and then the stage of fuel combustion. To avoid the reverse movement of gases, it is worth thinking about an electric fan. Boilers with top combustion can work up to five days with a single supply of coal. Air is constantly moving. This phenomenon is facilitated by an ordinary fan.

Non-volatile boilers in operation allow ignition using a piezoelectric element. When the fuel ignites, it is possible to manually adjust the strength of the flame. After extinguishing, the burner is extinguished at high fuel temperatures, and the pilot burner operates in the normal mode, evenly giving off heat.

Boilers that have a built-in electric ignition do not start when the gas supply stops.

The non-volatile heating system starts working after the fuel has completely cooled down to the set temperature. Electricity is needed to run the fan, which supplies air.

So how do you decide which is better? If your home is located away from a power line, or the power supply is unstable, it is better to choose the option independent heating. The non-volatile boiler runs on gas without being connected to electricity. This heating option is economical, it allows you to reduce costs by 20% annually. You also get a system that lends itself to manual regulation of the flow of supplied heat and fuel consumption.

In order for the house not to cool down in the event of a power outage, we recommend that you do the following. The boiler is connected to a UPS with a capacious battery. You can also purchase a boiler that runs on diesel fuel.

In apartment buildings, residents mainly use the services of the central heating network for space heating. The quality of these services is influenced by many factors: the age of the house, wear and tear of equipment, the condition of the heating main, etc. In the heating system, a special scheme is also essential, according to which the connection to the heating network is carried out.

Connection types

Connection schemes can be of two types: dependent and independent. Connecting by dependent method is the simplest and most common option. An independent heating system has gained its popularity recently, and is widely used in the construction of new residential areas. What solution is more effective for providing warmth, comfort and coziness to any room?

dependent

Such a connection scheme, as a rule, provides for the presence of in-house heating points, often equipped with elevators. IN mixing unit At the heat station, superheated water from the main external network is mixed with the return one, while acquiring a sufficient temperature (about 100 ° C). Thus, the internal heating system of the house is completely dependent on external heat supply.

Advantages

The main feature of such a scheme is that it provides for the flow of water into the heating and water supply systems directly from the heating main, while the price pays off rather quickly.

disadvantages

Along with the advantages, this connection also has some disadvantages:

inefficiency;
temperature control is much more difficult during weather changes;
overexpenditure of energy resources.

Connection methods

The connection can be made in several ways:

Independent

The heat supply system of an independent type allows you to save consumed resources by 10-40%.

Operating principle

The connection of the heating system of consumers occurs with the help of an additional heat exchanger. Thus, heating is carried out by two hydraulic isolated circuits. The circuit of the external heating main heats the water of the closed internal heating network. In this case, mixing of water, as in the dependent variant, does not occur.

However, such a connection requires considerable costs for both maintenance and repair work.

water circulation

The movement of the coolant is carried out in the heating mechanism due to circulation pumps, due to which there is a regular supply of water through heating devices. An independent connection scheme may have an expansion vessel containing a supply of water in case of leaks.

Components of an independent system.

Scope of application

Widely used to connect to the heating system of multi-storey buildings or buildings that require advanced level reliability of the heating mechanism.

For objects that have available premises where unauthorized access is undesirable service personnel. Provided that the pressure in the return heating systems or heating networks above the permissible level - more than 0.6 MPa.

Advantages

Negative points

high price;
complexity of maintenance and repair.

Comparison of two types

The quality of heat supply according to a dependent scheme is significantly affected by the operation of the central heat source. This is a simple, cheap, low maintenance and repair cost method. However, the advantages of a modern independent connection scheme, despite the financial costs and complexity of operation, are obvious.