Heating system with forced circulation of the coolant. Open heat supply system: elements and diagrams, how an open hot water heat supply system works. Closed heating system

The stage of design and construction, when the heating scheme of a private house is determined, is a rather crucial moment in the process of thermal insulation. After all, an improperly planned system “threatens” your home with a lack of quality heat, "oversaturation" of the house with elements of the "interior" in the form of extra heating radiators, the inability to quickly control the operating mode of the system ... and at the same time, the money spent is yours.

Parsing great amount schemes that are presented on the pages of literature and sites on the topic of insulation and heating, you can get a little "lost". Therefore, we will focus on several of the most commonly used schemes, having studied their advantages and disadvantages.

As you probably already know, there are two types of schemes:

scheme of the heating system with natural circulation of the coolant;
with forced circulation coolant.

There are also single-pipe and two-pipe heating systems that can be implemented both in systems with natural circulation and in "forced" ones.

The coolant in such systems can be:

ordinary water;
antifreeze (non-freezing liquid for heating systems)

Attention! When using antifreeze, it is necessary to clarify its compatibility with the material. gaskets sections of heating radiators. In such systems, the use of aluminum radiators is highly undesirable!

Heating scheme with natural circulation

Heating schemes with natural circulation of the coolant are not particularly popular today due to their “moral senility”, low efficiency, bulkiness, high cost of materials and installation, the impossibility of differential temperature control in individual radiators, etc.

But they are indispensable in those homes where there is no electricity, since such systems equipped with a solid fuel boiler can work autonomously (with the periodic presence of a person, of course).

The principle of operation of a heating system with natural circulation (it is also called gravity) is to create a temperature difference between the coolant at the outlet of the boiler and its inlet. Due to the different density of the coolant at different temperatures, it moves through the pipes by gravity, without using a circulation pump, that is, warm water rises, and already cooled water “comes” from the return pipe in its place. As it sequentially passes through the radiators, the coolant lowers its temperature, giving off heat to environment, and after a “full circle” and return to the boiler heat exchanger, it heats up again, and the cycle repeats.

Sequential one-pipe scheme of the heating system of a private house with natural circulation

Attention! For the functioning of such a system, the prerequisites are: a sufficiently large diameter of the pipes (d>=1 inch), especially the central riser and the slope of the main pipes throughout the system (at least 1 cm per 1 m of length).

In addition, the point of "water intake" of the coolant from the riser must be located above the uppermost radiator, and the boiler itself must be below the outermost radiator.

The volume of coolant in such systems is quite large and depends on the diameter of the pipes and the length of the system. On average, the volume of water will be 3 times more in a natural circulation system than in a forced circulation system. And this is at equal area heated rooms.

A large amount of coolant in the system increases its inertia. There is also a positive point in this, if the boiler "goes out", the heat in the system will remain for some time. And if antifreeze is used in the heating system, you will simply pay for additional tens of liters of this substance.

The successive passage of the coolant through the heating radiators leads to its cooling. Thus, those radiators that are at the beginning of the system (from the central riser) will heat up more than those that are at the end of the heating main (in front of the boiler). It is almost impossible to regulate the degree of heating of radiators with such a connection.

Another feature of such a system is its "selectivity" to the material of the pipes used. AT without fail they must be metal - usually steel. Polymer pipes simply cannot withstand the high temperature that can occur in the system when the coolant in the boiler overheats. The consequences of such a “restriction” in the choice of materials are the low efficiency of the entire system as a whole, the high cost of installation and the negation of the aesthetics of modern large-diameter heaters steel pipes and bulkiness of the whole system.

An obligatory element of such a heating system is an open-type expansion tank, which must necessarily be located in top point systems. Its volume should be approximately 1/10 of the volume of the coolant in the system. For example, with a volume of coolant in the system of 200 liters, the tank capacity should be 15-20 liters. The open type of the tank assumes that the system is constantly in contact with atmospheric pressure. It is also a prerequisite for the existence of the system.

Let's sum up.

Gravity water heating scheme has the following advantages:

the possibility of autonomous use;
sufficiently high thermal inertia.

Disadvantages:

a large volume of coolant (antifreeze);
unaesthetic "bulky";
low efficiency;
expensive (difficult to self-fulfillment) mounting;
rather high cost;
inability to adjust the temperature.

Plus info! In gravity-flowing serial one-pipe systems, a series-parallel connection of heating radiators is also possible. In such cases, it becomes possible to regulate the flow of water through some of them. But! The use of thermostats is limited - you can install such a device only on one of the two parallel radiators. The closed flow of the coolant through the system cannot be completely blocked - overheating will occur!

Parallel two-pipe version of the heating system of a private house

In the system, the scheme of which is shown in the figure, the temperature of individual radiators will no longer depend strongly on the location, it is already possible to regulate the temperature of individual radiators, but not all! The slope of horizontal pipes (risers) and their sufficiently large diameter are also required.

Let's move on to the next scheme of the heating system.

Heating scheme with forced circulation of the coolant

The schemes of the heating system discussed in the previous section of the article can be easily turned into systems with forced circulation of the coolant. To do this, a circulation pump “cuts” into the system “in front of the boiler on the return pipe. In addition to the pump, the system changes from an open type to a closed one.

But comfortable use of the system is possible only with its two-pipe design and with forced circulation. Parallel connection radiators allows you to adjust the temperature of each separately, both manually using a valve, and by putting an automatic thermostat on each battery. It is also possible to fully automate the operation of such a heating system, but for additional considerable money.

Saving! This ability to control the temperature of radiators in different rooms, depending on the needs, saves up to 20% of the energy used in the boiler.

What are the "merits" of the circulation pump in such heating systems. He:

It increases the speed of movement of the coolant, which contributes to a more dynamic change in the temperature of the entire system as a whole during regulation and, in general, increases the efficiency of the system.
Allows you to reduce the temperature of the coolant, which entails the possibility of using plastic pipes.
Allows you to significantly reduce pipe diameters, which reduces material costs and installation complexity.

The purchase of a pump and its energy consumption pays off with these already listed advantages.

Attention! When buying gas or electric boiler pay attention to such a moment - the circulation pump may already be built into the boiler. Therefore, the binding scheme wall boiler heating may not "contain" an external circulation pump. And when using long contours of the “warm floor”, you will (possibly) also install additional pump to these contours.

The heating scheme with forced circulation has a “pleasant” difference from systems with natural circulation of the coolant - the independence of the boiler installation height from the installation height of heating radiators.

The circulation pump is usually installed on the return pipe, based on the fact that more cold water will extend the life of the pump.

Such a parallel connection scheme allows you to use a water-heated floor in the heating system (Link) and combine any number of radiators depending on the boiler power, that is, use complex schemes heating wiring. This type has a heating scheme for a two-story house.

In more detail, we will consider such schemes for heating a private house in specific articles about the organization of heating. various premises private house.

Heating radiator connection diagrams

The schemes used for connecting heating radiators can be different and also depend on the type of the heating scheme of a private house itself.

Different kinds connecting radiators to the heating system also have different heat loss coefficients during heat transfer.

Among many heating schemes, a system with forced circulation of the coolant is distinguished by its versatility and wide functionality. It can be used in the heat supply of a small private cottage or apartment, as well as in a large high-rise building. Is it difficult to do it yourself, without the involvement of specialists? Let's find out what is the heating of a house with forced circulation with our own hands, schemes and the optimal configuration of a particular system.

Features of heating with forced circulation

Contemporary water heating with forced circulation has replaced the gravitational scheme. In the second, the movement of the coolant is carried out due to the thermal expansion of water when it is heated. This principle significantly reduced the efficiency of heat supply.

One of the determining factors for the expediency of installing a water heating system with forced circulation is the relatively rapid movement of the coolant along the main. Due to this, there is an even distribution of heat over all radiators in the circuit.

In addition, the following features of heating by pumping groups should be noted:

Possibility to install small pipes: 20, 25 mm. This reduces the total volume warm water in the system, which affects the energy consumption;
Choice of several piping schemes in. The forced heating system of a private house can be one-pipe, two-pipe or collector;
Temperature control both for individual elements and for the system as a whole. Collector heating copes with this task best of all;
Increased operating comfort.

However, along with this, it should be noted the disadvantages that a two-pipe or one-pipe heating system with forced circulation has. First of all, this is the installation of a pumping group to increase the flow rate of the coolant. This entails an increase in primary costs, and also makes the operation of the entire system dependent on the supply of electricity. But these shortcomings are offset by the above advantages.

You can upgrade what you already have. To do this, it is enough to install a pump. However, first you need to calculate the parameters of the system - not always pipes large diameter suitable for circuits with forced circulation.

Types of heating circuits with forced circulation

The basic principle of operation of a forced circulation heating system is to install pumps to increase the flow rate of the coolant. The place of their installation directly depends on the chosen piping layout.

In addition, the heating system of a private house with forced circulation must include security groups. This is necessary for the timely stabilization of pressure in the pipes due to possible overheating of the coolant. Each type of heating with forced circulation has a number of features that directly affect the choice in a particular case. But regardless of this, a do-it-yourself forced circulation heating system, in addition to the pump, should include the following components:

Security group: air vent and drain valve. Installed immediately after the boiler;
Expansion tank. It is best to choose a diaphragm-type design with the possibility of replacing an elastic valve;
In the piping of each radiator must be balancing valve, crane Mayevsky. It is advisable to install a thermostat;
Shut-off valves. It is necessary for partial or complete blocking of the coolant flow in a specific section of the system.

Each of the above components must be performance characteristics, corresponding to the parameters of a particular heating system. Otherwise, they will not perform the functions assigned to them.

The choice of certain components of the system is carried out according to a pre-made scheme for heating a house with forced circulation. The calculation should be as accurate as possible - using specialized programs or done by professionals.

Single pipe system

This is an outdated scheme, which is practically not used for individual heat supply at home. In a single-pipe forced circulation heating system, there is only one supply line in which radiators and batteries are connected in series.

The only advantage of this scheme is the small footage of pipelines. However, in addition to this, the single-pipe system has several significant drawbacks:

Uneven distribution of the coolant. The further the radiator is located from the boiler, the lower the degree of heating of the hot water entering it;
For repair work it is necessary to stop the heating boiler and wait until the temperature of the coolant drops to a normal level.

The power of the pump for single-pipe heating with forced circulation will be much less than for two-pipe. This is due to the smaller volume of coolant in the system. Also, for laying pipelines, it is necessary less space- they can be installed under the floor, skirting boards.

For a single-pipe heating system with forced circulation, it is imperative to provide for the installation of a bypass for each radiator. This will make it possible to turn off the device without completely stopping the heat supply to the house.

Two-pipe system

The scheme of a two-pipe heating system with forced circulation differs from a single-pipe one by the presence of another line for the cooled coolant. It runs parallel to the main one and cooled water from the radiators enters it.

During the design of the system, it is necessary to correctly draw up the layout of the pipelines. The direct and return lines must be installed in close proximity to each other, but not more than 15 cm, in addition, the system can be with the same direction of movement of the coolant, with different vectors, as well as a dead end. Most often, a one-way directivity scheme is selected.

Water heating with forced circulation has several important features:

Small pipe diameter - from 15 to 24 mm. This will be enough to create the required pressure indicators;
Possibility to install both horizontal and vertical piping;
A large number of rotary elements will affect the hydrodynamic performance of the system for the worse. Therefore, they should be made as small as possible;
When choosing concealed installation inspection hatches are installed at the junctions of the pipes.

In each forced heating system of a private house, it is necessary to provide a bypass channel in the circulation pump assembly. It is designed for the gravitational movement of the coolant in the event of a power outage.

Work pumping equipment should ensure normal circulation in the system. To do this, you should correctly calculate its power and performance.

If the hot water heating system with forced circulation is equipped with polymer pipelines- they must be reinforced layer from aluminum foil or polyester.

Collector system

If the area of \u200b\u200bthe house exceeds 150 m² or it has 2 or more floors, it is recommended to make a collector heating system with forced circulation with your own hands. It is one of the modifications of the two-pipe scheme and is designed to increase the efficiency of heat supply.

main element collector circuit heating is a distributor. It is a pipe with a round or rectangular cross section, on which several branch pipes are installed. They are necessary for the distribution of the coolant to the individual heating circuits of the house.

A distinctive principle of operation of a heating system with forced circulation of the collector type is the arrangement of pipelines independent of each other. This makes it possible to regulate the heat transfer of each of them, and also stabilizes the pressure in the system.

A circulation pump is installed on each branch pipe of the collector to ensure the proper speed of the coolant. Such a heating system of a private house with forced circulation has a number of important features:

Increase in the number of pipes and fittings. Each circuit is a separate heating system connected via a collector into a single network;
To adjust the volume of the coolant, special elements are needed - thermostats and servo drives with temperature sensors;
For the most effective work system, it is recommended to install a mixing unit. It connects the direct and return pipes and mixes the water flows to achieve the optimum temperature of the coolant.

The collector circuit for heating a house with forced circulation may consist of several distribution nodes. It all depends on total area home, as well as the location of the premises in it.

The sum of the diameters of the nozzles on the manifold must not exceed its cross section. Otherwise, destabilization of pressure in the system will occur.

Designing heating with forced circulation

The primary task for self-installation of water heating with a circulation pump is to draw up the correct scheme. To do this, you need a plan of the house, on which the location of pipes, radiators, valves and safety groups is applied.

System calculation

At the stage of drawing up the schemes, it is necessary to correctly calculate the parameters of the pump for the forced heating system of a private house. To do this, you can use special programs or do the calculations yourself. There are a number of simple formulas that will help make the calculation:

Pн=(p*Q*H)/367*efficiency

Where pH- rated power of the pump, kW, R- the density of the coolant, for water this indicator is 0.998 g / cm³, Q– coolant flow rate, l, H- required pressure, m.

To calculate the pressure indicator in the forced heating system of a house, it is necessary to know the total resistance of the pipeline and heat supply as a whole. Alas, it is almost impossible to do it yourself. To do this, you should use special software systems.

Having calculated the resistance of the pipeline in a water heating system with circulation, it is possible to calculate the required pressure indicator using the following formula:

H=R*L*ZF/10000

Where H- calculated pressure, m, R- pipeline resistance, L- the length of the largest straight section of the highway, m, ZF- coefficient, which is usually equal to 2.2.

Based on the results obtained, a optimal model circulation pump.

If the calculated pump power indicators for a self-installed forced circulation heating system are large, it is recommended to purchase paired models.

Installation of heating with circulation

Based on the calculated data, pipes are selected desired diameter, and to them - shutoff valves. However, the diagram does not show the method of mounting the trunk. Piping can be installed hidden or open way. The first is recommended to be used only with full confidence in the reliability of the entire heating system of a private cottage with forced circulation.

It must be remembered that the quality of the components of the system will depend on its performance and performance. In particular, this applies to the material for the manufacture of pipes and valves. In addition, for a two-pipe scheme of a forced circulation heating system, it is recommended to heed the advice of professionals:

Installation of an emergency power supply for the circulation pump in the event of a power outage;
When using antifreeze as a coolant, check its compatibility with the materials for the manufacture of pipes, radiators and the boiler;
According to the house heating scheme with forced circulation, the boiler should be located at the lowest point in the system;
In addition to the pump power, it is necessary to make a calculation expansion tank.

The technology for installing circulation type heating is no different from the standard one. It is important to take into account the features of the contour house - the material for making the walls, its heat loss. The latter directly affects the power of the entire system.

Analysis of the parameters of heating systems with forced circulation will help to form an objective opinion about it:

Heating of a house or cottage can be provided using one of two types of heating systems that differ from each other in the way the coolant circulates. With the natural movement of water or antifreeze through pipes, it is not necessary to use optional equipment, but it is necessary to ensure the appropriate slope of the pipeline. If a heating scheme with forced circulation is selected, then a circulation pump cuts into the pipeline, which is responsible for the speed of the coolant in the heating system. The higher this indicator, the faster all the rooms in the house warm up. The operation of the circulation pump depends on the availability of electricity, therefore, in case of possible power failures and outages for a long time, it is necessary to stock up on a gas generator.

How are open systems different from closed systems?

Any hydraulic heating system can be represented as a complex heating equipment and heating devices, combined in a certain order into one whole with the help of pipes.

In heating systems, an expansion tank is installed, since the heated coolant increases in volume. If the tank communicates with the outside atmospheric air, then the heating system is called open. By isolating the expansion tank from interaction with atmospheric air, a closed-type heating system is obtained. The coolant evaporates, so you have to monitor the water level in the tank and top up if necessary. In equipped with expansion tanks of the membrane type, this problem does not arise.

Installation of a heating system, including a boiler, an open expansion tank, radiators, shut-off valves, air vents, a circulation pump that provides forced circulation of the coolant

Why install a circulation pump?

Advantages of installing a circulation pump:

Installation is simplified, since there is no need to build a complex and inconvenient top wiring of the pipeline in compliance with the slope angle. It is not required to construct the main risers from pipes of a larger diameter. Thanks to this, it is possible to improve the interior of the room.
You can choose a collector type of piping, which ensures uniform heating of all heaters, regardless of their distance from the boiler.
It becomes possible to increase the length of pipelines.
With a forced circulating carrier, it can be built into the heating system additional elements, for example, "heat-insulated floors".

The circulation pump is installed in front of the heating boiler on the return main pipe. It is also recommended to install a membrane (expansion) tank, which is necessary element closed type heating systems.

Elements of a closed-type heating circuit

The main elements of a forced circulation heating system are:

boiler (solid fuel, gas, etc.);
expansion sealed tank of membrane type;
circulation pump, selected by power;
heating radiators (batteries);
pipes for the construction of risers, jumpers and connections;
adapters for connecting pipes (fittings);
ball and plug valves;
check valves;
air vents;
filters necessary to maintain the efficiency of the heating boiler and pumps;
fasteners (clamps, etc.).

Scheme of the device in a private house of a closed-type heating system with the installation of a circulation pump and a sealed membrane tank on the return

Important points during installation

In order for forced circulation heating to function without problems for a long time, it is necessary to correctly install important components on which the efficiency of the entire system depends.

To increase the duration of the life of the circulation pump, it is cut into the return line. It is explained simply. The water moves through the return pipeline in a chilled form, since the heat has already been given away heating devices. In the design of the pump, manufacturers use cuffs and seals made of rubber, which can change properties when under constant exposure to high temperatures. The cooled coolant entering the return does not have a significant effect on rubber parts, which allows them to retain their original properties longer.

For mounting compulsory system heating, pipes with a minimum diameter can be used. At the same time, it is possible to reduce the cost of work on the device of the heating system at home. After all, the volume of coolant that fills the system is reduced. This, in turn, affects the choice of an expansion tank of a suitable volume and power of the purchased heating boiler.

In forced circulation heating systems, it is recommended to use modern heating boilers, the design of which provides for the presence of automation. These devices provide control and regulation of all processes with minimal human intervention in the operation of the equipment. Fuel is used more efficiently and the indoor temperature is regulated, taking into account various factors that affect the course of the home heating process.

How to choose a circulation pump model?

When choosing pumping equipment, attention is paid to the simplicity and reliability of its operation, as well as to energy consumption. In addition to these important qualities, pump power and pressure are important. These characteristics are determined by the size of the heated room. You can refer to the following examples:

for houses with an area of 250 sq. meters, acquire pumps with a pressure of 0.4 atmospheres and a capacity of 3.5 cubic meters. meters per hour;
for houses whose area is in the range of 250-350 sq. meters, acquire pumps with a pressure of 0.6 atmospheres and a capacity of 4.5 cubic meters. m/h;
for houses with an area exceeding 350 sq. meters up to 800 sq. meters, purchase pumps with a pressure of 0.8 atm. And with a capacity of 11 cubic meters. m/h

Mounting the circulation pump on the bypass (jumper) makes it easy to remove equipment for replacement or current repair and maintenance

Interfering with the normal circulation of the coolant in the heating system can be air pockets that form in each radiator and in places where the pipeline rises vertically. You can deal with air accumulations by installing Mayevsky taps on each radiator or special automatic air vents. The installation of these devices will prevent "airing" of individual sections of the system and violations in the operation of heating, affecting the microclimate in the room.

Advantages of installing a two-pipe system

When designing water heating with forced circulation for a private house, they choose, based on the material capabilities of the owner, a one-pipe or two-pipe scheme. A single-pipe system is cheaper, easier to install, and a two-pipe system is more efficient in operation. When installing a horizontal two-pipe heating system, three pipeline laying schemes are possible: dead-end, associated and collector.

We note right away that the latter has the greatest efficiency, namely. However, its implementation increases the consumption of materials, as well as the complexity of the installation work.

One of the main advantages of gravitational heating schemes is reliability. Despite this, today they are increasingly being replaced by schemes with forced movement of the coolant. Many people ask why is this happening? At first glance, it's all about the shortcomings of gravity heating, which are solved by simply installing a pump. If you look deeper, it turns out that for the most part, modern boiler plants are already equipped at the factory with equipment that makes it easy to create a heating system with all the advantages of forced circulation of the coolant in the circuits.

Advantages and disadvantages

First of all, consider all the pros and cons of this heating system (CO).

Heating with a pump can perfectly cope with the coolant, which moves along a circuit made of fairly thin pipes. There is a reduction in the estimated cost due to the smaller section of the pipeline.
The boiler plant will heat up a smaller volume of water in the pipes faster. In such COs, inertia is reduced.
With a heating system with forced circulation, there is no need to observe the slope of the circuit.
With such a CO, you can use the bottom wiring diagram, which makes it more aesthetic.
You can significantly increase the length of the circuit, and not be limited to 30 meters, as with the natural movement of the coolant.
You can use multi-circuit schemes, "warm floor", etc.
In forced CO, you can mount an expansion tank in any place convenient for you.

And these are only the main advantages of this method of moving the coolant. There are much fewer disadvantages, but we have no right not to consider them:

Noise from the pump. If you organize a boiler room, then this drawback immediately becomes insignificant.
The cost of electricity for the operation of pumping equipment. Average electricity consumption modern devices(depending on model and performance) is 50 - 120 Wh. Hence the costs are minimal.
Dependence on the supply of electricity. In areas with unstable power supply, the creation of combined heating is recommended.

In addition, if we use the IPB, then this shortcoming may not be taken into account.

Types, varieties, schemes

There are two types of CO: one-pipe and two-pipe. A single-pipe heating system with forced circulation can be horizontal and vertical.

When horizontal, the coolant from the boiler installation moves through the main pipeline, to which radiators are connected in series.

This figure shows a modernized, closed-circuit heating system with forced circulation, with jumpers (bypasses) between the input and output of each battery. The circuit is equipped with a safety group, which includes: a pressure gauge, a blast valve, an automatic air vent.

Vertical single-pipe CO works as follows: the coolant heated in the boiler unit rises along the vertical riser. With the lower wiring, the coolant passes through the series-connected radiators and, already cooled, again descends along the vertical riser into the boiler plant.

With the upper wiring, the heated water rises along the vertical pipeline, moves along the distribution pipeline, after which, descending, it passes through all connected heating appliances.

A two-pipe forced circulation heating system can be laid out horizontally and vertical way with various options wiring. There are three types of horizontal CO:

Important! The dead-end circuit can be implemented both in horizontal and vertical COs.

Equipment selection

In order to turn any gravity heating system into a scheme with forced displacement coolant, you need to choose the right equipment. From this will depend on its effectiveness and efficiency.

The pump is the central figure in ensuring the circulation of water around the circuit. As a rule, centrifugal-type devices with straight impeller blades are used for domestic heating systems. The pumps differ in the operating pressure that they can create in the system, in the performance, power consumption, head height and diameter of the connecting pipes.

The required performance of the circulation pump can be calculated by the formula (Q / c * Dt) / P, where Q is the heat loss of the house;

C - how much heat water can carry in itself (the value is 1.16);

DT is temperature delta;

P - water density at nominal t ° C (table value).

For residential buildings with an area of up to 250 m 2 it is recommended to use a circulation pump with the following characteristics: productivity 3 - 4 m 3 / h; pressure 0.4 - 0.5 atmospheres.
Up to 350 m 2 - 4 - 5 m 3 / h; pressure 0.6 atmosphere.
Up to 800 m 2 - 11 - 12 m 3 / h; pressure 0.9 atmospheres.

Important! It should be understood that the above figures are approximate. The correct calculation depends on many factors (type and degree of insulation of the house, material of pipes and fittings, system configuration, etc.) For a more accurate selection of the circulation pump, contact the experts.

Pump, self-sufficient element of circulating CO. But for reliable operation this device requires competent strapping, which includes:

Ball valves on both sides of the pump.
Sump.

The expansion tank is another essential element CO with forced circulation. Depending on its design, schemes of open heating systems with forced circulation and closed ones are distinguished.

In open COs, atmospheric devices are used to compensate for the thermal expansion of the coolant. In case of excess pressure in the system, part of the coolant is discharged. To replenish water in CO, a float valve is used, which is connected directly to the water supply.

In modern heating systems membrane expansion tanks are used. Due to the tightness of the latter, the circuits in which they are applied? called closed. The hermetic expansion tank works in closed heating systems with forced circulation very simply: in the housing this device rubber membrane installed. On one side of the membrane there is a coolant, on the other - air pumped into the tank under a certain pressure.

When the pressure in CO is exceeded, the membrane bends towards the air, when falling - towards the coolant. Thanks to this simple technology, pressure surges in heating systems are leveled.

Tip: The capacity of the expansion tank depends on many factors. Based on experience, expansion tanks with a capacity of 10% of the amount of coolant are used in domestic COs.

Stages of planning a heating system with forced movement of the coolant

Consider the stages of creating a heating system one-story house with forced circulation. The first thing to do is a hydrodynamic calculation, which includes the following steps:

Determination of the power of the boiler plant.

The choice of scheme: one-pipe, two-pipe.
Calculation of resistance on each section of the highway.
Calculation of the number of batteries and sections.
The choice of their connection scheme.
Diameter calculation main pipeline and withdrawals.
Equipment selection, installation, pressure testing, CO balancing.

Advice! Creation of economical and reliable system heating requires knowledge and competent calculations. We strongly recommend that you seek expert advice.

To date, a closed heating system with forced circulation of the coolant has been successfully used to heat the vast majority of country houses. Its difference from open circuit- in the movement of water under pressure through a closed network of pipelines in complete isolation from external environment. If you have not yet decided which type of heating wiring to choose for your home, we recommend that you read this article, which outlines all the necessary information about closed systems.

Composition and principle of operation

Regardless of the chosen scheme (we will consider their varieties below), it always includes the following main elements:

heat source - gas, diesel, electric or solid fuel boiler;
consumers - radiator network and (or) water heated floors;
circulation pump;
sealed expansion tank of membrane type;
safety group, including a device for air release (air vent), safety valve and manometer;
mesh filter - mud collector;
pipeline fittings for balancing, emptying and adjustment;
main and supply pipes.

Note. The heating system can be supplemented with other elements and equipment provided for in the project, for example, a distribution manifold, a buffer tank and various means automation. A typical two-pipe scheme, the most common in private homes, is shown in the figure above.

The principle of operation of a modern closed system is to transfer thermal energy from the boiler to the radiators with the help of a liquid under excess pressure (from 1 to 2 bar). The expansion of its volume from heating is compensated by stretching the rubber membrane inside the tank, completely isolated from the atmosphere.

Airtight expansion tank device

Airing the heating network is prevented by an automatic air vent installed in the security group. The blast valve located in the same place is triggered in the event of a critical increase in pressure in the pipelines, it is usually set to 3 bar. The mud collector is placed on the return line in front of the entrance to the heat generator and collects the sludge coming from the heating network.

An important point. The circulation pump, forcibly pumping the coolant, can be built into both the return and supply pipelines next to the boiler. Both ways are correct.

Positive aspects and disadvantages

The closed version of the water system has gained popularity due to its numerous advantages:

no contact with the atmosphere - no loss of coolant due to evaporation;
antifreeze can be used to fill the network in a periodically heated building;
there is no need for pipes of large diameters, laid with a significant slope, as is done when installing pipelines with natural water circulation;
there is no heat loss through a sealed expansion tank, so the scheme is considered more economical;
pressurized water heats up much faster, and boils at more high temperature, which reduces the risk of vapor lock formation in case of an emergency;
the closed system is well regulated both on separate sections, as well as in general.

Note. Tightness gives another important plus - the coolant is not saturated with atmospheric air through an open tank. Air bubbles can only enter the pipelines through make-up from the water supply or through cracks in the tank membrane.

Laying pipelines in the floor and inside the walls

Small pipeline diameters and forced circulation are the most important arguments in favor of modern closed heating networks. All wiring can be hidden in walls or floors, and pipes can be laid with a minimum slope. It serves only to drain water when repairing or flushing radiators and lines.

Now about a fly in the ointment in a barrel of honey. The fact is that the closed heating system of a private house is unable to function autonomously, since it depends on the electricity that feeds the pump. Therefore, with frequent power outages, it is recommended to acquire a block uninterruptible power supply or an electric generator, so as not to be left without heat.

Reference. On the Internet, you can find alternative options - closed systems, modeled after gravity (gravity). That is, large pipes with significant slopes. But then half of the above advantages are lost, and the cost of installation increases.

The second negative point is the difficulty of removal air locks in the process of pouring water, pressure testing and starting heating. But this minus will not become a problem if air is removed according to generally accepted technology.

Closed systems diagrams

For heating suburban and country houses The following types of wiring apply:

Single pipe. All radiators are connected to a single line running around the perimeter of the room or building. Since the hot and cooled coolant move along the same pipe, each subsequent battery receives less heat than the previous one.
Two-pipe. Here, heated water enters the heating devices through one line, and leaves through the second. The most common and reliable option for any residential buildings.
Associated (Tikhelman's loop). Same as two-pipe, only chilled water flows in the same direction as hot water, and does not return in the opposite direction (shown in the diagram below).
Collector or beam. Each battery receives coolant through a separate pipeline connected to a common comb.

Single-pipe horizontal wiring (Leningradka)

Reference. Single-pipe systems are horizontal (the so-called Leningradka) and vertical. The latter, where water is distributed to heating devices from risers, are often used in two-story houses.

Single pipe horizontal scheme justifies itself in one-story houses a small area (up to 100 m²), where heating is provided by 4-5 radiators. You should not connect more to one branch, the last batteries will be too cold. The option with vertical risers is suitable for a building of 2-3 floors, but in the process of implementation, almost every room will have to be covered with pipes.

One-pipe scheme with top wiring and vertical risers

Advice. If your choice fell on a single-pipe closed circuit, it is better to entrust its design and commissioning to specialists. They must make a calculation and select the diameter of the main line so that there is enough heat for all consumers. To learn more practical information, a video from an expert will help you:

The two-pipe circuit with dead ends (shown at the beginning of the article) is quite simple, reliable and unambiguously recommended for use. If you are the owner of a cottage with an area of up to 200 m² with a height of 2 floors, then make the wiring of the mains with pipes with a flow section of DN 15 and 20 (outer diameter - 20 and 25 mm), and for connecting radiators, take DN 10 (outside - 16 mm).

Passing scheme of water movement (Tichelmann's loop)

The Tichelman loop is the most hydraulically balanced, but more difficult to install. Pipelines will have to be laid around the perimeter of the rooms or the whole house and pass under the doors. In fact, a “ride” will cost more than a two-pipe one, and the result will be approximately the same.

The beam system is also simple and reliable, in addition, all wiring is successfully hidden in the floor. The connection of the nearest batteries to the comb is carried out with 16 mm pipes, the distant ones - 20 mm. The diameter of the line from the boiler is 25 mm (DN 20). The disadvantage of this option is the price of the collector assembly and the laboriousness of installation with the laying of highways, when the flooring has already been done.

Scheme with individual connection of batteries to the collector

How to choose equipment

One of important points- selection of a heat source according to the power and type of energy carrier used:

on natural or liquefied gas;
on solid fuel - wood, coal, pellets;
on electricity;
on the liquid fuel- diesel fuel, waste oil.

Reference. If necessary, you can choose a combined multi-fuel installation, for example, on wood and electricity or gas + diesel fuel.

The power of the boiler plant is calculated in a standard way: the heated area of \u200b\u200bthe dwelling is multiplied by 0.1 to convert to kilowatts and by a safety factor of 1.3. That is, for a house of 100 m², a heat source with a capacity of 100 x 0.1 x 1.3 = 13 kW is needed.

For a closed heating system, it does not matter which heat generator you buy, so we will not consider this issue in detail. But you will greatly facilitate your task if you purchase a wall-mounted gas boiler equipped with its own circulation pump and expansion tank, as shown in the photo. For a small house, it remains only to pick up pipes and heating appliances, which will be discussed later.

Varieties of pipes

The heating network of a private house can be mounted from the following pipes:

PPR (polypropylene);
cross-linked polyethylene - PEX, PE-RT;
metal-plastic;
metal options: copper, steel and corrugated stainless steel.

Under execution self-assembly with low financial costs, it is better to take polymer pipes. For the assembly of crimp connections made of metal-plastic and polyethylene, it is not required special tools, and polypropylene will have to be soldered ( welding machine rented out). Of course, PPR material has no equal in terms of cost, but for reasons of reliability and durability, we recommend using PEX pipelines made of cross-linked polyethylene.

Copper and corrugated stainless steel can also be mounted on compression fittings, but the first is different high price, and the second - significant hydraulic resistance. As for ferrous metal, it is inconvenient in all respects - welding installation and susceptibility to corrosion push it to the last place. More information about the choice of pipes is described in the next video:

Which radiators are better

Now the distribution network offers heating devices of the following types:

steel panel;
made of an alloy of aluminum with silicon (silumin);
the same, but with a frame made of steel pipes, the name is bimetallic;
cast-iron batteries - analogues of the Soviet "accordions" MS 140 and retro-style models.

Note. The last 3 types of radiators are recruited from the required number of heat transfer sections.

Steel panel radiator

From the point of view of economy, it is more profitable to buy steel batteries, which are distinguished by a democratic price. Aluminum appliances are more expensive, but they give off heat more intensively. These 2 varieties are most in demand for closed heating systems of private houses.

Aluminum heater

Bimetallic radiators are designed for heating networks with low-quality coolant supplied with pressure drops, which is typical for district heating apartment buildings. Buy these expensive items Vacation home with independent heating meaningless.

Cast iron "accordions" are much inferior to other batteries in terms of appearance and weight. But due to the low price, they are used in industrial buildings and outbuildings. At the same time, vintage cast iron radiators have an impeccable design, but are too expensive for the price.

To select a heater by power, make a simple calculation: divide the heat transfer indicated in the passport by 1.5. So you will find out the real power of the radiator, because the documentation reflects the characteristics for certain conditions exploitation that do not correspond to reality.

Advice. Do not forget to purchase radiator fittings - a ball valve for supply and a balancing valve for the return. If you decide to put energy-saving thermostats with presetting on the batteries, then a conventional shut-off valve should be installed at the outlet of the device.

Pump and expansion tank

In closed heating systems of private dwellings, 3 types of domestic circulation pumps are usually used, developing a head of 4, 6 and 8 m of water column (this pressure is 0.4, 0.6 and 0.8 Bar, respectively). We propose not to delve into complex hydraulic calculations, but to select pump unit on the following grounds:

For a one- and two-storey building with an area of up to 200 m², a head of 4 m is sufficient.
A cottage with an area of 200-300 m² will need a pump with a pressure of 0.6 bar (6 m).
The circulation in the network of a three-story mansion of 400-500 m² will be provided by a unit with a head of 8 m of water column.

Reference. The power of the pump must be judged by its marking. For example, a Grundfos 25-40 brand product has a connection diameter of 25 mm and develops a pressure of 0.4 bar.

To select the size of the expansion tank, you should calculate the volume of water in the entire closed heating system, including the boiler tank. Given the fact that when heated from 10 to 90 ° C, water expands by about 5%, the capacity of the tank should be 1/10 of the total amount of coolant.

How to fill heating pipelines

We decided to highlight this issue, since the filling of a closed system must be carried out according to a certain algorithm so that there are no air pockets left:

First, all heating devices must be cut off from the mains with the help of taps. Open the rest of the fittings completely and turn on the make-up from the water supply. Fill the pipes slowly to allow air to escape through the valve on the safety group.
When the pressure reaches 1 bar (watch the pressure gauge), stop filling and turn on the circulation pump for a few minutes to squeeze out the remaining air.
Leave the assistant to maintain the pressure at 1 bar, and you yourself open the radiator valves one by one and bleed the air with Mayevsky taps.
Upon completion, start the boiler and pump, warm up the coolant and bleed the air from the batteries again.

After making sure that all pipelines and heating devices are fully warmed up, raise the pressure in the network to 1.5-2 bar at a boiler temperature of 80 °C.

Conclusion

Despite the popularity of closed-type water systems, they are not a panacea at all. In many settlements with an unstable power supply, it makes no sense to mount such circuits, because you will have to bear the cost of buying a UPS or a generator, and this is not practical. In this situation, there is no alternative to gravity systems with natural circulation.

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