Adjustment of heating supply or return. Two-pipe heating system: implementation features. Types of control devices

Any heating circuit functions at certain values ​​of pressure and temperature of the coolant, which are calculated at the stage of its design. However, during operation, situations are possible when the pressure drop in the heating system deviates from the standard level up or down and, as a rule, requires adjustment to ensure efficiency, and in some cases safety.

Operating pressure in the heating system

The working pressure is considered to be the value of which ensures the optimal operation of all heating equipment (including the heating source, pump, expansion tank). In this case, it is taken equal to the sum of pressures:

• static - created by a column of water in the system (in the calculations, the ratio is taken: 1 atmosphere (0.1 MPa) per 10 meters);
• dynamic - due to the operation of the circulation pump and the convective movement of the coolant when it is heated.

It is clear that in different heating schemes the value of the working pressure will be different. So, if natural circulation of the coolant is provided for the heat supply of the house (applicable to individual low-rise construction), its value will exceed the static indicator by only a small amount. In forced schemes, it is taken as the maximum allowable to ensure higher efficiency.

It should be borne in mind that the operating pressure limits are determined by the characteristics of the elements of the heating system. For example, when using cast-iron radiators, it should not exceed 0.6 MPa.

Numerically, the value of the working pressure is:

• for one-story buildings with an open circuit and natural water circulation - 0.1 MPa (1 atmosphere) for every 10 m of the liquid column;
• for low-rise buildings with a closed circuit - 0.2-0.4 MPa;
• for multi-storey buildings - up to 1 MPa.

Operating pressure control in heating circuits

For the normal trouble-free operation of the heat supply system, it is necessary to regularly monitor the temperature and pressure of the coolant.

To check the latter, deformation manometers with a Bourdon tube are usually used. To measure small pressures, their varieties can be used - diaphragm devices.

It must be remembered that after water hammer, such models need to be verified, because. they will show overestimated values ​​in subsequent control measurements.

Picture 1 - Deformation manometer with Bourdon tube

In systems where automatic control and regulation of pressure are provided, various types of sensors are additionally used (for example, electrocontact).

The placement of pressure gauges (tie-in points) is determined by the regulations: devices must be installed in the most important parts of the system:

• at the inlet and outlet of the heating source;
• before and after the pump, filters, mud collectors, pressure regulators (if any);
• at the exit of the highway from the CHP or boiler house and at its entrance to the building (with a centralized scheme).

Do not neglect these recommendations even when designing a small heating circuit using a low-power boiler, because. this not only ensures the safety of the system, but also its economy due to optimal water and fuel consumption.

Figure 2 - Section of the heating circuit with installed pressure gauges

To be able to zero, purge and replace devices without stopping the system, it is recommended to connect them through three-way valves.

Pressure drop and its significance for the functioning of the heating system

For the optimal functioning of any heating circuit, a stable and certain pressure difference is required, i.e. the difference between its values ​​on the coolant supply and return. As a rule, it should be 0.1-0.2 MPa.

If this indicator is less, this indicates a violation of the movement of the coolant through the pipelines, as a result of which water passes through the radiators without heating them to the required degree.

If the value of the drop exceeds the above value, we can talk about the “stagnation” of the system, one of the reasons for which is airing.

It should be noted that sudden changes in pressure negatively affect the performance of individual elements of the heating circuit, often putting them out of action.

Methods for regulating the working pressure and ensuring the stability of its difference in the supply and return

1. First of all, it must be remembered that the optimal operation of the heat supply system, incl. the creation of the required pressure in it depends on the correctness of the design, in particular, hydraulic calculations, and the installation of highways and pipelines, namely:
   - the supply line in most schemes should be located at the top, the return line, respectively, at the bottom;
   - for the manufacture of bottlings, pipes with a diameter of 50-80 mm should be used, for risers - 20-25 mm;
   - the connection to the heating devices can be made from the same pipes from which the risers are made, or one step less.

   It is allowed to underestimate the section of the radiator piping only if there is a jumper in front of them.

   

   Figure 3 - Jumper in front of the heating radiator

2. As you know, when the temperature rises, the coolant increases in volume and increases the pressure in the heating system. For example, at 20 0C it can increase by 0.13 MPa, at 70 0C - by 0.19 MPa. Therefore, one of the options for regulating the pressure is to change the degree of water heating.
3. To increase the pressure of the coolant, which is usually required to provide heat to the upper floors of high-rise buildings, circulation pumps are used.
4. Automatic regulation of the working pressure and its difference in the heating circuits of small houses is carried out by means of expansion tanks, as a rule, of a membrane type. They start working when the pressure in the system reaches 0.2 MPa. At the same time, these devices take away excess hot coolant, as a result of which the pressure is maintained at the required level.

   

   Picture 4 - Membrane expansion tank

   An expansion tank, the volume of which is usually taken to be about 10% of the total volume of the system, can be mounted in any part of the circuit. However, experts recommend installing it on a straight section of the return pipeline before the circulation pump (if any).

   To prevent a situation where the capacity of the device is not enough with a continuing increase in pressure, the schemes provide for the use of a safety valve that removes excess coolant from the system.

5. In large and complex heating systems, for example, in multi-storey buildings, regulators are used to maintain the standard pressure, which additionally prevent airing even with sudden changes in pressure in the mains, as well as noise generation on control valves. They are mounted either on the jumper between the supply and return pipelines, or on the bypass line of the pump.

   

   Picture 5 - Pressure regulator

6. Another way to regulate the pressure in the heat supply schemes of multi-level houses is the use of shut-off valves. For example, if it is necessary to increase the pressure, the cross section of the return pipeline is reduced using a valve.

Search for causes of drop and increase in differential pressure

The deviation of pressure up or down from the standard requires the establishment of the cause of this phenomenon and its elimination.

Pressure drop in the heating circuit

If the pressure in the heating system drops, then with a greater degree of probability we can talk about a coolant leak. The most vulnerable are the existing seams, joints and connections.

To check this, turn off the pump and monitor the changes in static pressure. With a continuing decrease in pressure, it is necessary to find the damaged area. To do this, it is recommended to sequentially turn off various sections of the circuit, and after determining the exact location, repair or replace worn elements.

If the static pressure remains stable, the reason for the decrease in pressure is due to a malfunction of either the pump or the heating equipment.

It should be borne in mind that a short-term pressure drop may be due to the peculiarity of the regulator, which at certain intervals bypasses part of the water from the supply to the return. In the case when heating radiators are heated evenly and to the required temperature, we can say that the drop was associated with the above cycle.

Other possible reasons include:

• removal of air through air vents, as a result of which the volume of coolant in the system decreases;
• decrease in water temperature.

System pressure increase

A similar situation is observed when slowing down or stopping the movement of the coolant in the heating circuit. The most likely reasons for this are:

• the occurrence of an air lock;
• contamination of filters and mud collectors;
• features of the functioning of the pressure regulator or incorrect setting of its operation;
• constant replenishment of the coolant due to a failure of automation or incorrectly adjusted valves on the supply and return.

It should be noted that pressure instability is most often noted in newly launched systems and is associated with the gradual removal of air. This can be considered normal if, after bringing the coolant volume and pressure to operating values, which lasts from several days to several weeks, no deviations are recorded.
Otherwise, we should talk about an incorrectly made hydraulic calculation, in particular, the accepted volume of the expansion tank.

When designing heating systems, professional craftsmen necessarily provide them with special technical means that in the future will allow you to control the pressure and temperature in the network. Valves and other devices act as such means. We will talk about the rules and features of adjusting heat supply systems in this article.

Heat supply regulation - what methods to use?

During heating operation, the coolant in the system heats up and expands, that is, it increases in volume. That is why the owner sometimes needs to adjust the radiators in his private house, thereby controlling the operation of the heat supply. There are several types of devices that allow you to do this job. All devices are usually divided into two categories:

1. 1. regulatory;
2. 2. controlling.

The former allow you to adjust the pressure and temperature in the system, reduce these parameters up or down. They can be installed on separate sections of the pipeline and used to regulate individual parts of the network, or regulate the operation of the entire system as a whole. Control devices are all kinds of thermometers and pressure gauges installed separately from the control means in systems or together with them. They allow you to get information about the operation of heat supply at any time and decide on the need to configure it.

So that during the operation of heating with its adjustment there are no difficulties, when designing engineering, it is necessary to provide for:

• installation of thermometers and pressure gauges before and after the heating boiler, in distribution collectors (in the lowest and highest parts of the network);
• installation of a pressure gauge before the circulation pump, if it is present in the system;
• installation of an expansion tank: leaky - in open networks and membrane - in closed ones;
• installation of safety valves and air vents necessary to prevent pressure increase in pipes to critical values.

During normal operation of the system, the water temperature in the pipes should not exceed 90 degrees, and the pressure should be in the range of 1.5-3 atmospheres. Some heating networks can operate at higher temperatures and pressures, but they use special elements that are not available in a standard home heating supply. The impossibility of adjusting the battery with a conventional thermostat may indicate the formation of an air lock. To eliminate it, you will have to use the Mayevsky crane.

How to set up heating in a private house - features and nuances

The heating networks of private houses and dwellings in apartment buildings differ greatly. In a separate residential building, only internal factors can affect the operation of heat supply - problems of autonomous heating, but not breakdowns in the general system. Most often, overlays occur due to the boiler, the operation of which is affected by its power and the type of fuel used.

Heating setting

The possibilities and methods of adjusting home heating depend on several factors, the most significant of which are the following:

1. 1. Material and pipe diameter. The larger the cross section of the pipeline, the faster the heating and expansion of the coolant.
2. 2. Features of radiators. It is possible to regulate radiators normally only if they are properly connected to the pipes. With proper installation during operation of the system, it will be possible to control the speed and volume of water passing through the device.
3. 3. The presence of mixing units. Mixing units in two-pipe systems allow you to reduce the temperature of the coolant by mixing cold and hot water flows.

The installation of mechanisms that allow you to comfortably and sensitively regulate the pressure and temperature in the system must be provided for at the design stages of a new autonomous communication. If such equipment is installed without preliminary calculations in an already functioning system, its efficiency can be significantly reduced.

Ways to stabilize pressure in the home system

When the coolant is heated, it significantly increases in volume, however, because of this, the pressure in the network can greatly jump, exceeding all possible critical values, which leads to the most unpleasant consequences. Expansion tanks are often used to regulate pressure in systems. A tank is a container divided into two chambers, one of which is filled with water from the heating network, and air is injected into the other. In the air chamber, the air pressure is equal to the normal pressure in the heating pipes, therefore, if the pressure in the system rises above the norm, a special membrane increases the volume of the water chamber, compensating for the expansion of the liquid in the pipes.

Before adjusting the pressure, it is necessary to check the settings and the general condition of the expansion tank. You can simply change the pressure if a tank is installed in your system that allows you to set the pressure value in the air chamber. To make it easier to control the pressure, you can also install a pressure gauge. However, in the event of a sharp jump in pressure in the network, one expansion tank will not be enough to stabilize it, so experts recommend using additional devices.

To adjust the pressure in the heating network at any, even critical values, you can use a special safety group. It includes a whole set of useful tools:

1. 1. A pressure gauge that allows you to visually monitor the operation of the network.
2. 2. An air vent with a valve through which excess air exits the pipes when the coolant temperature reaches 100 degrees.
3. 3. A safety valve, which, when the system reaches critical characteristics, automatically drains excess water from the pipes.

The safety block is needed to prevent accidents in the system as a whole, it cannot be used to adjust individual elements (radiators) of the heat supply of an apartment or a private house. To regulate the state of the batteries, it is necessary to use another device, namely the Mayevsky crane. In its design, such a valve is very similar to a safety valve, but it is small in size and can be installed on a radiator pipe even of a small diameter. The Mayevsky crane can be used in the following cases:

1. 1. When air locks occur in the batteries. By opening the faucet, you can slowly bleed excess air from the radiator and close the valve as soon as water starts to flow from the faucet.
2. 2. With high pressure in the radiator. In the event of an emergency expansion of the coolant due to high pressure, you can open the valve and stabilize the pressure in the system.

Despite the possibility of using the Mayevsky crane to stabilize pressure, it is used very rarely for these purposes. It is much easier and more efficient to use a special security group, but if it is not there, you can use this simple tool.

Heating problems - we control the temperature of the water in the network

An equally important characteristic of the operation of the heating network is the temperature of the coolant. In two-pipe systems, the optimal characteristics of the temperature of the hot and cooled coolant is the ratio of 75/50 degrees or 80/60 degrees. To easily regulate the temperature, you will have to install special equipment and elements in the system.

The easiest way is to create mixing nodes in the network. An obligatory element of such units are two- and three-way valves. One branch pipe of the mixing unit is connected to a pipe with hot water, and the second - to a pipe with cold water. The third branch pipe is installed on the section of the line, in which it is required to ensure a decrease in the temperature of the liquid, if such a need arises.

To simplify the use of mixing units, they are equipped with temperature sensors and a special thermostatic control unit. The sensor can give a signal about the temperature of the heat carrier and, based on the temperature level, close or open the mixing valve to control the heating. Typically, such equipment is mounted in underfloor heating collectors. To effectively adjust the water temperature in the heating of an apartment building, it is necessary to take into account the temperature regime in the pipes, usually the temperature of the pipes in the apartment does not exceed 45 degrees.

To reduce the temperature of the water in the pipes of an apartment building, you can use special valves. Sometimes it is enough to install simple taps that regulate the flow of coolant into the batteries, but in this case you will have to control the heating of the room yourself. It is much easier to regulate the heat supply with servo drives.

A servo drive is a device that includes a drive control unit and a thermostat. In order for the temperature in the rooms to always be maintained at the same level, it is necessary to set the desired value on the thermostat, and the servomotor will automatically open and close the flow of coolant to the radiator. To reduce repair costs, you can simply purchase a model with a thermostat only. But in this case, the adjustment will not be as accurate.

To regulate the temperature in apartments with old heating systems and cast-iron radiators, it is necessary to use special thermostats. These devices, however, do not allow you to change the pressure in the pipes, for this you have to use specialized tools.

The devices and methods of adjusting the heating system described above significantly increase the efficiency and safety of its operation. It will not be superfluous for the owner to know the rules for installing some individual elements of the network that directly affect the quality of its functioning. Battery adjustment begins at the design stages of a new communication and during installation. It is important to choose the right way to connect radiators, since the type of installation directly affects the efficiency of the device and the further possibility of installing special temperature controllers.

If you want to control and regulate the operation of the equipment, you must take into account the piping scheme. In single-pipe systems, there is always a jumper or bypass necessary to redirect the flow of hot water in case of radiator replacement and other repairs. In two-pipe networks, the heating elements are connected in parallel to each other, so it is much easier to regulate the temperature of the batteries in them.

In a private house, for any work with heating, it is necessary to take into account the characteristics and individual characteristics of the installed boiler. The efficiency of the engineering system depends on it. In order for the network to work correctly and it can be easily regulated, choose a boiler taking into account:

1. 1.Rated power. About 1 kW of boiler power is required per 10 m 2 of area with minimal heat loss.
2. 2. The ratio of the power of the heating boiler to the volume of water. To heat 15 liters of coolant, 1 kW of power is needed.
3. 3. Permissibility of smooth adjustment of the boiler. Typically, this function is available for gas boilers.

If you and the hired designers manage to correctly calculate the necessary parameters of the boiler, during the operation of the heating network it will be possible to regulate the temperature of the water in the radiators as simply and accurately as possible. A good boiler increases the safety of home engineering, makes the network more reliable and functional. Do not forget to take into account the climatic conditions in your area when calculating. In the northern regions of Russia, more powerful boilers are required, and in the southern regions, less powerful ones, which allow spending much less money and resources to maintain comfortable temperature conditions in the rooms.

Diagram of the system with regulators

Each heating season presents its own surprises with the difficulties of space heating, both for residents of multi-storey buildings and private cottages. The quality of uniform heating of all rooms of the house depends on how the temperature of the radiators is adjusted.

Why do you need to adjust

Setting the optimal temperature of the radiators allows you to create the most comfortable conditions for your stay indoors. In addition, the adjustment allows:

1. Remove the effect of airing in the batteries, allow the coolant to move freely through the pipeline of the heating system, effectively giving off its heat to the interior space of the room.
2. Reduce your heating costs by up to 25%.
3. Do not keep windows open all the time if the air in the room is too hot.

Setting the heating and adjusting the batteries, it is advisable to do before the start of the heating season. This is necessary so that later you do not experience discomfort in the apartment and do not adjust the heating temperature of the batteries in emergency mode. Before setting up and adjusting radiators, it is initially necessary to insulate all windows in the summer. In addition, you need to take into account the features of the location of the apartment:

• In the middle or in the corner of the house.
• Lower or upper floor.

After analyzing the situation, it is advisable to use energy-saving technologies to maximize the preservation of heat inside the apartment:

• Insulate walls, corners, floors.
• Conduct hydro and thermal insulation of the seams between the concrete joints of the panel house.

Without these works, it will be useless to regulate the temperature of the radiators, since the lion's share of the heat will heat the street.

Types of heating systems and the principle of adjusting radiators

In order to properly adjust the temperature of the radiators, you need to know the general structure of the heating system and the layout of the coolant pipes.

• In the case of individual heating, adjustment is easier when:

1. The system is powered by a powerful boiler.
2. Each battery is equipped with a three-way valve.
3. Forced pumping of the coolant has been installed.

At the stage of installation work for individual heating, it is necessary to take into account the minimum number of bends in the system. This is necessary in order to reduce heat loss and not reduce the pressure of the coolant supplied to the radiators.

For uniform heating and rational use of heat, a valve is mounted on each battery. With it, you can reduce the water supply or disconnect it from the general heating system in an unused room.

• In the central heating system of multi-storey buildings, equipped with the supply of coolant through the pipeline from top to bottom vertically, it is impossible to adjust the radiators. In this situation, the upper floors open windows due to the heat, and it is cold in the rooms of the lower floors, since the radiators there are barely warm.
• More perfect one-pipe network. Here, the coolant is supplied to each battery with its subsequent return to the central riser. Therefore, there is no noticeable temperature difference in the apartments of the upper and lower floors of these houses. In this case, the supply pipe of each radiator is equipped with a control valve.
• A two-pipe system, where two risers are mounted, provides the supply of coolant to the heating radiator and vice versa. To increase or decrease the coolant flow, each battery is equipped with a separate valve with a manual or automatic thermostat.

Types of control valves

Existing modern heat supply technologies make it possible to install a special tap on each radiator that controls the quality of heat. This control valve is a shut-off valve heat exchanger, which is connected via pipes to the radiator.

According to the principle of their work, these cranes are:

• Ball valves, which serve primarily as 100% protection against emergencies. These locking devices are a design that can rotate 90 degrees, and can let water in or prevent the passage of coolant.

The ball valve must not be left in a half-open state, as in this case the sealing ring may be damaged and a leak may occur.

• Standard, where there is no temperature scale. They are represented by traditional budget gates. They do not give absolute accuracy of adjustment. Partially blocking the access of the coolant to the radiator, they change the temperature in the apartment to an indefinite value.
• With a thermal head, which allow you to adjust and control the parameters of the heating system. Such thermostats are automatic and mechanical.

Conventional direct acting thermostat

A direct acting thermostat is a simple device for controlling the temperature in a heating radiator, which is installed near it. By its design, it is a sealed cylinder into which a siphon is inserted with a special liquid or gas that clearly reacts to changes in the temperature of the coolant.

When it rises, the liquid or gas expands. This leads to an increase in pressure on the stem in the thermostatic valve. He, in turn, moving, blocks the flow of coolant. When the radiator cools, the reverse process occurs.

Temperature controller with electronic sensor

This device according to the principle of operation does not differ from the previous version, the only difference is in the settings. If in a conventional thermostat they are performed manually, then the electronic sensor does not need this.

Here the temperature is set in advance, and the sensor monitors its maintenance within the specified limits. The electronic thermostatic sensor regulates the air temperature control parameters in the range from 6 to 26 degrees.

Step by step instructions for adjusting the temperature

To ensure comfortable conditions of stay in the room, you need to perform some basic actions.

1. Initially, on each battery, it is necessary to bleed the air until water flows in a trickle from the tap.
2. Then you need to adjust the pressure in the batteries.
3. To do this, in the first battery from the boiler, you need to open the valve by two turns, in the second - by three, and then in the same way, increasing the number of turns of the opened valve on each radiator. Thus, the coolant pressure is evenly distributed over all radiators. This will ensure its normal passage through the pipes and better heating of the batteries.
4. In a forced heating system, the pumping of the coolant, control of rational heat consumption will help to implement control valves.
5. In the flow system, the temperature is well regulated by the thermostats built into each battery.
6. In a two-pipe heating system, it is possible to control not only the temperature of the coolant, but also its amount in the batteries using both manual and automatic control systems.

Adjusting the heating batteries in the apartment allows you to simultaneously solve several problems, among which the main one is to reduce the cost of paying for some utilities.

This possibility is realized in different ways: mechanically and automatically. However, changing the parameters of the heating system does not increase the average room temperature. You can only reduce it to the desired level by adjusting the position of the reinforcement. It is advisable to install such devices on batteries in houses where it is cool in winter.

Why do you need to adjust

The main factors explaining the need to change the heating level of batteries using locking mechanisms, electronics:

1. Free movement of hot water through pipes and inside radiators. Air pockets can form in the heating system. For this reason, the coolant stops heating the batteries, since it gradually cools down. As a result, the microclimate in the room becomes less comfortable, and over time the room cools down. To keep the pipes warm, locking mechanisms mounted on radiators are used.
2. Adjusting the temperature of the batteries makes it possible to reduce the cost of heating your home. If the rooms are too hot, by changing the position of the valves on the radiators, you can reduce costs by 25%. Moreover, a decrease in the heating temperature of the batteries by 1 ° C provides a saving of 6%.
3. In the case when the radiators strongly heat the air in the apartment, you often have to open the windows. In winter, it is not advisable to do this, because you can catch a cold. In order not to have to constantly open windows in order to normalize the microclimate in the room, regulators should be installed on the batteries.
4. It becomes possible to change the heating temperature of the radiators at your own discretion, and individual parameters are set in each room.

How to regulate heating batteries

To influence the microclimate in the apartment, it is necessary to reduce the volume of coolant passing through the heater. In this case, it is only possible to lower the temperature value. The heating system is adjusted by turning the valve / cock or changing the parameters of the automation unit. The amount of hot water passing through the pipes and sections decreases, at the same time the battery heats up less intensively.

To understand how these phenomena are interconnected, you need to learn more about the principle of operation of the heating system, in particular, radiators: hot water entering the heater heats the metal, which, in turn, gives off heat to the air. However, the intensity of heating the room depends not only on the volume of hot water in the battery. The type of metal from which the heater is made also plays an important role.

Cast iron has a significant mass and slowly releases heat. For this reason, it is not advisable to install regulators on such radiators, since the device will cool for a long time. Aluminum, steel, copper - all these metals instantly warm up and cool down relatively quickly. Work on the installation of regulators should be carried out before the start of the heating season, when there is no coolant in the system.

In an apartment building, it is not possible to change the average value of the water temperature in the pipes of the heating system. For this reason, it is better to install regulators that allow you to influence the microclimate in the room in a different way. However, this cannot be realized if the coolant is supplied from top to bottom. In a private house there is access and the ability to change the individual parameters of the equipment and the temperature of the coolant. This means that in this case it is often impractical to mount regulators on batteries.

Valves and faucets

Such fittings are a heat exchanger of a locking device. This means that the radiator is adjusted by turning the tap / valve in the desired direction. If the valve is turned all the way 90 °, the water flow into the battery will no longer flow. To change the heating level of the heater, the locking mechanism is set to the half position. However, not all fittings have such an opportunity. Some faucets may leak after a short period of use in this position.

Installing shut-off valves allows you to manually control the heating system. The valve is cheap. This is the main advantage of such fittings. In addition, it is easy to operate, and no special knowledge is needed to change the microclimate. However, locking mechanisms also have disadvantages, for example, they are characterized by a low level of efficiency. The cooling rate of the battery is slow.

Stopcocks

A spherical design is used. First of all, it is customary to install them on a heating radiator in order to protect housing from coolant leakage. This type of valve has only two positions: open and closed. Its main task is to turn off the battery if such a need arises, for example, if there is a risk of flooding the apartment. For this reason, stopcocks are cut into the pipe in front of the radiator.

If the fitting is in the open position, the coolant circulates freely through the heating system and inside the battery. Such taps are used if the room is hot. Periodically, the batteries can be disconnected, which will reduce the value of the air temperature in the room.

However, ball locks must not be installed in the half position. With prolonged use, the risk of leakage increases in the area where the ball valve is located. This is due to the gradual damage to the locking element in the form of a ball, which is located inside the mechanism.

Manual valves

This group includes two types of fittings:

1. Needle valve. Its advantage is the possibility of a half installation. Such fittings can be located in any convenient position: completely opens / closes the access of the coolant to the radiator, significantly or slightly reduces the volume of water in the heaters. However, needle valves also have a disadvantage. So, they are characterized by a reduced throughput. This means that after installing such fittings, even in a fully open position, the amount of coolant in the pipe at the battery inlet will be significantly reduced.
2. Control valves. They are designed specifically to change the heating temperature of the batteries. The pluses include the ability to change the position at the discretion of the user. In addition, such fittings are reliable. It will not be necessary to frequently repair the valve if the structural elements are made of durable metal. There is a locking cone inside the valve. When the handle is turned in different directions, it rises or falls, which contributes to an increase / decrease in the area of ​​​​the flow section.

Automatic adjustment

The advantage of this method is that there is no need to constantly change the position of the valve / valve. The desired temperature will be maintained automatically. Adjusting the heating in this way provides the ability to set the desired parameters once. In the future, the heating level of the battery will be maintained by the automation unit or another device installed at the heater inlet.

If necessary, individual parameters can be set multiple times, which is influenced by the personal preferences of the residents. The disadvantages of this method include the significant cost of components. The more functional are the devices for controlling the amount of coolant in heating radiators, the higher their price.

Electronic thermostats

These devices outwardly resemble a control valve, but there is a significant difference - the display is embedded in the design. It displays the room temperature to be obtained. Such devices are paired with a remote temperature sensor. It transmits information to the electronic thermostat. To normalize the microclimate in the room, you just need to set the desired temperature value on the device, and the adjustment will be performed automatically. They have electronic thermostats at the battery inlet.

Adjustment of radiators with thermostats

Devices of this type consist of two nodes: the lower one (thermal valve) and the upper one (thermal head). The first of the elements resembles a manual valve. It is made of durable metal. The advantage of such an element is the ability to install not only an automatic, but also a mechanical valve, it all depends on the needs of the user. To change the value of the heating temperature of the battery, the design of the thermostat provides a bellows, which puts pressure on the spring-loaded mechanism, and the latter, in turn, changes the area of ​​the flow section.

Use of three-way valves

Such devices are made in the form of a tee and are designed for installation at the connection point of the bypass, the inlet pipe to the radiator, and the common riser of the heating system. To improve efficiency, the three-way valve is equipped with a thermostatic head, the same as that of the previously discussed thermostat. If the temperature at the inlet to the valve is higher than the desired value, the coolant does not enter the battery. Hot water is directed through the bypass and flows further along the heating riser.

When the valve cools down, the through hole opens again and the coolant enters the battery. It is advisable to install such a device if the heating system is single-pipe and the piping is vertical.

In order to be able to regulate the temperature of the battery in the apartment, any kind of valves are considered: they can be of a direct or angular type. The principle of installing such a device is simple, the main thing is to correctly determine its position. So, the direction of the coolant flow is indicated on the valve body. It must correspond to the direction of water movement inside the battery.

Valves / thermostats are located at the inlet of the heater, if necessary, they also cut in the tap at the outlet. This is done so that in the future it will be possible to independently drain the coolant. Control devices are installed on radiators, provided that the user knows exactly which pipe is the supply pipe, since a tie-in is made into it. At the same time, the direction of movement of hot water in the riser is taken into account: from top to bottom or from bottom to top.

Compression fittings are distinguished by increased reliability, so they are used more often. Connection with pipes - threaded. Thermostats can be equipped with a union nut. To seal the threaded connection, FUM tape, flax is used.

In the article we will touch on pressure-related problems diagnosed by a pressure gauge. We will build it in the form of answers to frequently asked questions. Not only the difference between the supply and return in the elevator unit will be discussed, but also the pressure drop in the closed-type heating system, the principle of operation of the expansion tank, and much more.

Pressure is no less important heating parameter than temperature.

Central heating

How the elevator assembly works

At the entrance of the elevator there are valves that cut it off from the heating main. On their closest flanges to the wall of the house, there is a division of areas of responsibility between residents and heat suppliers. The second pair of valves cuts off the elevator from the house.

The supply pipeline is always at the top, the return line is at the bottom. The heart of the elevator assembly is the mixing assembly, in which the nozzle is located. A jet of hotter water from the supply pipeline is poured into the water from the return, involving it in a repeated circulation cycle through the heating circuit.

By adjusting the diameter of the hole in the nozzle, you can change the temperature of the mixture entering the .

Strictly speaking, the elevator is not a room with pipes, but this node. In it, water from the supply is mixed with water from the return pipeline.

What is the difference between the supply and return pipelines of the route

• In normal operation, it is about 2-2.5 atmospheres. Typically, 6-7 kgf / cm2 enters the house at the supply and 3.5-4.5 at the return.

Please note: at the outlet of the CHP and the boiler house, the difference is greater. It is reduced both by losses due to the hydraulic resistance of the lines, and by consumers, each of which, to put it simply, is a jumper between both pipes.

• During the density test, the pumps are pumped into both pipelines at least 10 atmospheres. Tests are carried out with cold water with closed inlet valves of all elevators connected to the route.

What is the difference in the heating system

The difference on the highway and the difference in the heating system are two completely different things. If the return pressure before and after the elevator does not differ, then instead of supplying the house, a mixture enters, the pressure of which exceeds the readings of the pressure gauge on the return line by only 0.2-0.3 kgf / cm2. This corresponds to a height difference of 2-3 meters.

This difference is spent on overcoming the hydraulic resistance of spills, risers and heaters. The resistance is determined by the diameter of the channels through which the water moves.

What diameter should be the risers, fillings and connections to radiators in an apartment building

The exact values ​​are determined by hydraulic calculation.

In most modern houses, the following sections are used:

• Heating spills are made from pipes DU50 - DU80.
• For risers, a pipe DN20 - DU25 is used.
• The connection to the radiator is made either equal to the diameter of the riser, or one step thinner.

Nuance: it is possible to underestimate the diameter of the liner relative to the riser when installing heating with your own hands only if there is a jumper in front of the radiator. Moreover, it should be embedded in a thicker pipe.

In the photo - a more sensible solution. The diameter of the eyeliner is not underestimated.

What to do if the return temperature is too low

In such cases:

1. Reaming nozzle. Its new diameter is agreed with the heat supplier. The increased diameter will not only raise the temperature of the mixture, it will also increase the drop. The circulation through the heating circuit will be accelerated.
2. In case of a catastrophic lack of heat, the elevator is disassembled, the nozzle is removed, and the suction (pipe connecting the supply to the return) is suppressed.
   The heating system receives water from the supply pipeline directly. The temperature and pressure drop increase sharply.

Please note: this is an extreme measure that can only be taken if there is a risk of defrosting the heating. For the normal operation of CHPPs and boiler houses, a fixed return temperature is important; by stopping the suction and removing the nozzle, we will raise it by at least 15-20 degrees.

What to do if the return temperature is too high

1. The standard measure is to weld the nozzle and drill it again, with a smaller diameter.
2. When an urgent solution is needed without stopping the heating, the differential at the elevator inlet is reduced with the help of shutoff valves. This can be done with an inlet valve on the return line, controlling the process with a pressure gauge.
   This solution has three disadvantages:
   • The pressure in the heating system will increase. We're limiting the outflow of water; the lower pressure in the system will become closer to the supply pressure.
   • The wear of the cheeks and the valve stem will accelerate sharply: they will be in a turbulent flow of hot water with suspensions.
   • There is always a chance of falling worn cheeks. If they completely shut off the water, the heating (primarily the access one) will be defrosted within two to three hours.

Why do you need a lot of pressure in the track

Indeed, in private houses with autonomous heating systems, an overpressure of only 1.5 atmospheres is used. And, of course, more pressure means more money for stronger pipes and more power for the boost pumps.

The need for more pressure is associated with the number of storeys of apartment buildings. Yes, a minimum drop is needed for circulation; but after all, the water must be raised to the level of the jumper between the risers. Each atmosphere of excess pressure corresponds to a water column of 10 meters.

Knowing the pressure in the line, it is easy to calculate the maximum height of the house, which can be heated without the use of additional pumps. The calculation instruction is simple: 10 meters are multiplied by the return pressure. The pressure of the return pipeline of 4.5 kgf / cm2 corresponds to a water column of 45 meters, which, with a height of one floor of 3 meters, will give us 15 floors.

By the way, hot water is supplied in apartment buildings from the same elevator - from the supply (at a water temperature not higher than 90 C) or the return. With a lack of pressure, the upper floors will remain without water.

Heating system

Why do you need an expansion tank

Accommodates excess expanded coolant when it is heated. Without an expansion tank, the pressure can exceed the tensile strength of the pipe. The tank consists of a steel barrel and a rubber membrane that separates air from water.

Air, unlike liquids, is highly compressible; with an increase in the volume of the coolant by 5%, the pressure in the circuit due to the air tank will increase slightly.

The volume of the tank is usually taken to be approximately equal to 10% of the total volume of the heating system. The price of this device is low, so the purchase will not be ruinous.

Proper installation of the tank - eyeliner up. Then no more air will get into it.

Why does pressure decrease in a closed circuit?

Why does pressure drop in a closed heating system?

After all, the water has nowhere to go!

• If there are automatic air vents in the system, the air dissolved in the water at the time of filling will exit through them.
  Yes, it is a small part of the coolant volume; but after all, a large change in volume is not necessary for the pressure gauge to note the changes.
• Plastic and metal-plastic pipes can be slightly deformed under the influence of pressure. In combination with high water temperature, this process will accelerate.
• In the heating system, the pressure drops when the temperature of the coolant drops. Thermal expansion, remember?
• Finally, minor leaks are easy to see only in centralized heating by rusty traces. The water in a closed circuit is not so rich in iron, and the pipes in a private house are most often not steel; therefore, it is almost impossible to see traces of small leaks if the water has time to evaporate.

What is the danger of a pressure drop in a closed circuit

Boiler failure. In older models without thermal control - up to the explosion. In modern older models, there is often automatic control of not only temperature, but also pressure: when it falls below the threshold value, the boiler reports a problem.

In any case, it is better to maintain the pressure in the circuit at about one and a half atmospheres.

How to slow down the pressure drop

In order not to feed the heating system over and over again every day, a simple measure will help: put a second larger expansion tank.

The internal volumes of several tanks are summarized; the greater the total amount of air in them, the smaller the pressure drop will cause a decrease in the volume of the coolant by, say, 10 milliliters per day.

Where to put the expansion tank

In general, there is no big difference for a membrane tank: it can be connected to any part of the circuit. Manufacturers, however, recommend connecting it where the water flow is as close to laminar as possible. If there is a tank in the system, it can be mounted on a straight pipe section in front of it.

Conclusion

We hope that your question has not gone unnoticed. If this is not the case, you may be able to find the answer you need in the video at the end of the article. Warm winters!