Why does the pressure drop in the heating system of a private home? Pressure drop in heating when using double-circuit boilers. Pressure drop during the adaptation period

In some cases, the pressure in the heating system drops. In order to eliminate the difference, timely measures should be taken quickly. Fluctuations in compression indicators lead to breakdowns of heating devices up to the complete cessation of their operation. In order to eliminate the causes of the malfunction, some theoretical foundations should be studied. This will help you understand why the problem occurred.

Pressure control elements in the heating system

Types of pressure

In a closed heating system, there are several types of pressure:

1. static;
2. dynamic;
3. acceptable working.

Static compression reflects the force that the coolant has at rest. The indicator is determined by the height of the water column. Dynamic pressure occurs when the coolant moves. This indicator affects the walls of heating pipes. The permissible working compression reflects the maximum possible total pressure. It should not be exceeded.

The pressure drop is determined by the difference in compression values ​​in the return section and the supply section.

Pressure values

In the case of autonomous systems, the compression indicator should be within one and a half to two atmospheres. A value of three atmospheres will already be critical and will lead to depressurization and breakdown of heating devices.

When pumping liquid, the pressure should not exceed one and a half atmospheres. You need to understand that when the system warms up, the coolant increases its volume according to physical laws. Then the pressure will increase to the optimal operating value.

To maintain optimal pressure in the heating system, expansion tanks are provided to prevent excessive pressure increases. They begin to be used when a compression of two atmospheres is achieved. Excess coolant during its expansion is taken into expansion tanks.

If the volume of the expansion tank is insufficient, an increase in the compression value to critical values ​​may be observed.

To correct this problem, safety valves are provided. They release excess coolant, maintaining the operation of the heating system of the house within normal limits.

The operation of safety valves with incorrect calculation of the volume of the expansion tank in some cases leads to a decrease in the compression value.

Why does blood pressure drop?

It is important to understand why the compression ratio decreases. A decrease in pressure in the heating system can be caused by the following factors:

• boiler malfunction;
• leakage in pipes;
• Leaks in heating appliances.

When checking the heating system, you should consistently examine the tightness of the pipeline, radiators, and also check the serviceability of the boiler equipment. This will allow you to determine the level of the problem and take timely measures to eliminate it.

The diagram shows an example of a closed-type heating system. It includes: a heating boiler, radiators, an expansion tank, a pump, and a pipeline. Blue and red lines show the movement of heated and cooled coolant through the pipeline. Knowledge of the design of the heating system of a private home will help in determining the reasons for the drop in compression indicators.

Finding leaks

The method for searching for coolant leaks depends on the type of pipe routing in the heating system of a private home. With an open heating pipe layout, identifying the location of the leak is not so difficult. The quality of installation of heating pipes and the tightness of the connection of each element should be assessed. Water under pipes and heating radiators indicates a leak.

Sections of the heating device must be carefully inspected to detect traces of corrosion. Traces of rust on radiator devices indicate damage.

When the compression decreases in a heating system with hidden piping, it is quite difficult to identify the location of the leak. To do this, you need to call a plumber who, using professional equipment, will determine the location of the leaking section of the pipe.

After this, the coolant should be completely drained. To make this feasible, when designing the heating system of the house, the installation of a drain valve is provided. After draining, air is pumped into the pipeline using a compressor. Before this, it is necessary to cut off the boiler and heating radiators using taps. The air that enters the pipeline under pressure is released with a characteristic sound in places of weak connections and microscopic cracks.

Repairing the leak

After identifying the location of the leak, the necessary repairs are carried out, which includes the following actions:

• cutting out and replacing the damaged section of the pipeline;
• securing weak connections;
• wrapping with sealing tape;
• replacement of faulty system components with working elements.

Repairs to broken pipes should be carried out by a qualified plumber. If the pressure loss is not determined, then you should check whether the boiler equipment is working properly.

Determining the health of the boiler

Boiler equipment is examined by an engineer with the appropriate level of qualifications. The constant and slow decrease in pressure, which is recorded by the boiler pressure gauge, should require periodic replenishment of the system. A boiler malfunction is possible in the following cases:

• the appearance of microscopic cracks in the heat exchange unit;
• damage due to water hammer;
• breakdown of the make-up valve.

It should be understood that after turning on the heating boiler, a decrease in compression in the system is observed for several days. This is a normal phenomenon and may be due to the presence of air dissolved in the water in the system. It is eliminated over time automatically or by manually de-airing the batteries.

For some time after switching on, you should frequently recharge the heating system to bring the compression values ​​to acceptable values. If the operation has already exceeded a month, but the pressure in the heating system still drops, the volume of the expansion tank was incorrectly calculated. This is why the safety valve is activated and the liquid is released. As the water temperature decreases, a decrease in pressure is observed. If the volume of the tank is calculated correctly, but the compression still decreases, areas of depressurization should be determined.

Competent expert advice on what to do if the pressure in the system drops is presented in this video.

Thus, a decrease in pressure is caused either by leaks in the heating pipes, or by incorrect operation of the boiler, or by incorrect calculation of the volume of the expansion tank. When the pressure decreases, all these factors should be checked and eliminated if detected.

You should not try to fix the problem yourself unless you have professional plumbing skills. Only an experienced specialist will quickly determine the location of the problem and be able to take measures to eliminate it.

In contact with

Following a failure of pressure in the heating system, a problem comes - the quality of heating the premises in the house decreases. You can, of course, adjust the heating operation once and for a long time, but this period will not be indefinitely long. One day, the normal pressure in the heating system will change, and significantly.

We will tell you how to keep the physical parameters of the coolant under control. Here you will learn how to ensure a stable speed of movement of heated water through the pipeline to the devices. You will understand how to obtain and maintain a comfortable indoor temperature.

The article proposed for consideration describes in detail the reasons for the pressure drop in closed and open systems. Effective balancing methods are given. The information presented for review is supplemented with diagrams, step-by-step instructions, photos and video tutorials.

Depending on the current principle of coolant movement in the heat pipeline of the circuit, in heating systems the main role is played by static or dynamic pressure.

Static pressure, also called gravitational pressure, develops due to the gravitational force of our planet. The higher the water rises along the contour, the more its weight presses on the walls of the pipes.

When the coolant rises to a height of 10 meters, the static pressure will be 1 bar (0.981 atmosphere). An open heating system is designed for static pressure; its maximum value is about 1.52 bar (1.5 atmospheres).

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The dynamic pressure in the heating circuit develops artificially -. As a rule, closed heating systems are designed for dynamic pressure, the contour of which is formed by pipes of significantly smaller diameter than in open heating systems.

The normal value of dynamic pressure in a closed heating system is 2.4 bar or 2.36 atmospheres.

Consequences of instability in circuits

Insufficient or higher pressure in the heating circuit is equally bad. In the first case, some of the radiators will not effectively heat the rooms; in the second, the integrity of the heating system will be compromised and its individual elements will fail.

Correct piping will allow you to connect the boiler to the heating circuit as necessary for high-quality operation of the heating system

An increase in dynamic pressure in the heating pipeline occurs if:

• the coolant is too overheated;
• the pipe cross-section is insufficient;
• the boiler and pipeline are overgrown with scale;
• air pockets in the system;
• a booster pump that is too powerful is installed;
• water replenishment occurs.

Also, increased pressure is caused by incorrect balancing of the taps (the system is over-regulated) or malfunction of individual regulator valves.

To monitor operating parameters in closed heating circuits and for their automatic adjustment, a safety group is installed:

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The pressure in the heating pipeline drops for the following reasons:

• coolant leak;
• pump malfunction;
• rupture of the expansion chamber membrane, cracks in the walls of a conventional expansion tank;
• security unit malfunction;
• water leakage from the heating system into the feed circuit.

The dynamic pressure will be increased if the cavities of the pipes and radiators are clogged, if the catch filters are dirty. In such situations, the pump works under increased load, and the efficiency of the heating circuit decreases. The standard result of exceeding pressure values ​​is leaks in connections and even pipe ruptures.

The pressure parameters will be lower than required for normal functionality if a pump of insufficient power is installed in the main line. It will not be able to move the coolant at the required speed, which means that a somewhat cooled working medium will be supplied to the device.

The second striking example of a drop in pressure is when the flow is blocked by a tap. A sign of these problems is the loss of pressure in a separate segment of the pipeline located after the obstacle to the coolant.

Since all heating circuits have devices that protect against excessive pressure (at least), the problem of low pressure occurs much more often. Let's consider the reasons for the drop and ways to increase pressure, and therefore improve water circulation, in open and closed heating systems.

Pressure in an open heating system

Unlike a closed thermal circuit, a properly constructed open heating system does not require balancing over years of operation - it is self-regulating. Boiler operation and static pressure ensure constant circulation of water in the system.

The density of the heated water following the supply riser is lower than the density of the cooled coolant. Hot water tends to occupy the highest possible point of the circuit, and cooled water tends to be at its very bottom.

The pressure required for water circulation is achieved by the pressure in the supply riser or by a booster pump (+)

The pressure developed by the water column in the supply riser promotes the circulation of the coolant and compensates for the resistance present in the circuit pipeline. It is caused by the friction of water on the inner surface of the pipes, as well as local resistance (turns and branches of the pipeline, boiler, fittings).

By the way, pipes of increased diameter are used for assembly precisely to reduce friction.

To understand how to increase pressure in an open heating system, you must first understand the principle of achieving circulation pressure in the thermal circuit.

Its formula:

R c = h (p o -r g),

• R c – circulation pressure;
• h – vertical distance between the centers of the boiler and the lower heating radiator;
• r g – density of the heated coolant;
• p o – density of the cooled coolant.

The static pressure will be higher if the distance between the central axes of the boiler and the battery closest to it is as significant as possible. Accordingly, the intensity of coolant circulation will be higher.

To achieve the maximum possible pressure in the heating circuit, it is necessary to lower the boiler as low as possible - into the basement.

The closer the radiator is to the boiler on the supply circuit, the better it warms up. Regulators allow you to distribute heat between all radiators of the heating system

The second reason for the drop in pressure in an open heating system is related to its self-regulation. When the heating temperature of the coolant changes, the intensity of its flow changes. By increasing the heating of water for the heating circuit on cold winter days, owners sharply reduce its density.

However, when passing through heating radiators, water gives off heat to the room atmosphere, and its density increases. And according to the formula presented above, a high difference in the densities of hot and chilled water helps to increase the circulation pressure.

The more the coolant is heated and the colder it is in the rooms of the house, the higher the pressure in the system will be. However, after the atmosphere of the premises warms up and the heat transfer from the radiators decreases, the pressure in the open system will drop - the difference between the supply and return water temperatures will decrease.

Balancing a double-circuit open heating system

Gravity heating systems are made with one or more circuits. In this case, the horizontal length of each looped pipeline should not exceed 30 m.

But to achieve optimal pressure and pressure in the open coolant, it is better to make the pipelines even shorter - less than 25 m. Then it will be easier for the water to deal with hydraulic resistance. In a circuit with several rings, in addition to limiting the length, the condition for heating radiators must be observed - the number of sections in all rings must be approximately equal.

Lack of pressure in an open double-circuit thermal system occurs due to design errors or contamination of the pipeline (+)

Balancing of the horizontal rings included in the vertical circuit is required at the design stage of the heating system. If the hydraulic resistance of any ring turns out to be higher than that of the others, the static pressure in it will not be enough and the pressure will practically stop.

To maintain the required pressure in a double-circuit heating system, it is necessary to reduce the cross-section of the pipes approaching the radiators. You can also install valves in front of the radiators that perform thermoregulation (manual or automatic).

You can balance an open-type dual-circuit system:

• Manually. We start the heating system, then measure the temperature of the atmosphere of each heated room. Where it is higher, we screw the valve, where it is lower, we unscrew it. To adjust the thermal balance, you will have to perform temperature measurements and adjust the valves several times;
• Using thermostatic valves. Balancing occurs almost independently; you just need to set the desired temperature in each room on the valve handles. Each such device will control the supply of coolant to the radiator itself, increasing or decreasing the supply of coolant.

It is especially important that the value of the total hydraulic resistance of the heating system (all rings in the circuits) does not exceed the value of the circulation pressure. Otherwise, warming up the coolant and attempting to balance the system will not improve circulation.

Circulation pump for open heating system

It happens that measures to balance the heating circuit of a gravity system have no effect. Not all causes of low pressure can be solved by adjustment - choosing the wrong pipe diameter cannot be corrected without a complete reconstruction of the circuit.

Then, to increase the pressure and improve the movement of water without significant modifications to the heating system or booster pumping device. The only thing that its installation will require is moving the expansion tank or replacing it with a membrane expansion tank (closed tank).

In case of a serious drop in pressure, not a circulation pump, but a more powerful booster pump is needed. However, booster pumps are not suitable for open heating systems, because develop significant dynamic pressure

The energy consumption of circulation pumps does not exceed 100 W. Therefore, there is no need to fear that it will push the coolant out of the circuit.

The volume of water in the heating system is more or less constant, provided that the filling of the open circuit is controlled. Therefore, no matter how much water the circulation pump pushes along the circuit in front of it, the same amount will flow into it from the return pipe.

By bringing the pressure in the thermal system to the required level, the pump will make it possible to lengthen it, reduce the diameter of the pipeline and achieve circuit balance with high hydraulic resistance.

Pressure in a closed heating system

Installing a modern boiler, especially a double-circuit boiler, is called by sellers the ideal solution for home heating. With high-quality installation, a new boiler will serve you well for several years, but one day the pressure in it drops sharply or gradually. How to find the cause of low dynamic pressure?

A closed heating system requires close attention. A drop or rise in pressure is equally dangerous for her. Being left without heating in winter is a homeowner's worst nightmare.

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First of all, both the boost and the ones present in the thermal circuit are checked. This device wears out faster than a boiler, expansion tank or pipeline, so its condition is determined first. It is important to make sure that the “silent” pump is receiving power and only then take measures to replace the device.

In general, it is more rational to integrate two pumps into the heating circuit in advance - one in the main pipe, the second in the bypass. A closed heating system cannot operate at low dynamic pressure. Therefore, a spare pump, turned on in time, will protect the house and pipeline from freezing.

If the pump is working properly, the source of the pressure loss is in the boiler or piping system. We check the boiler last, first the heating circuit.

Steps to find a coolant leak

It is possible to independently detect leaks in the heating system if the pipes are installed openly and there is access to the taps and all connecting elements. It is also necessary to remove the decorative trim of the heating radiators.

You need to walk along the entire thermal circuit with a flashlight, carefully studying every connection, every element of the system (boiler piping too). We are looking for puddles of water, wet spots on the floor, traces of dried water, rusty streaks on pipes, batteries and shut-off valves.

We take a small mirror, illuminate it with a flashlight and inspect the back side of each section. If the batteries are prefabricated, made of cast iron or aluminum, you should inspect the connections between the sections. Corrosion and streaks of rust are a sign of a leak, even if the floor is dry under the radiator.

There are situations when the pressure in the circuit drops slowly, day by day. Moreover, there are absolutely no visible traces of leakage on the elements of the heating system or on the floor. Or rather, there are leaks and there are a lot of them, but they cannot be detected.

Flowing water evaporates on a pipe, radiator or on the floor surface, i.e. no noticeable puddles are formed. It is necessary to identify places where coolant may leak, place sheets of soft paper under them - napkins or toilet paper will do. After a few hours, check the paper for moisture. If it's wet, that means there's a leak here.

The serviceability of the boiler safety group lies not only in the operation of the pressure gauge, safety valve and air vent. None of its elements or detachable connections should leak.

In a house equipped with a partially hidden heating piping system, it is impossible to find leaks on your own. All that remains is to call heating engineers who will search for leaks in the heating circuit using special equipment.

Thermal technical search for leaks in the heating system is performed in a certain sequence. First, the coolant is drained from the circuit.

Then a compressor is connected to the entire heating pipeline or to its individual segments equipped with shut-off valves via a threaded connection. As a last resort, you can connect a car pump to the pipeline.

A few minutes after the start of pumping air into the heating circuit, a distinct sound of escaping air will be heard in places of leakage. Each section of the heating system embedded in a wall or floor with a leak detected by sound must be opened from the cement screed.

Pressure drops in the heating boiler

Let us note right away that only a heating engineer from the service department can determine the exact breakdown of boiler equipment. Those. The homeowner will not be able to independently find out and, moreover, eliminate a serious breakdown that caused a drop in pressure in the heating boiler.

Let's consider the possible reasons for the “creeping” change in pressure on the boiler pressure gauge, which occurs when the boiler is in external condition.

Crack in the heat exchanger. Over the years of operation, the walls of the heat exchanger in the boiler may develop microcracks. The reasons for their formation are wear of the unit, weakening of strength during washing, pressure testing (water hammer) or manufacturing defects. The coolant flows through them and the boiler requires water replenishment every 3-5 days.

The leak cannot be detected visually - the water flows weakly, and when the burner is turned on, the moisture accumulated in the boiler evaporates. The heat exchanger needs to be replaced, less often it can be soldered.

The three-way valve is ideal for multi-ring heating systems. However, the throughput of such a faucet is closely related to how often it will be cleaned of contaminants.

The pressure rises due to the open make-up tap. Against the background of low dynamic pressure in the boiler and higher pressure in the water supply system, “excess” water enters the heating system through the make-up tap. The pressure in the heating circuit increases to the point where it needs to be released through the safety valve of the boiler unit.

If the pressure in the water supply drops, the coolant of the heating circuit will transfer its flow into the boiler, then the pressure in the heating system will decrease. A similar problem occurs with a faulty make-up tap. You need to either close the tap or replace it.

Increase in pressure due to three-way valve. If a valve installed on a double-circuit boiler malfunctions, water from the “household” heating sector will flow into the heating system. The three-way valve needs cleaning or replacement.

The boiler pressure gauge readings do not change. If, when the operating modes of the boiler change, or when the temperature in the circuit increases or decreases, the pressure gauge shows the same pressure, it is “stuck”. Those. dirt from the heating system got into it through the pipe. The pressure gauge needs to be replaced.

Low pressure due to expansion tank

In closed heating systems, the following situation often occurs: when starting in heating mode, the pressure on the boiler pressure gauge increases sharply. If the circuit is completely filled with water, the pressure increases to 3 bar and the relief valve is activated, releasing part of the water.

The homeowner turns off the burner and waits for the water to cool. At the same time, the pressure drops to a minimum. Next, the owner then tries to turn on the boiler. But the unit does not work, it gives an “emergency” signal. Although sometimes it is possible to activate the operation of a double-circuit boiler if the pressure does not drop too much.

The position of the expansion chamber next to the heating boiler is explained by its importance for the thermal system. The condition and serviceability of the expansion tank must be carefully monitored

All that remains is to try to increase the pressure by adding water to the system in “cold” mode (with the burner off) and achieving a pressure gauge reading of 1.2-1.5 bar. But restarting the boiler occurs with the same result: the pressure increases; the relief valve is activated; the water is drained; pressure at minimum; the boiler does not want to work.

There may be several reasons for this malfunction. However, a common source of the problem is. Moreover, it does not matter where it is located - inside the boiler or outside it.

The expanzomat is divided into two parts by a flexible membrane. One contains coolant, the other gas (usually nitrogen) under a pressure of 1.5 bar. The water contained in the thermal circuit, expanding when heated, presses through the membrane onto the gas compartment of the membrane tank. To compensate for the increased pressure in the system, the gas in the expansion chamber is compressed.

After years of using a closed heating circuit, the nipple through which gas was pumped into the expansion tank begins to leak. It happens that the gas is dumped by homeowners themselves who do not understand the purpose of the nipple.

In any scenario, the gas in the expansion chamber becomes less and less. Soon the expansion tank is no longer able to compensate for the pressure of the expanding coolant in the system; its values ​​reach a maximum.

A closed heating system will react to a malfunction of the expansion tank with a sharp rise and fall in dynamic pressure

Let's figure out how to solve the problem of lack of gas in the expansion tank. First we turn off the boiler; if it is electric, from the mains too.

If the expansion tank is built into the boiler, you need to block the access of water to both circuits (or one). Drain the water from the boiler completely. If the expanzomat is located separately from the boiler, you need “its” piece of pipeline from the general network and drain the water from there.

Then take a car pump equipped with a pressure gauge (a pressure gauge is required), attach it to the nipple on the expansion machine and pump it up. Water will flow from the blocked sector of the pipeline (or boiler, if the tank is in it) - pump further.

We monitor the pump pressure gauge. The water has stopped flowing out, and the pressure has reached 1.2-1.5 bar - we stop pumping air.

All that remains is to open the shut-off valves, fill the circuit with water to 1.2-1.5 bar, and then turn on the boiler. The heating system will work. If you discover that the problem with pressure has reappeared after a while, replace the expansion valve nipple, it is leaking heavily.

Note that there may be another problem with the tank, a more complex one - rupture of the membrane. Then pumping with air will not help, you will have to change the expansion chamber.

Conclusions and useful video on the topic

Video #1. How to balance heating radiators in a home heating system. Let us remind you that without valves on each heating radiator it will not be possible to balance the system.

A properly balanced heating system will perform its functions for several years. But one day the characteristics of the coolant will change or critical elements of the thermal circuit will fail. Therefore, it is necessary to constantly monitor coolant indicators using pressure gauges in order to promptly respond to pressure changes.

Please write comments if you have any questions about the topic of the article. We are waiting for your stories about your own experience in normalizing pressure in the heating circuit. We and site visitors are ready to discuss controversial issues in the block located under the text of the article.

Modern gas boilers and the pragmatic desire of the heat power industry for progressive solutions to heating issues in private households and apartments are increasingly leading to the use of closed heating systems with forced circulation of coolant. A closed loop of liquid circulation allows you to increase the operating pressure of the system and thereby increase its safety, because it is known that with increasing pressure in a liquid medium, its boiling point rises. In particular, the following ratios are characteristic of water: 1 atm. – 100 degrees, and 2 atm. – 120 degrees.

The state of the liquid filling of the system is monitored by measuring instruments. First of all, gas boilers equipped with a circulation pump and a safety group require the presence of a mechanical dial or electronic display that reflects the readings of temperature and pressure sensors located on the boiler outlet (supply). Additional pressure gauges are installed on distribution manifolds responsible for supplying coolant to various parts (floors) of the building. Systems that include indirect or combined water heating boilers, as well as complex systems that use a high-temperature circuit - radiator heating and a low-temperature circuit - cannot do without the readings of auxiliary pressure gauges.

System pressure drops

We will name the reasons that answer the question of why the pressure in the heating system drops, and we will suggest ways to eliminate them. So, the reasons for the negative phenomenon are:

• unauthorized leakage of coolant at the junction of pipes with heating devices or direct rupture of main pipelines, violation of the tightness of pipes in heated floors;
• breakdown of the heating unit itself, caused by the formation of microcracks in the heat exchanger housing;
• breakdown of a membrane-type blast valve, which is part of the safety group of boiler equipment;
• rupture of the membrane in the expansion tank, designed to compensate for the linear expansion of the coolant as its temperature increases;
• depressurization of the hot water supply (DHW) circuit in the bithermal version of the generating thermal installation, hence the pressure in the double-circuit boiler drops during intensive hot water collection and increases sharply when it stops.

Detection of coolant leaks

A leak is initially determined visually; for this, as a rule, the system is charged to the recommended level and the forced circulation of liquid is stopped. Particular attention is paid to shut-off and control valves installed on heating radiators and their direct connection to the main pipes. If it is not possible to independently determine what dictates the loss of pressure in the heating system, then resort to the services of specialists. By pressurizing air, a more intense release of coolant is achieved in leakage areas. Sometimes the solution simply requires repacking the connection or replacing the defective fitting. A more complex device requires detecting a break in pipes hidden in the wall or in the “snails” of a heated water floor. For this purpose, special scanners are used that accurately determine the concentration of excess moisture. Then it’s a matter of technique: dismantling the decor of wall or floor surfaces, excavating the damaged area and replacing it. Ways.

Pressure drops associated with boiler equipment malfunctions

If it is determined that the pressure in the gas boiler is dropping, then only employees of the service organization on whose balance sheet the heating unit is located are involved in troubleshooting, as a high-risk device. Qualified service center personnel will offer several options for solving the problem: soldering or replacing the entire heat exchanger. Everything will depend on the nature of the damage resulting from regular washing of the thermal “jacket” of the boiler from scale, a hidden factory defect or banal operational wear. After the specialists carry out the work, appropriate records are made about warranty or post-warranty repairs. Having determined that the pressure in a double-circuit boiler is falling due to damage to the rubber membrane of the expansion tank, it is necessary to replace the damaged product with a new tank so as not to expose the entire heating system to additional risks that will arise after replenishing the system to the established level. The liquid, having lost the opportunity for linear expansion, will cause the pressure in the circuit to rapidly increase, causing frequent operation of the safety valve. Damage to the diaphragm (EPDM) in the safety valve triggers the protective function of the device even in cases where the maximum pressure in the heating system has not been reached, requiring an emergency release of excess liquid from the circuit.

The fact that the pressure in the heating system increases indicates the presence of one of the reasons on this list. So:

• a drop is observed in a certain section of the circuit - circulation after the control devices is stopped;
• the system is continuously recharged;
• shut-off valves cut off entire circuits or sections of main pipelines;
• an obstacle that makes it impossible for the coolant to circulate in the system due to critical accumulation of air masses;
• mechanical clogging of systems and devices installed in the heating circuit for filtering liquid.

Troubleshooting involves a sequential examination of the entire space heating circuit. As a result of oversights, unauthorized intervention of curious children, it is possible that valves, gate valves, and ball valves will be closed. Disconnection of control devices from the electrical network (servo motors for collectors or thermostatic three-position taps when connecting DHW circuits in a combined boiler) can also have an effect. They resort to preventative washing of mechanical filter meshes. Particular attention is paid to self-washing filters, which are necessarily installed on old heating systems that use cast-iron heating devices and large-section metal pipes. They carry out pressure testing of the heating system, and if necessary, replace the device for automatic air release, and repair the valve responsible for feeding the heating circuit in the boiler.

Thus, by constantly maintaining the operating pressure in the heating system of 1.5-2 atm, we get the opportunity to use boiler equipment efficiently and safely, achieve optimal physical stress on heating devices and pipelines, thereby increasing the time of their trouble-free operation.

When installing or reconstructing a heating device, all owners of private houses are faced with an important question - what pressure should be in a closed-type heating system? The degree of heat generated, the operability of the pipeline, and the serviceable condition of the boiler completely depend on the decision.

The functioning of heating devices is characterized by several features, the main one of which is the temperature level, which depends on the technical properties of the unit and the layout of the pipes. At the time of heating and starting the circulation of process water, pressure is formed inside, the indicators of which have a direct impact on the functioning capabilities and characteristics of the system as a whole.

Optimal value for a private house or cottage

The pressure in the heating system of a private house should not be higher than the stability limit of one of the weakest components - the heat exchanger built into the boiler. The most durable devices can withstand pressure up to three atmospheres. The designation should not be confused with megapascal, since 1 unit of atmospheric pressure equals 0.1 MPa.

Elements located outside the boiler, for example, the radiator circuit, have a higher degree of strength and can withstand up to 6 atmospheres.

The solution to the problem of what pressure in the heating system of a private house is considered correct depends on the type of device.

The standard type of device is an installation with conventional, or rather natural circulation of heating fluid, which is called a thermosyphon or gravity installation. In this case, the pressure is generated due to the magnitude of the run-up in the heights of the nodes, the lowest and the highest.

If the gap is 10.34 m, a pressure of 1 atm is formed in the lower node. It turns out that with a maximum endurance level of 3 atm, the heating device will break down only if the unit is 31.02 m higher than it (multiply the gap by 3 atm).

It should be taken into account that the maximum level is formed in the lowest plane; with each meter of elevation, the static designation decreases.

The excess pressure level in the highest plane of the installation is zero; an expansion tank mounted on the circuit can look like a regular open tank. However, if the device is equipped with a circulation pump unit that pumps water, the system should be of a closed type.

Pressure in a closed heating system

The circulation pump unit generates high pressure in the area of ​​the pipeline located behind the device. This method has a number of advantages:

• The circuit with normal coolant circulation must be no more than thirty meters long; with a closed installation, the dimensions of the element are not limited.
• It becomes possible to use pipes with small diameters.
• Radiator elements can be connected in series.
• When installing radiators in parallel, two-pipe type, the circular pump is able to evenly distribute heat along the circuits.
• The device, equipped with a circulation pump unit, is suitable for operation at low temperatures. This factor allows you to heat the room between seasons. For comparison, a gravity-type device, due to low pressure, is not capable of forcing water to circulate through radiator sectors and pipelines at low temperatures.

VIDEO: Pressure dynamics in a closed loop

reference Information

The pressure in the heating system in a private house, which develops thanks to the circulation pump, is often called dynamic. It should also be remembered that its level cannot be unlimited and must meet several basic requirements:

• The pressure value cannot exceed the maximum level specified in the operating instructions for heating equipment and other additional elements.
• The power of the pressure developed must be set in such a way that it is able to withstand hydraulic resistance, which completely depends on their size, length, configuration, radius, and the value of the speed of water movement.

From the user's perspective, the calculation taking into account all of the above factors may seem complicated, but they are not required. It is enough just to correctly adjust the power of the pumping unit so that the temperature range at the inlet and outlet does not have a big difference; 20°C is often considered the standard indicator.

An easy way to calculate the problem of what pressure is in the heating system of a private house with a circular pump installed is to add the standard type of pressure and the statistical type. The result should be at least 1.5 atm, no more than 2.5. However, it should be taken into account that as the length of the pipeline increases, the pumping dynamic pressure decreases due to the hydraulic resistance in the circuit. In this situation, an open-type expansion tank requires an increase in the installation height of the equipment by more than 10 m/1 atm from the bottom of the pipeline, otherwise the coolant will splash out. That is why in such cases a membrane device with a built-in air cushion is used - closed-type heating.

The operating pressure in the heating system tends to decrease its level. This problem is due to the following reasons:

1. Coolant leak

Let's look at the most common causes of coolant leaks:

• Through the gaps of the membrane expansion tank. It is difficult to determine a leak, since the coolant still remains in the tank. To confirm or exclude an aspect, you should cover the spool pumping air with your hand. If liquid leaks from it, the membrane shell is damaged.
• A leak can occur due to boiling water passing through the heat exchanger, causing the coolant to flow out of the safety valve.
• Damage to rust, poor tightness of connecting elements or other pipeline malfunctions.

For the system to operate correctly, all elements must be assembled in the exact sequence

1. The water released air, which was then removed using an air vent

After the user has studied why the pressure in the system is needed, the heating installation should be correctly filled with coolant - in frequent cases, it is incorrect filling that can cause a drop in the pressure level.

To solve the problem, the coolant must be deaerated before filling the circuit, reducing the volume of dissolved oxygen by thirty times. Please note that the entire process takes place in slow motion, starting from the bottom of the system, using only cold water.

1. Combined heating device with aluminum radiators

The coolant, upon first contact with the aluminum material, breaks down into elements, after which it performs the following actions: the metal reacts with oxygen, then an oxide film is formed, hydrogen evaporates through the air vent.

The process will continue until all the aluminum walls of the radiators are covered with an oxidizing film. To increase the pressure in the device, the owner needs to supplement the missing water.

VIDEO: How performance indicators are improved

Why did the pressure rise sharply?

After the user has decided on the question of what pressure should be in the system, the following rules must be followed to prevent its sharp increase.

1. It is necessary to monitor the temperature of the water in the tank and eliminate the reasons that contribute to boiling of the coolant.
2. Regularly check pipelines for permeability. Often there are cases of a sharp increase in pressure due to build-up in radiators, airlock or dirty filters.

Performance indicators

Oddly enough, this question can be answered easily. Operating parameters depend on the specific room being heated:

1. If this is a private household or apartment, the operating pressure should be in the range of 0.7-1.5 atmospheres.

Indicators may vary depending on the power and modification of the boiler. In some cases, the difference in pressure at different nodes can vary from half to two atmospheres. If there is no data, choose 1.5 atm.

1. In houses with centralized heating, the operating pressure is much higher - up to 7 atm in nine-story buildings, up to 10 atm in houses with many floors.

If the apartment is monitored for exceeding operating parameters, you need to install regulators on the radiators. When the values ​​are below standard, you can separately install a 12 volt circulation pump.

Relationship between coolant temperature and operating parameters

After the boiler has been piped and the entire system has been assembled, a small amount of water is introduced into it for testing and pressure testing. Since it is still cold, the pressure will be minimal. As soon as the coolant begins to heat up, the pressure will increase proportionally. In an already functioning system, the role of a damper is played by expansion tanks (hydraulic accumulators), which take energy from the coolant and thereby control the pressure.

The hydraulic accumulator does not work constantly - it turns on as soon as the pressure reaches 2 atmospheres. When decreasing it turns off. The safety valve insures the operation of the expansion tank in the event that a critical indicator occurs - more than 3 atmospheres.

It is important to remember that maintaining a stable pressure value in the air chamber has a positive effect on the performance of the entire heating installation, including the pipeline and equipment. To solve the problem of what pressure should be in the system, there is a standard answer - no less than 1.5 atm and no more than 3, it all depends on the individual characteristics of the equipment. If the indicator falls below the minimum value, the membrane may rupture; if it rises above the maximum value, the water pressure will also increase.

VIDEO: How to properly pump and create pressure in the expansion tank

The pressure in the heating system of a two-story building constantly drops to
units and below, although there are no leaks anywhere. What could be causing this?

Alas, miracles do not happen. You can't argue with the laws of physics. If the pressure drops, it means there is a leak. You just don't notice it.

Let's look for the “weak spot” together. A heating system that uses fuel energy (there are others) includes three main components: heating devices, piping and boiler equipment. Let's look into the details:

Unfortunately, even specialists find it difficult to find a reliable cause of the pressure drop and the location of the leak. Often compressed air is pumped into the system in the hope of hearing a whistle or hiss. In some cases, painting the coolant in a noticeable color helps; after it dries, traces remain.

A pressure drop to one, like yours, can cause serious damage to equipment. Especially if it happens quickly. Find the leak or call a professional. And do not follow popular advice “from the Internet” to add mustard or radiator sealant to the water: you can damage the heating boiler.