Why does the pressure in the gas boiler drop or grow: the causes of the pressure of the pressure method of preventing problems
Work to ensure the correct functioning of heating equipment does not end on its installation. Service requires a certain level of knowledge from the owner and constant monitoring the state of the system. It is important to understand why the pressure in the gas boiler drops or grows, which is why the equipment functions with changes.
The article presented by us describes in detail all the reasons for the instability of pressure in the system of preparation of the coolant and hot water. We will talk about how to eliminate problems and maintain indicators in the normal range. Our recommendations will help to cope with planning breakdowns and prevent failures in work.
The pressure in the boiler slowly drops, you have to periodically add water to the boiler.
First, we consider cases when the pressure drops all the time. This is a fairly common problem. it is manifested in the fact that the pressure in the heating system is slow, sometimes decreases within a few days / weeks.
There are two reasons why this can happen:
The first is related to the leakage of the coolant from the system, consider what it is dangerous and how to look for a leak. The second will be associated with an expansion tank, but there is a whole bouquet, not only a decrease in pressure
Air pressure in the expansion tank
The air or nitrogen pressure indicator in the expansion tank for various gas boilers will not be the same, it all depends on the type of equipment and structural features. Standards are indicated by the manufacturer in the product passport.

Typically, the pressure in the new damper capacity is 1.5 atm. But such a setting may not be suitable for a specific heating system. Factory parameters are easy to drop. For these purposes, in the housing of the expansion tank there is a special fitting (some manufacturers are spool for pumping), through which air pressure is adjusted.
Nippel is located from the air chamber of the cylinder. With it, you can lower excess pressure or, conversely, pump up the tank
For the normal functioning of a gas boiler, it is necessary that in the membrane tank, the pressure is less than 0.2 atm than in the system itself. Otherwise the heated water that increased in volume will not be able to enter the container.
In small houses and apartments for closed heating systems, pressure in the expansion hydraulic tank is usually acceptable in the range of 0.8-1.0 bar (atm). But not less than 0.7 bar, because many gas boilers are protected and the device simply does not turn on.
Check the level of pressure of the tank annually. If pressure surges in the heating system are noticed, it means that air has come out of the damper capacity and it must be pumped up.
Pressure in the open heating system
Unlike a closed thermal circuit, a properly built open heating system does not require balancing over the years of operation. it is self.regulatory. The work of the boiler and static pressure provide constant circulation of water in the system.
The density of the heated water following the supply of the riser below the density of the chilled coolant. Hot water seeks to take the highest point of the circuit, and chilled. to be at its very bottom.
The pressure necessary for water circulation is achieved by pressure in the supply riser or an increasing pump
The pressure developed by the water column in the supply riser contributes to the circulation of the coolant and compensates for the resistance available in the contour pipeline. It causes friction of water on the inner surface of the pipes, as well as local resistances (turns and branches of the pipeline, boiler, reinforcement).
By the way, high.diameter pipes are used to assemble an open heating system to reduce friction.
To understand how to increase the pressure in the open heating system, you must first understand the principle of achieving circulation pressure in the thermal circuit.
- RC. circulation pressure;
- H is a vertical distance between the centers of the boiler and the lower heating radiator;
- RG. the density of the heated coolant;
- RO. density of chilled coolant.
Static pressure will be higher if the distance between the central axes of the boiler and the battery closest to it will be as significant as possible. Accordingly, the intensity of the circulation of the coolant 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 to the boiler, the better it warms up. Regulators allow distributing heat between all radiators of the heating system
The second reason for the fall pressure in the open heating system is associated with its self.regulation. When the temperature of the heating of the coolant changes, the intensity of its flow rate changes. Increasing the heating of water for the thermal circuit on cold winter days, the owners sharply reduce its density.
However, when passing through heating radiators, water gives the heat of the room atmosphere, while its density increases. And according to the formula presented above, the high difference in densities of hot and chilled water helps to increase circulation pressure.
The stronger the coolant warms up and the colder in the premises of the house, the higher the pressure in the system. However, after the atmosphere of the premises warms up and the heat transfer of the radiators decreases, the pressure in the open system will drop. the difference between the temperature of the water at the supply and on the return will be reduced.
Balancing of a double.circuit open heat system
Gravitational heating systems are performed with one or more contours. In this case, the length of each looped pipeline horizontally should not exceed 30 m.
But to achieve optimal pressure and pressure in an open system with a natural movement of the coolant, it is better to perform pipelines even shorter. less than 25 m. Then it will be easier to fight hydraulic resistance to water. In the circuit with several rings, in addition to limiting the length, you should observe the condition for heating radiators. the number of sections in all rings should be approximately equal.
Lack of pressure in an open double-circuit heat system occurs due to errors of design or pollution of the pipeline
Balance of horizontal rings included in the vertical circuit is required at the stage of designing the heating system. If the hydraulic resistance of a ring is higher than that of the rest-static pressure in it will not be enough and the pressure will virtually stop.
To maintain the necessary pressure in the double.circuit heating system, it is necessary to reduce the cross section of the pipes on the approach to the radiators. You can also install valves in front of radiators that perform thermoregulation (manual or automatic).
You can balance an open double.circuit system: you can:
- Manually. We start the heating system, follow the atmosphere temperature of each heated room. Where it is higher. we fasten the valve, where below. promote. To configure 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 handles of the valves. Each such device will control the supply of the coolant into the radiator itself, increasing or decreasing the supply of the coolant.
It is especially important that the total hydraulic resistance of the heating system (all rings in the contours) is not higher than the value of the circulation pressure. Otherwise, heating the coolant and attempts to balancing the system will not improve circulation.
Circulation pump for an open heat system
It happens that measures to balancing the heating circuit of the gravitational system do not give the effect. Not all causes of low pressure are solved by setting. the choice of incorrect diameter of the pipes cannot be fixed without a complete reconstruction of the contour.
Then, in order to increase pressure and improve the movement of water without a significant alteration of heating, a circulation pump or an increasing pumping device is mounted in the system. The only thing the installation will require is the transfer of an expansion tank or its replacement for a membrane expanomate (closed tank).
Briefly about the main thing
Having studied some possible causes of pressure falls, it must be said that the parameters in the system are not always emergency. So, during commissioning, a cold coolant is used, which causes the formation of air plugs in need of discharge. It is during this operation that the pressure is reduced.
If, after the verification, there were no coolant leaks, the expansion tank and the reset are working, and the pressure is still observed in the system, it is necessary to contact the service service so that the work is carried out by professionals.
You faced the fact that the pressure in the boiler fell? What was it connected with and whether it was possible to solve the problem?
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Nuances of pressure falling in boilers from different manufacturers
Ariston
This manufacturer has a bypass element, which allows you to solve the issue of how to raise the pressure in the Ariston boiler when you turn off the electricity.
Is Your Central Heating System Losing Pressure?
It allows you to reduce the excessive heat exchanger heating due to insufficient water consumption. The coolant in the system is launched, bypassing the circulation pump.
Baxi
The minimum pressure of these boilers is half a bar, with its insufficiency, E40 and E41 errors are issued on the boiler screen. It can be adjusted by the tire pump, the embassy valve on the Baxi boilers is a conventional car nipple.
note! At the first launch of the coolant into the system, the boiler can give out error E10, it passes automatically.
Navien
These Korean boilers are structurally designed to drop in pressure up to 0.1 bar, which minimizes emergency locks. Such units are ideal for high.rise buildings. The boiler is equipped with a system of nozzles, protective systems and feed devices that allow it to work with a pressure reduced to 4 MBAR. You can adjust the pressure with a remote control.
Pressure control in the thermal circuit
Manufacturers have developed and are produced in different design special devices that allow you to control the pressure in the heating contours. Almost all manufacturers that make blue.fuel heat generators equip the equipment with built.in manometers. They are installed on the outlet pipe of the device.
Important! Before reducing the pressure in the gas boiler, it is required to determine its real value. In modern models of heat.earning equipment on blue fuel, the normative indicator varies from 1 to 2.5 bar.
When the value on the measuring device approaches 3 bars or exceeds this mark, urgent measures are required. It is necessary to quickly reduce the indicator. If the value grows constantly, then delay even in a few seconds can lead to tragic consequences.
On a note! With a large pressure from the safety discharge valve mechanism, the thermal carrier will explode.
During the device of the intra.house thermal circuit, mechanical pressure gauges are more often mounted than digital measuring devices. Their installation is performed near the collector nodes, which are designed to distribute the heat transfer fluid through the premises and levels of the building.

The pressure gauge is also part of the security group of a boiler unit. In addition to the pressure measurement device, its composition contains an automatic air vent and a safety valve for the discharge of the excess of the heat carrier, which prevents the explosion of a heat.generating installation.
The level of control must be increased if the premises are heated by a double.circuit heat generator. In this case, the pressure can increase not only in the boiler unit, but also in different sections of the thermal intra.house circuit. The value of this parameter is influenced by the temperature of the heat supply fluid. In addition, its value is larger in a closed circuit. Therefore, the work of such a system is controlled as much as possible.
The manometer testimony is always checked when the boiler is launched. When the unit is turned on, the coolant is still in a non.gears. At this moment, his pressure will be almost zero. It will increase with an increase in temperature.
On a note! The setting of the heat generator should be performed by a specialist from the company that is engaged in the maintenance of gas equipment. The process is carried out with the initial launch of the heat circuit.
Setting should also be performed during the operation of the heating system. It is recommended to spend it once every 7 days. In the process, the system is often fed. In this case, the temperature of the heat carrier should not exceed 40 ° C.
Varieties of pressure
Why does pressure drop in the wall device? First, we will figure out what types are and how they affect the work of technology.
- Static. The greater the height, the higher the indicators. With each meter there is an increase by 0.1 bar.
- Dynamic. Forced operation of the pump creates a nominal pressure in a closed system.
- Working. Includes two of the above options.
- Excessive. It is defined by the manometer as the difference between atmospheric and fixed.
- Nominal. That which was indicated by the manufacturer in the documentation for a specific model.
- Maximum. The maximum that is allowed to avoid breakdowns and accidents.
- Pressing. Used in production when checking equipment.
In the heating circuit, indicators are measured by atmospheres. They may vary; It is important that the value does not exceed the permissible maximum and minimum thresholds. Low value is possible only when rolling the coolant into the circuit. In other cases, it should not deviate from the norm.
The remaining reasons
There are other reasons for such problems:
- Reinforcement is blocked. With the fence, the pressure rises, protective sensors block the equipment. Inspect the taps and valves, unscrew them all the way. Make sure valves performance.
- Zarori filter skeletons. It clogs with garbage, rust, mud. Remove and clean the part. If you have no desire to regularly engage in cleaning, install a magnetic or flushing filter.
- The fuel tap failed. Perhaps his gaskets have worn out, then you can do with a replacement. Otherwise, you will have to change the crane.
- Automation problems. A malfunction of a thermostat or controller. Reason for wear, factory marriage, incorrect connection. Diagnostics, repair are carried out.
Control whether the boiler protection details are working: a pressure gauge, a valve, an air discharge. Carry out radiators and other components from dust, soot, scale. Prevention helps to prevent serious breakdown of gas equipment.