What pressure should be in a closed heating system

It is imperative for both comfort and energy efficiency that your home remains toasty and comfortable during the winter months. A functional heating system is essential to reaching this objective. It’s possible, though, that many homeowners are unaware of how crucial it is to keep the proper pressure in their heating systems. This article will discuss the importance of pressure in a closed heating system and why it affects the insulation and heating efficiency of your house as a whole.

Let’s define a closed heating system first and foremost. A closed heating system uses a set amount of water to circulate through pipes and radiators, as opposed to an open system, which replenishes water continuously from a feed and expansion tank. Maintaining ideal pressure is essential to this closed-loop system’s ability to distribute heat throughout your house effectively.

For a closed heating system to operate properly, pressure is an essential component. Insufficient heat output, cold spots in radiators, and even boiler damage can be caused by excessively low pressure. Conversely, high pressure can result in water hammer, leaks, and possibly even safety risks. Therefore, maintaining the proper balance is crucial for your heating system to operate at its best and last a long time.

So, for a closed heating system, what pressure is ideal? When the system is cold, the recommended pressure range usually lies between 1 and 1.5 bar. This pressure makes sure that there is sufficient force to move the water around efficiently without putting too much strain on the parts. For precise pressure recommendations specific to your system, you should, however, refer to the handbook that came with your boiler or a licensed heating engineer.

Maintaining the optimal performance of your heating system requires routine maintenance. A quick and easy way to make sure everything is in working order is to check the pressure gauge from time to time. If you see a persistent drop in pressure, there may be a systemic leak that needs to be fixed. On the other hand, bleeding the radiators could assist in resolving the problem if the pressure is constantly excessive.

In conclusion, consistent and dependable operation of your closed heating system depends on maintaining the proper pressure. Your home can stay warm and cozy during the heating season if you recognize the significance of pressure and take proactive steps to monitor and adjust it as necessary.

Keeping the proper pressure in a closed heating system is essential for effective operation. The recommended pressure range is normally 12 to 25 pounds per square inch (psi), though this can change based on the system type and individual parts. While excessive pressure can harm the system and possibly result in leaks, excessive low pressure can result in inefficient heating. Regular pressure monitoring and adjustment is necessary to guarantee peak performance and avoid expensive repairs. Additionally, keeping a balanced and efficient heating system depends on knowing the variables that affect pressure, such as temperature variations and air pockets.

Incomital information on the topic

First, we suggest thinking about the reasons for creating excess pressure in the pipelines (above atmospheric pressure) and the environments where it is measured. Let’s begin at the conclusion: in these types of units, it is typical to show the water pressure in the closed heating system:

  • 1 bar = 10 m of water column;
  • 1 MPa is 10 bar or 100 m of water. Art.;
  • 1 kgf/cm² – the same as 1 technical atmosphere (atm.) = 0.98 bar.

As a point of reference. Kilogram-Wild on cm² was a common unit of measurement in the USSR. The more practical metric units of MPa or Bar are currently used to measure pressure.

Next, visualize a three-story cottage that needs to be heated during the winter and has ceilings that are three meters high. In order to accomplish this, as illustrated in the diagram, batteries are installed on both floors and connected to a common riser that originates from the boiler. Three elements will make up the actual pressure in the resulting closed heating system:

  1. The water column in the pipeline presses with a force equal to its height. In our example, this is 6 m or 0.6 bar (0.06 MPa).
  2. Pressure created by a circulation pump. It forces the coolant to move at the desired speed and overcome the resistance of three forces: severity, friction of the liquid against the walls of pipes and obstacles in the form of reinforcement and fittings (narrowing, tees, turns and the like).
  3. Additional pressure arising from thermal expansion of the liquid. Practice shows that cold water with a temperature of 10 ° C after heating to 100 ° C adds about 5% of the initial volume.

Note: Depending on the measurement site, the fluid column’s static pressure varies. The manometer at the lower end of the system will display the maximum value of 0.6 bar when the pump is disconnected, and zero at the upper end.

An extremely crucial point. The two primary parameters of water heating operation are the desired water temperature and its consumption, both of which must be provided in order to provide the necessary amount of heat to the premises. In this instance, the system is not the cause of the pressure; rather, it is merely one of its effects. He could be anything in theory, provided that a boiler room and radiators are kept up.

This gives rise to the idea of what the heating system’s working pressure is, which is the maximum value allowed in the equipment’s technical documentation, such as the boiler or the batteries. While some low-cost units cannot withstand more than 0.2 MPa, normative documents mandate that it not exceed 0.3 MPa in private homes.

Why raise pressure

Compared to the reverse line, the feeding line has a higher pressure. This distinction describes how effective heating is as follows:

  1. A small difference between the presentation and the return makes it clear that the coolant successfully overcomes all the resistances and gives the calculated amount of energy to the premises.
  2. An increased pressure drop indicates increased resistance of the site, decrease in flow rate and excessive cooling. That is, there is insufficient water consumption and heat transfer to the rooms.

As a point of reference. The ideal pressure differential in the supply and reverse pipelines, as per the standards, should be between 0.05 and 0.1 bar, with a maximum of 0.2 bar. If there is a greater difference between the readings from two pressure gauges placed on highways, the system is either misdesigned or requires repair (washing).

In order to prevent a significant disparity on lengthy heat-supply vehicles with numerous batteries that are fitted with thermostatic valves, an automated consumption regulator is positioned at the start of the highway, as illustrated in the diagram.

Consequently, the following factors lead to excessive pressure in the closed heating network:

  • to ensure the forced movement of the coolant with the desired speed and flow;
  • to control the state of the system according to the pressure gauge and feed it in time or repair it in time;
  • The coolant under pressure is heated faster, and in the case of emergency overheating, boils at a higher temperature.

The manometer’s testimony regarding the heating system’s performance and serviceability is the paragraph in the second list that piques our interest. They are the ones who are drawn to homeowners and apartment complex owners who perform their own independent upkeep on home technology and communications.

Pressure in pipes of apartment buildings

It is evident from the preceding sections’ content that the floor on which an apartment is located determines the size of the set in high-rise buildings’ central heating pipelines. The situation is as follows: the real pressure in the remaining apartments is unknown because it decreases with each meter of water lifting, even if the tenants of the first two floors can roughly operate the manometer placed in the basement heat point.

Remark: In newly constructed buildings with floor heating points equipped with common riser apartment heating wiring, the coolant pressure at each apartment’s entrance can be adjusted.

Furthermore, since the owner cannot influence him, knowing the amount of pressure in a centralized network is of no practical use. On the other hand, there are those who contend that a decrease in highway pressure implies a reduction in heat input, which is incorrect. An easy illustration would be to block the back line crane in the basement. This will cause the manometer arrow to jump, but it will also stop the flow of water and the production of thermal energy.

Specifically, let’s talk about numbers now. The power of the boiler room pumps and the diameters of the heat supply networks are calculated to guarantee that the proper amount of coolant rises to the top floor. Accordingly, the working pressure of the heating system at the multi-story building’s entrance will be:

  • In the old five -story buildings, where to this day there are cast -iron radiators – no more than 7 bar;
  • In nine -story buildings of Soviet construction, the minimum indicator is 5 bar, and the maximum depends on the proximity of the boiler room with pumps, but not higher than 10 bar;
  • in high -rises – no more than 15 bar.

As a point of reference. Pipelines and heating devices should undergo pressure testing at least once a year, with a worker participating 25% more often than not. However, in practice, public utilities only test external heat supply networks and do not take the chance of inspecting residential systems.

The only use for the information provided is in selecting new polymer pipes and radiators. It is evident that cast-iron and steel panel batteries, which are intended to withstand a maximum of 1 MPa, should not be installed in buildings with more stories than that. This is covered in detail in our selection and the expert’s video:

Pressure indicators in a private house and the reasons for its fall

It is typical for closed heating systems in cottages and country homes to withstand the following pressure values:

  • Immediately after filling the heating network with water and air release, the pressure gauge should show 1 bar;
  • After warming up to operating temperature, the minimum pressure in the pipes is 1.5 bar;
  • During operation in different modes, indicators can change within 1.5-2 bar.

A crucial aspect. Our recommendation regarding the recommended pressure for a cold heating system was not in vain. The truth is that most imported gas boilers with contemporary automation are made to start at 0.8–1 bar of pressure, and without it, they will not operate.

A separate set of instructions explains how to generate the necessary pressure value and remove air from the heating highways in an appropriate manner. The following list of causes will explain why pressure indicators may drop following a successful start-up and ultimately result in the wall boiler shutting off automatically:

  1. From the pipeline network, warm floor and channels of heating equipment, air residues come out. Water takes its place, which fixes the pressure gauge with a drop to 1-1.3 bar.
  2. Due to the leakage of the spool, the air chamber of the expansion tank emptied. The membrane is extended in the opposite direction and the container is filled with water. After heating, the pressure in the system jumps to a critical one, which is why the coolant is discharged through the safety valve and the pressure falls back to a minimum.
  3. The same, only after breaking through the membrane of the expansion tank.
  4. Small leaks at the joints of pipeline reinforcement, fittings or the pipes themselves as a result of damage. An example is the warming contours of the warm floors, where a leak can remain inconspicuous for a long time.
  5. The coil of an indirect heating or buffer capacity has leaned. Then there are pressure surges depending on the work of the water supply: the taps are open – the testimony of the pressure gauge fall, closed – rise (the plumber assumes through the heat exchanger crack).

Learn more about the reasons behind pressure drops and how to prevent them by watching the master’s video:


As you can see, there is a tendency to overstate the significance of pressure in centralized heat supply networks. even though the apartment’s owner is aware that there shouldn’t be any water in the pipes. 7 MPa, but he receives little from this. in addition to replacing the highways with the appropriate pipes and radiators.

In a private residence, however, the situation is different: the manometer’s testimony, along with the presence of a puddle close to the safety valve, serves as an indicator of minor or major malfunctions. These things need to be watched over and responded to promptly in order to force the system to rise above the norm. Remember to keep an eye on the membrane’s integrity and promptly pump up the air chamber in the expansion tank.

Recommended Pressure 1.5 – 2.0 bar
Reason To ensure optimal performance and prevent airlocks in the system.

For a closed heating system to function effectively and efficiently, the ideal pressure must be maintained. To keep the system in balance and guarantee that the heating medium—whether it be water or another fluid—is properly circulated, this pressure is usually kept within a certain range. While excessive pressure can strain components and cause leaks, too low pressure can result in insufficient heating.

The type of system and its component parts are important considerations when figuring out the right pressure for a closed heating system. The pressure requirements of different systems might differ, so it’s important to check the manufacturer’s instructions or get expert advice to make sure the pressure settings are appropriate for your particular setup.

In a closed heating system, the pressure is typically kept between 1 and 2 bar (14.5 and 29 psi). Without placing an excessive amount of strain on the system’s components, this range offers the force required to effectively circulate the heating medium through the pipes and radiators. It is important to remember that specific pressure requirements can change depending on the system’s size, the building’s height, and the kind of radiators being used.

To make sure the heating system’s pressure stays within the advised range, regular monitoring is essential. Variations in pressure can arise from multiple sources, such as air pockets within the system, leaks, or variations in temperature. Homeowners can avoid possible problems and maintain optimal heating performance by checking and adjusting the pressure on a regular basis.

In conclusion, a closed heating system’s ability to function effectively and without issues depends on maintaining the proper pressure within it. Through adherence to recommended pressure ranges and routine maintenance, homeowners can guarantee optimal operation of their heating system, thereby ensuring comfort and warmth throughout their home.

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Michael Kuznetsov

I love to create beauty and comfort with my own hands. In my articles I share tips on warming the house and repairing with my own hands.

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