What pressure should be in heating systems

Heating a house, organized with the help of a boiler, radiators and distribution pipes, is a complex engineering communication. The pressure in the heating system is a characteristic that directly affects the durability and proper functioning. Differences, decrease or increase in the indicator lead to the destruction of structural elements, shutdown of heating, and costly repairs.

Types of pressure

When designing and installing heating, specialists are guided by many parameters, each of which is necessary for proper operation.

The pressure is necessary to move the heated coolant through the pipelines from the boiler to the radiators, to lift the liquid to the upper floors of the building.

Allocate pressure and working pressure. The pressure test is created during the initial installation, as well as annually in the course of maintenance work in preparation for the heating season. At increased rates, the places of possible water leakage from the pipes are determined, the identified malfunctions are eliminated. A worker is understood to be such an indicator at which the system is in an operable state throughout the entire cold season.

The working indicator is summed up from the static and dynamic components. Static pressure creates a column of water in the risers due to gravity. The higher the house, the higher the indicator. The dynamic characteristic is determined by the operation of circulation pumps, which supply the coolant to the upper floors, pump liquid through pipelines and heat exchangers (radiators).

What is considered the norm

The indicator of the norm differs depending on the number of storeys of buildings, the heating design and the principles of operation. The pressure in heating systems in apartment buildings reaches 6-7 atm for the supply section of the pipeline. The return flow is characterized by an indicator of 4–5 atm. When pressing, the head should reach 10-12 atm.

When replacing radiators, pay attention to the characteristics indicated in the product data sheets. The maximum value for batteries installed in apartment buildings cannot be less than 12 atm. Pipes are initially designed for such a head, and the weak point is the threaded connections through which leaks occur.

In private houses, a pressure of 1.5–2 atm is sufficient to supply the coolant to the third floor. The same indicators are needed in individual heating schemes for apartment buildings.

In devices for heating a private house, copper tubes of boiler heat exchangers, which withstand 5-6 atm, are more likely to be destroyed.

Why are drops dangerous?

Reduced and increased pressure lead to malfunctions in the operation of the entire heating system or breakdowns that require expensive repairs.

At reduced rates, the automation (for modern models) stops the supply of energy and the boiler turns off. If the heating is stopped for a long time during the frosty season, the pipes, radiators, and the boiler heat exchanger will be destroyed.

In addition, at a low rate, the pressure may not be enough to effectively pump the coolant throughout the entire system. Upper floors and radiators farthest from the riser pipes will remain without heat.

The indicator is important for the operation of a warm water floor. The maximum length of the circuit reaches 100–120 m, which creates resistance to the movement of the coolant. With insufficient pressure, the circuit will stop heating up.

With increased pressure, water begins to ooze through the threaded joints of pipes and radiators. Destruction of structural parts is possible.

Low blood pressure reasons

The pressure depends on the design features of the heating. In communications with natural circulation and leaking expansion tanks, the pressure depends only on the height of the water column. The reason for the fall may be a low water level.

In leaky systems, water evaporates from the storage surface or can flow out through leaky connections. As the indicator decreases, the water is added to the required level. Water evaporates gradually, so if the pressure drops abruptly, you need to look for a leak.

In closed systems with sealed expansion tanks, there are more reasons:

• not enough water / antifreeze;
• there is no pressure in the air cavity of the expansion tank or air leaks through the pumping valve;
  
• membrane rupture;
• a gradual decrease in the internal section of pipes as the accumulation of deposits of rust, lime, dirt;
• malfunction of the circulation pump;
• air locks in lines and radiators.

After the initial filling of the system with a coolant, air remains in it. As it is vented through the diverting valves, the pressure will gradually decrease, and fluid will need to be topped up.

It is possible to reliably identify the problem only with an integrated approach and analysis of the circumstances under which the characteristic has decreased.

In multi-storey buildings, a decrease in the indicator occurs when the circulation pumps are turned off or the radiators or pipes are airing. To eliminate the last malfunction, Mayevsky cranes or automatic bleeders must be installed on the radiators.

In case of boiling or overheating of water in the system, oxygen can be released from it. The gas is easily compressed, so the pressure can drop.

Increased air emission is observed when installing new aluminum radiators. At the first heating, a sharp release of air from the coolant occurs, as a result of which the indicator decreases.

Why does the pressure rise

The volume of any liquid increases with increasing temperature. For example, when heated from 10 to 80 degrees, water will expand by 4%. If the internal volume of the pipeline and batteries is 100 liters, after heating it will be 104 liters. For antifreeze, the same indicator is close to 7%.

Water does not lend itself to compression at low atmospheric pressure. Excess coolant from a closed system cannot pour out, the pressure increases sharply.

To prevent increased pressure in the event of frequent changes in the temperature of the coolant (autumn and spring), as well as to create a reserve capacity for liquid, the volume of the expansion tank is chosen at the rate of 10% of the capacity of the radiators and pipelines.

Based on the above facts, after filling the heating with water and heating the coolant to the operating temperature, the pressure will surely increase.

At the initial filling, the coolant is poured into the closed system only until the parameter required to start the boiler is reached (1–1.3 atm). The final topping up is done only after warming up.

Increased pressure is observed in the sections from the boiler to the radiators if the pipeline is old. In this case, the internal passage of the pipe cannot pass the entire flow of the coolant - there are pressure drops between the supply and return.

Preventing accidents

Increased pressure can cause irreparable damage.To protect communications in closed systems, security groups must be installed.

The group includes:

• pressure gauge;
• automatic air vent;
• safety valve.

The pressure gauge is used to visually check the pressure in the system.

When air is released from the coolant, the air vent is activated. It is designed in such a way that only gases pass through, water will not flow out of the pipes.

For individual houses, a safety valve is selected that is configured to operate at 3 atm. With a further increase, the coolant will pour out of the pipe. The excess goes through the hose to the sewer or can be collected in a special container. A similar valve is installed in modern gas and electric boilers.

The safety group must be installed in systems with solid fuel boilers or non-volatile gas boilers.

In the event of a power outage, the circulation pump stops working, while the fuel continues to burn. The coolant, remaining in the boiler heat exchanger, heats up and boils. The pressure rises to critical values, an explosion occurs with the destruction of the boiler equipment.

The safety group is installed on the supply pipes when leaving the boiler, and not on the return line, which does not heat up above 50-60 ° C.

Centralized heating pressure regulation

In apartment buildings connected to centralized heating systems, water hammer often occurs. Especially often, drops occur during technological work, during pressure testing, at the first start of heating with the arrival of cold weather.

You can protect radiators by installing a gearbox in front of the radiator. You can install it yourself between the control valve and the battery. The work is carried out after the seasonal heating shutdown.

There is pressure in the pipes in summer, it is created by the water column in the main line.

Choose a gearbox designed for 6-7 atm. This figure is enough for radiators to work on any floor. All modern batteries can easily withstand this pressure.

Often, gearboxes are equipped with air vents, which simplifies the maintenance of the heating system.

Knowing the possible causes of pressure drops, decrease or increase in the indicator, it is easy to find and eliminate the cause of the malfunction. Equipment manufacturers took care of the user, developed and produce devices for automatic regulation of an important characteristic. Protection devices will help prevent accidents, which can be costly to eliminate.