Boiler water pressure rises

Why does the pressure drop in the gas boiler?

To stabilize jumps in the pressure gauge arrow in the circuit are placed special compensating tanks. The pressure in the heating expansion tank displaces the working fluid back into the pipe. They come in two varieties. Constructive differences allow them to be used in different types of systems:

In the open-type circuits the circulation of the working fluid is due to gravitation. What is the pressure in the expansion tank of the heating system of open type is not of key importance, more important is its volume. These systems are designed in such a way that at its highest point there is an expansion tank. It is a vessel of particular dimensions made of metal or plastic. It is not airtight and the coolant is in contact with the air. An open tank can be without a lid, but it is better to have a lid. It will prevent debris or insects, if any in the household, from getting into it;

without access of the working fluid to the air;

The pressure in the closed heating expansion tank is higher than in conventional ones. In closed circuits, the water is pumped by an electric pump, which is the primary cause of pressure. Without a pump there can be no circulation. Schemes of such systems presuppose installation of a sealed expansion tank. It can be installed at any point in the circuit, except for sections:

Its location in the space also matters. Air bubbles are pushed upward by the heat transfer fluid. You don’t want them to get into the tank. As it will affect what pressure will be in the expansion tank of a sealed heating system.

In the network, there is often talk about what should be the pressure in the expansion tank of the heating system. To find out the latter the average person will have to dig through a decent amount of information, since the answers are often contradictory and difficult to understand. Let’s try to break things down and start with the construction.

Pressure drop

Increased pressure in closed heating systems is not the only problem, in some cases there is a sharp drop in operating pressure, and among the reasons why the pressure level drops, we should highlight the following:

  • Hidden system leaks, the emergence of corrosion, loose connections, leaky fittings;
  • rupture of the tank membrane, which requires replacement or repair of the equipment;
  • Pressure drops in the system are observed if the nipple is trapped, such leakage of air leads to the deflation of the tank, and this causes damage to the membrane;
  • there are cracks on the heat exchanger of the boiler, which leads to the leakage of the coolant;
  • Pressure drops associated with the appearance of air bubbles, leads to a decrease in the overall temperature in the system and stopping it;
  • One of the reasons of pressure drop can become a sour or half-open tap used for water drainage into the sewage system.

What value of pressure is considered the norm

A stable number of atmospheres in the main line contributes to reducing the level of heat loss and the fact that the circulating coolant has almost the same temperature to which it was heated by the boiler.

About what should be the pressure, it is necessary to talk about, taking into account what kind of heating system we are talking about. Options:

Pressure in the heating system of a private home. An expansion vessel is a communicating link between the system and the atmosphere in an open heating system. Even with the circulation pump, the number of atmospheric pressure in the tank will be equal to atmospheric pressure, and the manometer will show 0 bar.

Pressure in the system of multi-storey house. A characteristic feature of heating devices in multi-storey buildings is a high static head. The higher the height of the house, the greater the number of atmospheres: in a 9-storey building. 5-7 Atm, a 12-storey building and higher. 7-10 Atm, with the value of the pressure in the supply line of 12 Atm. Therefore it is necessary to have powerful pumps with dry rotor.

Diagram of heating of multi-storey house

Pressure in a closed heating system. The situation with a closed mains is somewhat more complicated. In this case, we artificially increase the static component in order to improve the efficiency of the equipment, as well as to exclude the penetration of air. Required pressure in the heating system of a private home is calculated by multiplying by 0.1 the difference between the highest and lowest point in meters. This is the static head value. Having added to it 1,5 bar, we obtain the necessary value.

Thus, the pressure in the heating system in a private home with a closed circuit should be within 1.5-2 atmospheres. Critical is considered a parameter outside the range, and at a mark of 3, there is a high probability of an accident (depressurization of the main line, units failure).

Yes, high pressure can improve the operation of the equipment, but you should take into account the technical characteristics of the installed boiler. Some models can withstand 3 bar, but most are designed for 2, and in some cases 1.6 bar. It is important, when adjusting the equipment, to achieve a value in the cold system of 0.5 bar below the value declared in the passport. This way you will avoid permanent operation of the pressure relief valve.

Why is My Water Pressure So High?

It is important to remember that it makes no sense to measure the water pressure in the heating system or try to regulate it in a single apartment. The only thing that depends on the owners of the apartment. the choice of batteries and the diameter of pipes in the pipeline. For example, it is not recommended to use cast iron, as they can withstand only 6 bar. And the use of larger diameter pipes will reduce the head throughout the heating system of the house. When moving into an apartment with an old heating system, it is better to immediately replace all possible elements.

Another parameter that affects the value of the head in any heating line is the temperature of the coolant. A certain amount of cold water is pumped into the installed and closed circuit, which provides the minimum pressure. After heating, the substance will expand and increase the number of atmospheres. So by adjusting the temperature of the water heating, you can control the head of the circuit. Today, heating equipment companies offer to use equipment with hydroaccumulators (expansion tank). They do not allow the head to increase by storing the energy inside them. As a rule, they are activated when they reach 2 atmospheres.

boiler, water, pressure, rises

Temperature and pressure distribution in the apartment house

It is important to check the accumulator regularly, so that it can be emptied in time. Installation of safety valve which can be engaged at pressure of 3 atmospheres and full tank to avoid breakdown of water will not be superfluous.

Low water pressure in the boiler what to do

If there are no leaks in the radiators, then the reason why the pressure drops, is in the boiler. Why does it happen and how to raise (gain, inflate, increase) the pressure? If you often pump water, and the boiler does not hold pressure, there is a possibility that microcracks have formed in the heat exchanger. When heating up the boiler the cracks enlarge and leakage. Urgent intervention of a specialist or you can repair the fistula with your own hands. Brazing of the heat exchanger The cause of micro cracks is the wear and tear of the heat exchanger, frequent flushing with chemicals, poor quality of metal from which it is made, water hammer when the pressure in the line increases sharply. They usually occur after an accident in the water supply system. Locations where there are microcracks can be identified by the layer of scale. If it is not difficult to remove the heat exchanger, you can try to solder them. Bi-thermal heat exchangers are almost impossible to repair because of its design, it will have to be replaced. In the boiler does not rise (does not gain) the pressure, when the make-up faucet leaks. If the pressure in the mains is higher than the pressure in the boiler, the liquid through the make-up valve increases the pressure in the boiler to a critical point, is discharged through a safety valve. As a result, the pressure decreases, water from the heating system presses the liquid in the water supply and heating system. Close the valve, check the tightness of its connection or replace it in case of failure. Pressure goes out (drops) to 0 when the three-way valve is defective. Large pieces of scale or rust can get into the valve and obstruct the flow, clean the valve. The problem with the expansion vessel can cause pressure variations. When heated, the volume of water in the system increases, this excess flows into the expansion tank. There is a rubber membrane inside the tank. The space between the outer wall and the tank membrane is filled with gas. Excess fluid fills the diaphragm and depressurizes the heating system. The gas equalizes the excessive pressure. After the temperature drops, the liquid flows back into the system. If there is a gas leak this does not happen. The reason for the malfunction of the expansion tank is a worn nipple that needs to be replaced. Worse, when the membrane breaks, the tank itself must be replaced. Expansion vessel in sectional view A car pump can be used to pump air into the expansion vessel. How to add (supply, pump up) pressure in the expansion tank?

The modern house is a complex system of communications, automation of units allows you to reduce intervention in their work to a minimum. Despite this, the owners of heating systems face a number of problems. Experts have identified the five main causes of pressure drop in the closed heating system: failure of the radiator; errors during installation; mismatch between the capacity of the boiler and the “native” pipe; depressurization and leakage, interruption / spikes in gas supply.

Implementation of control

According to modern standards, the models of heating devices are equipped with control sensors. Their task is to monitor the pressure level and in case of surges temporarily or completely block the operation of the unit and the system. Thanks to the output of the error code on the information display of the boiler, the user can read the information in the manual or find the answer on the official website of the manufacturer. The most famous models of gas boilers support operation within 1.5-2 atm. Units brands “Bosch”, “Ariston”, “Baxi”, a boiler firm Navien. they are all available with a forced liquid system and the pump, the pressure drop is controlled by the program.

How it works

How the pressure works in gas boilers? Let’s consider in detail the process of the equipment functioning. Turning on the unit triggers the sensors, and from the first seconds the temperature of the coolant begins to be fixed. The external thermostat, if provided with the model, automatically activates and you see the arrow light up and the heating is performed. As the temperature rises, the pressure rises, the water heats up and expands. Periodically the safety valve is activated, which discharges the excess into the drain. Malfunction may occur if too much water goes into the drain. this causes the head to drop. The boiler shuts down automatically when the programmed temperature is reached. What happens inside the expansion tank? It consists of two parts separated by a diaphragm. Excess fluid accumulates in one part and nitrogen in the other. The heating medium fills the tank as much as the difference between the nitrogen and the system value. When it reaches the temperature set by the program, the nitrogen pushes the water out of the tank by deforming the diaphragm. the heating stops.

What pressure should be in the boiler?

The working pressure in a heating circuit is the sum of the static and dynamic components:

  • Head of the water column (coolant) and lifting of the expansion tank.
  • Pressure created by circulation pump operation and necessary to overcome hydraulic resistance of the system.

The first value is constant and the second value is variable. It depends not only on the head and capacity of the pump but also on the thermal expansion of the thermal fluid, thermostatic control heads and other automatic control valves. Therefore, the working pressure in the heating system with a boiler is a range of values that is safe for the tightness of the circuit and ensures its effective operation. In low-rise buildings its value is usually 1.5. 2 atmospheres.

Working pressure is one of the initial parameters for the hydraulic calculation of the system. And if its design, installation and adjustment at the first start-up were performed correctly, problems usually do not arise.

Preventive maintenance of equipment

Regular preventive maintenance of the boiler and boiler room equipment is necessary.

This must necessarily include the cleaning of dirt traps, adjusting the pressure in the membrane tanks, in the heating system, the gap in the ignition electrodes, the adjustment of gas fittings.

It is better to entrust this matter to professionals. because, independent intervention in the work of the gas equipment, can lead to damage to the equipment.

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Pressure increase in the closed heating systems

Causes of increased pressure due to the formation of an air lock in a closed system:

  • Filling the system with water quickly at startup;
  • The circuit is filled from the top point;
  • After repairing the heating radiators forgot to bleed the air through the Maevsky cocks;
  • Malfunctions of automatic air vents and Maevsky cocks;
  • Loose circulation pump impeller, through which air can be sucked in.

Fill the water circuit must be from the lowest point with open drain cocks. Fill slowly, until the air vent at the highest point of the circuit does not pour water. Before filling the circuit you can coat all the venting elements with soapy foam to check that they work. If the pump sucks air, you will probably find a leak under it.

The pressure in the heating system in the wall boiler is rising

Stable operating pressure in the heating system (1. 2 bar) is a guarantee of safe operation of the two-circuit gas boiler. The boiler will not start if the system pressure is less than 0.6 bar, with more than 3 bar there is an emergency water discharge.

    The reasons why the pressure in a two-circuit gas boiler can gradually, but constantly grow two:

Usually it happens like this: the pressure rises slowly (sometimes you may not notice it and leave for a few days) until the pressure relief valve is triggered (usually at 3 bar). And so several times, along the cycle. As a result of flooded floor in the kitchen, ruined furniture and mood.

The heating system is self-contained (not connected to the water supply). This is essentially a closed loop that can be heated by a gas burner. But there is a make-up valve to fill this heating circuit with water, and if it leaks, the water from the plumbing will leak into the heating system (increasing the pressure there).

And the second (unlikely) option. in a secondary heat exchanger water and heating pipes are located next to each other, literally through a thin wall. And if there is a fistula, it can leak from the water system to the heating system (until the pressure equalizes). And if the cold water tap pressure is over 3 bar, the same pressure will eventually be in the heating system. Which will trigger the emergency valve (and dump some water).

Why do you need a make-up valve on the gas boiler

Make-up valve serves for primary filling of the heating circuit with coolant (water) and compensation for loss of coolant.

    But the loss of coolant itself is possible for several reasons:

Boiler make-up valve how it works

The fill and make-up tap on compact boilers is usually located at the bottom of the body, next to the cold water inlet pipe. And is a manual valve that connects this line to the heating return line.

Boiler is a two-circuit gas boiler does not hold the make-up valve

How to tighten makeup tap: select the free stroke of the stem (while spinning the tap with almost no effort) and when you feel that the rubber covered the cone. turn half a turn more.

Repair of boiler make-up valve

In most cases it is not necessary to change the make-up valve, it is enough to relieve water pressure in the boiler through the valve, unscrew the swivel from the valve and replace the small rubber ring on it.

Dips and their causes

Pressure jumps indicate improper operation of the system. The calculation of pressure losses in the heating system is determined by summing up the losses at individual intervals, of which the entire cycle consists of. Timely identification of the cause and its elimination can prevent more serious problems that lead to costly repairs.

If the pressure in the heating system drops, it can be caused by the following reasons:

  • The appearance of leaks;
  • Failure of the expansion tank settings;
  • Failure of pumps;
  • appearance of microcracks in the boiler heat exchanger;
  • power outage.

How to increase the pressure in the heating system?

The expansion tank regulates the pressure drop

If there is a leakage it is necessary to check all connections. If the cause is not visually detected, each area should be examined individually. To do this, close the valves one by one. The pressure gauges will show the change in pressure after a section is shut off. If you find a problem connection, it must be tightened, with additional compression. If necessary, the node or part of the pipe is replaced.

The expansion tank regulates the differences in temperature due to the heating and cooling of the fluid. A sign of malfunction of the tank or insufficient volume of the tank is the pressure increase and further decrease.

Calculating the pressure in the heating system necessarily includes calculating the volume of the expansion tank:

How to set hot water boiler pressure

(Temperature expansion for water (%)Total system volume (l)(Maximum pressure level 1))/(Maximum pressure level. Gas pressure in the tank itself)

Add 1.25% clearance to the result obtained. The heated liquid expands, forcing the air out of the tank through the valve in the air compartment. After water cools down, it will decrease in volume and the pressure in the system will be less than necessary. If the expansion tank is smaller than required, it must be replaced.

Increased pressure can be caused by a damaged diaphragm or improper adjustment of the heating system pressure regulator. If the diaphragm is damaged, the plug must be replaced. This is quick and easy. To adjust the reservoir, it must be disconnected from the system. Then use a pump to pump the necessary amount of atmospheres into the air chamber and put it back in.

You can determine the fault of the pump by disconnecting it. If after turning off nothing happened, then the pump is not working. The reason could be a defect in its mechanisms or a lack of power. It is necessary to make sure that it is connected to the network.

If there is a problem with the heat exchanger it must be replaced. During operation microcracks in the metal structure may appear. This cannot be eliminated, only replaced.

Why the pressure in the heating system increases?

Causes of such a phenomenon can be improper circulation of liquid or complete stoppage due to:

  • airlock formation;
  • clogging of pipelines or filters;
  • Operation of the heating pressure regulator;
  • incessant feeding;
  • The blocking of the shutoff valves.

How to eliminate the drops?

An air lock in the system prevents the fluid from leaking. The air can only be blown out. To do this during the installation should provide installation of a pressure regulator for the heating system. spring air vent. It works in automatic mode. Radiators of the new type are equipped with similar elements. They are located on top of the battery and work in manual mode.

Why the pressure in the heating system increases if there is a build-up of dirt and limescale in the filters and on the pipe walls? Because the flow of the fluid is obstructed. The water filter can be cleaned by removing the filter element. To get rid of limescale and clogging in the pipes is more difficult. In some cases flushing with special agents helps. Sometimes the problem can only be solved by replacing a section of pipe.

The heating pressure regulator in case of temperature increase closes the valves through which the liquid flows into the system. If this is unreasonable from a technical point of view, the problem can be eliminated by adjusting the. If this procedure is not possible, the unit must be replaced. In the case of failure of the electronic make-up control system, it must be adjusted or changed.

The notorious human factor has not been canceled yet. Therefore in practice happens overlapping of valves, which leads to increased pressure in the heating system. To normalize this value, simply open the valves.

The pressure in the heating system should be in the norm. 1.5. 2.0 atmospheres for private houses up to 2 floors. If the pressure deviates from the specified limits, the system must be “treated”.

boiler, water, pressure, rises

In this article we will analyze the nuances of the heating system and boiler room equipment. Let’s define what pressure it is necessary to maintain, how to set it, what it depends on The material above will probably help readers in matters related to the efficiency of the heating system and use of equipment.

What pressure should be in the heating system

In low-rise private houses, the working pressure of the heating system is about 2 atm. often 1.5. 2.0 atmospheres. The maximum pressure rise is allowed up to 3 atmospheres, and above. should trigger an emergency valve.

In high-rise buildings the pressure rate is within 5. 10 atm. Most often 5. 8 atm. The maximum that the heating radiators in apartments of high-rise buildings are designed for is 12 atm.

The same pressure. 12 atm, can be in the main pipes of heating systems.

In high-rise buildings, to reduce the pressure, hydraulic pressure reducers are installed on the heating risers.

Why does the pressure rise

According to the laws of physics, when a liquid or gas is heated, its volume increases. Therefore, if the liquid is in a closed heating system, its pressure will increase with increasing temperature.

A liquid cannot compress as much as a gas. If the space is enclosed, there could be a large pressure surge and the shell will burst.

In a “wrong” heating system of the closed type this is what happens. the weakest link, for example, the heat exchanger of the boiler, is destroyed and the liquid finds its way out.

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