Pressure in a closed-type heating expansion tank: instructions, principle of operation

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Pressure in a closed-type heating expansion tank: instructions, principle of operation
Pressure in a closed-type heating expansion tank: instructions, principle of operation

As is known from the school course of physics, the liquid expands in volume when heated. Since the elasticity of pipes in heating systems is not high enough to accommodate the increased volume, the pressure rises sharply. This often leads to rupture of radiators and lines. If you don't find a way to remove the excess water, the entire system can easily fail in just a few hours. To do this, additional communications are installed, allowing the accumulation of pressure in the expansion tank of a closed-type heating.

Heating installation

Working principle

Without this auxiliary equipment, normal operation of any space heating system is impossible. The simplest devices make it possible to compensate for the expansion of the heated liquid and avoid water hammer. For this reason, it is imperative to follow safety rules during use. It is quite easy to select the necessary unit and carry out installation. With the right choice of equipmentcontinuous stable operation of the entire heating system will be guaranteed.

Selecting a tank

When designing a reliable heating system, everyone will have to wisely choose such a tank and mount it in the heating system. The characteristics of the device will depend on the functions performed and the type of structure to be installed. There are only three options available on the market.

Expansion tank for closed type heating. The price of such units in the domestic market can vary from 2,500 to 75,000 rubles, depending on the required volume. An ordinary sealed tank is filled with air. When the pressure in the system increases, the tank space is filled by compressing air. A special membrane is installed in the inside of the tank. It is necessary to protect the unit from rust after the increase in corrosive activity of water as a result of mixing with oxygen.

The open tank does not have an airtight lid. The average cost in the domestic market is about 3000 rubles. Such devices are used not only to compensate for expansion, but also to remove air pockets from the system. A coolant can be added to the design through such a tank to compensate for its gradual evaporation.

Hot water heating at home can be designed using a tank with top filling. This is a sealed container equipped with a valve. With the help of such a tank, you can quickly bleed water from your home heating system.

Expansion tank for heating closed type price

Instructions forinstallation

Installation of expansion tanks must be carried out in strict accordance with the technology for the best performance of heating devices. The device must be installed above the boiler, while the water pipes must be directed downwards for easy draining of the coolant in case of membrane breakage.

This system is based on the forced circulation of energy carriers, so it must be compensated by circulation pumps. A flat expansion tank for closed-type heating is much more difficult to select and install when compared with other types of devices, since they are not designed to compensate for thermal expansion. The stable functioning of the entire system will depend on the quality of the installation.

Such tanks are installed in areas where there are no turbulences in the flow of the coolant. For this reason, it would be correct to locate it on straight sections of pipelines in front of the circulation pumps. You will have to familiarize yourself with some general rules for the selection and installation of tanks, which must be observed when designing and assembling the system.

Membrane tank for closed type heating

Volume calculation

A tenth of the coolant passing through the system should be placed in the tank. Under no circumstances should a smaller size be chosen, because the pressure in the closed-type heating expansion tank will be too high, and hydraulic fracturing will not be prevented. Such a calculation is only suitable in cases where water is used as a heat carrier.You need to choose a larger capacity if ethylene glycol circulates in the system.

This expansion tank must be equipped with a special safety valve. Almost always it is included in the factory kit. If the tank valve is not provided, you need to buy it and install it. The pressure in the closed-type heating expansion tank can be reduced thanks to this device.

If the calculation was carried out incorrectly, and a unit with insufficient volume was purchased, you can buy another one. A frequent increase in pressure in heating systems will be a clear sign of a mistake made when choosing a tank.


The height of the tank from the floor will play absolutely no role. The tightness will be maintained, and the air will be removed through special valves. During installation, it is advisable to take into account that the flow of coolant from above will be the best option. This makes it possible to get rid of air entering the fluid compartments.

When a closed-type heating expansion tank is selected, the price of the entire system may be higher when compared with the option of buying double-circuit electric or gas boilers, which already have a mechanism to reduce pressure.

Expansion tank for heating closed type malfunction

Adequate amount of water

In heating systems, the required volume of water is determined depending on the size of the room, the power of the boiler and the number of heating elements. In conventional systems per 1 kWvoltage is calculated 14 liters. This amount should be sufficient for good circulation and normal heat transfer.

Calculation methods

It is not always easy to find the right expansion tank for closed heating. Instructions for installing a space heating system can sometimes only be completed with the help of outside help. Each owner can use several available ways to select a suitable tank. The easiest way is to find a special calculator program on the Internet, which facilitates the calculation of the specified parameters and makes it possible to determine the size of the tank for full compensation of excess pressure in the system.

You can also ask this question to specialists working in design bureaus. This is the most reliable and most costly option. Thanks to this method, design errors can be avoided and it can be prepared for stable long-term operation.

Some people try to calculate the required volume of the tank using formulas on their own. At the same time, it is necessary to take into account how much the pressure in the expansion tank of the closed-type heating can change. The coefficient of increase in volume at a coolant temperature of 95 degrees is 0.04, and at 85 heating boilers.

Accurate calculations determine the overall efficiency of heating, ensuring uninterrupted operation, excluding possible malfunctions in case of violations induring operation of the equipment.

Expansion tank for heating closed type instruction

Recommendations from experts

The maximum allowable pressure in a closed type heating expansion tank is determined by the threshold values ​​of the safety valves. Wish they could be regulated. The volumes of tanks are initially selected with a margin so that they can perform all the necessary functions with inaccuracies in the calculations without creating a threat of accidents. You should not save money when buying, and it is preferable to trust the installation of all equipment only to professionals.

Do not forget that the level of protection of housing from the cold will depend on the reliability of the heating system, since any malfunctions can leave the building without heat completely. Proper installation avoids many problems, and any home will be protected during the most severe cold weather. Naturally, over time, each expansion tank for closed-type heating can be damaged. Malfunctions in the operation of the heating system occur from time to time. For troubleshooting, it is best to seek help from qualified professionals.

Water heating at home

Membrane tank for closed type heating

This type of equipment is separated by rubber partitions. Air is pumped into the upper part of them to supply the initial pressure. The coolant is supplied to the lower part, and the heating installation starts. As the temperature rises, the amount of water increases, and its excess is released into thetank. When the coolant returns to its original volume, the heating system automatically adjusts the pressure. The membrane then assumes its normal position.

Tanks with cylinder installation

Such equipment makes it possible to regulate the pressure more accurately. The air chamber is located around the entire perimeter of the tank. The rubber compartment expands when coolant enters it. The main feature of such membranes is the possibility of replacement in case of wear. Rubber material must always comply with sanitary standards and specific requirements for elasticity, heat resistance, duration of possible operation, moisture resistance.

Pressure in the expansion tank of closed type heating


The heating installation must always be equipped with an expansion tank. This equipment is designed to maintain a stable and constant pressure, ensuring the normal functioning and proper operation of closed-type systems and the circulation of the coolant in them.

The main task of such tanks is to reduce the possibility of hydraulic fracturing due to a sharp increase in pressure in the pipes. This can lead to a malfunction in the operation of individual elements of the heating system.

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