The volume of the coolant changes depending on the shift temperature regimes, which can lead to dangerous consequences. For a safe and long-term operation coolant, it is necessary to maintain its stable characteristics. A diaphragm expansion vessel can be used for this.

Purpose and design features

In heating systems, fluids that are in the process of weak compression act as heat carriers. For safe work heating system it is necessary to use a stabilizing device - a diaphragm expansion tank, which is capable of receiving a certain amount of liquid in the process of increasing pressure and volume, and then returning it to the circulation circuit when these indicators decrease.

Diaphragm expansion vessels have a number of advantages over other devices for the same purpose, namely:

• suitable for any water, even if it contains a large number of calcium;
• safe to use for drinking water;
• have a larger displaced useful volume than a pressure tank without a membrane;
• minimum air pumping is required;
• economically and quickly assembled;
• low operating costs.

However, these devices also have disadvantages, namely:

• the large size of the expansion tank makes the installation process quite problematic;
• due to the release of its heat by the coolant to the expansomat, heat loss increases;
• the risk of rust formation increases.

To avoid uncontrolled loss of heat, experts advise to insulate the device.

Differences from a hydraulic accumulator

The design of sealed expansion tanks is similar to the design of hydraulic accumulators, however, the purpose of these devices is different. Expansion tank compensates for the expansion of water that occurs due to heating in the heating system. The hydraulic accumulator accumulates the volume of water under pressure in a water supply system with a pressure pump in order to reduce the frequency of activation of this pump and smooth out water hammer. In addition, more often inside the accumulator there is a pear made of food-grade rubber. It is she who is pumped with water, as a result, the water does not come into contact with the tank body. The expansion tank for heating systems is made with a membrane made of technical rubber. It divides the body into two compartments, and the coolant has contact with the body.

Device and principle of operation

The membrane tank is a hermetically sealed metal container, divided into two compartments (chambers) by an elastic membrane. One of these chambers is a pneumatic chamber that contains gas or air under pressure. The second chamber, the hydrochamber, receives the coolant.

The device operates as follows:

• the air pressure, which is in equilibrium, in the pneumatic chamber compensates for the fluid pressure in the heating system, the volume of the coolant and the hydrochamber is minimized;
• when the fluid pressure rises in the system, including during heating, the pressure also increases in the hydrochamber, where the excess coolant enters;
• due to the elasticity of the membrane, the volume of the pneumatic chamber decreases, which is accompanied by an increase in gas pressure;
• when the pressure in the pneumatic chamber increases, the increase in pressure in the hydraulic chamber is compensated, and the system returns to a state of equilibrium.

With a decrease in the pressure of the coolant in the system, the opposite actions take place. The gas (air) compressed in the pneumatic chamber expands and displaces the liquid from the hydraulic chamber into the system until the pressure difference is restored. The design makes it possible to exclude the possibility of contact between the coolant and air, reducing the likelihood of rusting not only in the tank, but also in other parts of the heating system - the pipeline, the boiler. Sealed expansion vessels are equipped with safety valves to limit the maximum pressure in the heating system by acceptable level... This also characterizes the tank as a protection device for the heating system.

Types and selection criteria

To compensate for the volume of the coolant in the system during temperature changes, two types of expansion tanks are used: open and closed (sealed).

Open expansion tanks are widespread, but have the following disadvantages:

• high installation costs, since such tanks are mounted at the top point of the system to create the required level of increased pressure;
• it is necessary to constantly monitor the liquid level;
• there is a risk of rust in the system due to prolonged contact of the heating coolant with air.

Sealed expansion tanks do not have these disadvantages. For heating systems, tanks are produced that differ in the use of a membrane. Membranes are divided into balloon and diaphragm types. A balloon membrane is a container installed inside the tank, made of high quality rubber that can withstand significant temperature fluctuations. The flange mounting of such a membrane will allow it to be replaced quickly and easily.

Balloon diaphragms have such advantages as:

• a wide range of operating pressures, making it possible to use a sealed expansion tank;
• the ability to change the membrane, which helps to make the repair of this device cheaper and faster;
• simple setting of the minimum pressure for any system.

The diaphragm membrane is a non-removable baffle, which is most often made of elastic polymer or thin metal. This diaphragm has a low intrinsic capacity and the ability to compensate for small pressure drops in the system. If such a tank fails, it will need to be completely replaced. One of the privileges of this device is low price... In addition, the tank with a diaphragm membrane is simple in design and reliable in operation.

Choosing the right expansion tank means ensuring the safe operation of the heating system, therefore when choosing an expansion tank, you should pay attention to the following main characteristics:

• membrane material, its resistance to high absolute values ​​of temperatures, pressures and differences in these indicators;
• body material and coating, resistance to rust;
• compliance with sanitary and hygienic standards;
• execution (installation method).

Restrictions

Manufacturers impose certain restrictions on the use of membrane expansion tanks, which depend on the design and materials used in the manufacture of the device. Manufacturers have clear requirements for the properties and composition of the liquid in the heating system. The content, for example, of ethylene glycol in the antifreeze solution is limited. The use of a diaphragm expansion vessel at pressures exceeding the permissible standards is prohibited. It is mandatory to install a safety group that controls and limits the pressure in the tank. In heating systems of apartments autonomous heating and private houses, equipment is used, the working pressure of which is at least 3 bar.

Volume calculation

Volume is main characteristic, by which the expansion tank is selected. Many sources advise choosing the volume of the expansion tank within 10% of the total volume of the coolant in the heating system. This method for determining the capacity of the device is based on the fact that the coefficients of thermal expansion of the coolant, even with a glycol content of up to 90% and heating +100 degrees, do not exceed 0.08. This calculation method does not take into account the pressure in the system, therefore it can give inaccuracies. There is a more accurate method for calculating the volume of a diaphragm expansion tank. Here the ratio is used:

V = C * Bt / (1 - (Pmin / Pmax)), where

• C is the volume of the coolant in the system;
• Bt is the coefficient of thermal expansion of the coolant;
• Pmin - initial pressure in the tank;
• Pmax - allowable pressure in system.

The volume of the coolant in the heating system is determined taking into account all its nodes. This parameter is obtained from the design documentation for heating. If this is not possible, you can use an approximate calculation, which is based on the fact that the volume of the coolant in heating systems is related to the heating power - for every kW, there are 15 liters of liquid. The coefficient of thermal expansion of a liquid is determined using its composition - most often, in heating systems of apartments and houses, it is possible to add glycols to the water to improve its characteristics. This coefficient may also depend on the temperature of the coolant. The required values ​​can be found in the tables for the volume of water in the pipe.

The maximum pressure in the heating system is determined using the minimum of the values ​​that are allowed for different nodes. The transition valve is tuned to it. The initial pressure in the heating system with cooled heat carrier corresponds to the setting (minimum) pressure. For many devices, it can be precisely controlled by common means (bleeding air from the tank or pumping it up with a pump). The pressure in the tank is monitored during the installation of a pressure gauge on it. The calculated data will give an increase in the volume of the coolant in the system during its heating. To select a tank, the fill factor is rounded up. The coefficient depends on the maximum and initial pressure and can be found using tables provided by manufacturers or in special literature.

Installation

It is not difficult to install a diaphragm expansion tank, but it is better to entrust it to a specialist. First of all, the instructions for the device must be used. When installing this device in a heating system, it is important to carefully check the tightness of the connections. The expansion vessel must not be opened or disassembled. It is simply connected to the pipeline closest to the boiler. To prevent pressure build-up, safety devices are installed.

When installing the tank, the following rules should be taken into account:

• the tank is installed before the bifurcation;
• the temperature in the room must be constantly above 0;
• you need to double-check all calculations before installing;
• a tank with a volume of more than 30 liters is not mounted on the walls, but placed on legs;
• to control the pressure at the outlet of the tank, a pressure gauge is installed, at the inlet - check valve(if there is no pump);

• the device must be located in a place that is comfortable for maintenance and adjustment;
• when attaching the tank to the wall, the bracket must maintain a height that will be convenient for access to shut-off valves and to airspace;
• the underwater pipe and the crane should not overload the expansion tank with their weight, the liner must be strengthened separately;
• to the membrane tank located on the floor, it is impossible to lay the supply line across the floor across the passage;
• there must be a distance between the wall and the container for inspection.

Due to temperature fluctuations, the volume of the heating system coolant may change, which can lead to accidents. Therefore, everything must be done to make it work stably and this does not happen.

For this, special devices are used, for example, a diaphragm expansion tank. It is one of the key components of the heating circuit.

Purpose, pros and cons

When the coolant heats up, the pressure in the heating system circuit and boilers increases due to an increase in the volume of liquid. Since it is an incompressible medium, and the system itself is sealed, this can lead to breakage of pipes or boilers.

Some people believe that to solve the problem, it is enough to install a valve to squeeze out the excess volume of heated media, but this is not the case. When cooled, the liquid will be compressed, and air will enter the circuit in its place, which will become an obstacle to circulation. Therefore, the air will need to be constantly drained from the radiators, and it will be very expensive to add a new coolant and heat the water.

For this reason, it is recommended to install a membrane expansion tank for heating. It is a reservoir connected by a pipe to the system. Excessive pressure in it will be compensated for by volume, which will provide the circuit with full operation. The expander takes in a certain amount of liquid when the volume and pressure increase, and then, when these indicators decrease, returns it back. Such devices differ from similar devices of another type. a number of advantages:

• they can be used in any water, even if it contains a lot of calcium;
• allowed to be used for drinking water;
• have a large usable displaced volume (compared to tanks without a membrane);
• air pumping is required in a minimum amount;
• installation is quick and low-cost;
• operating costs will be minimal.

But it has an expansion tank and disadvantages. Sometimes you can run into problems when installing it, because it is quite large. Heat loss increases due to the fact that the coolant gives off heat to the expansomat.

In addition, there is an increased risk of rust formation in such devices. To avoid uncontrolled heat loss, it is recommended to insulate the device.

Choosing an expansion tank for heating and water supply systems

How and where is the expansion tank installed for heating

Product design

In rooms, heating networks can have open and closed circuits. The first type is used in centralized networks, due to which it is possible to directly take water for the needs of hot water... The devices are placed in the upper part of the circuit. Expansion tanks will not only allow you to control the process of pressure drops, but will also perform the function of separating air from the system. If it belongs to the closed type, then a design with a membrane inside is used.

The expansion tank of the membrane type has a relatively simple device. It includes a water reservoir and a rubber membrane that can be balloon or diaphragm.

If the membrane belongs to the first type, then the coolant is located inside the rubber cylinder, and outside there is nitrogen or air. If necessary, such a part can be replaced, which will save on repairs and not change the entire device.

The diaphragm diaphragm for the expansion tank is a non-removable partition based on a thin metal or elastic polymer.

It has a small capacity and compensates for small pressure drops. If it breaks down, it is impossible to replace it, so you will have to change the tank completely. But compared to a balloon membrane, it is cheaper.

Expansion tank. Operating principle, selection, pumping pressure

Principle of operation

For each system, the gas pressure is adjusted according to the instructions for the device. The type of membrane does not affect the efficiency of the device. But if it belongs to the balloon type, more heat-transfer fluid can be placed in the tank. The principle of operation of the diaphragm expansion tank of the heating system at constructions different kind is not different:

Constant pressure is automatically regulated. For the system to work stably, you need to choose the right tank and make calculations. The required pressure will not be able to form if the tank turns out to be larger than necessary, and if it is smaller, it may not hold the excess liquid. This can cause an accident.

Selection rules

In order for a product to work fully, it is necessary not only to correctly select it in terms of volume, but also to take into account its other characteristics. Invert Special attention follows the following nuances:

Now on the market you can see a large number of models of Russian and foreign production. They differ in cost, while the suspiciously low price should alert you. It may be due to the fact that low-quality materials of Chinese origin were used in the production. Domestic models are much better in quality, they are cheaper. foreign counterparts from famous brands, however, are not inferior to them in terms of characteristics.

As already mentioned, the main characteristic that you need to focus on when buying a tank is its volume. Some experts recommend choosing products whose size is within 10% of the total volume of the coolant in the heating system. The fact is that the coefficients of thermal expansion, even at high heating, cannot be higher than 0.08. Therefore, calculations should be carried out as accurately as possible, taking into account indicators such as:

• the maximum allowable pressure of the heating system;
• coolant volume;
• initial pressure in the tank;
• thermal expansion coefficient.

When selecting the volume, you must take into account all the nodes of the heating system. This can be found out by examining the project documentation. If it is absent, then the calculation is allowed to be performed approximately, being guided by the fact that 15 liters of water will fall on 1 kW. The thermal expansion coefficient of the coolant is determined using the composition of the liquid. In apartment buildings it often contains glycols to enhance its performance.

Also, the coefficient can be calculated from the temperature of the coolant. The ultimate pressure of the system is determined using the minimum value allowed for the components. The transition valve is adjusted to it. The initial pressure in the system, provided the coolant is cooled, corresponds to the minimum pressure. On some devices, it is regulated by inflating or bleeding air. The pressure in the tank is controlled by installing a pressure gauge.

The use of a membrane tank for heating has a number of limitations, depending on the manufacturer, design and material of manufacture. In some cases, the requirements for the composition of the coolant are very strict. In particular, this concerns the limitation of the amount of antifreeze and ethylene glycol in its composition.

In addition, expansion vessels cannot be used when the pressure limits are exceeded. Also, it is imperative that a security group be established that limits and controls it.

Installation requirements

It is not so difficult to install a membrane tank with your own hands; it is not necessary to involve a specialist for the work. Installation requirements are as follows:

If the container has a volume of 30 liters or more, it is prohibited to attach it to supporting structures... Most often it is equipped with special legs and is placed on the floor. When installing, it is recommended to observe such tips:

• the branch pipe must have a circumference of three quarters, respectively, a similar threaded channel must be present in the return;
• installation is carried out so that parts of the system or other objects do not interfere with work;
• it is recommended to use paronite gaskets that are resistant to high temperatures or pressure;
• in order to regulate or maintain the pressure in the gas compartment, the expander must be equipped with an air valve.

If the system is closed, then each time after it is turned on, there is a high pressure... Therefore, you should check its condition at least once every 2 years and, if necessary, replace it. In some cases, everything changes completely.

During installation, gross mistakes must not be made, otherwise the equipment will not function normally. The most common miscalculation is the incorrect indication of the maximum pressure in the gas compartment, which is about 90% of the critical one. If this is allowed, the membrane will not expand towards the compartment. As a result, the pipe will burst, because of which the heating batteries will not be able to work. To correct the error, you need to install a certified pressure gauge. You also need to make sure that there is no tank in the boiler itself. If, after calculations, it is established that its volume is small, then additional capacity will be required.

The expansion vessel in the heating system is very important. It depends on him how correctly it will work. It is not difficult to install it, but you need to pay special attention to this process, since even a small oversight can cause an emergency in the future.

Expansive membrane tank- an obligatory component, without which the functioning of the system is not possible. It is he who creates the necessary pressure for the full operation of the water supply system, makes reserve water supplies and even performs a number of protective functions. In connection with such a high importance of the equipment, the expected question arises: how to choose and correctly install a tank? To understand, let's approach the issue comprehensively: to your attention the structure and principles of operation of the expansion device, its types, selection features, as well as the connection diagram and useful instruction on commissioning with video.

Functions and working principle

The diaphragm tank is a sealed, predominantly metal tank, consisting of two separated chambers: air and water. A special rubber membrane acts as a separator - as a rule, it is made of strong butyl, which is resistant to the development of bacterial microorganisms. The water chamber is equipped with a pipe through which water is supplied directly.

The main task of the expansion membrane tank is to accumulate a certain volume of water and supply it at the user's request under necessary pressure... But the functions of the device are not limited to this - it also:

• protects the pump from premature deformation: thanks to the water reservoir, the pump does not turn on every time the tap is opened, but only when the tank is empty;
• protects against water pressure drops when several taps are used in parallel;
• protects against water hammer that can potentially occur when the pumping unit is turned on.

Operation of the device

The principle of operation of the tank is as follows. When the pump turns on, water chamber water begins to be pumped under pressure, and the volume of the air chamber decreases at this time. When the pressure reaches the maximum allowable mark, the pump turns off and the water supply stops. Then, as water is taken from the tank, the pressure decreases and when it decreases to the minimum allowable mark, the pump turns on again and resumes pumping water.

Advice. During the operation of the tank, air can accumulate in the water chamber, which provokes a decrease in the efficiency of the equipment, therefore, at least once every 3 months, the compartment must be serviced - to bleed excess air from it.

Types of membrane tanks

There are two types of diaphragm expansion tanks:

Advice. When choosing between removable and stationary diaphragms, consider one important factor: in the first case, the water is completely in the membrane and does not come into contact with inner surface tank, which excludes corrosion processes, and in the second case, the contact is maintained, therefore, it is impossible to achieve maximum protection against corrosion.

Features of the choice of the tank

The main factor in choosing a membrane tank is its volume. When calculating the optimal volume of the tank, the following nuances should be taken into account:

• number of users of the plumbing system;
• number of water intake points: taps, shower and jacuzzi outlets, outlets for household appliances and boilers that work with water;
• pump performance;
• maximum number of pump on / off cycles per hour.

To calculate the approximate volume of the tank, you can use the following guidelines from specialists: if the number of users is no more than three, and the pump capacity is no more than 2 cubic meters / h, then a tank with a volume of 20-24 liters is sufficient; if the number of users is from four to eight, and the pump performance fluctuates within 3-3.5 cubic meters / h, a tank with a volume of 50-55 liters will be required.

When choosing a tank, remember: the more modest its volume, the more often the pump will have to be turned on and the higher the risk of pressure drops in the water supply system.

Advice. If you expect that over time there will be a need to increase the volume of the membrane tank, buy equipment with the ability to connect additional tanks.

Tank connection diagram

The membrane tank can be installed both vertically and horizontally, but in both cases the connection diagram will be identical:

1. Determine the installation location. The device must be located on the suction side circulation pump and before the branching of the water supply. Make sure that the tank is easily accessible for service work.
2. Fasten the tank to a wall or floor with rubber grommets and ground it.
3. Connect the 5-way nipple to the tank nozzle using an American fitting.
4. Connect in series to the four free terminals: a pressure switch, a pipe from the pump, a pressure gauge and a distribution pipe that supplies water directly to the intake points.

Tank connection

It is important that the cross-section of the connected water supply pipe is equal or slightly larger in relation to the cross-section of the inlet pipe, but in no case should it be smaller. Another nuance: it is advisable not to place any technical devices, so as not to provoke an increase in hydraulic resistance in the water supply system.

Instructions for setting up equipment

After the membrane tank is installed and connected, it is important to correctly configure and start it. Let us dwell on the main points of this stage.

The first step is to find out the value of the internal pressure of the tank. In theory, it should be 1.5 atm, but it is possible that during storage of the device in a warehouse or during transportation, a leak occurred, which provoked a decrease in such important indicator... To make sure the pressure is correct, remove the spool cap and measure with a pressure gauge. The latter can be of three types: plastic - cheap, but not always accurate; mechanical automobile - more reliable and relatively affordable in price; electronic - expensive, but as accurate as possible.

After measurements, you need to decide what pressure will be most optimal in your case. Practice shows that for the normal functioning of plumbing and household appliances, the pressure in the membrane tank should vary within 1.4-2.8 atm. Suppose you selected these metrics - what to do next? First, if the initial pressure in the tank is below 1.4-1.5 atm, it must be increased by pumping air into the corresponding chamber of the tank. Then adjust the pressure switch: open its cover and set the maximum pressure value with the large nut P, ​​and the minimum value with the small ∆P nut.

The equipment setup process is simple

Now you can start the system: as water is pumped in, observe the pressure gauge - the pressure should gradually rise, and after it reaches the maximum set point, the pump should turn off.

As you can see, without an expansion membrane tank, you really can not even count on the full operation of an individual water supply. Therefore, if you want to uninterruptedly enjoy the benefits of civilization, thoroughly approach the selection and connection of the device - all the principles and subtleties are before you, so we advise you to study them well and only then proceed to active actions.

Calculating the volume of the accumulator: video

Diaphragm expansion tank for water supply: photo

The heating system, being a complex engineering structure, consists of many elements with different functional purpose... The expansion tank for heating is one of the most important parts of the heating circuit.

When the coolant is heated, the pressure in the boiler and the heating system circuit rises significantly due to the temperature increase in the volume of the heat-carrying liquid. Considering that the liquid is a practically incompressible medium, and the heating system is hermetically sealed, this physical phenomenon can lead to the destruction of the boiler or pipelines. The problem could be solved by installing a simple valve that can bleed off the excess volume of hot coolant into external environment, if not for one important factor.

During cooling, the liquid is compressed and air enters the heating circuit in place of the discharged heat carrier. Air congestion- a headache for any heating system, because of them, circulation in the network becomes impossible. Therefore it is necessary. The constant addition of a new coolant to the system is very costly, heating cold water costs much more than heating the heat-transfer fluid that came to the boiler through the return pipeline.

This problem is solved by installing a so-called expansion tank, which is a tank connected to the system by one pipe. Excessive pressure in the expansion tank of the heating is compensated by its volume and ensures stable operation of the circuit. Externally, expansion tanks for the heating system, based on the results of the calculation and the type of heating circuit, are different in shape and size. Tanks are currently being produced different forms, from classic cylindrical tanks to so-called "tablets".

Types of heating systems

There are two schemes of heating networks of the building -. An open (gravity) heating system is used in centralized heating networks and allows you to directly draw water for hot water supply, which is impossible in private housing construction. Such a device is located at the highest point of the heating system circuit. In addition to leveling pressure drops, the heating expansion tank performs the function of natural air separation from the system, since it has the ability to communicate with the outside atmosphere.

Thus, structurally, such a device is a pressureless expansion tank of the heating system. Sometimes, by mistake, a system with gravitational (natural) circulation of a heat-carrying fluid can be called open, which is fundamentally wrong.

With a more modern closed circuit, an expansion tank of the heating system is used closed type with built-in inner membrane.

Sometimes such a device can be called a vacuum expansion tank for heating, which is also true. Such a system provides forced circulation coolant, air from the circuit is discharged through special taps (valves) installed on heating devices and at the top of the system piping.

Device and principle of operation

The structurally closed expansion tank in the heating system is a cylindrical tank with a rubber membrane installed inside, which divides the internal volume of the vessel into air and liquid chambers.

Membranes are of the following types:

The gas pressure is adjusted for each system on an individual basis, which is described by the instruction attached to such devices as an expansion tank for closed-type heating. Some manufacturers in the design of their expansion tanks provide for the possibility of replacing the membrane. This approach somewhat increases the initial cost of the device, but later, if the membrane is destroyed or damaged, the cost of replacing it will be lower than the price of a new expansion tank.

From a practical point of view, the shape of the membrane does not in any way affect the efficiency of the devices, it should only be noted that a slightly larger volume of heat-carrying liquid can be accommodated in a closed-type balloon expansion tank for heating.

Their principle of operation is also the same - when the water pressure in the network increases due to expansion during heating, the membrane stretches, compressing the gas on the other side and allows excess coolant to enter the tank. When cooling down and, accordingly, a drop in pressure in the network, the process takes place in the reverse order. Thus, the regulation of constant pressure in the network is automatic.

It is necessary to focus on the fact that if you buy an expansion tank of the heating system at random, without the necessary calculation, then the stability of the heating network will be very difficult to achieve. If the tank size is much larger than necessary, the pressure required for the system will not be created. If the tank is smaller than the required size, then it will not be able to accommodate the excess volume of the heat-carrying fluid, which can result in an emergency.

Expansion tank calculation

To calculate the expansion tank for closed-type heating, you first need to calculate the total volume of the system, which consists of the volumes of the pipelines of the circuit, the heating boiler and heating devices. The volumes of the boiler and heating radiators are indicated in their passports, and the volume of pipelines is determined by multiplying the area of ​​the internal cross-section of the pipes by their length. If there are pipelines in the system different diameters, then you should determine their volumes separately, and then add.

Further, for such devices as an expansion tank for closed-type heating, the calculation is carried out according to the formula V = (Vc x k) / D, where:

Vс - the volume of the heat-carrying liquid in the heating system,
k - coeff. volumetric thermal expansion, taken for water 4%, for 10% ethylene glycol - 4.4%, for 20% ethylene glycol - 4.8%;
D is an indicator of the efficiency of the membrane unit. Usually it is indicated by the manufacturer or it can be determined by the formula: D = (Rm - Rn) / (Rm +1), where:

Рм - the maximum possible pressure in the heating network, usually it is equal to the maximum operating pressure safety valve(for private houses rarely exceeds 2.5 - 3 atm.)
Рн is the pressure of the initial pumping of the expansion tank air chamber, taken as 0.5 atm. for every 5 meters of height of the heating system circuit.

In any case, it should be considered that expansion tanks for heating should provide an increase in the volume of the coolant in the network within 10%, that is, with a volume of heating fluid in the system of 500 liters, the volume together with the tank should be 550 liters. Accordingly, a tank is required expansion system heating with a volume of at least 50 liters. This method of determining the volume is very approximate and can result in unnecessary costs for purchasing a larger expansion tank.

Currently on the Internet there are online calculators for calculating expansion tanks. In the case of using such services for the selection of equipment, it is necessary to carry out calculations on at least three sites in order to determine how correct the algorithm for calculating one or another Internet calculator is.

Manufacturers and prices

Currently, the problem to buy an expansion tank for heating is only correct selection the type and volume of the device, as well as in the financial capabilities of the buyer. Presented on the market wide choose models of devices of both domestic and foreign manufacturers. However, it should be noted that if for such devices as a closed-type expansion tank for heating the purchase price is much lower than that of the main competitors, then it is better to refuse such an acquisition.

The low cost indicates the unreliability of the manufacturer and the low quality of the materials used in its manufacture. Often these are products from China. As with all other goods, for a high-quality expansion tank for heating, the price will not have a significant difference of the order of two - three times... Conscientious manufacturers use approximately the same materials and the difference in price of models with similar parameters of the order of 10-15% is due only to the location of production and the price policy of sellers.

Domestic manufacturers have proven themselves well in this market segment. Having installed modern technological lines in their production, they achieved the release of products that are not inferior in their parameters to the best world brands at a lower cost.

It should be borne in mind that it is important not only to buy an expansion tank for closed-type heating, it also needs to be correctly installed.

Having the necessary skills and following the instructions, it is possible self-installation... If the master has any doubts about his knowledge, then it is best to turn to professionals for guaranteed stable operation of the heating network and exclude possible malfunctions.

Heating is a key life support system for a private house and its stable operation is very important. One of the parameters that needs to be monitored is pressure. If it is too low, the boiler will not work; if it is too low, the equipment will wear out too quickly. An expansion vessel for heating is required to stabilize the pressure in the system. The device is simple, but without it the heating will not work for a long time.

What is an expansion tank for heating for?

When the heating system is operating, the coolant often changes its temperature - it heats up, then it cools down. Understandably, the volume of the liquid changes. It increases and decreases. Excess coolant is just displaced into the expansion tank. So the purpose of this device is to compensate for changes in the volume of the coolant.

Types and device

There are two hot water heating systems - open and closed. V closed system the circulation of the coolant is provided by a circulation pump. It does not create additional pressure, it simply pushes water at a given speed through the pipes. In such a heating system, there is an expansion tank for closed-type heating. It is called closed because it is a sealed container, which is divided into two parts by an elastic membrane. In one part there is air, in the other excess coolant is displaced. Due to the presence of a membrane, the tank is also called a membrane one.

An open heating system does not provide for a circulation pump. In this case, an expansion tank for heating is just any container - even a bucket - to which the heating pipes are connected. It doesn't even need a cover, although it might be.

In the very simple version this is a metal-welded container that is installed in the attic. This option has a significant drawback. Since the tank is leaking, the coolant evaporates and it is necessary to monitor its amount - top up all the time. You can do this manually - from a bucket. This is not very convenient - there is a risk of forgetting to replenish water supplies. This threatens the system with airing, which can lead to its breakdown.

Automated control of the water level is more convenient. True, then in the attic, in addition to the heating pipes, you will also have to pull the water supply and also remove the overflow hose (pipe) somewhere in case the tank is overfilled. But there is no need to regularly check the amount of coolant.

Volume calculation

There is a very simple method for determining the volume of the expansion tank for heating: 10% of the volume of the coolant in the system is calculated. You had to calculate it when developing the project. If these data are not available, you can determine the volume empirically - drain the coolant, and then fill in a new one, while measuring it (put it through the meter). The second way is to calculate. Determine in the system, add the volume of radiators. This will be the volume of the heating system. Here we find 10% of this figure.

Formula

The second way to determine the volume of the expansion tank for heating is to calculate it using the formula. Here, too, the volume of the system will be required (indicated by the letter C), but other data will also be needed:

• maximum pressure Pmax at which the system can operate (usually the maximum boiler pressure is taken);
• initial pressure Pmin - from which the system begins to work (this is the pressure in the expansion tank, indicated in the passport);
• coefficient of expansion of the heat carrier E (for water 0.04 or 0.05, for antifreeze it is indicated on the label, but usually in the range of 0.1-0.13);

Having all these values, we calculate the exact volume of the expansion tank for the heating system using the formula:

The calculations are not very complicated, but is it worth messing around with them? If the system open type the answer is unequivocal - no. The cost of the container does not depend very much on the volume, plus everything you can do it yourself.

Expansion tanks for closed-type heating are worth counting. Their price depends on the volume. But, in this case, it is still better to take with a margin, since insufficient volume leads to rapid wear of the system or even to its failure.

If the boiler has an expansion tank, but its capacity is not enough for your system, put a second one. In total, they should give the required volume (the installation is no different).

What will the insufficient volume of the expansion tank lead to?

When heated, the coolant expands, its surplus ends up in the expansion tank for heating. If all the excess does not fit, it is vented through the emergency pressure relief valve. That is, the coolant goes down the drain.

Then, when the temperature drops, the volume of the coolant decreases. But since there is already less of it in the system than there was, the pressure in the system drops. If the lack of volume is insignificant, such a decrease may not be critical, but if it is too small, the boiler may not work. This equipment has a lower pressure limit at which it will operate. When the lower limit is reached, the equipment is blocked. If you are at home at this time, you can remedy the situation by adding a coolant. If you are not there, the system may unfreeze. By the way, working at the limit does not lead to anything good either - the equipment quickly breaks down. Therefore, it is better to play it safe a little and take a slightly larger volume.

Tank pressure

In some boilers (usually gas ones), the passport indicates what pressure must be set on the expander. If there is no such record, for normal operation of the system, the pressure in the tank should be 0.2-0.3 atm lower than the operating pressure.

The heating system of a low-rise private house usually operates at 1.5-1.8 atm. Accordingly, the tank should be 1.2-1.6 atm. The pressure is measured with a conventional manometer, which is connected to the nipple, which is located at the top of the tank. The nipple is hidden under a plastic cover, you unscrew it, you get access to the spool. Excess pressure can also be relieved through it. The principle of operation is the same as that of an automobile spool - bend the plate with something thin, releasing the air to the required values.

It is also possible to increase the pressure in the expansion vessel. This will require a car pump with a pressure gauge. Connect it to the nipple, pump it up to the required readings.

All the above procedures are carried out with the tank disconnected from the system. If it is already installed, you do not need to remove it. The pressure in the expansion vessel of the heating system can be checked on site. Just be careful! It is necessary to check and adjust the pressure in the expansion tank for heating when the system is not working and the coolant is drained from the boiler. For the accuracy of measurements and tank adjustment, it is important that the pressure on the boiler is zero. Therefore, we drain the water thoroughly. Then we connect the pump with a pressure gauge and adjust the parameters.

Where to put in the system

An expansion tank in a closed system is placed after the boiler before the pump, that is, so that it creates a flow in the opposite direction. This makes the system more reliable. So the exact place of installation depends on where you have the circulation pump.

It is connected to the system through a tee. You cut a tee into the pipe, direct the perpendicular outlet upward, the tank is screwed onto it. If the wall does not allow the container to be placed, you will have to make a knee, but the tank is turned up. You can now assume that the expansion vessel is installed.

But for the convenience of checking, it is advisable to put another tee after the tank, on the free outlet of which to install a shut-off valve. This makes it possible to check the membrane tank without draining the entire system - it cuts off the tank. Turn off the tap, bleed water from the boiler. Check the pressure on the disconnected branch (in the boiler). It should be zero. After that, you can carry out all the rest of the configuration work.