Temporary expansion tank in the heating system. Expansion tank for the heating system: installation of the expansion tank according to the instructions

A properly selected and connected expansion tank for closed-type heating plays an important role. It will protect the heating circuit and extend the operating life of the equipment. A closed, sealed container will eliminate the need to endlessly repair the system and change devices. It's worth getting to know her. Is it true?

We will tell you how to choose a closed expansion tank model in accordance with the technical data of the system. We'll show you how to install and connect it correctly. In addition, the article provides recommendations that must be followed to extend the life of the equipment.

All of them, regardless of volume and performance, are designed to level out the expansion (special liquids, water) that occurs when its temperature increases.

This is done in order to avoid destructive damage to fittings, fittings, rupture of pipes, and extrusion of gaskets.

Any closed tank is a sealed steel tank, divided into parts by an elastic membrane, which changes its position as the temperature of the coolant increases/decreases

Example: the coolant (water) expands by four percent as the temperature rises to 95 °C. Which is quite enough for the engineering system to fail.

Expanzomat design and components

Any such modern product consists of the following structural elements:

housings;
coolant chambers;
a gas chamber into which ordinary air or inert gas is pumped;
membranes.

The option of filling the gas chamber with inert gas is more preferable, because it provides the container with greater durability. But regular air is more accessible.

The membrane is made of elastic materials, therefore it is able to change its position as the temperature of the coolant increases or decreases. This structural element can be of the diaphragm or balloon type, and their operating principle is similar.

The tanks are connected to the heating system using a special pipe. A valve is provided for pumping gas. Closed-type containers are manufactured in a horizontal or vertical layout, which makes it easier to complete the heating system.

The reason is that when the pressure rises to critical standards, the device will start working and bleed it. That is, this valve can significantly increase the safety of the entire heating system.

When purchasing a container, you should take into account that red paint is most often used to mark expansion tanks used for heating.

This feature will help to distinguish the desired product from other similar ones, for example, water supply tanks of similar size and shape - which are predominantly covered with blue enamel.

But if necessary, you can find tanks of various colors, which will help you place the one you need in any room without compromising its aesthetic qualities.

Containers can be horizontal or vertical, and manufacturers also provide the opportunity to mount them in different places. For this product, they are equipped with various accessories. And when purchasing, you should pay attention to this, determining the best option in advance.

When choosing, you should also pay attention to the quality of the materials used in the production of the container body and membrane. And the presence of a guarantee for the purchased equipment and instructions for installing and connecting it to the system.

How to install?

There are no significant restrictions affecting the place in the system. Nevertheless, it is advisable to carry out the installation at any convenient point in the return line of the existing heating system.

The reason is that the coolant there is cooler. And this allows you to significantly extend the life of the expansion tank and its membrane.

In addition, if you install the tank near a solid fuel boiler, then in certain situations steam may enter the coolant chamber. As a result, the container will lose the ability to compensate for the expansion of the coolant.

Installation of the tank can be done in two ways. These include installation:

on the wall;
on the floor.

But it should be understood that the first option is intended only for cases where the expansion tank has a moderate volume.

Tanks should be installed as far as possible from boilers. And the optimal solution would be to locate it in the return line. Since the coolant temperature there is noticeably lower, which eliminates premature failure of the membrane

You should not skimp on connecting the tank to the heating system.

So this procedure should be performed using:

a shut-off valve with a so-called “American” - this design element will allow you to quickly remove the tank from service and, if necessary, replace it, without waiting for the coolant to cool down;
a tee with a drain tap, which will allow you to quickly empty it before replacing the tank;
pressure gauge for measuring pressure;
safety valve or nipple to regulate the pressure inside the equipment.

After installing the tank, it must be configured correctly, taking into account the manufacturer’s recommendations given in the instructions for the purchased equipment. So that the pressure in the tank is appropriate, i.e. less than in the system, which will allow the membrane to deform when the coolant heats up.

If the calculations were carried out incorrectly and the heating system contains a tank of a smaller volume than required, then it will not cope with its duties, but the error can be corrected.

Why do you need to purchase and install a second container in the system? The capacity of which is the difference between the required volume and that available in the tank operating in the system. This method will reduce financial losses.

Operational Maintenance

It must be remembered that during breaks in use, the tanks, like other components of the heating system, should be emptied and then dried. This point should not be ignored, as failure to comply will lead to corrosion and reduced service life.

The main structural element that responds to changes in pressure from the coolant is an elastic membrane. Which is affected by a neutral gas (for example, nitrogen) or air on one side, and pressure from the coolant on the other. And the membrane takes position depending on which side has the stronger impact

When using any closed tank, owners should regularly perform a number of simple operations.

Which include:

periodic inspections to detect corrosion and mechanical damage - this procedure should be carried out twice a year;
checking the pressure in the system, which is performed every six months;
periodic inspections of the integrity of the membrane - such operations are carried out according to the manufacturer’s recommendations.

And in addition, throughout the entire operation, users will have to comply with the requirements regarding permissible temperature and pressure standards.

To repair tanks, you should use only original components, as this will ensure not only the required performance, but also safety of use.

You can read about the rules and features of selecting an expansion tank for open-type heating systems, which owners of houses with open heating circuits should read.

Conclusions and useful video on the topic

The first video will help you understand the features of modern expansion tanks and their correct choice:

The following video will give you an opportunity to understand how to properly install a purchased expansion tank:

The closed cistern is a practical, durable, efficient and safe solution for the heating system. But in order to get the expected result, it is necessary to make the correct selection and installation of the product in the heating system and its configuration.

Please write comments in the block below, share useful information and photos on the topic of the article. Tell us about how you selected a closed tank for the heating system in a country house. Discover your technological secrets that will be useful to site visitors.

To extend the service life of heating equipment and compensate for the thermal expansion of the coolant, an expansion tank is installed in the heating system. We will consider which expansion tank for heating to choose in this article.

Features and functions of an expansion tank for heating

With an increase in temperature in the heating system by 15 degrees, due to thermal expansion, the volume of coolant increases by half a percent. The expansion tank compensates for this expansion; excess coolant enters the tank capacity. When the coolant cools, the expansion tank mechanism pushes the missing liquid back into the system.

If a small water leak occurs, so that there is no decrease in the pressure level in the system, the expansion tank pushes out the coolant, thereby compensating for the losses.

If there is no expansion tank in a closed heating system, expansion of the coolant leads to increased pressure, rapid wear of heating system components, or breakage and rupture of pipes and taps.

Scope of use of the expansion tank for heating:

heating system powered by heat pumps and solar collectors;
autonomous heating system;
independent heating system, which is connected to the central heating system;
closed loop system.

Advantages of installing an expansion tank for heating:

no water pollution;
low cost;
ensuring safety and reliability;
no heat loss;
minimum amount of air in the system;

pressure regulation;
the use of an expansion tank does not depend on the type and quality of the coolant;
increasing the service life of radiators, pipes, taps and boilers.

Types of expansion tanks for heating

Photo expansion tank for heating:

Depending on the principle of operation, there are:

expansion tanks for open heating;
closed heating expansion tanks.

Open type expansion tanks are less popular. Such devices are installed in systems where water circulation occurs spontaneously without the use of a pump. The open expansion tank for heating contains a lid that can be easily opened when adding water is necessary. The disadvantage of an expansion tank for open-type heating is the connection of the coolant with oxygen, which leads to the formation of corrosion in the heating system. If there is no tightness in the open heating tank, water evaporates from the system faster and must be constantly refilled. The installation of an open expansion tank should be carried out at the highest point of the heating system, and this procedure is not always available.

A closed or membrane expansion tank of a heating system is installed in a system where the movement of coolant is provided by a pump. A closed-type expansion tank is made in the form of a steel tank without a lid, which has an internal partition in the form of a rubber membrane. One half is used to fill the coolant, and the second contains air or nitrogen. The expansion tank is coated with powder paint to avoid mechanical damage to the walls of the vessel at high coolant temperatures. On one side, the membrane expansion tank is attached to the heating system using a fitting or flange, and the other side is used for pumping air. The pressure in the heating expansion tank allows you to automatically regulate the flow of coolant into the system or back into the vessel.

Closed expansion tanks are divided into:

replaceable,
non-replaceable.

Replaceable expansion tanks are more expensive, but have a number of advantages:

the ability to replace the membrane if damaged or ruptured;
savings on pipes, since there is no need to install a closed expansion tank at the top point of the heating system;
ensuring minimal heat loss;
since the coolant does not come into contact with the oxygen of the pipe and the entire system is protected from rust formation;
vertical or horizontal arrangement of the membrane;
exclusion of connection with the metal inner wall of the tank;
easy replacement of the membrane is carried out through the flange of the expansion tank.

Non-replaceable expansion tanks although have a lower cost and do not allow membrane replacement. The membrane in a non-replaceable expansion tank is located tightly and is rigidly pressed against the inner surface of the tank wall. Damage to the membrane occurs only if the heating system is not started correctly, when the pressure rises quickly and exceeds the maximum permissible norm.

Depending on the type of membrane, expansion tanks are distinguished with:

balloon membrane,
diaphragm membrane.

An expansion tank with a balloon membrane is more reliable and has a larger volume. The coolant does not come into contact with the walls of the tank, which prevents the formation of corrosion.

The flat expansion tank for heating is equipped with a dividing partition in the form of a diaphragm, which cannot be replaced if damaged.

Selection of expansion tank for heating

The size of the expansion tank capacity for heating depends on the following factors:

type and capacity of the entire heating system;
limit value of the operating temperature of the coolant;
maximum pressure;
the height at which the expansion tank is installed.

To determine the approximate volume of the expansion tank, you need to find out the total volume of the entire heating system: pipeline, heating appliances and heating boiler. 10% should be calculated from this volume. For example, if the total volume of the heating system is 600 liters, then you should choose an expansion tank with a capacity of 60 liters.

3% of the volume of the expansion tank for heating accounts for the reserve supply of coolant to compensate for possible leaks.

An accurate calculation of the expansion tank for heating is made with the help of specialists or special online calculators.

Tips for choosing the right expansion tank:

1. After carrying out the calculations, care should be taken to ensure that pressure surges in the heating system do not exceed the maximum units specified in the technical data sheet of the device.

2. It is better to increase the calculation, which will determine the volume of the expansion tank, by a couple of units. A larger expansion tank will not bring any negative consequences, but a smaller expansion tank can negatively affect the operation of the system.

3. Before installing the expansion tank, find out the parameters of the device to avoid problems with transporting the tank indoors.

4. If glycol mixtures are used as the coolant, the preliminary calculation of the expansion tank should be increased by half.

5. If the safety valve frequently operates, the installation and selection of the expansion tank was carried out incorrectly.

1. It is better to give preference to a membrane or closed expansion tank. Although such a tank is more expensive, a heating system in which a closed expansion tank is installed will last longer due to the lack of contact between the coolant and oxygen.

2. Pay attention to the material of the rubber partition of the closed expansion tank. Manufacturers use rubber made from natural butyl rubber or EPDM for these purposes.

3. If the expansion tank will be used in conjunction with a central heating system, the rubber for the membrane must be durable and resistant to high temperatures. Since central heating does not involve large pressure surges, the temperature of the coolant can be quite high.

4. A tank with high membrane elasticity is suitable for a private heating system, since high pressure drops are characteristic of this type of heating system.

5. To use the expansion tank not only in the heating system, but also in the water supply system, the rubber for the membrane must be food-grade so as not to reduce the quality characteristics of the water.

6. When choosing between a replaceable and non-replaceable membrane, it is better to give preference to the first option. Since if the non-replaceable membrane is damaged, the expansion tank must be changed completely.

7. Before purchasing an expansion tank, study the technical characteristics of the device and request quality certificates for the purchased products.

8. Be sure to issue a warranty card.

9. The main conditions for the correct choice of an expansion tank are resistance to diffusion, temperature and pressure changes, durability, compliance with sanitary and hygienic standards, and the use of high-quality materials in manufacturing.

Manufacturers of expansion tanks for heating

1. Expansion tank for heating Wester (UK)

Peculiarities:

made of high quality steel;
do an excellent job of compensating for coolant expansion;
the membrane is made of EPDM;
availability of a quality certificate;
tanks are equipped with replaceable membranes;
lack of contact of water with air;
Wester expansion tanks are available in volumes from 8 to 2000 liters.

Expansion tank for heating system price: from $18 for an expansion tank with a volume of 8 liters, to $3600 for an expansion tank with a volume of 2000 liters.

2. Expansion tank Zilmet (Italy)

Peculiarities:

designed for installation in an individual heating system;
carbon steel is the basis for the metal body of the Zilmet expansion tank;
the presence of a pneumatic valve inside the expansion tank;
the minimum tank volume is 4 l, and the maximum is 1000 l;
color scheme: red;
operating temperature from 0 to +98 °C;
the company produces expansion tanks for heating systems and water supply systems;
expansion tanks for heating are produced in two series: Cal PRO - expansion tanks for the heating system, OEM PRO - flat expansion tanks for boilers;
price: from 30 to 2600 $.

3. Expansion tank for heating system Reflex (Germany)

Peculiarities:

high level of hydraulic stability;
lack of air in the heating system;
protection against pressure drops;
variety of expansion tanks.

Types of Reflex expansion tanks:

series N, NG - represents expansion tanks with irreplaceable membranes and polymer coating. The maximum operating temperature is 70 °C. Tank volume varies from 8 to 1000 l;
The S series represents white and red expansion tanks for use in heating and water supply systems. Limit temperature 70 °C. Minimum volume 8 l, maximum - 600 l;
the G series represents expansion tanks only in red, which have a replaceable membrane and a pneumomanometer.

Price: from 20 to 4000 $.

4. Expansion tank for heating Cimm (Italy)

Peculiarities:

expansion tanks of a non-replaceable type are produced for the heating system;
for the manufacture of membranes of expansion tanks intended for installation in the water supply system;
The minimum volume of expansion tanks is 6 l, and the maximum is 1000 l.

Varieties:

The CP series represents flat expansion tanks with a volume of 6 to 18 l, maximum operating temperature +90 °C;
The ERE series represents membrane cylinder expansion tanks that can withstand temperatures of +100 °C.

5. Expansion tanks Gilex (Russia)

Peculiarities:

purpose: removal of additional coolant volume;
varieties: expansion tanks of open and closed type;
volume from 6 to 300 l;
models with a volume of more than 12 liters can withstand a pressure of 6 atmospheres.

6. Flexcon expansion tank (Netherlands)

Peculiarities:

variety of expansion tanks, according to the type of pressure in the system: expansion tanks for high, medium and low pressure;
a reliable membrane that covers the walls of the tank;
a special clamping ring is capable of maintaining pressure, preventing the water level from decreasing;
minimal air entry into the system;
no water evaporation;
use in heating systems with ethylene glycol mixtures;
application: closed heating systems, air conditioning systems;
operating temperature from -10 to 120 °C;
volume from 6 to 12000 l.

Varieties:

Series C models are designed for heating systems with low pressure up to 3 bar, the maximum temperature for normal operation of the device is +70 °C;
CE series is designed for heating systems with medium pressure levels, maximum pressure 6 bar;
the CE series for high pressure represents expansion tanks that can withstand pressures up to 10 bar;
PRO, M series are represented by collapsible expansion tanks for heating in vertical or horizontal design, with a maximum filling volume of 62% and an operating temperature of 70 °C.

When planning to create a water heating system in your own home, the owner is faced with a choice of several options. The list of the most important questions includes the type of system (will it be open or closed), and what principle will be used to transfer coolant through pipes (natural circulation due to gravitational forces, or forced, requiring the installation of a special pump).

Each of the schemes has its own advantages and disadvantages. But still, nowadays preference is increasingly given to a closed system with forced circulation. This scheme is more compact, easier and faster to install, and has a number of other operational advantages. One of the main distinctive features is a completely sealed expansion tank for closed-type heating, the installation of which will be discussed in this publication.

But before purchasing an expansion tank and proceeding with its installation, you need to at least become familiar with its structure, operating principle, as well as which model will be optimal for a particular heating system.

IN What are the advantages of a closed heating system

Although Recently, many modern devices and systems for space heating have appeared; the principle of heat transfer through a liquid with high heat capacity circulating through pipes undoubtedly remains the most widespread. Water is most often used as a carrier of thermal energy, although in some circumstances it is necessary to use other liquids with a low freezing point (antifreeze).

The coolant receives heat from the boiler (ovens with water circuit) and transfers heat to heating devices (radiators, convectors, “warm floor” circuits) installed in the premises in the required quantity.

How to decide on the type and number of heating radiators?

Even the most powerful boiler will not be able to create a comfortable atmosphere in the premises if the parameters of the heat exchange points do not correspond to the conditions of a particular room. How to do it right - in a special publication on our portal.

But any liquid has general physical properties. Firstly, when heated, it increases significantly in volume. And secondly, unlike gases, this is an incompressible substance; its thermal expansion must be compensated in some way by providing free volume for this. And at the same time, it is necessary to ensure that as it cools and decreases in volume, air does not enter the pipe contours from the outside, which will create a “plug” that prevents the normal circulation of the coolant.

These are the functions that the expansion tank performs.

Not yet in private construction, there was no particular alternative - an open expansion tank was installed at the highest point of the system, which completely coped with the tasks.

1 – heating boiler;

2 – supply riser;

3 – open expansion tank;

4 – heating radiator;

5 – optional – circulation pump. In this case, a pumping unit with a bypass loop and a valve system is shown. If desired or if the need arises, you can switch forced circulation to natural circulation, and vice versa.

You may be interested in information on how to properly carry out

Prices for circulation pumps

circulation pumps

A closed system is completely isolated from the atmosphere. A certain pressure is maintained in it, and the thermal expansion of the liquid is compensated by installing a sealed tank of a special design.

The tank in the diagram is shown pos. 6, embedded in the return pipe (item 7).

It would seem - why “fence the garden”? A regular open expansion tank, if it fully copes with its functions, seems to be a simpler and less expensive solution. It probably doesn’t cost much, and besides, with certain skills, it’s easy to make it yourself - weld it from steel sheets, use an unnecessary metal container, for example, an old can, etc. Moreover, you can meet examples applications old plastic cans.

Does it make sense to spend money on purchasing a sealed expansion tank? It turns out that there is, since a closed heating system has many advantages:

Complete tightness absolutely eliminates the process of evaporation of the coolant. This opens up the possibility of using, in addition to water, special antifreezes. The measure is more than necessary if the country house in the winter is not used constantly, but “intermittently”, occasionally.
In an open heating system, the expansion tank, as already mentioned, must be mounted at the highest point. Very often, an unheated attic becomes such a place. And this entails additional efforts to thermally insulate the container so that even in the most severe frosts the coolant in it does not freeze.

And in a closed system, the expansion tank can be installed in almost any area. The most appropriate installation location is the return pipe directly in front of the boiler entrance - here the tank parts will be less exposed to temperature effects from the heated coolant. But this is by no means a dogma, and it can be mounted in such a way that it does not create interference and does not disharmonize its appearance with the interior of the room, if, say, the system uses a wall-mounted boiler installed in the hallway or in the kitchen.

In an open expansion tank, the coolant is always in contact with the atmosphere. This leads to constant saturation of the liquid with dissolved air, which causes increased corrosion in the circuit pipes and radiators, and increased gas formation during the heating process. Aluminum radiators are especially intolerant of this.
A closed heating system with forced circulation is less inert - it warms up much faster when starting up, and is much more sensitive to adjustments. Completely unjustified losses in the area of the open expansion tank are eliminated.
The temperature difference in the supply and return pipes in the connection currents with the boiler is less than in an open system. This is important for the safety and longevity of heating equipment.
A closed scheme with forced circulation to create circuits will require pipes of smaller diameter - there is a benefit both in the cost of materials and in simplifying installation work.
An open-type expansion tank requires control to prevent overflow when filling, and to prevent the liquid level in it from falling below a critical level during operation. Of course, all this can be solved by installing additional devices, for example, float valves, overflow pipes, etc., but these are unnecessary complications. In a closed heating system, such problems do not arise.
And finally, such a system is the most universal, as it is suitable for any type of battery and allows you to connect underfloor heating circuits, convectors, and heat curtains. In addition, if desired, you can organize hot heat supply by installing an indirect heating boiler into the system.

Of the serious shortcomings, only one can be mentioned. This — mandatory “safety group”, including control and measuring instruments (pressure gauge, thermometer), safety valve and automatic air vent. However, this is more likely no no wealth, but a technological cost that ensures the safe operation of the heating system.

In a word, the advantages of a closed system clearly outweigh, and spending on a special sealed expansion tank looks completely justified.

How does an expansion tank for closed heating work and how does it work?

The design of an expansion tank for a closed type system is not very complicated:

Usually the entire structure is housed in a stamped steel body (item 1) of a cylindrical shape (there are tanks in the shape of a “tablet”). For production, high-quality metal with an anti-corrosion coating is used. The outside of the tank is covered with enamel. Products with a red body are used for heating. (There are blue tanks - but these are water batteries for the water supply system. They are not designed for elevated temperatures, and all their parts are subject to increased sanitary and hygienic requirements).

On one side of the tank there is a threaded pipe (item 2) for insertion into the heating system. Sometimes fittings are included in the package to facilitate installation work.

On the opposite side there is a nipple valve (item 3), which serves to pre-create the required pressure in the air chamber.

Inside, the entire cavity of the tank is divided by a membrane (item 6) into two chambers. On the side of the pipe there is a chamber for coolant (item 4), on the opposite side there is an air chamber (item 5)

The membrane is made of elastic material with a low diffusion rate. It is given a special shape, which ensures “orderly” deformation when the pressure in the chambers changes.

The principle of operation is simple.

In the initial position, when the tank is connected to the system and filled with coolant, a certain volume of liquid enters the water chamber through the pipe. The pressure in the chambers is equalized, and this closed system acquires a static position.
As the temperature rises, the volume of coolant in the heating system expands, accompanied by an increase in pressure. Excess fluid enters the expansion tank (red arrow), and its pressure bends the membrane (yellow arrow). In this case, the volume of the coolant chamber increases, and the air chamber correspondingly decreases, and the air pressure in it increases.
As the temperature decreases and the total volume of the coolant decreases, excess pressure in the air chamber causes the membrane to move backward (green arrow), and the coolant moves back into the pipes of the heating system (blue arrow).

If the pressure in the heating system reaches a critical threshold, then the valve in the “safety group” should operate, which will release excess liquid. Some expansion tank models have their own safety valve.

Different tank models may have their own design features. So, they can be non-separable or with the ability to replace the membrane (a special flange is provided for this). The kit may include brackets or clamps for mounting the tank on the wall, or it can be provided with stands - legs for placing it on the floor.

In addition, they may differ in the design of the membrane itself.

On the left is an expansion tank with a membrane diaphragm (it has already been discussed above). As a rule, these are non-separable models. A balloon-type membrane (picture on the right), made of elastic material, is often used. In fact, it itself is a water chamber. As pressure increases, such a membrane stretches, increasing in volume. It is these tanks that are equipped with a collapsible flange, which allows you to independently replace the membrane in the event of its failure. But the basic principle This doesn't change the work at all.

Video: installation of Flexcon brand expansion tanks FLAMCO»

Prices for Flexcon expansion tanks FLAMCO

Flexcon expansion tanks

How to calculate the required parameters of the expansion tank?

When choosing an expansion tank for a specific heating system, the fundamental point should be its working volume.

Calculation using formulas

You can find recommendations to install a tank, the volume of which is approximately 10% of the total volume of coolant circulating through the system circuits. However, a more accurate calculation can be made - there is a special formula for this:

Vb =Vwith ×k / D

The symbols in the formula indicate:

Vb– required working volume of the expansion tank;

Vс– the total volume of coolant in the heating system;

k– coefficient taking into account the volumetric expansion of the coolant during heating;

D– efficiency coefficient of the expansion tank.

Where to get the initial values? Let's look at it in order:

Total system volume ( VWith) can be determined in several ways:

You can use a water meter to determine how much total volume will fit when filling the system with water.
The most accurate method used when calculating a heating system is the summation of the total volume of pipes of all circuits, the capacity of the heat exchanger of the existing boiler (it is indicated in the passport data), and the volume of all heat exchange devices in the premises - radiators, convectors, etc.
The simplest method gives a completely acceptable error. It is based on the fact that to provide 1 kW of heating power, 15 liters of coolant are required. Thus, the rated power of the boiler is simply multiplied by 15.

2. The value of the coefficient of thermal expansion ( k) is a tabular value. It varies nonlinearly depending on the heating temperature of the liquid and the percentage of antifreeze in it ethylene glycol additives The values are shown in the table below. The heating value line is taken from the calculation of the planned operating temperature of the heating system. For water, the percentage value of ethylene glycol is taken as 0. For antifreeze - based on the specific concentration.

Coolant heating temperature, °C	Glycol content, % of total volume
	0	10	20	30	40	50	70	90
0	0.00013	0.0032	0.0064	0.0096	0.0128	0.016	0.0224	0.0288
10	0.00027	0.0034	0.0066	0.0098	0.013	0.0162	0.0226	0.029
20	0.00177	0.0048	0.008	0.0112	0.0144	0.0176	0.024	0.0304
30	0.00435	0.0074	0.0106	0.0138	0.017	0.0202	0.0266	0.033
40	0.0078	0.0109	0.0141	0.0173	0.0205	0.0237	0.0301	0.0365
50	0.0121	0.0151	0.0183	0.0215	0.0247	0.0279	0.0343	0.0407
60	0.0171	0.0201	0.0232	0.0263	0.0294	0.0325	0.0387	0.0449
70	0.0227	0.0258	0.0288	0.0318	0.0348	0.0378	0.0438	0.0498
80	0.029	0.032	0.0349	0.0378	0.0407	0.0436	0.0494	0.0552
90	0.0359	0.0389	0.0417	0.0445	0.0473	0.0501	0.0557	0.0613
100	0.0434	0.0465	0.0491	0.0517	0.0543	0.0569	0.0621	0.0729

3. Expansion tank efficiency coefficient value ( D) will have to be calculated using a separate formula:

D = (Qm – Qb)/(Qm + 1 )

Qm— maximum permissible pressure in the heating system. It will be determined by the response threshold of the safety valve in the “safety group”, which must be indicated in the product passport.

Qb— pre-pumping pressure of the air chamber of the expansion tank. It may also be indicated on the packaging and in the product documentation. It is possible to change it - pumping it up using a car pump or, conversely, bleeding it through a nipple. It is usually recommended to set this pressure within 1.0 – 1.5 atmospheres.

Calculator for calculating the required volume of the expansion tank

To simplify the calculation procedure for the reader, the article contains a special calculator in which the indicated dependencies are included. Enter the requested values, and after pressing the “CALCULATE” button you will receive the required volume of the expansion tank.

Diaphragm expansion tank for a closed heating system

The membrane expansion tank is designed to compensate for the thermal expansion of the coolant and maintain the required pressure in closed heating systems.

Liquids that are used in heating systems increase their volume when heated due to thermal expansion. For example, the volume of water when heated to 90 o C increases by 3.55%. If ethylene glycol-based antifreeze is used as a coolant in the heating system, the volume of the liquid increases even more.

Diaphragm expansion tank for heating. Device and operation scheme. Through the air valve (nipple), the air chamber is filled with compressed air using a car pump.

In a closed heating system without an expansion tank, even a slight increase in temperature will lead to a sharp increase in pressure and activation of the safety valve. Excessive coolant will flow out through the valve.

A membrane expansion tank for heating is a vessel divided into two parts by a movable membrane. One part of the vessel is connected to the heating system and filled with coolant. Air is pumped into another part of the vessel at a certain pressure.

When the volume of liquid in the heating system changes, the membrane in the tank moves in one direction or another. As a result, the volume occupied by the liquid in the tank also changes. The compressed air on the other side of the membrane acts as a spring, maintaining the operating pressure of the coolant and preventing the safety valve from operating.

Operating limitations and safety requirements

Depending on the design of the expansion tank and the materials used, manufacturers impose certain restrictions on their use in heating systems.

As a rule, manufacturers impose certain requirements on the composition and corrosive properties of the coolant fluid in the heating system. For example, they limit the content of ethylene glycol in an antifreeze solution.

It is prohibited to use the expansion tank at pressures exceeding the permissible values specified in the manufacturer’s technical documentation. At the point where the expansion tank is connected to the heating system, it is necessary to install a safety group that monitors and limits the pressure in the tank.

In heating systems of private houses and autonomous heating of apartments, tanks and other heating equipment with an operating pressure of at least 3 are used. bar.

The expansion tank for heating is not allowed to be used in drinking water supply systems.

Installation, installation and connection of the expansion tank

The expansion tank is connected to the return pipeline of the heating system on the suction side of the circulation pump. 1 - membrane expansion tank; 2 - connecting shut-off valves and drain valve; 3 - circulation pump; 4 — make-up valve

The expansion tank is installed in a heated room. The tank is placed in a place that is easily accessible for maintenance. Installation is carried out in such a way that there is access to the air nipple, flange and connecting fittings.

Small expansion tanks are usually attached to the wall using a bracket. Fastening parts, as a rule, are not included in the product package and must be ordered separately. Large tanks are installed on the floor, on legs.

The expansion tank is connected to the return pipeline of the heating system on the suction side of the circulation pump.

The connecting fittings for the expansion tank allow you to disconnect the tank from the system, drain water from the tank, and seal the shut-off valve.

At the connection point, on the line to the tank, it is necessary to install shut-off valves that are protected from accidental closure. In addition, a drain valve should be installed to empty the tank. Manufacturers of tanks usually offer special connecting shut-off and drainage fittings for their products. These kits must be ordered separately.

To connect the tank to the return pipeline, pipes with an internal diameter equal to the diameter of the tank connecting pipe should be used.

The expansion tank is connected to the heating system after flushing the system.

The built-in membrane expansion tank is located on the rear wall of the double-circuit gas boiler

Membrane expansion tanks are sometimes built into boilers. For example, double-circuit gas boilers, as a rule, already have a built-in expansion tank of a certain capacity. If the volume of the built-in expansion tank turns out to be small for the heating system, then it is necessary to install a new tank outside in front of the boiler on the return pipeline. The volume of the new tank is selected as usual, without taking into account the capacity of the built-in tank.

Setting the pressure in the expansion tank

Before commissioning the heating system, before filling the tank with coolant, air is pumped into the expansion tank through the air valve - nipple using a car pump. The amount of air pressure is controlled by a car pressure gauge built into the pump or a separate device. Many manufacturers sell expansion tanks already filled with air or nitrogen to a certain pressure specified in the technical documentation. In any case, it is necessary to check that the initial air pressure in the tank is sufficient.

Initial pressure in the air chamber expansion tank - R o :

P o > P st + 0.2 bar ,

Where R st— the static pressure of the heating system at the location where the tank is installed is equal to the height of the water column from the expansion tank connection point to the top point of the heating system (column height 10 m = 1bar)

The initial pressure in the air chamber must be checked and adjusted when there is no liquid in the tank— open the connecting fitting and pour out the remaining coolant from the tank. The expansion tanks built into the boiler are also emptied of liquid.

In the heating system of a private house, it is convenient to install an expansion tank with the air chamber factory-filled with air or nitrogen pressure P o = 0.75 - 1.5 bar . This pressure value set at the factory can be left unchanged, even if it is significantly greater than calculated using the formula R o. In most cases, this pressure is quite sufficient for the heating systems of a private house or apartment.

The expansion tanks built into the boiler are usually already filled with air or nitrogen to the pressure specified in the boiler instructions. Before installing the boiler, it is necessary to check the air pressure in the expansion tank and, if necessary, adjust it - pump in or bleed air.

The initial pressure exceeds the static pressure by at least 0.2 bar. necessary to create pressure in the system, which reduces the risk of vacuum formation, vaporization and cavitation.

At the next stage the tank is connected to the heating system. Then the make-up valve opens and the heating system and tank are filled with coolant with the initial make-up pressure - R start.:

P start > or = P o + 0.3 bar

(for example, if P o = 1 bar, then P start >= 1.3 bar)

R o— initial pressure in the air chamber of the expansion tank.

Often, manufacturers of boilers, for example gas boilers, indicate in the technical documentation the recommended initial pressure for recharging the coolant in the system. The instructions also indicate the minimum coolant pressure, below which the boiler simply will not start working. In this case, fill the system with the initial pressure specified in the instructions for the boiler.

Further, turn on the boiler and heat the heating system to the maximum operating temperature (for example, 75 o C). When water is heated, air dissolved in it is released. We remove air from the heating system. We monitor the pressure gauge readings and record the pressure value in the system with expanded water - R ext.

In custody turn off the circulation pump and turn on the make-up again and bring the pressure in the system at the maximum temperature of the coolant to the final one - R con:

R con< или = Р кл — 0,5 bar ,

Where R cl— opening pressure of the safety valve of the heating system.

(for example, if R cl = 3 bar, then we bring the pressure in the system to P con<= 2,5 bar at coolant temperature 75 o C)

The method described above for adjusting the pressure of the expansion tank allows you to increase the effective usable volume of the expansion tank to the maximum. The tank will be able to absorb the largest amount of water, and then return it to the system. This can be useful in the case of, for example, small leaks in the system. The tank will be able to release water into the system for a long time - the pressure in the system will decrease at a slower rate. The heating system will remain operational for a longer time. Or, as a result of cooling of the coolant, the pressure in the system may drop below the minimum required to turn on the boiler. In this case, the automation will not be able to start the heating. When adjusting the pressure according to the above method, the risk of such a development is reduced to a minimum.

These advantages of the pressure adjustment method described here are especially relevant for heating systems in country houses, where owners do not visit every day.

Checking membrane integrity

Operate the air valve (nipple) briefly. If water is leaking from the valve, the tank must be replaced, or, in tanks with a replaceable membrane, the membrane must be replaced.

If it is necessary to remove gas from the air chamber of the expansion tank, be sure to empty its water chamber first, and not vice versa!

Before refilling the tank with water, set the required pre-pressure in the air chamber. If these instructions are not followed, there is a risk of diaphragm rupture.

Calculation of the volume of the expansion tank for heating

The volume of the expansion tank is selected in such a way that when the coolant is heated to the maximum operating temperature, the increase in pressure in the heating system does not exceed the permissible value (remains below the response pressure of the safety valve).

Expansion tank volume for heating systems with a capacity of up to 150 liters

For heating systems containing a small amount of coolant, up to 150 liters, the volume of the expansion tank is selected using a simplified formula:

Vn = 10 - 12% x Vs ,

Where: Vn— calculated volume of the expansion tank; V s- full volume of the heating system.

Calculation of the capacity of the expansion tank for a heating system with a volume of over 150 liters

The calculation begins with determining the increment in coolant volume - the additional volume that is formed as a result of heating the liquid to operating temperature - V e.

V e = V s x n%,

Where, V s— full volume of the heating system; n%— coefficient of expansion of the liquid in the heating system.

Expansion coefficient value n%, at the maximum operating temperature of the coolant (water) in the heating system, is determined from the table:

T oC	40	50	60	70	80	90	100
nv%	0,75	1,17	1,67	2,24	2,86	3,55	4,34

The expansion coefficient for antifreeze based on an aqueous solution of ethylene glycol (Tosol, etc.) is determined by the formula:

n a % = n v % x (1 + e a % / 100),

Where nv%— water expansion coefficient from the table above; e a %- percentage of ethylene glycol in the antifreeze solution.

At the second stage of calculation(second step) determine the volume of the water seal in the tank, Vv- this is the volume of coolant that initially fills the expansion tank under the influence of static pressure in the heating system. The water seal capacity is determined by the formula:

V v = V s x 0.5%, but not less than 3 liters.

At the third stage find the initial pressure in the heating system - P o. It is equal to the static pressure in the heating system and is determined from the calculation 1 bar= 10 meters of water column. The height of the water column in a heating system is equal to the vertical distance between the lowest and highest points of the system where the coolant is located. Using drawings or in situ, determine the vertical marks of the extreme points of the heating system. The difference between the upper and lower marks will be equal to the height of the water column of liquid in the system.

At the fourth stage calculations determine the maximum operating pressure in the heating system - P e. The maximum operating pressure must be less than the response pressure of the safety valve in the heating system by at least 0.5 bar.

P e = P k — (P k x 10%), but definitely P k - P e => 0.5 bar .

Where: Pk— response pressure of the safety valve.

At the conclusion of the calculation determine the required volume of the membrane expansion tank for heating using the formula:

V n = (V e + V v) x (P e + 1)/(P e - P o)

Choose a tank with a nominal volume greater than the calculated one.

Example of expansion tank calculation

Let's calculate the expansion tank for the heating system with the initial data:

Overall volume Vs = 270 l.

Water column height 6 m., hence the initial pressure P o = 6/10 = 0.6 bar.

Maximum operating temperature of coolant (water) 90 o C. Using the table, we determine the expansion coefficient n% = 3.55%.

The safety valve is set to operate at pressure P k = 3 bar .

We make the calculation:

V e = 270 l. x 3.55% = 9.58 l.;

V v = 270 l. x 0.5% = 1.35 l., since 1.35< 3, то принимаем V v = 3 l. ;

P o = 0.6 bar. ;

P e = 3 bar. — (3 bar. x 10%) = 2.7 bar., since the condition P k - P e => 0.5 bar must be met, then we accept P e = 2.5bar.

Vn = (9.58 l. + 3 l.) x (2.5 bar. + 1) / (2,5 bar. — 0,6 bar.) = 23,18 l.

Result:

We accept for installation an expansion tank with a nominal volume of 24 liters.

In addition to the volume, when choosing a specific type of expansion tank, the maximum operating pressure must be taken into account, for which the tank is designed.

The heating system is a complex engineering structure. The expansion tank is an important element of the system. Let's take a closer look at why it is used in a heating system, and also figure out how to make the calculation.

Features of a closed system

In open heating circuits that are in contact with the atmosphere, there is a problem with the expansion of the coolant. You can solve it as follows:

At the highest point of the house, a tank is installed.
If there is excess pressure, excess liquid will flow into a pre-installed container.
After the liquid cools, it will flow back into the system under the influence of atmospheric pressure.

The main disadvantage is the need to air the system, as water evaporates. This disadvantage can be avoided with a hermetically sealed heating system.

The expansion tank is used for closed-type heating to compensate for the expansion of the coolant. In this case, there will be no direct contact with the atmosphere.

Why install an expansion tank in a heating system?

In the heating system, pressure increases when the coolant heats up. As a result, destruction of pipelines and the boiler may occur. Even installing a simple valve that can discharge excess coolant into the atmosphere will not help solve the problem. Since when cooling the liquid will compress, and air will flow into the free space. And, consequently, air jams will form, due to which the circulation of the heating system will be disrupted.

The only way to solve this problem is to install an expansion tank. Due to its volume, the tank can ensure high-quality operation of the circuit.

Expansion tanks for closed heating differ in size and shape. They can be either cylindrical or tablet-shaped.

Design and principle of operation of the tank

Compared to open vessels, the most convenient are membrane tanks, which are completely sealed. To stabilize the pressure inside the cold water system, blue hydraulic accumulators are produced. To prevent airing of the circuit in a closed-type heating system, a red expansion tank is installed in the heating circuits. It is also installed to remove excess water when heated.

Membrane tanks are similar in structure, but have some differences:

Expansion tank for closed type heating. It is separated by a rubber partition in the middle. It is usually cylindrical in shape. But they also produce tanks that are shaped like tablets. Such expansion tanks are used for small volumes of coolant. When water is heated, the coolant expands, so excess liquid easily flows into the tank.
A rubber bulb is installed in the hydraulic accumulator, which easily follows the contours of the internal chamber.

You should be aware of the prohibition of installing a red membrane sealed tank after the circulation pump.

Materials from which membrane tanks are made:

In the expansion tank, technical rubber is used to make the membrane, and the inner surface is coated with anti-corrosion. In a hydraulic accumulator, the membranes are made of food-grade rubber, and the shape must not allow water to pass through. Thus, contact of the metal case with water is excluded.

If you install a red membrane tank for a cold water system, the water will not meet sanitary standards. And if you install a blue tank, which is not suitable for hot water, then the performance of the system will decrease.

Calculation of expansion tanks

In order to calculate the expansion tank, it is necessary to calculate the total volume of the entire system. It is equal to the sum of the volumes: the heating boiler, pipelines and heating appliances. In order to determine the volume of the radiator and boiler, no calculations need to be made, since the value is indicated on the equipment passport. To calculate the volume of pipelines, you need to find out the internal cross-sectional area of the pipes, and then multiply it by the length. If pipelines with different diameters are installed in the heating system, then each pipe should be calculated separately and the resulting volumes added up.

The expansion tank should provide an increase in fluid volume by approximately 10%. If the coolant volume is 400 liters, then the volume together with the expansion tank should be 440 liters. Therefore, the volume of the tank should be 40 liters. But such a calculation is approximate and may differ greatly from the real one, so it is better to make an accurate calculation. There are many calculators on the Internet that will calculate the expansion tank online. For a more accurate result, it is better to use several calculators.

Installing the tank yourself

To prevent water hammer inside the heating system, you must adhere to the following rules when installing the expansion tank:

It is impossible to make a tie-in after installing a circulation pump.
To be able to regulate pressure, it is necessary to provide access to the shut-off valves.
There must be no static pressure in the circuit piping.

Expansion tanks on the return line in front of the boiler are considered a profitable option. For floor-mounted installations, special stands are sold, and for wall-mounted installations, brackets should be used. There are brackets that are pre-welded to the body, and there are also separate ones that are included in the kit and need to be assembled yourself.

If you need to replace the membranes, you will need to completely disassemble the entire system. To avoid this, you can screw a ball valve onto the expansion tank pipe. This way you can remove the tank without disassembling it.

The general diagram of the device looks like this:

First of all, the expansion tank is unpacked;
The threaded fitting is being installed;
Ball valve device;
If the bracket is not pre-installed, then it is necessary to assemble it and attach it with a band clamp;
Installation of the tank depending on the type;
Next, you need to drain the coolant and then relieve pressure from the heating system;
Tie with a composite steel or polymer pipe;
Carry out pressure testing with working pressure;
Adjust the pressure in the air chamber if necessary. This can be done using a car pump.

For a more precise position of the expansion tank, brackets with a safety group are made, which facilitate installation.

For high-quality sealing of threaded connections, it is not recommended to use FUM tape. A better option would be Unipack winding.

The expansion tank is an indispensable part of closed-type heating.