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Expansion tanks for heat supply systems are installed to compensate for temperature changes in the volume of the coolant in closed heat supply systems. Even at school, in physics lessons, they study that water, when heated, significantly increases the specific volume, and since the circuit is closed, it needs to go somewhere. The tank will not only accept the excess liquid formed during heating, but also make up for its deficiency during cooling.

When there is no expansion device, in the event of an increase in temperature, the hydraulic pressure in the system increases and, since water is incompressible, the destruction of the heating structure becomes possible.

Features of the use of an expansion tank

The use of an expansion tank, such as in the photo, is justified by the fact that heating water by 10 degrees leads to an increase in its volume by 0.3%. Thus, when the temperature of the coolant in the system increases from 10-15°C to 80-95°C, then its volume will increase by about 2.4-2.8%. With the amount of liquid in the system equal to 100 - 300 liters, the difference can reach from 2.5 to 8 liters of water. And this is a considerable amount of coolant that cannot be hidden in pipes and radiators.

An additional capacity is required, or rather an expansion tank of sufficient volume and a suitable type. During heating, excess water will be directed into it, and vice versa, a coolant will flow from the device into the system if the liquid is cooled.

The purpose of the expansion tank

An expansion device is required:

• for temporary removal of excess coolant from the system when heating water and for draining when it is exceeded maximum level tank;
• to return the coolant to the heating system when it is cooled;
• to maintain the required hydrostatic pressure in the circuit by adjusting the volume of water;
• for the accumulation and removal of air and vapors from the liquid heat carrier, which begin to appear during its heating. So water contains a certain volume of air: it is up to 40 milligrams per liter. When the water warms up, almost 90% of this air is in the form of bubbles. The expansion tank removes excess air to the atmosphere.

Types of expansion tanks

Depending on the features of the design solution, these devices are of the following types:

• open ;
• a closed expansion tank with a replaceable or non-replaceable (diaphragm) membrane (read: "").

Open expansion tanks

An open-type expansion tank for heating has advantages and disadvantages. These devices are mounted at the top point of the heating structure (main riser), as a rule, in the attic and they are a cylindrical or rectangular container of an open or semi-open type. Most often, the tank looks like a parallelepiped made of sheet steel and necessarily insulated from the surrounding air.

The disadvantages that an open-type expansion tank for heating has are, first of all, its openness (contacts with atmospheric air) and large dimensions. Since the device is open or semi-open, there is a significant evaporation of water from the heating system, which means that constant monitoring of the level of the coolant is required. In case of its deficiency, fluid volumes should be replenished in a timely manner.

The presence of an open structure at the expansion tank leads to additional air inflow into the heating system, which causes increased corrosion of its individual elements. It should be noted that this type of device can now be found in residential buildings that have been in operation for more than a dozen years.

To mount an expansion tank for open-type heating and ensure its reliable thermal insulation, additional efforts and financial costs will be required, since it is necessary to strengthen the ceiling and purchase materials for insulation, etc.

Closed expansion tanks

Closed for structures providing heat supply, it is a metal closed container having an oval or spherical shape. Inside the device there are two chambers delimited by a sealed membrane. One of them is intended for a liquid coolant, the second is air - it has a valve, the function of which is to maintain the pressure in the chamber at the desired level.

When the first chamber is filled with a heat carrier, the membrane begins to sag and thereby an overpressure is created in the air part of the tank (more details: ""). When this parameter reaches a certain level, the valve opens slightly and the air leaves the chamber.

Membrane-type expansion devices are produced in two design solutions:

• in a non-replaceable version - with a diaphragmatic membrane;
• in a replaceable version - flange-type tanks.

Expansion tanks of diaphragm type consist of two parts of the body, which is made of carbon steel by deep cold forging. A membrane is fixed along the perimeter of the two chambers during the assembly process. From the inside, the surface of the tank is covered with moisture-resistant epoxy paint, and from the outside - enamel, often red.

Initially, the second part of the closed expansion device is filled with air in such a way that it completely occupies 100% of its volume. In the process of heating the coolant, its excess enters the liquid chamber, and the air part is compressed at this time. It increases the pressure that regulates the volume of fluid in the heating system. Some manufacturers fill the air chamber with nitrogen at a pressure that is equal to the water pressure in the heating system.

It is convenient to mount an expansion tank of this type - it can be installed in the immediate vicinity of the heating boiler (modern small-capacity units are produced, including with built-in expansion devices).

Expansion tanks of closed type have the following advantages:

• the coolant in them does not come into contact with air. As a result, the liquid does not evaporate from them, and pipes and radiators do not oxidize;
• the probability of water overflowing over the edge of the device approaches zero (if an expansion tank for open-type heating is installed, this happens quite often);
• convenient installation almost anywhere (with the exception of the pipeline immediately after the pump);
• low probability of air congestion;
• safety during operation and reliability in operation at low financial costs.

When calculating the tank, you need to consider a number of points:

• the volume of the device depends on the capacity of the heating system;
• when a high temperature is required for heat supply, a larger product is installed;
• the smaller the difference in height between the tank installation site and the highest point of the system, the smaller the capacity of the tank can be used.
  

Watch the video of calculating the expansion tank of the heating system:

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 (whether it will be open or closed), and what principle the coolant will be transferred through pipes (natural circulation due to the action of gravitational forces, or forced, requiring the installation of a special pump).

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

But before you purchase an expansion tank and proceed with its installation, you need to at least get a little familiar with its device, the principle of operation, as well as which model will be optimal for a particular heating system.

IN what are the advantages of a closed heating system

Although V Lately many modern devices and systems for space heating have appeared, the principle of heat transfer through a liquid with a high heat capacity circulating through pipes - without a doubt, remains the most widespread. Water is most often used as a carrier of thermal energy, although in some circumstances other liquids with a low freezing point (antifreeze) must be used.

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

How to determine 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. As it is right - in a special publication of our portal.

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

It is these functions that the expansion tank performs.

Still not so much in private construction, there was no special alternative - at the highest point of the system, an open expansion tank was installed, which completely coped with the tasks.

1 - heating boiler;

2 - supply riser;

3 - an 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 necessary, you can switch forced circulation to natural, 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 the installation of a sealed tank of a special design.

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

It would seem - why "to fence the garden"? A conventional open expansion tank, if it fully copes with its functions, seems to be a simpler and more inexpensive solution. It probably costs a little, and besides, with certain skills, it is easy to make it yourself - weld it from steel sheets, use an unnecessary metal container, for example, an old can, etc. Moreover, one can meet examples applications old plastic cans.

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

• Complete tightness absolutely excludes 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 winter is not used constantly, but “arrivals”, 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 troubles for thermal insulation of the container, so that even in the most very coldy the coolant in it is not frozen.

And in a closed system, an expansion tank can be installed in almost any part of it. The most appropriate place for installation is the return pipe directly in front of the boiler inlet - here the parts of the tank 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 interfere and does not disharmony with its appearance with the interior of the room, if, say, the system uses a wall-mounted boiler installed in the corridor or in the kitchen.

• In an open expansion tank, the coolant is always in contact with the atmosphere. This leads to a constant saturation of the liquid with dissolved air, which is the reason for the activation of corrosion in the pipes of the circuit and in radiators, to 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 at start-up, much more sensitive to adjustments. Completely unjustified losses in the area of ​​the open expansion tank are excluded.
• The temperature difference in the supply pipe and in the return pipe in the currents connected to the boiler is less than in an open system. This is important for the safety and durability of heating equipment.
• A closed circuit with forced circulation to create circuits will require tons of smaller diameter pipes - there is a gain both in material costs and in simplifying installation work.
• An open-type expansion tank must be controlled to prevent overflow during 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 versatile, as it is suitable for any type of battery, it allows you to connect underfloor heating circuits, convectors, and thermal curtains. In addition, if desired, hot heat supply can also be arranged by installing an indirect heating boiler in the system.

Of the serious shortcomings, only one can be mentioned. This — obligatory "security group", including control and measuring devices (pressure gauge, thermometer), safety valve and automatic air vent. However, it is rather no no prosperity, 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 hermetic expansion tank looks quite justified.

How is the expansion tank for closed-type heating arranged and how does it work?

The expansion tank device for a closed-type system is not very complicated:

Usually the whole structure is placed in a steel stamped case (pos. 1) of a cylindrical shape (there are tanks in the form of a “tablet”). For the manufacture of high-quality metal with an anti-corrosion coating is used. Outside the tank is covered with enamel. For heating, products with a red body are used. (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 (pos. 2) for tapping into the heating system. Sometimes fittings are included in the package to facilitate installation work.

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

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

The membrane is made from elastic material with low diffusion. It is given a special shape, which provides an "ordered" 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 equalizes, and this closed system takes on a static position.
• With an increase in temperature, the volume of the coolant in the heating system expands, accompanied by an increase in pressure. Excess liquid enters the expansion tank (red arrow), and bends the membrane with its pressure (yellow arrow). At the same time, the volume of the chamber for the coolant increases, and the volume of the chamber for the air, respectively, decreases, and the air pressure in it increases.
• With a decrease in temperature and a decrease in the total volume of the coolant, the excess pressure in the air chamber contributes to the movement of the membrane back (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 work, which will release excess fluid. Some models of expansion tanks have their own safety valve.

Different models of tanks may have their own design features. So, they are non-separable or with the possibility of replacing the membrane (a special flange is provided for this). The kit may include brackets or clamps for mounting the tank on the wall, or there may be 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. Often a balloon-type membrane is used (figure on the right), made of an elastic material. In fact, it is itself a water chamber. With increasing pressure, such a membrane is stretched, 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 work does not change at all.

Video: device expansion tanks brand "Flexcon 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 particular heating system, its working volume should be a fundamental point.

Calculation by 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 circuits of the system. However, it is possible to carry out a more accurate calculation - for this there is a special formula:

Vb =Vwith ×k / D

The symbols in the formula are:

Vb- the required working volume of the expansion tank;

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

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

D- coefficient of efficiency of the expansion tank.

Where to get the initial values? Let's go in order:

1. The total volume of the system ( VWith) can be defined in several ways:

• It is possible to detect by the water meter what total volume will fit when the system is filled with water.
• The most accurate method that is used in calculating the 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.
• Quite acceptable error gives the simplest way. It is based on the fact that 15 liters of coolant are required to provide 1 kW of heating power. Thus, the nominal 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 non-linearly depending on the heating temperature of the liquid and on 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 value of the percentage of ethylene glycol is taken - 0. For antifreeze - based on a specific concentration.

Heat carrier heating temperature, °С	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. The value of the efficiency coefficient of the expansion tank ( D) will have to be calculated using a separate formula:

D = (Qm – Qb ) / (Qm + 1 )

Qm- the maximum allowable pressure in the heating system. It will be determined by the 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 can also be indicated on the packaging and in the product documentation. It is possible to change it - pumping with a car pump or, conversely, bleeding through a nipple. It is usually recommended to set this pressure within 1.0 - 1.5 atmospheres.

Expansion tank volume calculator

To simplify the calculation procedure for the reader, a special calculator is placed in the article, 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.

The expansion tank for closed-type heating is considered one of the most important elements engineering systems V country house. You can buy it in a specialized store of any locality. The cost of such a device is quite high, so people with little financial resources prefer to make it on their own at home.

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General information

Before proceeding with the purchase and installation of the product, it is necessary to decide where the expansion tank will be located and how best to install it. In addition, it is necessary to take into account all specifications and study the rules of operation in detail.

How and where is the expansion tank for heating installed



Structural elements

The device of an expansion tank for a heating system is distinguished by its simplicity and a minimum number of elements. All this allows to reduce the cost of the structure and simplify its installation in a private house.

The expansion tank consists of the following parts:

1. 1. Stamped body. It has a cylindrical shape and is made of various kinds become. In the process of creating this element, only high-quality material is used that has the necessary characteristics (resistance to elevated temperatures, strength). The inside of the case is coated with an anti-corrosion compound, and the outside - with enamel. All this allows you to extend its life and prevent the occurrence of emergencies.
2. 2. Fittings (the connecting part of the pipeline installed for branching, turns, transitions to a different diameter, as well as, if necessary, frequent assembly and disassembly of pipes). They are used to simplify the installation process and achieve better system sealing.
3. 3. Threaded pipe. This part is used for insertion into the heating system and is located on one side of the tank.
4. 4. Nipple valve. It is installed on the opposite side and acts as a device that creates the necessary pressure in the air chamber.
5. 5. Seal diaphragm. This element is located in the inner part of the expander and divides it into 2 compartments. Near the pipe, a chamber is formed for the coolant, and on the other hand - for air. As a rule, the membrane is made of a material that has good elasticity and low diffusion. It has a certain shape, which helps to deform during pressure surges in one of the chambers.






Operating principle

The operation of a closed-type expansion tank is quite simple. Not only a specialist will be able to understand it, but also a beginner who has an elementary idea of ​​​​the process.

The device fulfills its obligations in the following way:



If there is a sharp increase in pressure and its indicators reach the limit values, then a special valve is activated, which releases part of the liquid. Thanks to this, the pressure is normalized, and the risk of an accident is reduced.

Proper filling of a closed heating system.



Advantages and disadvantages

A closed-type expansion tank, like any other product, has its advantages and disadvantages. They must be taken into account before installation, which will avoid unforeseen situations that can bring many problems to the owners of a private house.

Among the advantages are the following:



Despite a large number of advantages, the expansion tank of the closed type has several disadvantages. They lead to increased financial costs and reduced efficiency.

The negatives include:



Where to install the expansion tank

Installation steps

In order for the expander to work efficiently and not cause an accident, it must be installed correctly. To do this, you need to carry out a number of preparatory measures that will greatly simplify the process and reduce the risk of making mistakes.

Volume calculation

Professionals advise using an expansion tank, which will increase the total volume by about 10%. This will be enough for the normal and uninterrupted functioning of the entire heating system. If not water, but glycol is used as a coolant, then this figure should be increased to 50%. Such a large difference is due to the value of the expansion coefficient. The same applies to open-type vacuum tanks.

The calculation can be done in the following ways:



The principle of operation and the selection of an expansion tank

Basic Rules

To ensure high efficiency and maximum safety, it is necessary to take into account the basic rules for installing a closed heating expansion tank. In addition, they will help to avoid negative consequences and eliminate the likelihood of breakdowns during operation.

1. 1. Experts recommend installing such structures on the return line before circulation pump(relative to the direction of movement of the coolant). If such an arrangement is not possible, then a straight horizontal section is selected.
2. 2. It is best to connect an expander that has a built-in safety valve. With its help, it will be possible to relieve pressure in the system and avoid an emergency.
3. 3. If the safety valve operates frequently, it is necessary to replace the expander with a larger tank. Another way out of the situation would be the parallel installation of an additional tank.
4. 4. The tank must be equipped with a pressure gauge, which will simplify the control of the operation of the device.

1. Types of expansion tanks
2. Features of the installation of expansion tanks
3. Mistakes made when installing the expansion tank

Today, it is possible to equip a heat supply system in a private house as soon as possible.

The main thing that is necessary for this is sufficient financial capabilities of the property owner, and then the planned will be implemented, since the domestic building materials market offers a wide selection of heating equipment and components.

One of the highlights of creating a system is the installation of an expansion tank in the heating system.

It is on him that the performance of the heating network of a private house largely depends.

Types of expansion tanks

The place where the expansion tank of the heating system should be installed, such as in the photo, is determined based on the type of construction, which happens:

• open;
• closed.

It should be noted that open-type heating systems are rarely installed today.

They are found in buildings built about a few decades ago. The expansion tank, the device of which is made according to the open type, has the form of a container with an open top and threaded connection below, at the bottom. Through it, an open-type expansion tank is connected for heating. The tank of this outdated model is located in the highest place of the system.

In a closed-type heating structure, an expansion device is used, the installation and further operation of which have their own characteristics and differences.

The tank is made in the form of a sealed capsule with two chambers separated from each other by a rubber membrane. Therefore, the product is also called a membrane expansion tank of the heating system.

The device of an expansion tank of a closed type is allowed anywhere in the heating network, with the exception of the tie-in tank after the circulation pump in its immediate vicinity.

Otherwise, pressure surges throughout the system are possible.
The principle of operation of a closed type tank is simple. After the coolant has heated up and increased in volume, its excess fills the empty space in the membrane device. As a result, the pressure in the system continues to remain at an acceptable level (read: “We make the selection of an expansion tank for heating”).

The installation of an expansion tank in the heating system is carried out taking into account some points:

• installation of the device is allowed in a room where the temperature does not fall below zero;
• easy access to the air valve should be provided in order to regulate the pressure in the air part of the tank if necessary;
• when the installation of the device is completed, access to the shut-off equipment, drain cock and nameplate must be available;
• it is impossible to allow the application of a static load to the membrane tank (pressure from pipes and other devices);
• if the reducer is located after the water meter, such a measure will allow maintaining a constant initial pressure in the membrane tank.

  When the safety valve is triggered, the pressure should not exceed the level of the maximum allowable working pressure in the tank (read: “Safety valve for heating - what are there, how to use it correctly”);

• the expansion tank for heating is fastened in such a way that the safety valve is up to the flow fittings in the direction of the coolant.

The heating scheme with an expansion tank always provides that its installation is carried out only from the side from which the supply is made. cold water to the heating boiler.

Installing an outlet device is prohibited.

Mistakes made when installing an expansion tank

Many property owners try to do many of the work on arranging the heat supply system on their own, including mounting an expansion tank with their own hands.

At first glance, it seems that there will be no problems with such work, but in reality it has certain difficulties, which are well known to specialists.

The most common mistakes made when installing an expansion tank in a heating network occur for a number of reasons:

• lack of a complete set of necessary tools or their poor quality.

  When doing work, they often use keys - universal (gas) and adjustable.

  In addition to them, a special key is also required, which is necessary when installing a metal-plastic pipeline, and a stepped key for detachable connections;

• application for sealing materials that are not intended for these purposes. For example, instead of high-quality sealant, they use cheap products for PVC windows, which are intended for a different temperature regime.

  The first time after applying the connections look attractive, but after commissioning the heating structure, this type of sealant cannot withstand the load and high operating temperatures.

  Expansion tank for heating - installation diagram in open and closed systems

  It is good if a leak is found as a result, but often the consequences are more serious;

• the installation of an expansion tank in the heating system was made in a hard-to-reach place and the approach is almost impossible;
• the calculation of the volume that the expansion tank should have is incorrectly calculated, or the device was purchased at random.

It should be noted that the installation and fastening of the heating expansion tank must be carried out in accordance with accepted norms and rules that ensure safe operation.

Before installation, you must correctly determine the installation location of the device.

After the installation of the expansion membrane tank is completed on its own, everything seems to look great, and the inaccuracies made at the same time are invisible. The disadvantages will become apparent after the heating season has started, and most importantly, this will happen at the most inopportune moment.

For example, it is cold outside heating system out of order.
Watch a video on installing an expansion tank in a heating system:

In order not to run into problems in the future, it is necessary to familiarize yourself with the recommendations from the manufacturer for the installation of such an element of the heat supply system as an expansion tank.

This information will help to avoid unnecessary expenses: time, physical and financial.

One of the key elements of the cooling system in modern car is the expansion tank. This is a kind of reserve reservoir for an additional amount of liquid during the operation of the system.

I'm thinking about the meaning of the reservoir looking for faults in the thermostat or the radiator itself.

However, expansion vessel problems are often caused by air overload in the cooling system, which leaves the car without heat during the cold season.

An alarming symptom for the car owner is the regular overheating of the engine. It is important to check the status of this part, but first you need to know exactly how the device works.

What is the purpose of an expansion vessel and how does it work?

The urgent need for such a reservoir was created when a special liquid was used instead of cooling water, which is able to maintain its physical properties even at extremely low temperatures.

The basis of these solutions is alcohol and ethylene glycol (rarely propylene glycol).

As it heats up, the alcohol expands and starts to seep through the pressurized radiator fan valve. During the ICE cooling process, the temperature of the antifreeze or antifreeze is reduced by the formation of an empty void.

How to fill the expansion vessel for heating?

The spaces are filled with air, which, with the subsequent activation of the engine, creates plugs that prevent the free passage of fluid into the cooling system. This can lead to a general overheating of the engine.

To avoid overheating problems, an expansion vessel was supported, which was connected to the radiator by a pipe. The center of the reservoir is at the level of the top of the radiator, so that the heated fluid rises and freely flows from the radiator space into the reservoir.

The hose itself is attached to the bottom of the unit, allowing excess antifreeze or antifreeze to flow back to the radiator during cooling without air being drawn in.

Where is the expansion tank

In different models, the tanks are located in the most suitable areas of the cooling system.

A container is needed next to the radiator.

The material for the manufacture of the container is durable and transparent plastic. In one part of the product there are always scale marks that allow you to control the level of antifreeze in the system. The last risk on the bottom shows the minimum liquid level.

The maximum amount of cold wind antifreeze should be just over 30 mm above the upper risk level on the tank scale.

Main problems and malfunction of the expansion vessel

Most often, car owners complain about a problem such as a leaking expansion vessel.

This may be due to a violation of the integrity of the tank (for example, after a bad parking or other collision), as well as violations of the pipeline that connects the drain tank and the radiator.

The strong pressure in the container is emptied using a special release valve on the container lid. It is necessary to carefully monitor the condition of the cover, remove it from the scale and corrosion, otherwise the valve and the entire system will quickly work.

An error in the expansion vessel causes a strong drop in the liquid in the engine cooling system, which has a very bad influence to her job.

Installation of an expansion tank for closed-type heating

Installing an expansion tank for closed-type heating allows you to equip a heat supply system in a private house in the shortest possible time.

The main thing in this business is enough finances for the implementation of the conceived idea. Today Russian market building materials presents a wide range of thermal equipment, as well as components for heat supply schemes.

When arranging a heating system, it is very important to install a closed type heating expansion tank.

In the future, the functionality of the entire heating network of the dwelling will depend on this detail.

Types of expansion tanks

Elements to prevent air leakage into the line are of different designs.

Based on this, a specific installation of the expansion tank of the heating system is carried out. There are closed and open heat supply schemes.

Installing an expansion tank in an open heating system is rarely used.

As a rule, it is characteristic of buildings Soviet period. The expansion tank, the design of which is made according to this type, is a container with an open top and a threaded connection at the bottom, at the bottom. Using such a connector, an open type element is connected to the heating circuit. The scheme for installing an open expansion tank for heating - provides that it must be located at the highest point of the system.

The closed-type heating structure has a special device, so the installation of an expansion tank for closed-type heating has its own characteristics.

The container is made as a sealed capsule, which has two chambers separated by a rubber membrane. Therefore, this design is also called a membrane tank of the heating system. This part is used anywhere in the heating system except for the place behind the circulation pump, as well as directly next to it.

Failure to comply with this precaution may result in pressure drops within the system.

The scheme for installing an expansion tank in a closed-type heating system is simple.

The heated coolant expands, its excess squeezes air out of the membrane device, and the system pressure remains unchanged.

Features of mounting expansion tanks

The installation of a vacuum heating expansion tank must be carried out taking into account some aspects:

• installation of the structure is carried out in a room with positive temperature;
• it is necessary to provide free access to the air valve to adjust the pressure if necessary;
• upon completion of the installation of the tank, access to the drain valve and shut-off equipment is left free;
• the scheme for installing a membrane expansion tank for heating is carried out so that the safety valve is located before the flow fitting.

To be fulfilled correct installation expansion tank in the heating system, you will need the following tools:

• adjustable and stepped wrench;
• wrench for mounting PVC pipes.

First, you should do the preparatory stage, which includes disconnecting the boiler from gas supply, electricity or water supply.

Then the valve is closed, which is responsible for the circulation of the coolant, it is drained from the system.

Step-by-step steps for installing an expansion tank in a closed heating system:

Why do you need an expansion tank for a closed heating system?

Install a drain and stopcock on the supply pipe to drain and shut off the water.

2. Connect the expansion vessel to the system using screws.

If the options for installing an expansion tank in the heating system require the presence of polypropylene pipes, a soldering machine, fittings, couplings and corners should be used.

Before installing the fitting, it is necessary to wrap linen tape around the thread and apply sealing paste.

4. After draining the water system, cut the pipe with scissors and install a tee.

Before putting the system into operation, be sure to blow out the coarse filter.

Be sure to check the working pressure with the pump.

7. After connecting the expansion tank to the network, start all the coolant supply valves, turn on the boiler.

It is advisable to install a safety valve that comes with the tank; if it is not available, it should be bought separately.

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In order to compensate for the thermal expansion of the coolant in the heating system, tanks of an open or closed type are arranged. They come with natural and forced circulation. The volume of the liquid tends to change, as the coolant expands and contracts during operation.

To stabilize the pressure on internal walls elements in the heating system, as well as to compensate for changes in the volume of liquid, expansion tanks are used.

Types of tanks
2. Expansion tank open type
2.1 Advantages and disadvantages
2.2 How an open tank works. Installation rules
3. Expansion tank of closed type
3.1 Membraneless tanks
3.2 Diaphragm tanks
3.3 Advantages and disadvantages of a membrane tank
3.4 How to choose a membrane tank
3.5 Installing closed expanders

Types of tanks

There are two types of expansion tank:

1. Expansion tank of open type.
2. Expansion tank of the closed type.

When the temperature of the liquid in the pipeline decreases and for its natural return, an open-type tank is installed at the highest point of the heating system.

A tank of this type is a volumetric container that communicates with the atmosphere.

The expansion tank of a closed type has the form of a sealed vessel, which is filled in one half with liquid, and in the other with gas or air, which is under pressure.

After heating, the liquid moves into the expander, and the gas is compressed at this time. The liquid is returned back after cooling, and the resulting difference in volume is filled with gas.

Expansion tank open type

Let us consider in more detail all the features of an open type tank. The tank is used with a small leak to replenish water. And also for air intake from the system.

Such a tank can be cylindrical or rectangular and is usually made of steel or polymeric materials.

Since the expansion mat is installed at the top, the heating pipelines must be long. For maintenance of this device, as well as cleaning from contamination, a cover is provided on top of the tank.

You can install an open-type expansion tank in a special room on the roof of the house, in a stairway or in the attic.

If your house has high ceilings, then such a tank is well placed in a bathroom or household. room. If the containers go beyond the heated room, then they should be insulated to avoid heat loss.

Advantages and disadvantages

Advantages of open tanks:

1. Relieves pressure and removes air from the heating system.
2. Low cost device.

The disadvantages include:

1. Large heat loss and the need for insulation of some elements.
2. Before installation, it is necessary to arrange additional heating pipelines.
3. Since the system evaporates a certain amount of coolant, it is necessary to replenish it periodically.
4. Possibility of corrosion of steel elements due to contact with the atmosphere.

Due to the shortcomings of this equipment, it is used less and less, giving preference to closed tanks.

How does an open tank work?

Installation rules

To prevent stagnation of water in the tank, it is necessary to arrange circulation. A contour is arranged between the tank and the main pipeline. It should consist of a circulation and expansion pipe. The opening of the circulation pipe must be located 0.5 cm below the expansion pipe.

Due to the circulation from the heating system, air bubbles are released into the atmosphere. Such a system is suitable for forced circulation. If the system is equipped with natural circulation, then it is necessary to connect an expander at the top of the supply pipe.

Expansion tank closed type

The tank of the closed type has the form of a sealed vessel, which is made of steel. Part of the tank is filled with an inert gas, and the second part is filled with liquid. The expansion tank of the closed type is of two types: membrane and membraneless.

Membraneless tanks

In such tanks there is no internal separation of space, so the coolant is in direct contact with the gas.

A gas cylinder or compressor is installed outside to maintain pressure inside the tank. Gas supply and pressure control occur automatically.

Membrane tanks

Membrane tanks are more popular, as they are separated by a flexible membrane. Therefore, gas and liquid do not come into contact.

There are tanks with a disk-shaped membrane and with a pear-shaped (balloon) membrane.

The first membrane is attached in the middle of the tank and looks like a hemisphere.

It can become concave or convex depending on changes in water temperature.

The second membrane is similar to a vessel and is attached to different ends of the vessel. There is gas between the membrane and metal walls, so the coolant does not come into contact with the walls of the tank. Therefore, such a tank is protected from corrosion and has a long service life.

In this tank, the membrane can be replaced. Expanders are produced with butyl and ethylene propylene membranes. They are highly durable.

Advantages and disadvantages of a membrane tank

Advantages of a membrane tank:

• It is not necessary to arrange thermal insulation;
• Heat loss is minimal;
• Operates at high pressure;
• Small size;
• You can install the tank almost anywhere;
• The tank is well protected against corrosion, as it does not come into direct contact with the atmosphere.

The disadvantages include:

• Periodic pumping of air or gas;
• Great cost;
• The pressure in the system must be controlled.

How to choose a membrane tank

Membrane tanks are oval and flat with a diaphragm.

The second option is more compact, it can be installed between the wall and the interior. Thus, you will save space in your home. The main parameters of such a tank is the required volume of liquid. It is pre-calculated.

The service life of the tank depends on the quality and parameters of the membrane.

The main characteristics of the membrane:

1. The material from which the membrane is made.
2. Operating temperatures and pressure.
3. diffusion stability.

Tanks that are used for heating are painted red, and those used for the water supply system are painted blue.

Installation of closed expanders

If the tank is closed type with forced circulation, it is recommended to install it before the circulation pump.

Installation can be done in any position, but most good option there will be an upper liquid supply. Since the air bubbles will be discharged naturally. The tank will work even if the membrane is damaged.

Some heaters already have an expansion tank built in, in which case there is no need to install an additional one.

Do-it-yourself installation and installation of an expansion tank in a heating system

If you decide to change the water to another coolant, you may have to replace the tank with a higher volume. But you can also install an additional expander.

When installing a closed type tank with natural circulation, it is necessary to install an automatic float valve. It is arranged at the top of the system to release air when the system is full. If, when using the tank, you notice that its volume is not enough for you, instead of buying a new one, it will be more profitable to install an additional tank of the right size.

One of the advantages of an autonomous heating system is the ability to maintain comfortable temperature in the house, regardless of the timing of the start and end of the heating season, and save on bills for public utilities. Schematically, it consists of a heating boiler and a circuit through which the hot coolant circulates. Water is usually used as the heat carrier. An important role in heating equipment is played by the hot water circulation system, which consists of several parts. The correctness of its operation largely depends on such a structural element as an expansion tank.

An example of arranging heating with an expansion tank

Comparison of closed and open heating systems

The functioning of an open heating system is based on the laws of thermodynamics, due to which the movement of the coolant is carried out. From the area of ​​high pressure and the corresponding temperature at the boiler outlet, the water moves through pipes to the area of ​​lower pressure, and its temperature decreases. The cooled coolant is sent back to the boiler, and the process is repeated. Thus, there is a natural circulation of the liquid, according to the laws of physics.

Since when water is heated, its volume increases, an expansion tank is provided in the design of an open heating system. For efficient movement of an open-type coolant, the expansion tank is installed at the highest point of the system, and the heating boiler at the lowest. Installation of an expansion tank in the attic is represented the best option. Its device is not complicated.

Open type heating scheme

Over time, water evaporates, so its level must be replenished in a timely manner. During interruptions in the use of heating and at negative ambient temperatures, the water must be drained, otherwise it will freeze in the pipes and break them. An open heating system has the following advantages:

• independence from sources of electrical energy;
• no noise;
• ease of maintenance;
• quick start and stop.

You can choose radiators for any type of heating system based on the recommendations of the article

In a closed heating system, water evaporation does not occur, since it is airtight. The movement of the coolant is carried out using a pressure or circulation pump, which can be found in the article At the same time, for effective work an expansion tank made of durable metal is also required. The closed heating system consists of a heating boiler, a circulation pump, a pipeline network, radiators and an expansion tank. A closed heating system has the following advantages:

• no need for constant monitoring of the coolant level;
• the possibility of using antifreeze;
• adjustment of internal pressure;
• the ability to connect additional devices.

Closed heating system

With proper installation of heating equipment, both options will work perfectly. The choice between them is determined by the operating conditions and placement features. There are the following differences between the two systems:

• In an open heating system, the expansion tank is located at the highest point. In a closed heating system, it can be located almost anywhere.
• The likelihood of air locks in a closed heating system is much lower. This is due to the increased internal pressure and the lack of direct contact with the atmosphere.
• For the operation of an open heating system, pipes of large diameter are required. Installation work are complicated by the need to take into account the rules of hydraulics when distributing flows, making turns, slopes, and so on.
• Small-diameter pipes used in a closed heating system reduce its cost. Here it is important to correctly install the circulation pump so that during its operation it creates as little noise as possible.

The device and functions of the expansion tank in the heating circuit

The function of the expansion tank in an open heating circuit is to receive excess water when it expands due to heating, and return it to the system when the temperature drops. The container is not sealed, and the coolant is in direct contact with environment, therefore, in an open heating system, water evaporates. The device is simple in design, if necessary, it can be done by hand.

Expansion tank open type

The disadvantages of an open system include the need for constant monitoring of the water level, as it evaporates, the danger of freezing the liquid in the expansion tank, and the impossibility of using antifreeze as a coolant. In addition, air entering the system causes air pockets, corrosion of internal parts and their cavitation.

In a closed heating circuit, the expansion tank is made of high-strength metal. The device consists of two halves, sealed to each other. The design includes a receiving valve and an internal membrane. When the temperature of the coolant rises, the valve opens, and the excess of the increased volume of liquid enters the expansion tank.

The diaphragm, made of heat-resistant high-strength rubber, divides it into two parts. Gas is pumped into the upper part of the sealed container, and a hot coolant enters the lower part, compressing the membrane and the gaseous medium located behind it. When the working fluid cools, due to the expansion of the gaseous medium, the diaphragm squeezes it back into the heating circuit.

The membrane tank can be installed horizontally or vertically in any position.

Closed type expansion tank device

The performance of a closed-type expansion tank does not depend on its orientation in space, which cannot be said about the service life. To extend the operating period of the membrane tank, it is better to position it so that the air chamber is on top. Over time, cracks appear in the diaphragm, and until their size and number reach a critical level, the system will work properly when the container is placed vertically. In a horizontal position (in the event of cracks in the diaphragm), air from its half will quickly penetrate into the coolant and vice versa, and therefore an urgent replacement of the tank will be required.

What causes the insufficient volume of the built-in boiler tank

Insufficient volume of the built-in boiler tank can lead to malfunctions in the heating system. When heated, the liquid expands, and its excess enters the expansion tank. If its volume is insufficient, the tank overflows, and the emergency pressure relief valve bleeds the coolant into the drain. The rest of the cooled coolant is returned to the heating circuit.

Pressure in the system with insufficient volume of the expansion tank

As a result of a decrease in its amount, a decrease in the internal pressure in the system occurs. If it decreases by a small amount, the boiler will function, with a significant decrease in pressure, the operation of the heating equipment will be blocked.

If the coolant level is not replenished to normal in a timely manner, the system may defrost, so such emergencies should not be allowed to occur.

Calculation of the required volume of the membrane tank

The required volume of the membrane tank is calculated using a simple formula. Its value is ten percent of the total amount of coolant circulating through the system, if water acts as this. The total volume of the coolant can be determined from the readings of the water meter when filling the heating system.

A more accurate figure is obtained by summing up the volume of all pipes, the capacity of the boiler and batteries. It is believed that fifteen liters of coolant are required for one kilowatt of boiler equipment power, that is, the total volume of liquid is determined by multiplying the nominal power of the boiler by fifteen. This value will lie within the margin of error.

Illustration of the change in volume in the tank with fluctuations in pressure in the system

For example, if three hundred liters of water are needed for the operation of heating equipment, then the volume of the membrane tank should be thirty liters. This parameter increases by fifty percent when using an antifreeze liquid as a coolant, that is, in this case, the required volume will be forty-five liters. In addition, the possibility of leaks must be taken into account and the calculated value must be increased by about three percent more. When the size of the membrane tank is correctly determined, the emergency pressure relief valve does not work.

Set the optimal pressure in the tank

Before connecting the expansion tank and filling it with coolant, it is necessary to set the optimum pressure in its air chamber corresponding to this parameter in the heating network. To perform this procedure, a plastic cover is removed from the air compartment, under which there is a nipple, the same as in automobile tires. The pressure measured by the pressure gauge is adjusted to the desired value by pumping with a pump or by bleeding when pressing the nipple stem.

Protection group monitors system pressure

The optimum pressure in the tank is obtained by adjusting the internal pressure in a closed heating system downwards. This is done so that the rubber diaphragm is pressed from the side of the coolant. Otherwise, when it cools down, air will be drawn in through automatic vents, which should never be allowed. For example, if the internal pressure in the network is 1.2 atmospheres, then its optimal value in the expansion tank will be one atmosphere. After setting this value, you can open the tap and fill the system with coolant.

At intervals of six months in a closed-type compensation tank, it is necessary to check the pressure and perform a visual inspection for mechanical damage.

With a sharp change in internal pressure and temperature in the heating network, there is a risk of damage to the membrane, and in this case it will need to be replaced. To do this, you must perform the following manipulations:

• disconnect the expansion tank from the line;
• relieve pressure in it by pressing the spool rod;
• remove the damaged membrane, drain excess water and install a new one;
• after setting the optimum pressure, attach the container in place.

Choosing the location of the expansion tank

The installation of an expansion tank depends on the type of heating system and the purpose of the tank itself. It is better to install a closed type compensation tank on the return line in front of the heating boiler and circulation pump.

Expansion tank placement and mounting options

If it is located on the supply line, the life of the membrane will decrease due to the constant exposure to a higher temperature of the coolant. In addition, in this case, in the event of an emergency, steam can penetrate into the expansion tank, as a result of which the diaphragm will no longer compensate for the coolant pressure, since the mixture of air and steam is a compressible medium.

The expansion tank is connected through a shut-off ball valve. This is done so that, if necessary, it is possible to quickly replace the compensation tank without waiting for the coolant to cool down. Installing a second tap makes it possible to pre-drain hot water from the tank.

How to install a closed expansion tank with your own hands

The connection scheme is not particularly complicated. You can correctly mount a closed expansion tank with your own hands by observing the following connection diagram. The pre-heating boiler is de-energized, the coolant supply is shut off, water is drained from the radiators.

If polypropylene pipes are used for installation, a special soldering iron is required for their installation. You will also need couplings and corners. Of the fittings, it is better to use the "American", as it makes it possible to easily remove the container for maintenance and repair. The following is a sequential diagram of the steps for installing an expansion tank.

1. A sealing thread is wound on the threaded part of the tank fitting.
2. An adapter is screwed onto the fitting for installing a tap.
3. A sealing thread is wound on the threaded part of the adapter.
4. A shut-off valve is installed on the adapter.
5. A sealing thread is wound on the threaded part of the "American". "American" is wrapped in a tap with the help of pliers and an adjustable wrench.
6. A sealing thread is wound on the threaded part of the corner. The corner is wrapped in an "American".
7. A collar for fastening the tank, which is included in the delivery set, is put on the tank body.
8. On the opposite side of the tank there is a nipple for air injection, on which a plastic cap is screwed.

After placing the expansion tank in the selected location, the quality of all connections is checked, and the coolant is supplied to the system. After the internal pressure in the batteries reaches the calculated values, air pockets are bled from them, and the heating system starts up at full capacity. The compensation tank is installed so that it is convenient to maintain, that is, free space is left between it and the wall.

Seal all joints with sealants that are resistant to high temperatures, otherwise leakage is inevitable. The membrane expansion tank in a closed heating system is installed on the side of the cold water supply. When performing all manipulations, safety requirements must be observed.