How to install the expansion valve correctly. How to install a membrane tank for water supply? Expansion tank functions

25.11.2019

Reviews of the book The True, Mad, Guilty Moriarty l The True, Mad, Guilty

Life at Full Power - Jim Lauer, Tony Schwartz

Famous pirates of the Caribbean, next to whom the movie Jack Sparrow is just a boy

Why do you need a membrane tank for water supply? When organizing an autonomous water supply for a private home from wells or wells, it is necessary to create an emergency water supply. An expansion tank for water supply is perfect for these purposes. These containers are practical and have a large volume, but to ensure normal operating conditions it is necessary to use a number of devices and not limit yourself to just one installation.

When a tank is included in the water supply system, the autonomy of the water supply is significantly increased. The created reserve will allow solving problems with water supply that may arise during and during operational maintenance of equipment and the well. At the moment, the industry produces a huge number of different models, which significantly complicates the choice.

An expansion tank for water supply is used to maintain the required pressure level for autonomous water supply. Membrane (expansion tanks) are most often used for these purposes. These are containers with rubber membranes inside that divide the tank into chambers. One chamber is water, the other is air.

The tank is connected to the water supply system of an autonomous water supply system so that the input branch supplies water to the tank, filling it, and only after a certain volume is filled is water supplied to consumers.

The operating principle is as follows: when the system is turned on (started), the pump pumps water into the water chamber until it is filled. At the same time, the volume of the second chamber is significantly reduced. When the air chamber contracts, the amount of air inside it does not change, so the pressure on the membrane increases. Accordingly, the pressure in the system increases.

Expansion tanks use a membrane to divide it into 2 reservoirs, one containing air and the other containing liquid. In this case, it is necessary to have pressure monitoring equipment (pressure switch) in the tank. This is necessary to automatically turn off the pump; the same sensor automatically starts the pump when the pressure in the tank drops below the programmed value. This will allow automatic operation of the entire water supply system.

How to connect an expansion tank

How to reliably connect an expansion tank in an open system!? An open-type heating system is characterized by the fact that the movement of coolant in it is ensured by convection.

The principle of operation is as follows: the coolant heated by the boiler unit is delivered directly to the highest point of the system, as a result of which it flows by gravity into the heating radiators and, when cooled, returns to the boiler through the return pipeline. There is always dissolved oxygen in water, which is released through the process of convection, which means that air bubbles tend to rise.

When considering this diagram, it becomes obvious that the only possible installation location for the expansion tank is the top point of the system. For a single-pipe system, this is the upper part of the accelerating manifold.

Connection diagram for a membrane tank in an open type heating system

As a tank, you can use any container of a suitable size made of heat-resistant material. A lid (not sealed) is needed only to protect it from debris getting into the system. If you don’t have a small metal barrel at hand, the tank is welded from sheet steel 3-4 mm thick.

The tank must be installed in compliance with certain rules, in particular:

the tank must be placed above the boiler unit and connected by a vertical riser through which heated water is supplied;
It is recommended to insulate the body of the tank to reduce heat loss, especially if the tank is located in an uninsulated attic of the house.

Over time, the water from the tank evaporates and needs to be topped up periodically. This can be done using an ordinary bucket. If the tank is installed in the attic, where it is difficult to reach, a water supply pipe is led to the installation site of the tank, and an emergency overflow is organized to avoid flooding the house with hot water in the event of an emergency. The emergency overflow pipe is usually connected to the sewer network, but owners of private houses often simplify the task by leading it outside through a wall or roof.

Expansion tank in a closed heating system

Equipment for the heating system is selected at the design stage, taking into account the requirements for the performance of the boiler unit, the length of pipelines and the volume of coolant involved. A diagram is being developed that indicates the installation locations of all system elements, including the expansion tank. In a closed heating system, it is necessary to use a membrane device.

Expander in a closed heating system

When linking a project to an existing boiler room, it is important to take into account the following points:

The tank should be placed in such a way as to ensure normal access for installation and further maintenance. Floor-standing models are not recommended to be installed close to the wall.
If the device is mounted on a wall, it is advisable to place it at such a level that you can easily reach the air spool and shut-off valve. Typically, the tank is placed under the ceiling of the room only if it is not possible to mount it at a convenient height.
The supply pipe should not be placed on the floor across the passage or suspended at human height.
The pipes connected to the expansion tank must be secured to the wall. It is important to avoid a situation where the load from them and from the shut-off valves falls on the tank pipes. Separate mounting of pipes and taps makes it easier to replace the expansion device in case of failure.

At the equipment selection stage, it is necessary to calculate the required volume of the expansion tank. The minimum value of this parameter is 1/10 of the total volume of liquid circulating in the system. It is permissible to use a larger tank. But a tank that is not large enough can become a source of problems, since it is not able to compensate for the increased pressure in the system.

Rules for placing the expansion tank

For approximate calculations of the volume of coolant in the system, you can take the thermal power of the boiler unit as a basis. On average, 15 liters of liquid are used per kilowatt. Exact calculations are made taking into account the length of pipelines, volume of radiators, etc.

Important! Many models of gas and electric boilers are mini-boiler rooms, that is, they are immediately equipped with a pump for forced circulation of the coolant, as well as an expansion tank. There is no need to purchase a separate tank if the parameters of the built-in membrane tank are sufficient to ensure the functionality and safety of the existing heating system.

When purchasing a membrane expansion tank, pay attention to whether the selected model has a safety valve, thanks to which excess pressure is automatically released. If one is not provided for by the design of the device, you should buy a safety valve separately and install it in close proximity to the tank.

Where is the best place to put the tank?

The optimal place for installing a membrane tank is a straight section of the pipeline, which is characterized by laminar flow of water, that is, the absence or minimal amount of turbulence. A convenient place is the spill area near the circulation pump.

Note! The expansion tank of a closed heating system can be installed at any convenient height. There is no need to place it at the highest point as it functions solely as a surge protector. Unlike an open-type heating system, the air accumulated in the pipeline is released using special valves - air taps.

From a hydraulic point of view, it is best to install the membrane tank on the return line so that the circulation pump is located between it and the boiler. In this case, the pumping equipment will function optimally.

Scheme of possible tank placement

If desired, the tank can also be placed on the supply line; this will not affect the operational properties of the heating system. But the membrane tank itself will not last a relatively long time, since the polymer membrane will be in constant contact with the coolant that has just been heated to 90 degrees, and not with water that has cooled to 45-60 degrees and returned through the pipeline.

Attention! Installing a membrane tank on the supply line is highly not recommended if the heating boiler is solid fuel. There is a risk that due to an emergency, the water in the boiler will begin to boil and steam will enter the tank. Water vapor, like air, is a compressible medium, which is why the membrane will not be able to compensate for the thermal expansion of water.

Expansion tank installation process

Now let's figure out how to install an expansion tank in the heating system. There is an important rule for connecting the device: the tank must be connected to the heating system mains using a shut-off ball valve with an American connection. This installation principle makes it possible, if necessary, to shut off the flow of water in the system at any time, remove the faulty membrane tank and install a new one.

Otherwise, you would have to wait for the coolant to cool down and dismantle part of the piping. Ideally, a tee is installed on the supply line, as well as a second tap - in this case, before removing the expansion tank, it can be emptied into a substitute container.

By hanging the expander upside down, if the diaphragm malfunctions, the unit will fail immediately

How to correctly orient a membrane expansion tank in space? The tank is installed with the air chamber up or down, and the container is placed “on its side”. From the point of view of operational characteristics, this does not matter much, since in any case the device will perform its functions properly.

However, it is worth considering this point: if the air compartment is located at the bottom, then the coolant is supplied from above, and the bubbles of air dissolved in it will rise into the pipeline and be removed using an air valve. Otherwise, an air bubble will form in the “water” compartment of the membrane tank over time.

In turn, when the tank is positioned with the air chamber upward, its service life is extended. Over time, from constant contact with hot water, the polymer membrane loses its tightness and cracks appear in it. If the air chamber is located at the bottom, then water will immediately begin to seep into the air compartment, which will quickly damage the expansion tank, while air will penetrate into the coolant. When the air chamber is located on top, the diffusion of water through cracks occurs many times slower, and the device can operate much longer.

Useful tips:

If you install a pressure gauge next to the expansion tank and the valve, thanks to which the heating system is fed from the water supply, it will allow you to control the pressure in the system in order to bleed off excess in time if the safety valve spool is stuck and does not operate automatically.
Frequently repeated release of pressure by the valve indicates that the capacity of the expansion tank is selected incorrectly. Instead of changing it to a larger tank, just connect a second tank in parallel.
Replacing the existing expansion tank with a larger one or connecting a second one will also be required if it is decided to replace the water in the system with antifreeze. This is due to the fact that non-freezing coolants have a higher coefficient of thermal expansion.

If there is no pressure gauge, the circuit of the expansion tank should be equipped with a safety group

Settings

Before connecting the tank and filling it with coolant, you need to check the pressure level in the air chamber of the tank - it must correspond to the pressure in the heating system. For this purpose, you should remove or unscrew the plastic plug that covers the spool valve (similar to those installed in car cameras). Using a pressure gauge, it is necessary to measure the pressure and adjust it to the indicators of the heating system. To do this, air is pumped up by a pump or, vice versa, it is bleed by pressing the spool rod.

Note! The tank should be adjusted so that the pressure in its air chamber is 0.2 bar less than the design pressure in the system filled with coolant. If the pear-shaped membrane is not pressed on the water injection side, the coolant, compressing during the cooling process, will be able to draw air through.

After completing the settings, open the tap and fill the entire system with coolant. Then the boiler unit starts up.

The adjustment step is not required if the factory pressure in the air compartment of the expansion tank corresponds to the required parameters. Manufacturers of some brands of equipment indicate the pressure level in the tank on the packaging, which makes it possible to select the optimal option when purchasing.

Conclusion

You can correctly install the expansion tank and prepare the customized membrane tank for operation yourself, without the help of a specialist. The experience gained may be useful in the future if you need to quickly determine the source of problems associated with a decrease or surge in pressure in the system, due to which the burner flame goes out. In such cases, it is recommended that you first carefully inspect the system for coolant leaks and measure the pressure in the air chamber of the membrane reservoir.

Setup Guidelines
Conclusion

You have successfully selected and purchased a membrane-type tank for your heating system. The time has come to install it, and a lot of questions arise: where to put it, how to connect it, and so on. There is a lot of advice on this topic on the Internet, all of it contradictory. To clarify all controversial issues and consider in detail how to properly install an expansion tank, we bring to your attention this article.

Where to place the expansion tank in a closed heating system?

By the way, in private houses there are no open and closed systems; there are gravity and pressure (pump) systems. In the first, water moves due to the difference in specific gravity (natural circulation), and in the second, it is forced by a pump.

For reference. An open system works simultaneously for heating and hot water supply, and is used only in large centralized networks. This is why all individual systems are closed.

To correctly install the expansion tank in the heating system, the following requirements must be met:

the location of the tank is the combustion room, not far from the boiler;
the device must be placed in a place where it can be easily accessed for setup and maintenance;
if the tank is mounted to the wall on a bracket, it is recommended to maintain a height convenient for access to its air valve and shut-off valves;
The supply pipe together with the taps should not load the expansion tank with its weight. That is, the eyeliner should be attached to the wall separately;
the supply line to the floor expansion tank for heating is not allowed to be laid across the floor across the passage;
Do not place the container close to the wall; leave enough clearance for inspection.

Tanks of small capacity can be hung from the wall, provided that its load-bearing capacity is sufficient. As for the orientation of the tank in space, there is a lot of conflicting advice. Some recommend an installation method in which the pipe is connected to the container from above, and the air chamber, accordingly, is located below. Rationale - it is easier to remove air from under the membrane when filling; water will displace it.

In fact, in its original state, the rubber “bulb”, pressed on one side by air pressure, leaves no room for it on the other side, as shown in the photo above. Installation specialists advise installing the expansion tank with the connecting pipe downwards, and only this way. In some models, the fitting is initially located on the side wall, in its lower part, and it is impossible to position the vessel differently (see photo below).

It's easy to explain. The device will function in any position, even lying on its side. Another thing is that sooner or later cracks will appear in the membrane. When the membrane expansion tank is installed with the air chamber up and the pipe down, the air will penetrate through the cracks into the coolant very slowly and the tank will last for some time. If it stands upside down, then the air, being lighter than water, will quickly flow into the coolant chamber and the tank will have to be urgently changed.

Note. Some manufacturers suggest installing the expansion tank of the heating system by hanging it “head down” on a bracket. This is not prohibited, everything will work, only if the membrane malfunctions, the unit will fail immediately.

How to connect an expansion tank

After the container is securely attached to the wall or fixed to the floor, it is necessary to correctly connect the expansion tank to the heating pipelines. To do this, you need to outline a route for the pipe that runs the shortest route to the connection point. It is believed that the best connection point for closed membrane tanks is on the return pipeline. Just not just before the entrance to the boiler, but before the circulation pump (if it is not installed on the supply) and the accompanying shut-off valves. The expansion tank installation diagram is shown below:

There are several justifications for this sidebar:

in the return, the coolant temperature is much lower, which will extend the service life of the membrane;
if the installation and tapping location is on the return pipeline, then the circulation pump operates in comfortable mode;

In the supply pipeline of a solid fuel boiler, critical pressure and a steam-water mixture may occur due to overheating for various reasons. If this mixture gets into the rubber “bulb” of the container, it will stop performing its functions.

In fact, practice shows that there is no big difference in connection between supply and return. It is simply customary to connect the expansion tank to the heating system via a return pipeline, it is more reliable. But what definitely won’t hurt is a shut-off ball valve on the inlet, or even better, a fitting for emptying and a second tap. Then at any time the tank can be cut off from the system, the water drained from it and removed for repair or replacement.

Advice. For those whose gas boiler is not equipped with a pressure gauge or a safety group, it would be useful to integrate it into the circuit of the expansion tank using the following installation diagram:

Setup Guidelines

After installation and insertion of the device into the heating network, it is required to configure it. It is to provide the necessary pressure in the air chamber to match your system. This is necessary to avoid water hammer in the network; they can be created by the membrane of the tank while the coolant cools and its excess is pushed out of the chamber. The operation is performed in the following sequence:

when the installation of a closed tank is completed, the system is filled with cold water;
using Mayevsky valves and taps, air pockets are removed from pipes and radiators;
a pressure gauge measures the pressure in the system, and then in the air chamber of the tank;
By bleeding or pumping up, the pressure in the chamber is set 0.2 Bar lower than the pressure in the system.

Now that the expansion tank has been correctly installed and then configured, you can start the boiler. The pressure in the container will increase equally smoothly as the coolant heats up and cools down.

Conclusion

In principle, installing a compensating tank is not a very complicated procedure. Any special tools or devices are also not required; a regular set, which every thrifty owner has, is enough. But in order to install the tank in the heating system and configure it, you need to be more careful and not miss any little details. Then the device will last a long time and without problems.

cotlix.com

Correct connection and installation of the expansion tank

Installing an expansion tank in the heating system ensures its performance and reliability. Devices of this type are used in open and closed systems, with gravity or forced circulation of coolant.

Expansion tank functions

The main task is to perform reliable installation of the tank

How to connect an expansion tank

How to reliably connect an expansion tank in an open system!? An open-type heating system is characterized by the fact that the movement of coolant in it is ensured by convection.

Connection diagram for a membrane tank in an open type heating system

The tank must be installed in compliance with certain rules, in particular:

the tank must be placed above the boiler unit and connected by a vertical riser through which heated water is supplied;
It is recommended to insulate the body of the tank to reduce heat loss, especially if the tank is located in an uninsulated attic of the house.

Expansion tank in a closed heating system

Expander in a closed heating system

When linking a project to an existing boiler room, it is important to take into account the following points:

The tank should be placed in such a way as to ensure normal access for installation and further maintenance. Floor-standing models are not recommended to be installed close to the wall.
If the device is mounted on a wall, it is advisable to place it at such a level that you can easily reach the air spool and shut-off valve. Typically, the tank is placed under the ceiling of the room only if it is not possible to mount it at a convenient height.
The supply pipe should not be placed on the floor across the passage or suspended at human height.
The pipes connected to the expansion tank must be secured to the wall. It is important to avoid a situation where the load from them and from the shut-off valves falls on the tank pipes. Separate mounting of pipes and taps makes it easier to replace the expansion device in case of failure.

Rules for placing the expansion tank

Important! Many models of gas and electric boilers are mini-boiler rooms, that is, they are immediately equipped with a pump for forced circulation of the coolant, as well as an expansion tank. There is no need to purchase a separate tank if the parameters of the built-in membrane tank are sufficient to ensure the functionality and safety of the existing heating system.

Where is the best place to put the tank?

Note! The expansion tank of a closed heating system can be installed at any convenient height. There is no need to place it at the highest point as it functions solely as a surge protector. Unlike an open-type heating system, the air accumulated in the pipeline is released using special valves - air taps.

Scheme of possible tank placement

Attention! Installing a membrane tank on the supply line is highly not recommended if the heating boiler is solid fuel. There is a risk that due to an emergency, the water in the boiler will begin to boil and steam will enter the tank. Water vapor, like air, is a compressible medium, which is why the membrane will not be able to compensate for the thermal expansion of water.

Expansion tank installation process

By hanging the expander upside down, if the diaphragm malfunctions, the unit will fail immediately

Helpful Tips:

If you install a pressure gauge next to the expansion tank and the valve, thanks to which the heating system is fed from the water supply, it will allow you to control the pressure in the system in order to bleed off excess in time if the safety valve spool is stuck and does not operate automatically.
Frequently repeated release of pressure by the valve indicates that the capacity of the expansion tank is selected incorrectly. Instead of changing it to a larger tank, just connect a second tank in parallel.
Replacing the existing expansion tank with a larger one or connecting a second one will also be required if it is decided to replace the water in the system with antifreeze. This is due to the fact that non-freezing coolants have a higher coefficient of thermal expansion.

If there is no pressure gauge, the circuit of the expansion tank should be equipped with a safety group

Settings

Note! The tank should be adjusted so that the pressure in its air chamber is 0.2 bar less than the design pressure in the system filled with coolant. If the pear-shaped membrane is not pressed on the water injection side, the coolant, compressing during the cooling process, will be able to draw in air through automatic air vents.

After completing the settings, open the tap and fill the entire system with coolant. Then the boiler unit starts up.

Conclusion

Video on the topic:

profiteplo.com

How to properly install an expansion tank

For the heating system to operate efficiently, it is important to create conditions for uninterrupted coolant circulation and ensure its optimal temperature and pressure. This is only possible with accurate calculations and correct installation of each element separately. The correct selection and installation of the expansion tank affects the efficiency and reliability of all circuits of the heating system. Since this element is responsible for the safety and uniformity of the coolant, we understand the designs of modern expansion tanks and the features of installing devices in heating systems of all types.

We all know very well from our school physics course that any liquid tends to expand when heated. Since water is used as a coolant in modern heating systems, as its temperature increases, the pressure in all branches of the heating system increases significantly. If the heating circuit is an open system, then it will simply lose part of the coolant. In closed circuits, further heating will lead to an accident and depressurization.

Expansion tanks for heating systems

The problem of excess volume is solved simply - a hollow reservoir, called an expansion tank, is introduced into the heating system. It is he who receives excess water when heated, and then returns it back, eliminating the formation of air pockets. Since the reliability of the functioning of all circuits depends on this element, it is important not only to choose the right design, but also to install the tank in accordance with all rules and recommendations.

The second, no less important function of the expansion tank is to protect utilities from water hammer. Systems equipped with circulation pumps are subject to water hammer every time the pump is turned on. The expansion tank helps compensate for sudden pressure surges, acting as a kind of buffer tank.

In open-type heating systems, the tank is designed simply - it is a container connected to the atmosphere, into which a thin pipe is led from the highest point of the heating circuit. The tank is filled with water in such a way that at the minimum temperature the tube is immersed in the liquid by at least 10 cm. This water seal prevents air from entering the heating system.

The expansion tank of an open heating system can be made from any suitable container

An even more common design of an open heating system is with a tank at the highest point. The heating circuit is connected at the bottom of the tank, which allows air to be effectively removed from the pipes.

In closed heating systems, compensation tanks of a complicated design are used, and their installation and operation have distinctive features. Structurally, such a tank is a sealed capsule with a rubber separator, which forms two chambers in its internal space. Expanding coolant enters one chamber. Inert gas or air is pumped into the other.

Expansion tank design for closed heating systems

During heating, the working fluid fills one part of the tank, compressing the air that is in the other part. When the temperature drops, the coolant is squeezed out of the container back into the heating system. Depending on the separator configuration, compensation tanks of heating systems are divided into two types:

expansion tanks of the diaphragm (membrane) type;
balloon (flanged) expansion tanks.

The use of a rubber barrier allows you to separate the coolant from the air, while allowing it to freely change its volume.

Diaphragm Tanks

Structurally, such an expansion tank is made of two hemispheres, between which a rubber membrane is installed. A pipe for connection to the heating system is embedded in one hemisphere, and a valve for air injection is installed in the other. The membrane is fastened rigidly, since both containers are connected to each other by the flaring method. Under the influence of pumped air, the diaphragm is initially pressed against the wall of the coolant chamber. During the heating process, the volume is filled with liquid and the pressure in the air chamber increases. Despite the high reliability of tanks of this type, there is a risk of rupture of the membrane when the pump is turned on, with a sharp surge in pressure in the system. The second disadvantage of membrane containers is their low maintainability - it is not possible to replace the diaphragm at home. And the third disadvantage is that due to the design features, such tanks have a small volume, which significantly narrows the possibilities of their use.

Compensation devices for closed heating systems

The design of the flanged compensation tank eliminates all the disadvantages inherent in membrane tanks. Firstly, using a rubber balloon (bulb) as a separator allows you not to worry about its damage when the circulation pump is turned on, since the operating pressure of the balloon tank is much higher than that of a diaphragm compensator. Secondly, if necessary, the bulb can be easily replaced through a removable flange. Thirdly, the line of separation tanks with a cylinder inside is presented in a very wide range of volumes. However, in this barrel of honey there is also that fly in the ointment - the cost of flanged expansion tanks is much higher than the price of membrane devices.

Installation of compensation tanks

Installation of expansion tanks is carried out in accordance with the installation rules and depends on the type of heating system.

Open systems

Installation diagram of expansion tanks in open heating systems

The main requirement for an open-type heating system is the rapid rise of the expanding coolant to the top point of the system and the possibility of its movement through the pipes by gravity. At the same time, the air from the circuit also rises upward. By installing an expansion tank at the highest point of the system, both conditions are successfully solved.

The compensation tank itself for this case is a water tank with an open top, into the bottom of which there is a pipe cut in for connecting the pressure heating branch. Installation of the device is carried out both by welding steel pipes and by connecting polypropylene elements using a soldering iron. It is only important to ensure the required flow area of the pipeline.

Closed system

Place of expansion tank in a closed heating system

In closed circuit heating, installation of an expansion tank requires compliance with certain rules:

installation can only be carried out at positive temperatures;
the expansion tank is connected on a straight section of the line in front of the circulation pump;
it is mandatory to install a safety valve in parallel with the compensation tank;
when choosing an installation location, it is necessary to ensure access to the tank valve, safety valve and shut-off valves;
The minimum volume of the expansion tank is taken equal to 10% of the coolant volume.

Modern gas boilers are often equipped with small-volume expansion tanks (6-8 l), so if it is necessary to connect a long heating circuit, an additional tank is installed.

If during heating operation the pressure is released from the system through the safety valve too often, this means that the volume of the expansion tank is insufficient.

Preparatory work

Before starting work, the expansion tank must be adjusted. To do this, remove the plastic cover from its valve, connect a compressor or pump and pump air into the device using a pressure gauge until the pressure rises to 1.1 kPa. During operation, you will have to make additional adjustments to this parameter. The pressure in the pressure line should be 0.1-0.2 kPa higher than in the compensation tank.

Installation instructions

As in open systems, the connection of the expansion tank can be done by welding metal or polypropylene elements or metal-plastic pipes. It should be said that the last option is the least preferable. Welding steel pipes, of course, is the most reliable connection, but most likely such installation will be entrusted to a specialist, therefore, there is no need to describe the welding technology here. But the connection with polypropylene pipes is quite reliable and easy to repeat with your own hands. We'll tell you more about it.

The boiler is disconnected from the network, and the water supply taps to the unit are closed.
Drain the liquid from the heating system.
They tie the tank. To do this, cut a pipe of the required length, to which an “American” fitting is soldered on one side. A “tee” fitting is attached to its other end.
At the selected location of the return line, a tee with piping is inserted.
A safety valve is installed on the tank pipe, and a shut-off valve is installed below. This arrangement will allow you to drain water to check the pressure in the air chamber of the device. The joints are sealed with tow or fum tape.
Connect the assembled structure to the system.
The heating system is filled with water by first opening the Mayevsky taps on the radiators.
The system is considered filled with liquid when the pressure reaches 1.2-1.3 kPa.

Installing a shut-off valve in the area between the expansion tank and the heating circuit will allow you to remove the device for repair or replacement without draining the water from the heating system.

Possible installation errors

Expansion tanks of the membrane type must be installed with a top supply of coolant, while cylinder devices are undemanding in terms of location in space.

When installing an expansion tank, make sure that it does not interfere with the boiler and other utilities during maintenance. It is best to place the container on the floor in the corner of the room.

Video: examples of installation of expansion tanks

The performance of the heating system depends on how correctly you choose and install the expansion tank. Therefore, even at the design stage, calculate the required volume, decide on the design and study existing proposals. And the key to reliable and efficient operation of the device will be proper installation, taking into account existing rules and recommendations.

remkasam.ru

Installation of expansion tank | Construction portal

The use of an expansion tank is necessary in every closed heating system, and even in some systems connected to central heating. The process of installing an expansion tank is quite complicated, but if you carefully study the instructions, doing it yourself, without involving specialists, is quite possible.

Operating principle of the expansion tank

The expansion tank is a metal tank that is connected to the heating system. The main function of this device is to eliminate the increase in pressure in the pipeline due to expansion of the coolant.

Expansion tanks come in two types: open and closed. The operating principle of each of these tanks differs from each other.

The open expansion tank has a metal lid that opens to add coolant to the system.

A closed expansion tank consists of a metal container that does not have any openings other than the connection to the system. The container is separated by an internal membrane made of rubber. When the pressure increases, the rubber bends and the coolant enters the tank; when the pressure decreases or the coolant leaks, the rubber presses on half of the tank in which the gas is located and the coolant enters the system. Thus, the expansion tank is a pressure regulator that prevents high voltage surges in the system. If you do not use an expansion tank, the heating system will not function properly, and taps, pipes and the boiler will quickly fail.

Expansion tanks are used in a private heating system, and in some cases also in a system connected to central heating.

Types of expansion tanks for heating

Expansion tanks are divided into:

An open expansion tank has a number of disadvantages, so it is rarely used, mainly in cases where the system is not connected to a pump and water circulates freely.

Disadvantages of an open expansion tank:

due to frequent opening of the lid, contact between components of the oxygen heating system occurs, which causes rust to form on the walls of pipes and radiators;
when the water temperature rises, the liquid evaporates, so you should periodically add coolant to the system;
an open expansion tank is installed at the highest point compared to the heating system, so installing such a device takes a lot of time.

The only advantage of an open expansion tank is its low cost compared to a closed one.

A closed expansion tank is called a membrane tank; depending on the type of membrane, there are:

expansion tanks of replaceable type,
non-replaceable expansion tanks.

Replaceable expansion tanks require replacing the membrane if damaged. To replace the membrane, simply unscrew the flange.

Non-replaceable expansion tanks mean replacing the entire tank if the membrane is damaged. Such tanks are more resistant to pressure changes, and the membrane fits perfectly and hermetically to the outer wall of the container.

Expansion tanks come in two forms:

The balloon shape resembles a large container in which a membrane or lid is located, depending on the type of tank.

Flat expansion tanks have a flattened shape and a membrane in the form of a diaphragm. The advantage of flat expansion tanks is that they take up little space and are easy to install.

Calculation of expansion tank for heating

The size and volume of the expansion tank is affected by:

system type;
system capacity;
maximum permissible pressure;
installation location of the expansion tank.

The easiest way to determine the volume of the expansion tank is to find out the capacity of the heating system and divide this amount by 10%. For example, if the heating system contains 400 liters of coolant, then the volume of the expansion tank will be 40 liters if the coolant is water. If glycol fluid is used as a coolant, then another 50% must be added to this amount.

Please note that 3% of the coolant in the closed expansion tank goes to compensate for possible leaks. In any case, the volume of the tank obtained as a result of the calculation should be slightly increased.

To obtain an accurate calculation in large or complex heating systems, it is better to trust specialists or use an online calculator.

The correct design of the expansion tank is indicated by the failure of the safety valve.

Installation of an expansion tank for open heating

The open expansion tank is where water comes into contact with oxygen. An open container is used when water moves freely through the system without using a pump or when the system is connected to central heating.

Since air comes into contact with water, the entire heating system is designed at a slope so that excess oxygen is forced out of the radiators.

Expansion tank installation location: the highest point in relation to the heating system. The installation height of the expansion tank must exceed the installation height of the heating system.

Expansion tank installation diagram:

An additional expansion tank is installed if it is impossible to mount the heating system at an angle. The installation level of the main and additional expansion tanks must be the same.

The open expansion tank includes pipes:

expansion,
signal,
circulation,
overflow.

Using an expansion pipe, the tank is connected to the heating system.

In most cases, an open expansion tank is mounted near the boiler and connected to the water supply system using a signal pipe that monitors the coolant level.

The overflow pipe connects the tank to the sewer; when the tank overflows, the liquid is automatically drained into the sewer.

The circulation pipe ensures the supply of coolant if the expansion tank is located in an unheated room.

Installation of a closed expansion tank

Before studying the rules for installing a closed expansion tank, let’s consider the advantages of this device over an open expansion tank:

minimal heat loss;
do not need isolation;
work at high pressure surges;
installation anywhere, without reference to the highest point;
closed type devices are more compact and easier to install;
no rust formation on the internal walls of the heating system;
ease of maintenance.

Tools for work:

adjustable wrench;
wrench for installing plastic pipes;
step key.

The preparatory stage includes:

disconnecting the boiler from electricity, gas or water supply;
turning off the tap responsible for coolant circulation;
draining the coolant from the heating section on which the expansion tank is installed.

Instructions for installing the expansion tank:

1. Install a shut-off and drain valve on the supply pipe to shut off and drain the water.

2. Connect the expansion tank to the system using screws or flanges. If the heating system pipes are polypropylene, you need to use a soldering apparatus, couplings, angles and fittings.

3. A fitting called “American” will help you easily remove the tank for replacement or repair in the future. Before installing the fitting onto the expansion tank, wrap linen tape around the threads and apply sealing paste.

4. When the water has been drained from the system, cut the pipe with special scissors and install a tee.

5. Install the safety valve and pressure gauge.

6. Before starting the system, clean the coarse filter.

7. Before connecting the expansion tank to the system, you need to create operating pressure. To do this, use a pump.

8. When the expansion tank is connected to the network, turn on all coolant supply taps and turn on the boiler.

1. Install the expansion tank so that the coolant flows from the top.

2. In the absence of data on the exact volume of the heating system, the capacity of the expansion tank is calculated based on the boiler power: 15 liters of liquid are calculated for 1 kW of power.

3. Before purchasing and installing an expansion tank, inspect the heating boiler. Many modern boilers have a hidden expansion tank, which is located in the middle of the boiler.

4. Do not install a closed expansion tank near the circulation pump, due to the occurrence of large pressure drops.

5. Installation of a vacuum expansion tank is carried out only at positive temperatures.

6. Installation of a closed type membrane expansion tank is carried out on the side of the cold water supply to the boiler.

7. As a sealant, use only those sealants that are resistant to high temperatures, otherwise leakage is inevitable.

8. When determining the location and installation of the expansion tank, you should think about the further approach or maintenance of the device. Do not install the expansion tank in hard-to-reach places.

9. When installing the expansion tank, follow safety rules and generally accepted instructions.

10. Be sure to read the manufacturer's instructions for installing the expansion tank.

11. Be sure to install a safety valve, which sometimes comes with the tank; if there is no valve, buy it separately.

Maintenance of the expansion tank for heating

1. Once every 6-7 months, the expansion tank should be inspected for mechanical damage or rust. If they are present, you need to fix the problem.

2. In closed expansion tanks, the pressure should be checked once every six months.

3. In devices with a replaceable membrane, the membrane must be periodically checked for integrity or damage.

4. If the expansion tank is not used for a long time, store the tank in a dry place, making sure to drain all water and dry the device.

6. It is best to use an inert gas, such as nitrogen, to fill the air chamber.

7. The correct operation of the expansion tank depends on the pressure and temperature of the heating system.

8. If the pressure drops sharply, there is a risk of damage to the membrane. To replace the membrane you need to perform a number of steps:

disconnect the expansion tank from the system;
relieve pressure in the tank using the valve located at the top of the tank;
remove the flange located at the point where the tank is connected to the system;
remove the membrane and drain excess water;
insert the membrane and install the flange;
attach the tank, having previously set the desired pressure.

The purpose of such equipment is to protect the system from water hammer and ensure uninterrupted operation of the entire engineering system. Once you purchase this machine, you will need to consider how to install the diaphragm tank to ensure it works properly.

For reliable and correct installation you will need to follow some technical recommendations.

Read the instructions carefully.
Carry out all the necessary technical calculations of temperature and pressure values. They must be specified in the operating standards manual.
Prepare tools: a wrench, a wrench for mounting plastic pipes and working with detachable connections.
If the tank has a large capacity, then you will need to purchase additional mounting brackets.

Before installing a membrane tank, consult a specialist; he will correctly carry out all measurements and calculations of the necessary equipment.

When you have everything ready, you can safely get to work.

Conclusions that can be drawn from many years of equipment installation practice say that horizontal tanks are the best option, at least they are easier to install. Vertical mechanisms are most often chosen to work with submersible pumps.

When installing and connecting, you need to follow some recommendations.

It must be located in such a way as to provide unimpeded access to it in the future (this is necessary for carrying out repair work).
Provision should be made for possible dismantling of connecting pipes.
The diameter of the connecting pipe must be the same as the connected pipeline.
It is important to properly equip the system with temperature sensors.
Provide and calculate the connection of shut-off valves.

Tank installation

Hanging should be done from the side of the flow-through coolant inlet, towards the heating unit.

Having marked the mounting location, you should drill the required number of holes for the bracket. To do this, we attach it to the wall and mark the connection points. Having drilled the required amount, we fix the anchor bolts in them, hang the bracket and check the quality of the fastening. If everything is in order, install the tank and secure it with clamps.

Installation must be done from the side of the circular pump, namely where the suction side is located. In this case, there should be no elements between the tank and the pump that could affect the hydraulic resistance. Connect the make-up line to the circular circuit.

You cannot install equipment in sub-zero temperatures. Also ensure that after installation the air valve is located in an accessible area for ease of setting the required pressure.

All control mechanisms (shut-off and control valves, nameplate and drain valve) must be located in an accessible area. Pipes should be located so that they do not exert physical pressure on the equipment.

The pressure reducer is installed after connecting the measuring meter, in order to avoid possible load on the tank. The safety valve, according to the installation rules, is mounted in front of the flow pipe.

To avoid unforeseen situations, it is better to install two shut-off valves into the system, before and after the expansion tank, as well as one drain valve in front of it.

Tank setup

After you have completed all installation work in the correct order, you can begin setting up the equipment. First you need to gain the necessary pressure in it. This is done by pumping air. The pressure gauge will show when enough is enough. Then, using a pump, you pump in water, balance the pressure and bring the membrane to a floating state. The tank is ready for use, you can turn on the system and check its functionality.

Tank repair - membrane replacement

Tanks differ in the way the membrane is installed: they can be removable or fixed. And if the second option has a large margin of safety and can last a long time, then in the case of the removable option they can be replaced.

First you need to unscrew the bolts on the flange connection, pull out the flange and membrane, put a new one in place and fasten everything again. Anyone can do this job and it only takes about 20 minutes.

Mistakes that are made during installation

During self-installation, many people make some mistakes that directly affect the quality of operation of the entire heating line.

The main mistake is using seals that are not intended for such work. In particular, during operation they cannot withstand pressure, and rupture occurs with subsequent leakage of water.

An important role is played by the correct location of the membrane tank, a balanced selection of volume and the availability of the necessary tools: stepped and adjustable wrenches.

Bottom line: if you did everything correctly, then throughout the entire heating season you will not experience problems with the operation of the membrane tank.

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 pipe and in the return pipe 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, this 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 takes on 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 one by one:

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 that is 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 changes 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.

How to install the expansion valve correctly. How to install a membrane tank for water supply? Expansion tank functions

Read also

How to connect an expansion tank

Expansion tank in a closed heating system

Where is the best place to put the tank?

Expansion tank installation process

Settings

Conclusion

Where to place the expansion tank in a closed heating system?

How to connect an expansion tank

Setup Guidelines

Conclusion

Correct connection and installation of the expansion tank

Expansion tank functions

How to connect an expansion tank

Expansion tank in a closed heating system

Where is the best place to put the tank?

Expansion tank installation process

Settings

Conclusion

How to properly install an expansion tank

Diaphragm Tanks

Installation of compensation tanks

Open systems

Closed system

Preparatory work

Installation instructions

Possible installation errors

Video: examples of installation of expansion tanks

Installation of expansion tank | Construction portal

Operating principle of the expansion tank

Types of expansion tanks for heating

Calculation of expansion tank for heating

Installation of an expansion tank for open heating

Installation of a closed expansion tank

Maintenance of the expansion tank for heating

Tank installation

Tank setup

Tank repair - membrane replacement

Mistakes that are made during installation

IN What are the advantages of a closed heating system

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

Video: installation of Flexcon brand expansion tanks FLAMCO»

How to calculate the required parameters of the expansion tank?

Calculation using formulas

Calculator for calculating the required volume of the expansion tank