Expansion membrane tank for heating: design features and principle of operation. The nuances of selecting an expansion tank for a heating system Water expansion tank

The next step is to install the tank into the system or open the shut-off valve, if it has been installed. Then the make-up valve is unscrewed and the pressure Pnach is set according to the following formula:

• Pinit> or = P0 + 0.3 bar.
• Having fixed and established the obtained data, you can start the water. In this case, it is important to read the readings of the pressure gauge relative to the pressure Ppl. The latter is to re-enable the make-up and bring the pressure up to Рcon. Its size is calculated by the formula:
• Pcon< или = Pкл – 0,5 бар.
• In this case, Pkl is the pressure of the safety valve. For private households, this figure is 3 bars.

Do not forget that in the event of a complete breakdown, you can.

The correct setting of the tank is the prerogative of specialists. What are the above calculations for? These data will help the user to independently configure the tank in such cases:

• pressure has dropped to critical levels or is absent at all;
• it is necessary to replace the membrane;
• setting up a tank for an object of a non-standard plan.

The working principle of the diaphragm expansion tank

As a result of water heating, the coolant expands, the membrane gradually expands, displacing air from the chamber. Thus, there is an increase in pressure in the entire system as a whole. When the temperature drops, the water in the expansion tank is pushed back into the system. And this will happen exactly until the moment when the air and water pressure indicators are balanced.

Wester WRV-8 is a membrane tank for heating systems.

An expansion membrane tank is an element of a closed heating system designed to compensate for the thermal expansion of the coolant and maintain the required pressure.

Note! In addition to being used in heating systems, membrane tanks are also used in water supply systems. They "soften" the water hammer that occurs when the pumping stations are turned on / off, and also maintain a constant pressure in the system.

Diaphragm tank design

The expansion membrane tank for heating is a sealed cylindrical steel body coated with red epoxy lacquer (there are also blue lacquered tanks, but they are designed for cold water). There are 2 chambers in the body: gas and water, which are separated from each other by a movable gas-tight membrane (diaphragm) made of butyl rubber. Thanks to this material, the membrane is able to function stably at various temperatures (from -10 to + 100 ° C) and perform up to 100,000 cycles.

The membrane almost completely eliminates the interaction of the coolant and gas. The absence of such interaction allows the pre-pressure in the gas chamber to be maintained longer, which has a positive effect on the service life of the tank.

Note! Modern high-quality membranes are not simply pulled out under the pressure of the expanding coolant, but, as it were, "stick" to the walls of the tank. This principle of operation allows to increase the service life of the membrane.

Sectional view of the Reflex tank.

Both chambers have the same pressure, which allows maintaining the tightness of this section of the heating system. The air chamber is filled with a nitrogen-containing mixture. When the coolant expands, nitrogen is "compressed", allowing the coolant to "enter" into the water chamber.

Most modern membrane heating tanks have a nipple built into the body (similar to a conventional automobile one), with which you can "pump up" the air chamber by increasing the pressure in it. You can do this yourself at home using a pump or compressor. However, it should be remembered that it is recommended to inject nitrogen, and not air. The fact is that the oxygen contained in the air will cause accelerated corrosion of the walls of the tank body, which will inevitably shorten the service life of the device. Nitrogen, on the other hand, is neutral and does not corrode.

Tank beam and safety group. Manufacturer: LLC ROSTERM North-West, St. Petersburg.

Expansion tank of the Imera membrane type.

The tank body has an external threaded outlet for easy installation. Depending on the model, the thread can be:

• For low pressure tanks (from 0.5 to 1.5 bar) - 3/4 ″ or 1 ″;
• For medium pressure tanks (1.5 bar) - 1 ″;
• For high-pressure tanks (from 3 bar and above) - from 1 ″ to DN 100 flanged connections;

The principle of operation of the diaphragm tank

When the heating system starts up, the coolant heats up and increases in volume. This excess volume moves into the water chamber of the expansion vessel. After the coolant has cooled down, the pressure in the air chamber squeezes out the membrane, thereby displacing the coolant from the water chamber back into the heating circuit.

In addition, as noted above, the membrane tank maintains the required pressure in the entire heating system. So, for example, if an insignificant leakage of the coolant has occurred somewhere, then the pressure in the entire system should drop, but this does not happen, because the pressure in the air chamber will push the membrane and, with it, the coolant back into the system, thereby creating a limited make-up.

Diaphragm tank with safety group.

The diaphragm can be damaged by improper use:

• There is a possibility of membrane rupture if, when filling the water chamber with a coolant, the required pressure in the air chamber was not created;
• Before releasing gas from the air chamber, it is necessary to shut off and drain the coolant from the water chamber.

Tank calculation

Heating for every 10 ° C gives an increase in the volume of the coolant by an average of 0.3-0.4%. Based on these data, the required tank volume is calculated.

Percentage of expansion of the heat carrier (water) depending on the heating temperature:

Important! Any membrane tank for heating is equipped with a ball valve with a drain, which allows you to shut off the flow of the coolant to the tank. This is necessary for the implementation of a quick, convenient replacement of the tank in the event of a failure.

Expansion tank, open type

At the moment, this type of expansion tanks is practically not used, because has the following disadvantages:

Open expansion tank.

1. The coolant is in constant contact with air, which leads to the airing of the system and the appearance of air locks. Therefore, it is necessary to regularly remove air or is required. Otherwise, air can lead to corrosion of individual elements of the heating system, as well as to a decrease in heat transfer from heating devices;
2. Due to the constant presence of the coolant in contact with air, it evaporates. You have to regularly add coolant to the system;
3. Air microbubbles circulating through the heating system create unpleasant noises in pipes and radiators, and also lead to premature wear of parts. In addition, microbubbles "de-rate" the circulation pump;
4. Unlike the membrane tank, which can be installed at any point in the system (next to the boiler, in the basement, ...), the open-type expansion tank is installed only at the highest point. This leads to an increase in the cost of the system, because additional pipes and fittings must be used to mount the tank at the highest point.

Video

In an autonomous heating system, there is always an expansion tank for heating, or a compensator. Its function is to compensate for the excess pressure that occurs in the system when the coolant expands due to heating. With a rapid increase in temperature, the heat transfer fluid expands and a pressure jump occurs, the so-called water hammer. It can destroy pipeline elements and fittings. Other names for the expansion device: hydraulic accumulator, expansomat.

The device and principle of operation of expansion tanks for heating

Heating systems are open and closed. Accordingly, expansion tanks for heating exist of an open type and a closed one.

Open type tanks

An open expansion tank for heating is a parallelepiped-shaped container made of stainless steel. Such a tank is placed at the highest point of an open heating system, usually in the attic.

Pipes are connected to the tank:

• trunk;
• circulating;
• signaling, with a locking device.

In a heating system of this type, the coolant (water) circulates naturally, without pumps. Despite the relative cheapness and simplicity of such heating, it is gradually becoming a thing of the past due to numerous shortcomings.

• In an open tank, the coolant constantly evaporates, so you need to control the water level and add as needed. For the same reason, it is problematic to use another coolant, for example antifreeze - it evaporates even faster.
• Overflow of water from the tank is possible, therefore, it is necessary to provide for its drainage into the sewer or drainage.
• An open expansion tank requires good thermal insulation so that the water does not freeze in severe frosts.
• Additional pipes and fittings are required for installation in the attic.
• Air entering the system from the expansion device provokes corrosion of the piping and radiators, and also leads to the appearance of air pockets.

The open expansion joint system is suitable for heating small one-story houses. Larger houses are heated by closed systems.

Closed tanks

A closed or membrane expansion tank of a heating system contains an elastic membrane inside that divides the internal volume of the expansion tank into two compartments, gas and liquid. The gas part contains air under pressure (in some models - nitrogen or inert gas), and surplus coolant enters the liquid part when heated.

Closed tank (membrane)

The higher the temperature, the more the liquid part of the accumulator is filled. At the same time, the gas part is reduced and the pressure in it increases. When the threshold value is reached, the safety valve is triggered, excess pressure is released. And when the heating system cools down, the reverse process takes place, and the coolant returns from the tank to the pipeline.

The working principle of the diaphragm expansion tank

There are two types of membrane expansion joints.

1. With a diaphragm-type membrane. These are small tanks. The diaphragm membrane in them is non-removable and cannot be replaced: if it breaks, you will have to completely change the device.
2. With a balloon (pear-shaped) membrane. It can be changed when worn and is used in large 1000 liter tanks.

The volume of expansion tanks for heating can vary widely from two to several thousand liters. The shape of the closed accumulator is flat or cylindrical. In a flat expansion tank, the diaphragm-membrane is located vertically, in a cylindrical one horizontally.

It is worth paying attention: the membrane expansion joint is sometimes mistakenly called a vacuum expansion tank for heating. However, this device does not use vacuum. The heating system may have a vacuum deaerator to remove air microbubbles from the water.

Installing a diaphragm expansion tank

Unlike an open one, a membrane accumulator can be installed for ease of maintenance right at the heating point, next to the boiler. Usually it is placed in a straight section in front of the circulation pump, preferably so that water (or another heat carrier) enters the expansion joint from above. It must be equipped with a pressure gauge, a safety valve and connected to the return line.

Hydraulic accumulators with a volume of up to 30 liters are mounted on the wall, larger ones are installed on the floor. When mounted on a wall, the tank must be securely fastened, as its weight increases dramatically when filled with water.

Several membrane tanks in a heating station

Important performance data and calculation of the expansion joint volume

When selecting an expansion vessel, take into account the maximum operating temperature and pressure. For example, the heating medium can be heated up to + 120 ° C, and the peak pressure in the heating expansion tank can reach 6-10 bar (typical average value is 2-4 bar). Therefore, the characteristics of the membrane, its durability, heat resistance, and compliance with sanitary standards are important.

The volume of the expansion joint depends on the volume of the heat carrier as a whole in the system. It is not necessary to calculate the volume mathematically accurately, a simplified method is often used: a tank with a capacity equal to 10% of the total volume of the coolant is chosen. And if this volume is unknown, then they proceed from the power of the boiler and the type of heating devices. The ratios are as follows: for heating batteries - 11 l / kW, for underfloor heating - 17.5 l / kW, for wall-floor heaters - 7.5 l / kW.

If the capacity of the selected expansion joint is insufficient, the relief valve will release pressure too often. In this case, it is enough to purchase and connect in parallel another expansion tank.

It is quite difficult to take into account all the nuances, especially since in every house the heating system necessarily has its own characteristics. In order not to be mistaken when choosing and installing a device, it is better to contact a specialized company.

Video: installation of an expansion tank

A membrane tank is needed to protect the engineering system from water hammer and fully ensure its high-quality operation. After purchasing equipment, you need to carefully consider , how to install a diaphragm tank so that it works flawlessly. A hydraulic accumulator in the water supply performs several functions: it accumulates a supply of water, maintains the required pressure in the system, serves as a reserve to reduce the frequency of turning on and off the pump.

Without the installation of a diaphragm tank, the service life of the pump is significantly reduced. In a system provided with a hydroaccumulator, water can be drawn even in the event of a power outage. During the first start of the pump, the water chamber of the tank is filled with water. The larger the volume of water in the tank, the lower the air volume and the higher the pressure. Having reached the set pressure, which is needed to turn off the pump, it is automatically turned off. As soon as the pressure in the system drops to an acceptable level, the water supply will immediately turn on. A pressure gauge is installed to check the pressure on the accumulator. It is also necessary to configure the required range of equipment operation.

Before proceeding with the connection of the accumulator to the water supply system, you should:

• Carefully study the instructions supplied with the equipment.
• Carry out technical calculations of pressure and compare with those specified in the standard operating manual.
• To carry out a high-quality installation, you need a wrench for detachable joints and plastic pipes, a wrench of the right size.
• Special brackets are required to mount large equipment.

Measurements and calculations of the operated equipment must be carried out by a highly qualified specialist. The quality of the water supply system depends on the accuracy of the calculations and measurements performed.

Many years of experience in using membrane tanks for water supply has shown that horizontal models are the best option. If you have a submersible pump connected, purchase and install vertical hydraulic accumulators.

1. The tank must be installed in a place accessible for maintenance.
2. During installation, it is necessary to provide for the possibility of dismantling the pipes of the system, if necessary.
3. The diameters of the pipeline and the connecting pipe must match.
4. Be sure to install a pressure gauge to monitor system pressure.
5. It is also necessary to calculate and install the shut-off valves.

Elements that affect hydraulic resistance must not be connected between the pump and the accumulator.

Install the membrane tank only at positive temperatures. For the convenience of regulating the pressure, the air valve is installed in an accessible area. The same rule applies to the connection of a drain valve, an awl and both types of fittings.

To avoid unwanted load on the unit, the pressure reducer should be installed after connecting the meter. The safety valve must be installed in front of the flow pipe.

Installed in the system, two shut-off valves on both sides of the tank will help to avoid unforeseen situations. Install a drain valve in front of the accumulator.

Setting up the diaphragm tank

When the installation work is carried out according to the recommendations, it is necessary to adjust the operation of the mechanism:

1. While pumping in air, select the required pressure indicated by the pressure gauge.
2. Switch on the water pump.
3. Equalize the pressure and float the membrane.
4. The setup is complete. The water supply system with the membrane tank installed is now ready for operation.

If you have purchased a tank with a removable membrane, it can be replaced after a while. To install a new diaphragm, first unscrew the bolts on the flange joint, then remove the flange and the obsolete diaphragm. Install a new one and tighten everything again.

Installation errors to avoid

• Do not use seals not intended for such work. They very often lead to water leakage.
• The location of the tank must be chosen correctly.
• Inconsistency of the volume of the tank with the water supply system.
• Incorrectly selected tools for the job.
• The diaphragm tank must not be forcefully opened or drilled out.

An expansion tank is a very important element in heating, it helps to remove excess pressure in the heating system when the temperature rises in it. Tanks for the heating system are closed and open. Open ones have a number of disadvantages, but membrane (closed) ones are more perfect and they do not have the disadvantages that open containers have.

The Reflex V 1000 expansion membrane tanks are designed to compensate for changes in water volume that can occur when the water is heated. When choosing an expansion tank for your heating system, you need to pay special attention to the material and quality of the product with a durable and reliable housing. One of these reliable tanks is the Reflex n 1000 model for closed heating systems.

Description of the design and principle of operation

All tanks of the German company Reflex are made of the highest quality sheet steel. A model such as the Reflex N 1000 is Expansion pressure vessel with non-replaceable diaphragm... It is intended for use in closed heating systems, refrigeration systems and solar systems. It was created to compensate for the volume of the coolant during the period of heating or cooling the liquid.

The container with a membrane is made of high quality materials and has a polymer coating, this model is offered in red and gray colors. Diaphragm tank Reflex N 1000 divided into two parts (chambers) membrane. In one of them there is a low-inert gas - nitrogen, it is specially pumped there under pressure, in the second chamber there is water.

When the water begins to heat up, then the excess volume of liquid enters the membrane tank, this process p leads to gas compression, which is contained in another part of the unit. A slight pressure begins to build up in the entire container so that the pre-valve does not work. When the water cools down, it comes back again under gas pressure.

Features and specifications

Expansion membrane tanks are widely used. Most often they are installed in private homes, but they are also used in industrial complexes. The Reflex N 1000 tank model has the following specifications:

1. Heating + cold supply
2. Non-replaceable membrane
3. Threaded connection
4. Modern, attractive design
5. High quality polymer coating.

Expansion vessel from the German manufacturer Reflex N 1000 has such characteristics as:

The membrane container has an important advantage - the tightness and mobility of the membrane creates in both chambers, where there is water and gas, the same pressure... This property protects the system as a whole from depressurization.

Assembling and maintaining the device

The expansion tank is connected through shut-off valves, this provides protection against unexpected disconnection of the tank from the heating system. It can also be connected to a multi-boiler system for each individual boiler or for the entire system.

The Reflex diaphragm expansion tank requires an annual maintenance inspection. It is necessary to conduct measurements of the initial pressure first in the air chamber and then measure the pressure in the water chamber. Before servicing the tank, it must be disconnected from the system, the water chamber must be empty, the water can be drained through the drain device.

Reflex membrane tank application and quality assurance

Reflex is a universal diaphragm expansion vessel with diaphragm. The entire line of Reflex products is distinguished by a robust design and reliability in operation, does not require additional energy costs during operation. Due to its distinctive properties and technical characteristics are successfully used in individual construction e, as well as in industrial and residential buildings.

A protective polymer coating serves as a reliable protection against damage from the outside. The system is equipped with everything necessary to be comfortable for specific operating conditions.

Conclusion

All expansion tanks from Germany, Reflex, are of high quality, their coating is resistant to any environment, withstand various temperature fluctuations. The whole structure is designed to provide compensation for the heating medium in the case when the temperature in the Reflex N 1000 unit heats up or cools down during operation.

Given the German quality, the whole system has shown itself to be very reliable, this unit has already been appreciated by many citizens, therefore, numerous reviews about the Reflex N 1000 tank are only positive. The products of the German company are confirmed by all the necessary certificates.