Expansion tank heating system: device, calculation and selection of the best variant

True selected and mounted expansion tank heating system will not allow its exit from the system will support pressure at the required level.

Depending on the type of system, a built-in extender can be open or closed.

Expanders open

Design feature expanders open coolant is contacted with the atmosphere. Circulation in systems with a spreader of this type of convection. Upon heating the liquid volume increases, its excess absorbed reservoir tank.

When the temperature fall performance liquid is returned by gravity, under the action of gravity. Due to zero pressure in the tank, the device does not require a solid metal structure, however:

• in the manufacture of any metal body is applied;
• finished container may be used from the heat-resistant plastic;
• It is not in principle form the reservoir.

In the lodges, such equipment can be assembled improvised. As the container can be used a plastic canister or barrel equipped with a receiving port and outlet for the overflow.

Open-type expanders can be manufactured in the form of a rectangular tank with ventilated caps on the upper plane

Outwardly, this conventional metal tank, the upper plane of which is provided with an opening for maintenance and adding of liquid. It provides protection against clogging vented cap. At the bottom or on the side of the plane provided fastening units.

Features an open tank installation

Open heating systems are used in low-rise buildings, where the volume of coolant and length of heating communications are relatively small. Installation requirements simple:

• expander is placed on the maximum height on the feed line;
• supply is connected to the tank through a nozzle;
• to drain excess liquid overflowing performed inset above the design level.

To circulate by gravity, for installation it is recommended to use pipes increased section.

They give an open structure at the top, where liquid flows by gravity

Usually they try to mount a tank in a heated room, equipped insulated attic, and if this is not possible, then the capacity required to insulate. The presence of insulation does not allow freezing of a liquid and loss of system performance.

Characteristics closed expander

Constructive modifications specificity closed tank is full tightness, thus maintaining the pressure required for circulation at any point in the system. The tank is divided in the membrane at the air and liquid parts. Each of the compartments is completely sealed - nitrogen-containing mixture of air department never mix with the coolant liquid filling the compartment.

The principle of operation of the expander is that the heated fluid is ejected from the system into the liquid part of the tank and starts to press with their sides at a sealed membrane. The septum is deformed and acts on the part of the air, compressing it.

The volume of air tank chamber decreases and the gas therein is compressed. This situation leads to an increase in pressure in the system. As soon as the pressure normalization, the coolant from the liquid chamber is pushed back.

If the pressure rapidly increases, then, when reaching a critical volume of liquid in the tank, a safety valve is triggered. The result will delete excessive amount of coolant from the tank.

The closed structure is completely sealed in its lower part is a receiving flange fitting at the top - the gas filling nipple

Depending on the shape of all closed expanders for installation are divided into these types of heating system:

1. Sharobraznye - a kind of membrane structure with a flexible partition. On admission of fluid it expands and takes the entire excess volume. Tank itself has a kind of spherical capsules.
2. Oval - another type of membrane lash. The balloon dilator traditionally divided by a flexible membrane into a gas and a liquid chamber, but the configuration of the housing has several vertically-elongated shape.

Externally oval balloon dilators are of cylindrical shape which is colored red. On the one hand, the nipple is provided for creating a pressure in the gas chamber on the other - a connection, through which the connection to the system.

On the case welded onto the fastening components, which provide a hinged assembly of equipment and able to withstand the operating weight. The spherical tank modification is different from the oval shape only.

By variety membrane closed expanders are divided into diaphragm and balloon modification

Subtleties of the closed tank installation

In systems gated gravity circulation will not be able to provide the necessary pressure. Therefore, in the structure include a circulating pump.

Sam expander can be placed anywhere in the system, but the installation work, it is desirable to consider the following recommendations:

• the best place for installation - a return line, to the point of tapping of the pump;
• supplying coolant better bring the top, which will reduce air infiltration, and maintain its operability in case of damage of the membrane;
• drawback can be compensated bulk installing additional expander with lower capacity.

When installing it is not forbidden to take into account the interior premises, if necessary. For pressure control extender must be equipped with a pressure gauge.

Indoor expander usually pose boiler to place a circulation pump installation

The ability to place near the boiler eliminates the need for insulation of the tank. The equipment is located in a warm room, which ensures ease of use.

Advantages and disadvantages of tanks

Systems, depending on the apparatus and the material expansion tank differ list pros and cons. But, according to experts and power users, the advantages in functionality on the side of the closed variants.

Pros and cons of open construction

Samoprotochnaya system needs a large-diameter pipes, which in turn directly increases the costs. Budget arrangement of the heating system with an open expansion increased slightly, although it remains relatively small.

The main advantages of this option are considered to be easy plus low cost of components and assembly work. Another positive feature is the lack of need to control pressure.

However, much more minuses:

• application nezamerzayki dangerous because of the toxic fumes;
• mounting possibilities are limited only by the top point of the system;
• permanent contact with the atmosphere increases the risk of air pockets or corrosion;
• Slow warm-up;
• temperature changes accompanying the convection circulation, accelerate the deterioration of the equipment;
• used for heating low-rise buildings, a maximum of two floors;
• large heat loss and energy consumption for heating.

Another disadvantage of the open system - evaporation losses and spillovers. Therefore, when installing the tank should ensure the availability of dolivnogo holes.

Outdoor expander for small systems can be assembled from improvised means, is simple and its installation

Advantages and disadvantages of a closed tank

If the price and ease of installation works win open expanders, the functionality - the strong side of the closed tank, which is also called ekspanzomat. That they are trying to replace open modifications when upgrading a heating system.

Ekspanzomaty have the following advantages:

• complete sealing can be used antifreeze;
• place expander placement does not affect the performance of the system;
• isolation tank interior space minimizes the possibility of air pockets and the occurrence of corrosion;
• after starting the system warms up faster, more sensitive to the adjustment of temperature conditions;
• the smaller the difference between the operating conditions of supply lines and return, which in turn improves the service life;
• It does not require the installation of large-diameter pipes that saves on construction;
• It does not require constant attention to the level and the fluid condition;
• the possibility of use in systems designed for several floors;
• small heat loss, reduces the cost to operate the equipment.

When selecting extenders of this type may occur sealed containers with sealed structure. In case of failure of the diaphragm tank should be changed to a new one.

To control the level of the working pressure on the cylinder mounted pressure gauge, for removing excess air bleed valve is set for automatic or mechanical type

Among the few drawbacks is important to note the complexity of the design, the special requirements for materials that increase the cost of the equipment. Added to this is the need for constant pressure control and restore when required.

Rules for calculating the storage volume

The expander of any kind will be effective only if the correct choice of size. For this purpose should take into account the ability of the liquid to expand during heating. Water in the heating rings extends at least 3% of total water system, antifreeze - nearly 5%.

Liquids are classified as incompressible fluids, so they tank should provide enough allowance for thermal expansion with a certain margin. Assuming complete filling of the coolant circuit even in thermal expansion calculated volumes can lead to fluid discharge through the pressure relief valve and a strait coolant on the floor.

Therefore, the excess amount of the expanding coolant is not led to accidents, closed containers for small contours in private homes gain so that their volume was equal to 10% of the total volume circulating through the system coolant. This rule applies to systems capacity up to 150 liters.

If the heating ring moves more than 150 liters of coolant, the closed tank capacity is calculated by multiplying total volume of fluid at its expansion coefficient for specific values ​​of the operating temperature system.

To the resulting value must be added the size of the water trap, i.e. coolant volume formed in the tank as a result of standard static fluid pressure. For large heating rings, this figure is usually equal to 0.5% of the total volume of the heating medium to small capacity of up to 150 liters, it takes 20%.

The resulting sum is multiplied by the correction coefficient determined by the values ​​of the preliminary and final pressure in the heating system. Preliminary taken into account that the 10 m contour height falls 1 bar. The final pressure is generated as a result of system operation.

Calculation of closed-type tank for heating large, complex structures like this:

The calculations used: Vn - nominal volume of the closed tank; Ve - amount of coolant during thermal expanded (calculated by the formula Vsistemy × n%, where n is the coefficient of thermal expansion of the coolant); Vv - water seal; po - preliminary pressure; pe - figure final pressure equal to the limit value of the pressure relief valve minus 0.5 bar

Capacity open standards are not strictly regulated, but there is a rule: the amount of open the overflow tank to the nozzle should be 3.5 - 4% of the total volume of coolant in the heating circuit.

Such an assessment is sufficient for a small country house, but the structure for permanent residence will require a more accurate calculation. Primarily need to find out the total amount of the heating system.

Embodiments calculate the total heating capacity

This rate can be determined with varying degrees of precision in three basic ways. First, based on passport data of the boiler.

Thus, per unit of power boilers need about 15 liters of liquid. To obtain the necessary data, it needs 15 times the capacity of the boiler as specified in the data sheet.

Secondly, it is possible to find out the volume using the water meter when filling the system. As the filling is taken into account the amount of used liquid. It is more accurate and troublesome option.

The third method involves calculate the total amount of all elements of the heating system. This is the most accurate option.

The capacity of the boiler heat exchangers, radiators, convectors, measuring instruments can be found out on the passport characteristics. To calculate pipe capacitance data from the table are used.

The table shows the pipe dimensions in inches and the volume in liters at 1 meter, which is used for summing the total (+)

The table shows the amount of pipes per meter, made of the most popular and advanced materials. The internal diameter is specified in inches of from 0.5 to 1.5 units.

Another way of applying for higher accuracy - the calculation according to the formula:

Vobsch = π x D2 x L / 4

Where:

• π is equal to 3.14;
• D denotes the inner diameter of tube parameters;
• L indicates the length of the pipeline system.

After obtaining the necessary data they are summed to give the total volume of the system which was used in subsequent calculations.

Selection of the expansion tank according to Table

With the necessary data an optimum variant of the expander can choose the volume and rated pressure table.

The total volume of the system is calculated according to the above procedure, only the pressure parameters relevant for closed modifications and equipment specified in passport data.

The data from the table allow to select the volume of the expander 4 to 300 liters (+)

This embodiment does not require special calculations other than calculating the total system. Using the table greatly simplifies and speeds up the selection of the expander with the necessary capacity of the reservoir.

Using the formulas for the calculation of

If the data table is not enough, it is possible to calculate the required storage volume indicator alone.

For this purpose, the following formula:

Vb = Vc x k / D

Where:

• Vb represents the required capacity of the expander;
• Vc - total capacity of the system;
• k - the coefficient of expansion of the liquid during heating;
• D - efficiency factor expander.

Of the necessary data for calculating the unknowns are the coefficients k and D. Origin - tabular value and the second calculated by a separate formula.

There is also a table and used thermal expansion. It enables to determine the coefficient for the systems with water or antifreeze. The quantity is not a linear change upon heating, depending on the presence and concentration of glycol in the liquid.

With these data it is possible to determine the parameters of fluid expansion coefficient during heating (k), required to calculate the volume expansion balloon (+)

For a water concentration of the ethylene glycol taken as "0", the antifreeze concentration is determined from the data declared by the manufacturer. Heating temperature is considered operational for a particular system.

To manually calculate the efficiency ratio of the expansion tank, the formula is used:

(Qm - Qb): (Qm + 1)

Where:

• Qm - the maximum system pressure for passport threshold of the safety valve;
• Qb - the pre-pressure in the air chamber of the expander at the data sheet.

If the latter option is not known, it is measured by pumping or by etching through a pin cylinder.

Other methods of calculation

In addition to independent calculation using formulas and tables there are alternative ways. Available version of the calculation - help online calculator.

Lack of network resources that offer online to calculate the required amount no. They are easy to find on the keyword

Another option to get the right data - an appeal to professional designers. This is the most reliable method, but the accuracy of the information received will cost quite expensive.

How to choose the extender

Determined the type of heating system is recommended at the planning stage. Selection tank usually delayed until after the erection of the box, when the system is mounted, its volume is known.

When selecting the optimal embodiment of the expansion tank is recommended

• focus on the volume of the closed expansion tank that exceeds the thermal expansion of coolant;
• when you buy should pay attention to the connection form of the vessel and the location of connectors for fixture - this will avoid surprises during assembly;
• it is important to pay attention to the instructions on the package, which contains useful information on installation and technical parameters.

When buying a better focus on the proven producer, even if it will cost more cylinders. This will ensure the durability of the heating system, however, subject to proper operation and regular maintenance.

Before connecting the initial pressure in the gas compartment membrane tank is set to a value equal to the column indices of coolant static pressure in the heating circuit. Adjustment is made in the usual motor pump controlled by a pressure gauge.

The main thing is not to buy a heating system boiler capacity - they are completely different in its specifications

Do not confuse expanders for heating systems and hydraulic accumulators for the cold water supply lines. They differ in appearance and design features. The first painted red and are usually not collapsible, and the latter have a blue color, equipped with a removable flange for membrane repair.

Useful videos on the topic

Video will help to define the parameters of the extender closed modifications to clarify differences cylinders for heating and boiler systems:

The principle of operation and characteristics of the container of choice in the video clip:

Heating private homes can be performed on an open or closed circuit, which requires the installation of an appropriate design of the expander. A key factor in his performance is the amount that can be calculated independently or entrust this work to a professional designer.

Correctly chosen equipment will help maintain the desired displacement of liquid in an open system, and in a sealed heating systems to support the working pressure.