Heating of a private house expansion tank. How to choose an expansion tank for a closed heating system? Expansion tank connection
Due to the constant rise in the cost of energy, many owners of private houses and cottages will improve their heating system by introducing new, more economical equipment. One of the elements of such equipment is an expansion tank for heating systems. In this article, we will try to tell about them in as much detail and as accessible as possible - why, for what and how much, avoiding unnecessary technical terms.
As we know, water tends to expand when heated. Yes, just like any other liquid. The coolant in the heating system is no exception. When the liquid expands, its excess needs to be put somewhere. For these purposes, in heating, they came up with expansion tanks.
First of all, let's remember the basic law of physics: when heated, bodies increase, and when cooled, they decrease. The circulating coolant (water) in the system, when heated, increases in volume by an average of 3-5%. To prevent accidents and maintain the efficiency of heating equipment, a container is needed, which will smooth out the temperature difference and, as a result, the pressure and volume of water. That is, when heated, the tank will take on excess fluid, and when cooled, it will drain it back into the system. Thus, the pressure in the boiler remains within acceptable limits. Otherwise, the automatic protection is activated and the system stops. Which can be unsafe in severe frosts.
Types of expansion tanks
There are two types of expansion tank for heating systems: open and closed - according to the type of heating system in a particular room.
The expansion tank compensates for the increase in the volume of the heated coolant, reducing the pressure in the wiring. Therefore, such a node must be present in both open and closed heating systems. Moreover, a tank for a closed system can even be made with your own hands, using home-made or ready-made containers.
Expansion tank - where it is most advantageous to place it
In most cases, the coolant compensator is mounted between the pressure fitting or nozzle of the boiler and the first battery. With this location, an open-type expansion tank replaces the safety valve - when the boiler overheats, the steam will not go into the system, but will break out, immediately into the atmosphere.
But for this to happen, the tank must be designed as the highest point of the system, raising it above the boiler, and above the batteries, and above the wiring. To do this, at the junction point of the vertical branch of the pressure pipeline with the horizontal section, a tee is equipped, to the upper outlet of which a piece of reinforcement is attached to connect the system and the tank.
Therefore, in multi-storey buildings, expanders are mounted in the attic area. Or under the ceiling in the boiler room, if, of course, the dimensions and volume of the tank allow it. Therefore, before assembly, we need to try to calculate the container geometry, starting from the recommended volume.
How to calculate the volume of a tank
The dimensions of the expansion tank for an open-type heating system are calculated based on the volume and temperature of the coolant. And the simplest formula operates on the first parameter only. In this case, the volume of the tank is equal to five percent of the same parameter of the system.
For example, if 200 liters of water were poured into the wiring, boiler and batteries, then the volume of the expansion tank is 10 liters (200 × 5%).
A more accurate and complex formula operates not only with the capacity of the system, but also with the temperature of the coolant. After all, heating by 10 degrees Celsius scales the volume by 0.3 percent. And since the initial water temperature is equal to room temperature (20 ° C), and the maximum heating temperature reaches only 100 ° C, then the scaling of the volume of liquid poured into the system is possible only up to 2.4% (((100-20) / 10) × 0.3).
That is, if the same 200 liters are poured into the wiring, then the volume of the tank according to the refined formula will not exceed 4.8 liters (200 × 2.4%).
In practice, it is better to use either a large value calculated according to a 5% proportion, or an average result, which is determined by half the sum of 5% and 2.4% of the coolant volume. And for a 200-liter system, the average volume is 7.4 liters ((10 + 4.8) / 2).
Now that we know the method for calculating the capacity of the tank, we can move on to the assembly technology of the product itself.
Homemade sheet metal construction
In a rare heating system, more than 200-300 liters of coolant will fit, therefore, the volume of our tank will be 10-15 liters. To make such a tank, we need a sheet of metal with dimensions of 50 × 75 centimeters. The thickness of the sheet can be arbitrary, but the 2 mm option is considered optimal.
Well, the build process itself is as follows:
- We cut the sheet with a grinder into two blanks 25 × 75 centimeters.
- We cut these strips with a grinder into six blanks 25 × 25 centimeters.
- We burn a hole in one workpiece with a cutter or an electrode and weld a fitting in this place with a threaded drive of 1.0 or ½ inches.
- We weld two workpieces at right angles to each other. We do the same with two more blanks. Next, we assemble a cube without a bottom and a lid, connecting these corners by welding.
- We weld the seams to a tight state. We test the joints with chalk and kerosene.
To check the tightness of the seam, we apply chalk from the outside, kerosene from the inside. If after some time greasy spots do not appear on the chalk strip, the seam is welded tightly.
- We weld the bottom to the cube - a blank with a welded pipe. We check the seams for tightness.
- We burn with a cutter or an arc from the electrode in the last workpiece a hole of 5 × 5 centimeters.
- We weld the workpiece with a hole on the side of the cube lid. The tightness of the seams in this case is not necessary to check.
As a result, we get a capacity of 15.6 liters (25 × 25 × 25 = 15625 cm3 = 15.625 liters). Moreover, in the assembly process, we consume metal without a trace, and the total capacity of such a tank is enough for a 300-liter system.
The only drawback of this option is the significant complexity of the process. Only an experienced welder will assemble such a tank. And if you don’t know how to weld sealed seams, then you’d better turn to a different type of metal structures, for example, to a tank based on a finished container - a cylinder.
Expansion tank from a cylinder
Both a 50-liter and a 27-liter cylinder can be put into the expansion tank. Only in the first case will a segment with a height of 25-30 centimeters be sufficient, and in the second case, the entire cylinder will have to be used.
Therefore, from the point of view of material savings, it is advantageous to use 27-liter or even 12-liter containers. After all, not even the largest 12-liter version can be connected to a system into which up to 240 liters of water have been poured. And the process of transforming a cylinder into a tank occurs according to the following scheme:
First, open the valve and release the remaining gas. Then twist the vanilla and pour off the fragrance, which is added to the bottles to form the specific flavor of the gas. It is better to drain the fragrance away from housing.
Secondly, pour water through the valve hole into the cylinder, filling it to the very top. After 5-10 hours, drain the water, away from housing.
Thirdly, cut off the conical part of the valve and weld it onto a fitting of the desired diameter with a drive - this is how you design the entrance to the tank. If welding does not work out, use the valve as an inlet, using a bellows connection for docking with the system, which can be screwed onto the external fitting of the valve.
Fourth, weld the legs to the cylinder body, orienting the container with the valve down. At the same time, the legs from the corners can be fixed with metal screws, using silicone washers for tightness.
Fifthly, cut through at the top point of the almost finished tank (from the side of the bottom of the cylinder) a hatch with dimensions of 50 × 50 millimeters. Through the hatch, you can pour water into the system or bleed steam or air from the coolant. In open tanks, this part must be present.
As you can see, it is not so difficult to assemble a tank from a cylinder, but there is an even simpler manufacturing method that involves using a polymer container as the basis.
Polymer tank
In this case, you simply take a plastic tank of the desired volume. It can be a canister of 10-40 liters, and a 5-liter container for oil or a glass cleaner, and even an ordinary 10- or 12-liter bucket. Although a base with square edges in this case would be preferable.
Next, you buy a regular threaded fitting with two spigots (threaded sections at the ends), a rubber washer, the inner diameter of which matches the outer diameter of the fitting, and two nuts (for the threaded spigots).
At the next stage, you heat one end of the fitting on fire (you can use gas stove) and burn the bottom of a canister, bucket or any other container with it. Next, you cut off the top (if it is closed) and burn three holes with a hot nail, placing them in triangles at the top. With these holes, we will attach the canister to the wall, so they should be located away from the bottom.
At the penultimate stage, you mount the fitting in the bottom of the tank. To do this, a nut is screwed onto the drive, and it is inserted into the hole. Then, from the inside, a rubber seal (washer) is put on the thread and the second nut is screwed on. It should press the rubber to the bottom, resting against the second (outer) nut.
At the last stage, you fasten the container under the ceiling using self-tapping screws or dowels that are inserted into holes pre-drilled or burned with a hot nail. Such a mount is enough to fix a 5-liter canister. For the 10-liter version, you will have to build a shelf.
How to connect an expander to a heating system
After the construction of the tank is completed, we must connect the expander to the system. And in this case, you need to act according to the following scheme:
- Drain the system. Moreover, it is possible to remove far from the entire volume, but only a tenth, by lowering the liquid level to the upper branch pipe of the batteries.
- Determine the highest point of the pressure pipe and cut a tee into this place. Note that a collet fitting can be used for polymer pipes, and if the heat pipe is assembled from steel reinforcement, then instead of a tee, a branch with a threaded end can be welded.
- Install the expansion tank near the ceiling or on the attic floor. In the latter case, the ceiling will have to be drilled, opening access to the wiring tee.
- Screw the bellows hose nut onto the tank fitting. Lower the other end of the bellows to the level of the tee. Screw it onto the wiring outlet (pipe or tee fitting).
Instead of a bellows hose, you can use a polymer or metal pipe, but this step will complicate the installation, so we choose not a rigid design, but a flexible hose. The valve at the tie-in point of the expander does not need to be mounted. Expansion tank for open type heating
The heating system, being a complex engineering structure, consists of many elements with different functional purposes. Expansion tank for heating - one of the most important parts of the circuit heating system.
When the coolant is heated, the pressure in the boiler and the heating system circuit increases significantly due to the temperature increase in the volume of the heat-carrying liquid. Given that the liquid is a practically incompressible medium, and the heating system is hermetic, this physical phenomenon may lead to the destruction of the boiler or pipelines. The problem could be solved by installing a simple valve that can bleed the excess volume of hot coolant into the external environment, if not for one important factor.
During cooling, the liquid contracts and air enters the place of the discharged coolant into the heating circuit. Air locks are a headache for any heating system, because of them, circulation in the network becomes impossible. Therefore it is necessary. The constant addition of a new coolant to the system is very expensive, heating cold water it is much more expensive than heating the heat-carrying liquid that came to the boiler through the return pipeline.
This problem is solved by installing the so-called expansion tank, which is a tank connected to the system with one pipe. Excessive pressure in the heating expansion tank is compensated by its volume and ensures stable operation of the circuit. Externally, expansion tanks for the heating system, based on the results of the calculation and type heating circuit, differ in their shape and size. Currently, tanks are produced in various shapes, from classic cylindrical tanks to the so-called "tablets".
Types of heating systems
There are two schemes for the heating networks of the building -. An open (gravity-flowing) heating system is used in centralized heating networks and allows you to directly take water for hot water needs, which is impossible in private housing construction. Such a device is located at the top point of the heating system circuit. In addition to leveling pressure drops, the heating expansion tank performs the function of natural air separation from the system, as it has the ability to communicate with the outside atmosphere.
Thus, structurally, such a device is a compensation tank of the heating system that is not under pressure. Sometimes, by mistake, a system with gravitational (natural) circulation of a heat-carrying fluid can be called open, which is fundamentally wrong.
With a more modern closed circuit, an expansion tank of a closed-type heating system with a built-in internal membrane is used.
Sometimes such a device can be called a vacuum expansion tank for heating, which is also true. Such a system provides for forced circulation of the coolant, while air is removed from the circuit through special taps (valves) installed on heating appliances and at the top of the system piping.
Device and principle of operation
Structurally, a closed expansion tank in a heating system is a cylindrical tank with a rubber membrane installed inside, which separates the internal volume of the vessel into air and liquid chambers.
The membranes are of the following types:
The gas pressure is adjusted for each system individually, which is described by the instructions attached to such devices as an expansion tank for heating a closed type. Some manufacturers in the design of their expansion tanks provide for the possibility of replacing the membrane. This approach somewhat increases the initial cost of the device, but later, if the membrane is destroyed or damaged, the cost of replacing it will be lower than the price of a new expansion tank.
From a practical point of view, the shape of the membrane does not affect the efficiency of the devices, it should only be noted that a slightly larger volume of heat-carrying liquid can fit into a closed-type balloon expansion tank for heating.
Their principle of operation is also the same - with an increase in water pressure in the network due to expansion when heated, the membrane stretches, compressing the gas on the other side and allowing excess coolant to enter the tank. During cooling and, accordingly, a drop in pressure in the network, the process takes place in the reverse order. Thus, the regulation of constant pressure in the network occurs automatically.
It is necessary to focus on the fact that if you buy an expansion tank of the heating system at random, without the necessary calculation, then it will be very difficult to achieve the stability of the heating network. If the tank is much larger than necessary, the pressure required for the system will not be created. If the tank is smaller than the required size, then it will not be able to accommodate the excess volume of the heat-carrying liquid, which can result in an emergency.
Calculation of expansion tanks
To calculate an expansion tank for closed-type heating, you first need to calculate the total volume of the system, which consists of the volumes of the pipelines of the circuit, the heating boiler and heating devices. The volumes of the boiler and heating radiators are indicated in their passports, and the volume of pipelines is determined by multiplying the internal cross-sectional area of \u200b\u200bthe pipes by their length. If there are pipelines of different diameters in the system, then their volumes should be determined separately, and then added up.
Further, for devices such as an expansion tank for closed-type heating, the calculation is carried out according to the formula V = (Vc x k) / D, where:
Vc is the volume of heat-carrying fluid in the heating system,
k - coefficient. volumetric thermal expansion, taken for water 4%, for 10% ethylene glycol - 4.4%, for 20% ethylene glycol - 4.8%;
D is the efficiency indicator of the membrane unit. Usually it is indicated by the manufacturer or it can be determined by the formula: D \u003d (Rm - Rn) / (Rm +1), where:
Pm - the maximum possible pressure in the heating network, usually it is equal to the maximum working pressure of the safety valve (for private houses it rarely exceeds 2.5 - 3 atm.)
Рн is the pressure of the initial pumping of the air chamber of the expansion tank, taken as 0.5 atm. for every 5 meters of the height of the heating circuit.
In any case, it should be assumed that expansion tanks for heating should provide an increase in the volume of coolant in the network within 10%, that is, with a volume of heat-carrying fluid in the system of 500 liters, the volume together with the tank should be 550 liters. Accordingly, an expansion tank of the heating system with a volume of at least 50 liters is required. This method of determining the volume is very approximate and may result in unnecessary costs for the purchase of a larger expansion tank.
At present, the Internet has online calculators for calculating expansion tanks. In the case of using such services for the selection of equipment, it is necessary to carry out calculations on at least three sites in order to determine how correct the algorithm for calculating one or another Internet calculator is.
Manufacturers and prices
At present, the problem of buying an expansion tank for heating lies only in the correct selection of the type and volume of the device, as well as in the financial capabilities of the buyer. There is a wide choice of models of devices of both domestic and foreign manufacturers on the market. However, it should be noted that if the purchase price for such devices as a closed-type expansion tank for heating is much lower than that of the main competitors, then it is better to refuse such an acquisition.
The low cost indicates the unreliability of the manufacturer and the low quality of the materials used in its manufacture. Often these are products from China. As with all other products, for a high-quality expansion tank for heating, the price will not have a significant difference of about two - three times. Conscientious manufacturers use approximately the same materials and the price difference of models similar in parameters of about 10-15% is determined only by the location of production and the pricing policy of sellers.
Domestic manufacturers have proven themselves well in this market segment. By installing modern technological lines in their production, they have achieved the release of products that, in their parameters, are not inferior to the best world brands at a lower cost.
It should be borne in mind that it is important not only to buy an expansion tank for closed-type heating, it also requires its correct installation.
Having the necessary skills, while following the instructions, it is possible to self-installation. If the master still has any doubts about his knowledge, then it is best to turn to professionals to ensure the stable operation of the heating network and eliminate possible malfunctions.
In the last few years, a closed heating system has become increasingly popular. Heating equipment is becoming more and more expensive, and you want it to last longer. In systems of a closed type, the possibility of free oxygen getting inside is practically excluded, which prolongs the life of the equipment.
Closed heating system - what is it
As you know, in any heating system of a private house there is an expansion tank. This is a container in which some coolant is removed. This tank is necessary to compensate for thermal expansion in various operating modes. By design, expansion tanks are open and closed, respectively, and heating systems are called open and closed.
AT last years It is the closed heating circuit that is becoming increasingly popular. Firstly, it is automated and works without human intervention for a long time. Secondly, any type of coolant can be used in it, including antifreeze (it evaporates from open tanks). Thirdly, the pressure is maintained constant, which makes it possible to use any household appliances. There are a few more advantages that relate to wiring and operation:
- There is no direct contact of the coolant with air, therefore, there is no (or almost no) free oxygen, which is a powerful oxidizing agent. This means that the heating elements will not oxidize, which will increase their service life.
- An expansion tank of a closed type is placed anywhere, usually not far from the boiler (wall-mounted gas boilers come immediately with expansion tanks). An open tank should be in the attic, and these are additional pipes, as well as insulation measures so that heat does not “leak” through the roof.
- In a closed system, there are automatic air vents, so there is no airing.
In general, a closed heating system is considered more convenient. Its main drawback is energy dependence. The movement of the coolant is provided by a circulation pump (forced circulation), and it does not work without electricity. Natural circulation in closed systems can be organized, but it is difficult - flow control is required using the thickness of the pipes. This is a rather complicated calculation, because it is often believed that a closed heating system only works with a pump.
To reduce energy dependence and increase the reliability of heating, they install uninterruptible power supplies with batteries and / or small generators that will provide emergency power.
Components and their purpose
In general, a closed heating system consists of a certain set of elements:
- Boiler with safety group. There are two options here. First - a safety group is built into the boiler (gas wall boilers, pellet and some solid fuel gas generators). The second - there is no safety group in the boiler, then it is installed at the outlet in the supply pipeline.
- Pipes, radiators, convectors.
- Circulation pump. Provides the movement of the coolant. It is installed mainly on the return pipeline (here the temperature is lower and there is less possibility of overheating).
- Expansion tank. Compensates for changes in the volume of the coolant, maintaining a stable pressure.
Now more about each element.
Boiler - which one to choose
Since the closed heating system of a private house can work offline, it makes sense to install a heating boiler with automation. In this case, after setting the parameters, you do not need to return to this. All modes are supported without human intervention.
The most convenient gas boilers in this regard. They have the ability to connect a room thermostat. The temperature set on it is maintained with an accuracy of one degree. She fell by a degree, the boiler turned on, heating the house. As soon as the thermostat has tripped (temperature reached), the operation stops. Comfortable, convenient and economical.
In some models, it is possible to connect weather-dependent automation - these are external sensors. According to their testimony, the boiler adjusts the power of the burners. Gas boilers in closed heating systems are good equipment that can provide comfort. The only pity is that gas is not everywhere.
Electric boilers can give a no lesser degree of automation. In addition to traditional units on heating elements, induction and electrode ones appeared not so long ago. They are compact in size and low inertia. Many believe that they are more economical than boilers on heating elements. But even this kind of heating units can not be used everywhere, since power outages in winter are a frequent occurrence in many regions of our country. And to provide electricity to the boiler power. 8-12 kW from the generator is a very difficult task.
Boilers for solid or liquid fuel are more versatile and independent in this regard. Important point: a separate room is required for the installation of a liquid fuel boiler - this is a requirement of the fire department. Solid fuel boilers can stand in the house, but this is inconvenient, since a lot of debris falls from the fuel during combustion.
Modern solid fuel boilers, although they remain intermittent equipment (they warm up during combustion, cool down when the bookmark burns out), they also have automation that allows you to maintain the set temperature in the system by adjusting the intensity of combustion. Although the degree of automation is not as high as that of gas or electric boilers, it is.
Boilers on pellets are not very common in our camp. In fact, this is also solid fuel, but boilers of this type operate continuously. Pellets are automatically fed into the firebox (until the stock in the burker is finished). With good fuel quality, ash cleaning is required once every few weeks, and all operating parameters are controlled by automation. Only its high price hinders the distribution of this equipment: the manufacturers are mainly European, and their prices are corresponding.
A little about the calculation of boiler power for closed-type heating systems. It is determined according to the general principle: per 10 sq. meters of area with normal insulation take 1 kW of boiler power. Only take "back to back" is not advised. Firstly, there are abnormally cold periods during which you may not have enough rated power. Secondly, work at the power limit leads to rapid wear of the equipment. Therefore, it is desirable to take the boiler power for the system with a margin of 30-50%.
Security group
A safety group is placed on the supply pipeline at the outlet of the boiler. It should control its operation and system parameters. It consists of a pressure gauge, an automatic air vent and a safety valve.
The manometer makes it possible to control the pressure in the system. According to the recommendations, it should be in the range of 1.5-3 bar (in one-story houses this is 1.5-2 Bar, in two-story - up to 3 Bar). In case of deviation from these parameters, appropriate measures must be taken. If the pressure has dropped below normal, it is necessary to check if there are any leaks, and then add a certain amount of coolant to the system. At high blood pressure everything is somewhat more complicated: it is necessary to check in what mode the boiler is operating, whether it has overheated the coolant. The operation of the circulation pump, the correct operation of the pressure gauge and the safety valve are also checked. It is he who should dump the excess coolant when the threshold pressure value is exceeded. A pipe / hose is connected to the free branch pipe of the safety valve, which is led into the sewer or drainage system. Here it is better to do it in such a way that it is possible to control whether the valve works - with frequent discharge of water, it is necessary to look for the causes and eliminate them.
The third element of the group is an automatic air vent. Through it, the air that has entered the system is removed. A very convenient device that allows you to get rid of the problem of air jams in the system.
Security groups are sold assembled (pictured above), or you can buy all the devices separately and connect them using the same pipes that were used to wire the system.
Expansion tank for closed heating system
The expansion tank for is designed to compensate for changes in the volume of the coolant depending on temperature. In closed heating systems, this is a sealed container, divided by an elastic membrane into two parts. In the upper part there is air or an inert gas (in expensive models). While the coolant temperature is low, the tank remains empty, the membrane is straightened (picture on the right in the figure).
When heated, the coolant increases in volume, its excess rises into the tank, pushing the membrane and compressing the gas pumped into the upper part (in the picture on the left). On the pressure gauge, this is displayed as an increase in pressure and can serve as a signal to reduce the intensity of combustion. Some models have a relief valve that releases excess air/gas when a pressure threshold is reached.
As the coolant cools, the pressure in the upper part of the tank squeezes the coolant out of the tank into the system, the pressure gauge returns to normal. That's the whole principle of operation of the expansion tank of the membrane type. By the way, there are two types of membranes - dish-shaped and pear-shaped. The shape of the membrane does not affect the principle of operation.
Volume calculation
According to generally accepted standards, the volume of the expansion tank should be 10% of the total volume of the coolant. This means that you must calculate how much water will fit in the pipes and radiators of your system (it is in the technical data of the radiators, but the volume of pipes can be calculated). 1/10 of this figure will be the volume of the required expansion tank. But this figure is valid only if the coolant is water. If an antifreeze liquid is used, the tank size is increased by 50% of the calculated volume.
Here is an example of calculating the volume of a membrane tank for a closed heating system:
- the volume of the heating system is 28 liters;
- expansion tank size for a system filled with water 2.8 liters;
- the size of the membrane tank for a system with antifreeze liquid is 2.8 + 0.5 * 2.8 = 4.2 liters.
When buying, choose the nearest larger volume. Do not take less - it is better to have a small supply.
What to look for when buying
The stores have red and blue tanks. Red tanks are suitable for heating. Blue ones are structurally the same, only they are designed for cold water and do not tolerate high temperatures.
What else to pay attention to? There are two types of tanks - with a replaceable membrane (they are also called flanged) and with an irreplaceable one. The second option is cheaper, and significantly, but if the membrane is damaged, you will have to buy the whole thing. In flanged models, only the membrane is bought.
Place for installation of expansion tank of membrane type
Usually they put an expansion tank on the return pipe in front of the circulation pump (when viewed in the direction of the coolant). A tee is installed in the pipeline, a small piece of pipe is connected to one of its parts, and an expander is connected to it through the fittings. It is better to place it at some distance from the pump so that pressure drops are not created. An important point is that the piping section of the membrane tank must be straight.
After the tee put a ball valve. It is necessary to be able to remove the tank without draining the heat carrier. It is more convenient to connect the container itself with the help of an American (flare nut). This again facilitates assembly/dismantling.
Please note that some boilers have an expansion tank. If its volume is sufficient, the installation of a second one is not required.
Empty device weighs not so much, but filled with water has a solid mass. Therefore, it is necessary to provide a method of fixing on the wall or additional supports.
Circulation pump
The circulation pump ensures the operability of a closed heating system. Its power depends on many factors: the material and diameter of the pipes, the number and type of radiators, the presence of shut-off and thermostatic valves, the length of the pipes, the operating mode of the equipment, etc. In order not to go into the intricacies of calculating power, the circulation pump can be selected from the table. Choose the nearest higher value according to the heated area or the planned thermal power of the system, in the corresponding line in the first columns find the required characteristics.
In the second column we find the power (how much coolant it is able to pump per hour), in the third - the pressure (system resistance) that it is able to overcome.
When choosing a circulation pump in a store, it is advisable not to save. The entire system depends on its performance. Therefore, it is better not to save and choose a trusted manufacturer. If you decide to buy unknown equipment, you need to somehow check it for noise levels. This indicator is especially critical if the heating unit is installed in a residential area.
Strapping scheme
As mentioned earlier, circulation pumps are installed mainly on the return pipeline. Previously, this requirement was mandatory, today it is only a wish. The materials that are used in the production can withstand temperatures up to 90 ° C, but it's still better not to risk it.
In systems that can also operate with natural circulation, it is necessary to provide during installation the possibility to remove or replace the pump without the need to drain the coolant, as well as to be able to work without a pump. To do this, a bypass is installed - a bypass through which the coolant can flow if necessary. The installation diagram of the circulation pump in this case is in the photo below.
In closed systems with forced circulation, a bypass is not needed - it is inoperative without a pump. But two ball valves on both sides and an inlet filter are needed. Ball valves make it possible, if necessary, to remove the device for maintenance, repair or replacement. The dirt filter prevents clogging. Sometimes, as an additional element of reliability, a check valve is also placed between the filter and the ball valve, which will prevent the coolant from moving in the opposite direction.
Scheme of connection (piping) of a circulation pump to a closed-type heating system
How to fill a closed heating system
At the lowest point of the system, as a rule, on the return pipeline, an additional tap is installed to supply / drain the system. In the simplest case, this is a tee installed in the pipeline, to which a ball valve is connected through a small section of the pipe.
In this case, when draining the system, it will be necessary to substitute some kind of container or connect a hose. When filling the coolant, a hand pump hose is connected to the ball valve. This simple device can be rented at plumbing stores.
There is a second option - when the coolant is just tap water. In this case, the water supply is connected either to a special boiler inlet (in wall gas boilers), or to a ball valve similarly installed on the return. But in this case, another point is needed to drain the system. In a two-pipe system, this may be one of the last in the radiator branch, to the lower free entrance of which a drain ball valve is installed. Another option is shown in the following diagram. It shows a single-pipe closed-type heating system.
Scheme of a closed single-pipe heating system with a system power supply unit
To extend the service life of heating equipment and compensate for the thermal expansion of the coolant, an expansion tank is installed in the heating system. Which expansion tank for heating to choose will be considered in this article.
Features and functions of the expansion tank for heating
With an increase in temperature in the heating system by 15 degrees, due to thermal expansion, the volume of the coolant increases by half a percent. The expansion tank compensates for this expansion, the excess heat transfer fluid enters the tank capacity. When the coolant cools down, the expansion tank mechanism pushes the missing liquid back into the system.
If a small water leak occurs, so that there is no decrease in the pressure level in the system, the expansion tank pushes the coolant out, thereby compensating for the losses.
If there is no expansion tank in a closed heating system, the expansion of the coolant leads to an increase in pressure, rapid wear of the heating system components, or breakage and rupture of pipes and taps.
The scope of use of the expansion tank for heating:
- heating system powered by heat pumps and solar collectors;
- autonomous heating system;
- independent heating system connected to the central heating;
- closed loop system.
Advantages of installing an expansion tank for heating:
- no water pollution;
- low cost;
- ensuring safety and reliability;
- no heat loss;
- the minimum amount of air in the system;
- pressure adjustment;
- the use of an expansion tank does not depend on the type and quality of the coolant;
- increasing the life of radiators, pipes, taps and the boiler.
Varieties of expansion tanks for heating
Photo expansion tank for heating:
Depending on the principle of work, there are:
- expansion tanks for open heating;
- closed heating expansion tanks.
Open type expansion tanks are less popular. Such devices are installed in systems where water circulation occurs without the use of a pump. The open expansion tank for heating contains a lid that can be easily opened when water needs to be added. The disadvantage of an expansion tank for open heating is the connection of the coolant with oxygen, which leads to the formation of corrosion in the heating system. In the absence of tightness in an open heating tank, water evaporates faster from the system, and it should be constantly added. The installation of an open expansion tank should be carried out at the highest point of the heating system, and this procedure is not always available.
A closed or membrane expansion tank of the heating system is installed in a system where the movement of the coolant is provided by a pump. The closed-type expansion tank is made in the form of a steel tank without a lid, which has an internal partition in the form of a rubber membrane. One half serves to fill with coolant, and the second is air or nitrogen. The expansion tank is coated with powder-type paint in order to avoid mechanical damage to the walls of the vessel at a high temperature of the coolant. On one side, the membrane expansion tank is attached to the heating system using a fitting or flange, and the other side is used for air injection. The pressure in the heating expansion tank allows you to automatically adjust the flow of coolant into the system or back into the vessel.
Closed expansion tanks are divided into:
- interchangeable,
- non-replaceable.
Replaceable type expansion tanks are more expensive, but have a number of advantages:
- the possibility of replacing the membrane in case of damage or rupture;
- savings on pipes, since there is no need to install a closed expansion tank at the top of the heating system;
- ensuring minimal heat loss;
- since the coolant does not come into contact with the oxygen of the pipe and the entire system is protected from rust formation;
- vertical or horizontal arrangement of the membrane;
- exclusion of communication with the metal inner wall of the tank;
- easy replacement of the membrane is carried out through the flange of the expansion tank.
Non-replaceable expansion tanks, although they have a lower cost and do not allow membrane replacement. The membrane in the non-replaceable type expansion tank is located tightly and is firmly pressed against the inner surface of the tank wall. Damage to the membrane occurs only if the heating system is not started correctly, when the pressure rises quickly and exceeds the maximum allowable rate.
Depending on the type of membrane, expansion tanks are distinguished with:
- balloon membrane,
- diaphragmatic membrane.
An expansion tank with a balloon membrane is more reliable and has a larger volume. The coolant does not come into contact with the walls of the tank, which prevents the formation of corrosion.
The flat expansion tank for heating is equipped with a diaphragm-shaped partition wall, which cannot be replaced if damaged.
Selection of an expansion tank for heating
The size of the expansion tank for heating depends on such factors:
- type and capacity of the entire heating system;
- limiting value of the operating temperature of the coolant;
- ultimate pressure;
- the height at which the expansion tank is installed.
To determine the approximate volume of the expansion tank, you need to know the total volume of the entire heating system: pipelines, heating appliances and a heating boiler. From this volume, 10% should be calculated. For example, if the total volume of the heating system is 600 liters, then an expansion tank with a capacity of 60 liters should be selected.
3% of the volume of the expansion tank for heating falls on the reserve supply of coolant to compensate for possible leaks.
The exact calculation of the expansion tank for heating is carried out with the help of specialists or special online calculators.
Tips for choosing the right expansion tank:
1. After carrying out the calculations, care should be taken that the pressure surges in the heating system do not exceed the maximum units indicated in technical passport devices.
2. The calculation, as a result of which the volume of the expansion tank will be revealed, is better to increase by a couple of units. A larger expansion tank will not bring any negative consequences, and a smaller expansion tank can adversely affect the operation of the system.
3. Before installing the expansion tank, find out the parameters of the device in order to avoid problems with transporting the tank to the room.
4. If glycol mixtures are used as the heating medium, the preliminary calculation of the expansion tank should be increased by half.
5. With frequent operation of the safety valve, the installation and selection of the expansion tank was done incorrectly.
1. It is better to give preference to a membrane or closed expansion tank. Although such a tank is more expensive, a heating system in which a closed-type expansion tank is installed will last longer due to the lack of contact between the coolant and oxygen.
2. Pay attention to the material of the rubber baffle of the closed expansion tank. Manufacturers use natural butyl rubber or EPDM rubber for these purposes.
3. If the expansion vessel is to be used in conjunction with a central heating system, the rubber for the membrane must be strong and resistant to high temperatures. Since central heating does not involve large pressure surges, but the temperature of the coolant is quite high.
4. The tank with high elasticity of the membrane is suitable for private system heating, as high pressure drops are typical for this type of heating system.
5. To use the expansion tank not only in the heating system, but also in the water supply system, the rubber for the membrane must be food grade so as not to lower the quality characteristics of the water.
6. When choosing between a replaceable and a non-replaceable membrane, it is better to give preference to the first option. Since if the non-replaceable membrane is damaged, the expansion tank must be completely changed.
7. Before buying an expansion tank, check specifications device, ask for quality certificates of the purchased products.
8. Be sure to issue a warranty card.
9. Main conditions right choice expansion tank is resistant to diffusion, temperature and pressure changes, durability, compliance with sanitary and hygienic standards, the use of high-quality materials in the manufacture.
Manufacturers of expansion tanks for heating
1. Expansion tank for heating Wester (UK)
Peculiarities:
- made of high quality steel;
- do an excellent job of compensating for the expansion of the coolant;
- the membrane is made of EPDM;
- availability of a quality certificate;
- tanks are equipped with replaceable membranes;
- lack of contact of water with air;
- Wester expansion tanks are available in capacities from 8 to 2000 liters.
Expansion tank of the heating system price: from $ 18 for an expansion tank with a volume of 8 liters, up to $ 3600 for an expansion tank with a volume of 2000 liters.
2. Expansion tank Zilmet (Italy)
Peculiarities:
- designed for installation in an individual heating system;
- carbon steel - the basis for the metal body of the Zilmet expansion tank;
- the presence of a pneumatic valve inside the expansion tank;
- the minimum tank volume is 4 liters, and the maximum is 1000 liters;
- color scheme: red;
- operating temperature from 0 to +98 °C;
- the company produces expansion tanks for the heating system and for the water supply system;
- expansion tanks for heating are produced in two series: Cal PRO - expansion tanks for the heating system, OEM PRO - flat expansion tanks for boilers;
- price: from 30 to 2600 $.
3. Expansion tank of the Reflex heating system (Germany)
Peculiarities:
- high level of hydraulic stability;
- lack of air in the heating system;
- protection against pressure drops;
- variety of expansion tanks.
Varieties of expansion tanks Reflex:
- series N, NG - represents expansion tanks with irreplaceable membranes and polymer coating. The limiting operating temperature is 70 °C. The volume of the tank varies from 8 to 1000 liters;
- The S series represents white and red expansion tanks for use in the heating and water supply system. Temperature limit 70 °C. The minimum volume is 8 l, the maximum is 600 l;
- the G series represents expansion tanks only in red color which have a replaceable diaphragm and pneumomanometer.
Price: from 20 to 4000 $.
4. Expansion tank for heating Cimm (Italy)
Peculiarities:
- non-replaceable expansion tanks are produced for the heating system;
- for the manufacture of expansion tank membranes intended for installation in a water supply system;
- the minimum volume of expansion tanks is 6 liters, and the maximum is 1000 liters.
Varieties:
- The CP series represents flat expansion tanks with a volume of 6 to 18 liters, a maximum operating temperature of +90 °C;
- The ERE series is a membrane balloon expansion tank that can withstand a temperature of +100 °C.
5. Expansion tanks Gilex (Russia)
Peculiarities:
- purpose: removal of an additional volume of coolant;
- varieties: expansion tanks of open and closed type;
- volume from 6 to 300 l;
- models with a volume of more than 12 liters withstand a pressure of 6 atmospheres.
6. Expansion tank Flexcon (Netherlands)
Peculiarities:
- a variety of expansion tanks, according to the type of pressure in the system: expansion tanks for high, medium and low pressure;
- a reliable membrane that covers the walls of the tank;
- a special clamping ring is able to hold pressure, preventing the water level from dropping;
- minimal air ingress into the system;
- lack of water evaporation;
- application in heating systems with ethylene glycol mixtures;
- application: closed heating systems, air conditioning systems;
- operating temperature from -10 to 120 °C;
- volume from 6 to 12000 l.
Varieties:
- models of the C series are designed for heating systems with low pressure up to 3 bar, the maximum temperature for normal operation of the device is +70 ° C;
- the CE series is designed for medium pressure heating systems, maximum pressure 6 bar;
- the CE series for high pressure represents expansion tanks that can withstand pressures up to 10 bar;
- the PRO, M series is represented by collapsible expansion tanks for heating of vertical or horizontal design, with a maximum filling volume of 62% and an operating temperature of 70 °C.