The main feature by which a closed heating system differs from an open one is its isolation from the influence environment. This scheme includes a circulation pump that stimulates the movement of the coolant. The scheme is devoid of many of the disadvantages inherent in an open heating circuit.
You will learn all about the pros and cons of closed heating schemes by reading the article we have proposed. It thoroughly examines the device options, the specifics of assembly and operation of systems. closed type. An example of hydraulic calculation is given for independent craftsmen.
The information presented for review is based on building regulations. To optimize the perception of a difficult topic, the text has been supplemented useful diagrams, collections of photos and video tutorials.
Temperature expansions in a closed system are compensated by using a membrane expansion tank, filled with water during heating. When cooling, water from the tank goes back into the system, thereby maintaining constant pressure in the circuit.
The pressure created in the closed heating circuit during installation is transmitted to the entire system. The circulation of the coolant is forced, so this system is energy-dependent. Without it, there will be no movement of heated water through the pipes to the appliances and back to the heat generator.
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Among life-sustaining engineering systems modern residential and industrial buildings water heating systems occupy a special position. They differ in design features their execution, architectural and construction requirements for placement and operation, technological characteristics. In addition, they must meet certain sanitary and hygienic requirements. Together they form specific, specific requirements for design, operation and maintenance. heating systems and devices.
Water heating systems modern buildings classified according to the following criteria.
1. By institutional characteristics:
2. According to technological requirements:
3. According to the requirements of architectural and construction norms, rules and
standards:
The main principle technological feature water heating systems, in contrast to single-flow (single-pipe) water supply, gas supply and sewerage systems, is that, in accordance with the laws of thermodynamics water heating systems can be circulation, two-flow, two-pipe.
The main elements of the heating system include: heat generator (heating boiler), coolant (water or antifreeze), supply and return pipelines, circulation pump (if the system has forced circulation coolant), safety group, expansion tank and heating devices(radiators).
The principle of operation of the heating system is that the coolant heated in the heat generator (heating boiler) is pumped to the heating devices of the building through supply pipelines at a temperature of t 1 ºС. In heating appliances, heat is released and the coolant cools, and accordingly, its temperature potential (heat content) decreases. Cooled to a temperature of t2, °C, it enters the return pipelines, through which it returns again to its original position - to the heat generator for subsequent heating.
Thus, in heating systems, thermal cycles are constantly occurring - the circulation of the coolant in the amount of G, kg/h, and the useful work of the system is performed to heat the room at the temperature difference t1 - t2, °C, with heat in the amount of Q, J/h.
As is known, each coolant has its own heat capacity c, J/(kg -°C). Water has a heat capacity c = 4.19 kJ/(kg -°C), which means that to heat 1 kg of water by 1°C it is necessary to expend 4.19 kJ of heat. Knowing the values of G, t1, t2, s, it is possible to determine the amount of heat Qnp given off by the coolant in heating devices for heated rooms in one hour or for a certain period of time z, h, using the formulas:
Qpr = G -s (t1 – t2), J/h (1)
Qpr = G -с (t1 -t2) -z, J. (2)
At the same time, in order to maintain a constant indoor air temperature t pump = Const, this amount of heat Q pr must correspond to the heat loss of the room (building) - Q room, equal to the amount heat losses through the external enclosing structures of the room (external walls, doors and windows, floors and ceilings), called transmission losses - Q transm, and heat losses for heating the incoming external ventilation air– Q vent, and in industrial buildings, in addition, and for heating technological materials and products – Q tech, imported from the street.
Thermal balance must be maintained:
Q pom =Q pr = Q transm + Q vent + O tech, J/h (3)
IN last years they also began to take into account internal heat inputs - heat releases: from people in the premises, from household electrical and cooking appliances, from technological devices, from finished products and products, from solar radiation, etc. These heat releases Q TV, J/h, reduce the need of the room (building) for heat, which it should receive from the heating system. The heat balance of the room, taking into account internal heat emissions, will look like this:
Q pom =Q pr = Q transm + Q vent + O tech – Q tvn, J/h (4)
To effectively fill a water heating system with coolant (usually water) and keep the circulation ring filled, as well as to empty the system, three more mandatory elements are required - a make-up device (pump), a drainage device and an expansion tank.
With the help of a make-up device, the entire system, including a heat supply source, a circulation pump, supply and return pipelines (supply and return), all heating devices located in the room, as well as an expansion tank, are slowly (through the return line) filled with coolant (water). During the process of filling or replenishing the system, the coolant displaces air from the internal cavities of pipelines and heating devices upward, into the expansion tank or into special, so-called vents. In some U-shaped heating systems, air vents (Mayevsky taps) are installed in the upper plugs of heating devices.
If air from the system cannot be completely removed, then air jams, which break the flow of coolant in pipelines and heating devices and prevent its circulation in the system. There are often cases of emergency failure of systems due to a violation of the circulation regime (overheating of the coolant due to air locks). For effective air removal, the supply pipelines are installed with a slight slope (i = 0.010) in the direction from the main riser towards the heating devices, and the pipelines performing the return supply are installed with the same slope from the heating devices towards the heating source (heat generator) to the drain valve.
When the coolant is heated, gases dissolved in cold water are released from it in the form of bubbles - oxygen, nitrogen and carbon dioxide, which in the same way (through an expansion tank or air vents) are removed from the system during its operation.
Laying distribution pipelines with a slope also allows you to quickly remove the coolant in cases of emptying them for repair purposes, and prevents the coolant from “hanging” in the pipes.
An expansion tank with a volume of V (m3) is mounted at the highest point of the system (usually this is attic space), and must be insulated. It is a kind of buffer for the heating system, and its volume allows you to compensate for changes in the volume of the circulating coolant - an increase during heating and a decrease during cooling, as well as to compensate for its slight loss due to evaporation and possible leaks through leaks in the system. Equipped with signal and overflow pipes, an open expansion tank allows personnel to periodically monitor the filling of the system with coolant (water), fill it and replenish it with a make-up device if necessary.
In small house and cottage heating systems, such filling and make-up are carried out from the drinking water supply by opening the tap on the make-up line. In the absence of running water, it is carried out either using an electric or manual pump connected to an intermediate pump that is periodically replenished with water when pumping the container. In large water heating systems multi-storey buildings For these purposes, special make-up pumps are installed and make-up is carried out with specially prepared softened and deaerated water to prevent corrosion and overgrowth of metal pipelines.
At the lowest point of the heating system on the return line of the pipeline (return) a drain valve is installed, with the help of which the coolant (water) is drained from the system, in cases of repair work or shutdown for a long period in order to avoid freezing in winter period. To avoid “hanging” of the coolant in the pipelines and heating devices during descent, the vents installed at the highest points of the system should be opened.
The circulation pump of the heating system is installed, as a rule, on the pipeline that performs the return flow (return) in front of the heating source (heat generator). In large branched heating systems of buildings, several (2-3) circulation pumps (one backup) are usually installed.
All mentioned required elements water heating systems - heat generator, circulation pump, heating devices, expansion tank, air vents and make-up device, instrumentation and automation devices are connected to each other by pipelines in a certain sequence and order, forming a complex hydraulic circulation system– a system of closed interconnected vessels and rings filled with coolant.
To organize maximum comfort when living in a house, an extremely necessary element, such as a heating system, must be installed in it. Only a heating system can truly create very pleasant and comfortable conditions life. Of course, the heat carrier is one of the most important parts.
Do not forget that sometimes home owners do not want to hire additional workers. Because of this, owners themselves install the heating system of a private house. In reality, everything is simple here. You need to follow the exact installation rules.
Most often, the core main part any heating system is . It is the boiler that carries out the process of heating the coolant. The duty of the coolant is to distribute heat throughout the house. Liquid can best cope with this task. Most heating systems use water as a heat carrier. A heating system with a heat carrier of this type is designed as a closed system. This means that the water in the system circulates in a circle. In this case, the need for topping up occurs quite rarely.
Two-pipe heating system
Nowadays, it is considered the most effective and trouble-free.
The design consists of two circuits that are closed on the boiler. This is the supply of heat carrier and its return. The first is intended for supplying liquid heated in the boiler. It is there that she transfers her warmth. After cooling, the coolant is returned to the boiler through the return pipes for subsequent heating.
For this, the most competent and efficient solution to the maximum would be a solution for parallel arrangement of radiators. At the same time, they will be able to warm up at the same time. Because of this, all rooms will warm up evenly. You also need to remember that the quality of heating is influenced by the distance between the return and coolant supply circuits. The minimum that is possible is the distance from the floor to the window sill.
Most professionals believe that such a heating system is less efficient than the old stove heating method.
We can agree that these experts are right to some extent. Since due to the passage through there is a process of a certain loss of the coolant. But we should not forget that heating with a stove does not allow simultaneous uniform heating of all rooms. Among other things, it is quite inconvenient due to the need to store an extensive supply of firewood. When using a boiler that runs on wood, the need for fuel will be significantly lower.
Stove heating scheme
The most often used is a fairly simple and at the same time efficient heating system of a two-pipe type using a coolant. This system allows for high-quality heating of the house, without the additional use of units for this purpose - circulation-type electric pumps. There is a great demand for this model of heating system due to the fact that power outages often occur. In the absence of electricity, the system will not simply function.
The most important thing that is needed for the effective and most productive operation of such a system is strict adherence to the rules when installing it and also a fuel supply.
The most important factor that must be observed for reliable operation of the system in the future is the technical implementation of the maximum long distance height between the system outlet and the highest point. It is for this reason that the most rational decision would be to install a boiler with a pipe in the basement. If there is no basement, it is done on the ground floor in a recessed place. Work to create a slope for the return line will also be important. This slope is made horizontally, starting from the first system radiator.
Heating boiler in the basement
In such a heating system there is another important part of the design -. Its purpose is to create maximum pressure in the system. This is very important for good circulation. The operation of the tank is based on the principle of ordinary gravity. It should be placed as high as possible. The most ideal solution would be to place it in the attic. The pressure will depend precisely on the height of the placement, and not on the volume of liquid contained in the tank.
The tank must have an average volume. One more functionality tank is to control the level of coolant. If necessary, it is drained from the tank.
Also, we must not forget that such systems function correctly only when water is a heat carrier. Such a scheme is called an open system.
Where the expansion tank has absolutely nothing to do with external environment. To put it simply, there is no way to pump out the coolant. Such systems usually use a compensation tank. The compensation tank is a small container, the inner part of which is divided in two using a flexible membrane. The heat carrier fills one of these parts. in such a system it is carried out by bending the membrane in different sides. Due to the fact that the system is closed, it is possible to use antifreeze as a heat carrier.
Expansion tank
For a long time, when installing a heating system, they installed only. This caused inconvenience, since installation required a lot of time, and rough seams then significantly worsened appearance systems.
But these days it is already possible to install a heating system of any design complexity using. These pipes are more flexible and thinner. The surface of these pipes is made of special heat-resistant plastic, and inner space using a thin aluminum layer. There are many on sale big choice elements for metal-plastic pipes. These are: taps, connections, corners. These elements make it possible to connect pipes to each other and connect other types of pipes to them.
Due to the fact that these days there is a wide selection of metal-plastic pipes, it is also important to pay attention to the markings. Pipes for heating systems are marked with the symbols “PE-RT-AL-PE-RT”.
An important advantage of metal-plastic pipes is the ease of working with them. They are quite light and flexible, and can be easily cut using a regular hacksaw or tin snips.
To achieve maximum tightness of the heating system, all components must be installed very securely. The best way to do this is to use a press fitting - they can well maintain the integrity of the pipe.
The decision to create a reliable and high-quality heating system in the house, working with a liquid heat carrier, can be considered accepted. The very first thing to do when creating any type of heating systems is to create detailed plan, . In this diagram you need to indicate: the level and location of the boiler, the length of the pipeline, the location of radiators and other parts of the system to the Mayevsky taps.
Heating system plan
Then you need to decide what kind of boiler power is exactly required. Since a weak boiler will not create the required level and speed of heating. It will also be unprofitable to use a more powerful one - since it will operate at half the power.
Is simple: 1 kW corresponds to 1 square meter. This simple match gives a specific parameter. The result obtained must be multiplied by 1.5 - this will be a suitable parameter for the boiler power.
Often, when designing a heating system, boilers made by . These boilers are more affordable, but it is not possible to calculate their exact power.
Provided that the client nevertheless decides to supplement his heating with the help of such a boiler, then he just needs to make calculations of the maximum volume of coolant that can fit in this boiler. For such calculations, you need the volume of the room (or the total volume of the rooms) that will be heated, divided by 1000 and the result is 300. This shows the amount of coolant that a home-made boiler will hold.
Also, we should not forget that the size of the boiler is entirely related to its power. Accordingly: higher power requires a larger boiler. Of course, before working on creating a heating system plan, you need to select appropriate place where the installed boiler will not create any interference.
You also need to consider the height. The boiler must be located at the very bottom of the entire system. Best choice the boiler will be installed in basement. If there is no basement, you should take care of a niche in the floor. It is recommended that the boiler be installed in a separate room where access is restricted for security reasons.
It is also important not to forget that individual models boilers (electric boilers, gas), need special conditions by placement. If the customer does not have information about this, before installing the system, it is imperative to seek advice from professionals.
When installing the main line, you need to take pipes that will have a diameter twice as large as those pipes through which the coolant will be supplied directly to the radiator. This standard is needed both for the pipes through which the supply goes and for the return. When installing the main line, the pipes are secured using special rings. With this it will be possible to avoid sagging.
Even if the entire system is made using metal-plastic pipes, vertical riser, which goes from the heating boiler to expansion tank, must be made of steel pipe. In the absence of a tank, the initial couple of meters of pipe are made of steel. If a membrane expansion tank is connected, it is possible to use pipes with a smaller diameter.
It is highly undesirable to use metal-plastic pipes in the room where the heating boiler is installed.
This is because the hot air that rises from the boiler can damage the plastic part of the pipe. The best solution There will be a placement of metal-plastic pipes only in rooms with heating.
If conditions exist, two heating circuits can be installed. Each of them will have supply and return pipes. Such heating solutions will be more expensive. But if there is a need for repair work, one of the contours may be blocked.
An example of heating boiler piping
On all radiators, as well as on the lines through which the coolant and return are supplied, it is necessary to install taps through which air is released.
A large excess of air in the system can lead to serious damage. Radiators are installed using important feature– the side from which the return pipe comes out must be located slightly lower. This is required for systems where the coolant circulates naturally.
When using a home-made boiler for heating, do not forget that the direct line pipe must be located as high as possible. This will make it possible to avoid dangerous water hammer. The heating boiler is mounted with a slope of 5 mm. This bias is made towards the return lines.
After complete installation of the system, it is filled with a coolant. When performing such work, all valves that bleed air must remain open. After filling the entire system with a heat carrier, you need to light the boiler using a small volume of fuel. This will provide an opportunity to check that the system is warming up evenly. Under these conditions there should not be very hot or cold areas. In such a situation, it is necessary to open the valve on the radiator and drain the water until it starts to get hot.
During the heating process, no extraneous sounds can be present in the boiler. A slight leakage of the coolant at the threaded connections is acceptable.
Upon completion of the initial launches, places with threaded connection will no longer let water through. Then it will be possible to light the boiler at maximum power.
Boiler power is an extremely important quantity. She has to get it right. If the power exceeds the norm, the boiler may boil. This can bring tragic results not only for heating, but for the entire building. If the boiler power is reduced, this will be reflected in the return temperature readings. It will not exceed 40 degrees.
Properly installed parts of the heating system should not produce any unnecessary noise. Among other things, the temperature difference between the supplied coolant and the return is no higher than 40 degrees. A video with information on installing the system is available below for viewing.
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Heating system operation country house we will look at the example of a standard one-story house 6x9 with total area 54 m2.Heating 1 m2 of a house usually requires a power of 170 W. If the house consists of a second, third, etc. floors, then for each of them the power should be 100 W per 1 m2. This begs the question: why is such power needed for the second and subsequent floors? The answer is obvious: by heating the first floor, hot air rushes upward and begins to heat the walls and ceiling of the rooms on subsequent floors, while giving away part of its heat in favor of the floor above. This is where the variation in power we see comes from.
IMPORTANT! During the design and calculation of the heating system, add a 30% power reserve to the radiator. This is necessary to quickly warm up the heating system.
After we have become acquainted with the power of radiators, let's find out which product can generate such an amount of heat. Of course it's a boiler.
Boiler design
Some of the boilers listed above have the following design: pump, expansion tank, safety group, additional devices in the form of on-board computers. Most boilers do not have peripheral components in their arsenal.
What equipment is needed for safe boiler operation?
Design and principle of operation
In a closed heating system, it is a sealed capsule, inside of which there is a membrane or rubber ball. At the top of the sealed capsule is a nipple through which air or nitrogen gas is pumped. Using a nipple, you can pump air into the capsule, thereby changing the pressure inside it and adjusting the operation of the heating system to a specific pressure.
For greater clarity, let's look at a simple example. We pumped the coolant system to 1 bar. We press the nipple located in the upper part of the expansion tank, build up the air in the tank, filling it with coolant. And as soon as the pressure gauge needle creeps down, you should immediately stop bleeding air. After the procedures have been completed, the system and expansion tanks will operate synchronously.
The question arises: for what purpose is the air vented and the expansion tank adjusted? The answer is quite simple. Closed systems operate at different pressures ranging from 0.5 to 3 bar. The parameter depends on the selected type of boiler and the pressure for which it is designed. Often the expansion tank, already set by the manufacturer, has a pressure of either 1.5 bar or 3 bar. This information placed on the label of the tank that the consumer purchases. It is this setting that facilitates the smooth operation of the heating system.
Installation location
The most suitable location for the expansion tank is close to the return pipe connection near the suction pipe circulation pump. This connection scheme ensures stable pressure in the heating system.
Heating in the house is complex device. Until recently, almost everywhere a system was used in which the coolant naturally circulated through it. But this system has many flaws, and significant increases in gas and electricity tariffs have made it expensive. Yes, that's it more people I started installing it at home, which we will talk about later.
It allows you to expand your capabilities natural heating, create several options for tying it and simplify the device. When using a pump, there is no need for large diameter pipes, which are necessary when natural circulation. This only improves the appearance of the heating junction.
The forced system provides automatic temperature control; thanks to this function, you can create more comfortable living conditions in the house. Its only drawback is its dependence on electricity.
Thus, the operation of a closed system is similar to heating based on natural circulation, but it is more productive, since the pump built into it provides a high coolant speed and thereby guarantees accelerated heating of the entire home.
Control taps are installed on each battery, which are necessary for uniform heating of all radiators. Naturally, the heating devices closest to the boiler heat up faster and stronger, and the very last ones may be a little warm. To avoid this, close the valves on the front radiators in time, and the coolant flows directly into subsequent heating devices.
The sequential connection of radiators leads to one single pipe, most often it is laid below the heating devices.
In such a system it is impossible to shut off one of the radiators. A single-pipe connection was installed in multi-apartment buildings built in the last century. This scheme was often chosen because of its ease of installation and savings on pipes, because they are needed in half as much as with a two-pipe scheme.
Some craftsmen, in order to eliminate its shortcomings, make independent taps into the main pipe, and thereby heat additional areas(balconies, loggias) or insulate cool rooms. More details about the single-pipe design -.
If it is used, two lines are installed simultaneously to each radiator: incoming and return. The parallel method of supplying coolant ensures heating of one radiator. Each battery in such a system can be easily disconnected from the pipe if necessary; this is convenient for repairs, as well as for adjusting the heating of the room. For these purposes, a thermostat or a regular tap is installed at the radiator inlet.
The two-pipe distribution system can be vertical or horizontal. Each of them is divided into several varieties.
A vertical heating connection scheme is protected from such air problems, but it is more expensive. It is used in multi-storey buildings, while the riser from it passes through the ceilings of all floors.
The circulation pump can operate effectively in any of the above heating schemes. The forced circulation of coolant created by it can ensure uniform heating of the entire home, regardless of the location of the radiators relative to the boiler.
