Independent scheme for connecting the heating system. Dependent and independent heating system - differences in schemes, pros and cons

Connection schemes for heating systems are dependent and independent. In dependent circuits, the coolant in heating appliances comes directly from the heating network. The same coolant circulates both in the heating network and in the heating system, so the pressure in the heating systems is determined by the pressure in the heating network. In independent schemes, the heat carrier from the heating network enters the heater, in which it heats the water circulating in the heating system. The heating system and the heating network are separated by the heating surface of the heat exchanger and are thus hydraulically isolated from each other.

Any schemes can be used, but you should choose the right type of connection for heating systems to ensure their reliable operation.

Independent scheme for connecting heating systems

Applies in the following cases:

1. for connecting high buildings (more than 12 floors), when the pressure in the heating network is not enough to fill the heaters on upper floors;
2. for buildings requiring increased reliability of heating systems (museums, archives, libraries, hospitals);
3. buildings with premises where access of unauthorized service personnel is undesirable;
4. if the pressure in the return pipeline of the heating network is higher than the permissible pressure for heating systems (more than 60 m. of water column or 0.6 MPa).

RS - expansion vessel, RD - pressure regulator, RT - temperature regulator: OK - check valve.

The network water from the supply line enters the heat exchanger and heats the water of the local heating system. Circulation in the heating system is carried out by a circulation pump, which ensures a constant flow of water through the heating devices. The heating system may have an expansion vessel that contains a supply of water to make up for leaks from the system. It is usually installed in top point and is connected to the return line to the suction of the circulation pump. During normal operation of the heating system, leakage is negligible, which makes it possible to fill the expansion tank once a week. Make-up is made from the return line through a jumper, made for reliability with two taps and a drain between them, or using a make-up pump if the pressure in the return line is not enough to fill the expansion vessel. The flow meter on the make-up line allows you to take into account the water intake from the heating network and make the correct payment. Presence of a heater allows to carry out the most rational mode of regulation. This is especially effective at above-zero outdoor temperatures and with central quality control in the kink zone. temperature chart.

The presence of heaters, a pump, an expansion tank in the circuit increases the cost of equipment and installation, and increases the size of the heating point, and also requires additional costs for maintenance and repair. The use of a heat exchanger increases specific consumption network water to the heating point and causes an increase in the temperature of the return network water by 3 ÷ 4ºС on average during the heating season.

Dependent schemes for connecting heating systems.

In this case, the heating systems operate under pressure close to the pressure in the return pipeline of the heating network. Circulation is provided by the pressure difference in the supply and return pipelines. This difference ∆Р must be sufficient to overcome the resistance of the heating system and thermal node.

If the pressure in the supply pipe exceeds the required pressure, it must be reduced by a pressure regulator or throttle washer.

Advantages of dependent schemes in comparison with independent schemes:

• simpler and cheaper subscriber input equipment;
• a greater temperature difference in the heating system can be obtained;
• reduced coolant consumption
• smaller pipeline diameters,
• operating costs are reduced.

Disadvantages of dependent schemes:

• rigid hydraulic connection of the heating network and heating systems and, as a result, reduced reliability;
• increased complexity of operation.

There are the following methods of dependent connection:

Scheme of direct connection of heating systems

She is the simplest circuit and is applied when the temperature and pressure of the coolant coincide with the parameters of the heating system. To connect residential buildings at the subscriber input, the temperature of the network water must not exceed 95ºС, for industrial buildings- no more than 150ºС).

This scheme can be used to connect industrial buildings and the residential sector to boiler rooms with cast iron hot water boilers working with maximum temperatures 95 - 105ºС or after CTP.

Buildings are connected directly, without mixing. It is enough to have valves on the supply and return pipelines of the heating system and the necessary instrumentation. The pressure in the heating network at the connection point must be less than the allowable one. Cast iron radiators have the least strength, for which the pressure should not exceed 60 m. Sometimes flow regulators are installed.

Scheme with an elevator

It is used when it is required to reduce the temperature of the heat carrier for heating systems according to sanitary and hygienic indicators (for example, from 150ºС to 95ºС). For this, water jet pumps (elevators) are used. In addition, the elevator is a circulation booster.

Most residential and public buildings are connected under this scheme. The advantage of this scheme is its low cost and, most importantly, the high degree of elevator reliability.

RDDS - pressure regulator to yourself; SPT is a heat meter consisting of a flow meter, two resistance thermometers and an electronic computing unit.

Advantages of the elevator:

• simplicity and reliability of work;
• no moving parts;
• does not require constant monitoring;
• productivity is easily regulated by the selection of the diameter of the replaceable nozzle;
• long service life;
• constant mixing ratio with fluctuations in the pressure drop in the heating network (within certain limits);
• due to the high resistance of the elevator increases hydraulic stability thermal network.

Elevator Disadvantages:

• low efficiency, equal to 0.25 ÷ 0.3, therefore, to create a pressure drop in the heating system, it is necessary to have an available pressure up to the elevator 8 ÷ 10 times greater;
• the constancy of the mixing ratio of the elevator, which leads to overheating of the premises during the warm period of the heating season, because it is impossible to change the ratio between the quantities of network water and mixed water;
• dependence of pressures in the heating system on pressures in the heating network;
• at emergency shutdown the heating network stops the circulation of water in the heating system, as a result of which there is a risk of freezing of water in the heating system.

Schematic with a jumper pump

Applicable:

1. with insufficient pressure drop at the subscriber input;
2. with a sufficient pressure difference, but if the pressure in the return pipe exceeds the static pressure of the heating system by no more than 5 m of water. Art.;
3. the required power of the thermal unit is large (more than 0.8 MW) and goes beyond the capacity of the produced elevators.

In case of an emergency shutdown of the heating network, the pump circulates water in the heating installation, which prevents it from defrosting for a relatively long period (8 - 12 hours). Such a pump installation scheme provides the lowest power consumption for pumping, because. the pump is selected according to the flow rate of the mixed water.

When installing mixing pumps in residential and public buildings, it is recommended to use noiseless foundationless pumps of the TsVTs type with a capacity of 2.5 to 25 t/h. More high reliability have imported pumps, which are now beginning to be used at heating points.

Replacing elevators with pumps is a progressive solution, because allows to reduce the consumption of network water by about 10% and reduce the diameter of pipelines.

The disadvantage is the noise of pumps (fundamental) and the need for their maintenance.

The scheme is widely used for central heating.

Scheme with a pump on the supply line.

This scheme is used when there is insufficient pressure in the supply line, i.e. when this pressure is lower than the static pressure of the heating system (in buildings elevated number of storeys).

The design head of the pump must correspond to the missing head, and the performance is chosen equal to the total flow of water in the heating installation. The filling of the heating system is provided by the pressure regulator RD, and the pressure difference between the supply and return lines is throttled in the control valve on the jumper (DK - throttle control valve). With it, the required mixing ratio is set. In the unstable hydraulic mode of the heating network, the check valve on the supply line is replaced by a downstream pressure regulator (RDPS), to which an impulse is applied when the booster pumps stop.

Scheme with a pump on the return line

This scheme is used when the pressure in the return line is unacceptably high. Most often used at the end sections, when the pressure in the return is increased, and the differential is insufficient. The pumps operate in the "mixing-pumping" mode, while the pressure in the return line decreases and the difference between the supply and return pipelines increases. The back pressure regulator on the return line is necessary in static mode, when the pumps operate as circulation pumps. In this case, the pressure regulators on the supply and return lines are forcibly closed, and the subscriber input is cut off from the heating network. To regulate the reduced pressure in the return line, a throttle control valve (DK) is installed on the jumper, with the help of which the mixing ratio is adjusted.

When using pump mixing at heating points, along with the working pump, it is necessary to install a backup pump. In addition, increased reliability in the power supply is required, since turning off the pump leads to the flow of superheated water from the heating network into the local heating system, which can damage it. In the event of an accident in the heating network, in order to save water in the local heating system, a check valve is additionally installed on the supply line and a pressure regulator on the return pipeline.

Schemes with a pump and an elevator

The noted shortcomings are eliminated in schemes with an elevator and a centrifugal pump. In this case, the failure of the centrifugal pump leads to a decrease in the mixing ratio of the elevator, but does not reduce it to zero, as with pure pump mixing. These schemes are applicable if the pressure difference in front of the elevator cannot provide required coefficient mixing, i.e. it is less than 10÷15 m of water. Art., but more than 5 m of water. Art. In existing thermal networks, such zones are extensive. The schemes allow for stepwise temperature control in the zone of high outdoor temperatures. Installing a centrifugal pump with a normally operating elevator when the pump is turned on allows you to increase the mixing ratio and reduce the temperature of the water supplied to the heating system.

There are 3 schemes for switching on the pump in relation to the elevator:

Scheme 1 is used if the head loss in the stopped pump is small and cannot significantly reduce the mixing ratio of the elevator. If this condition is not met, scheme 2 is used.

At small pressure drops, it is necessary to close the valve 1 in scheme 3.

Another scheme that can provide two-stage control in a high outdoor temperature zone is the two-elevator scheme.

Disabling one elevator leads to a decrease in network water consumption and an increase in the mixing ratio. Each elevator can be designed for 50% water flow, or one for 30-40% and the other for 70-60%.

Elevators with adjustable nozzle. By introducing a needle, the cross section of the nozzle changes and, accordingly, the mixing ratio. This allows in the warm period to reduce the flow of network water and increase the mixing ratio, while maintaining a constant flow in the heating system. No matter how perfect the design of the elevator, the error and maneuverability with dependent connection will not increase from this. In recent years, due to the increase in the construction of high-rise buildings, the use of independent schemes for connecting heating systems through water-water heaters has been growing. The transition to independent schemes makes it possible to widely use automation and improve the reliability of heat supply. It is advisable to use independent connection of heating systems in networks with direct water intake, which makes it possible to eliminate the main disadvantage of these systems, namely, low quality water for hot water supply.

santechnik.org.ua

Dependent and independent schemes for connecting heating systems

The heat supply system is one of the most important components of every residential building. Its main task is to provide thermal comfort for people in the premises. All systems central heating are connected according to a certain scheme - dependent or independent. These heat supply systems differ in the way they are connected and have fundamental differences. Not dependent system heating on this moment is gaining more and more popularity.

Dependent connection

It can be performed in two versions: directly or using a mixing unit.

If the connection is made according to the first option, then the superheated water from the heating networks is mixed in the boiler with the returning water from the heating system. In this way, the water acquires a sufficient temperature, up to approximately 100 0 . Its value depends on the power of the boiler. The temperature may be higher. Then it enters the heating source. Thermal points are supplied with pump mixers and water-jet elevators. For creating optimum temperature indoor air, low-temperature water is added to the pipeline, reducing the temperature regime. The second connection option implies that the hot and cold water are mixed, and the coolant liquid with a temperature of 70-80 0 C is sent to the heating radiators of residential buildings.

Dependent wiring diagram. Click on the photo to enlarge.

Direct connection can be used directly in low temperature heating networks, where two-pipe system with radiator throttling thermostats. Here, the parameters of heat carriers are constant throughout the year. Heating network reflect changes in consumer demand in terms of thermal volume, through instruments showing the pressure drop at the inlets. With their help, electronic regulators change the supply of common pumps of the heating network.

regulate this system can only be quantitative. The circulation of the heat source of the dependent circuit is carried out through differences in the values ​​of water pressure in the areas of connection to the elements outdoor system heating. Dependent connection and its connection scheme with a water mixing unit is structurally simple and easy to maintain.

The cost of the scheme is greatly reduced by eliminating some structural elements. The dependent scheme is selected if the heat-consuming system, including the heating system, allows an increase in hydraulic pressure to the value of the water pressure outside when it enters the heat pipeline. For some time dependent schema was popular in Russia, thanks to the ratio of its pros and cons.

Node independent heating system. Click on the photo to enlarge.

Heat supply of the heating system

A heat source for a water heating system until the middle of the 20th century. was mainly a local hot water boiler located in or near a heated building. It was also found, more often in the territory industrial enterprises, steam heat supply using a steam-water heat exchanger in a water heating system.

In the second half of the XX century. distributed centralized water heating, which uses high-temperature water supplied to the building from a distant heat source - a thermal power plant or a central heating plant.

Depending on the source of heat supply, the equipment of the local heat point of the heating system and its circuit diagram.

Which heating system is more profitable and why?

With the onset of the cool season, starting in autumn and ending in early spring, each owner of his house thinks about heating it. One option for this purpose is a dependent heating system. It is a consistent, direct method of transferring the thermal properties of the heat transfer medium from the heating source & CHP & to the end user & your heating device. The pressure throughout the heating network is constant and equals the pressure in the heating system.

Scheme for connecting batteries in a heating system with natural circulation of the coolant: 1 - Boiler; 2 - Overflow pipe; 3 - Expansion tank; 4 - Supply pipeline; 5 - Valves for regulating heating and water heating for each heating device; 6a - Diagonal connection batteries; 6b - Side connection batteries; 7 - Return water supply; 8 - sewer drain; 9 - Valve for draining water from the heating system; 10 - Valves for regulating heating and water heating for the entire system; 11 - Valve for feeding the system with water; 12 - Fine mechanical filter; 13 - Mayevsky crane.

Circulation in the heating system is achieved by a pressure difference in the supply and return pipelines.

To maintain the nominal mode of operation of the entire heating system, an employee of the CHP plant needs to monitor the pressure in the supply pipeline, you only need to paint the pipeline and pay for the use of heat.

Dependent heating schemes

• direct connection scheme;
• scheme using an elevator;
• scheme with the installation of the pump on the jumper;
• scheme with the installation of a pump on the supply line;
• scheme with the installation of a pump and an elevator at the same time.

Dependent heating helps to reduce heat carrier costs.

Each of them has its own differences, advantages and disadvantages, but the main thing is that the heating is efficient. So, the direct connection scheme is easy to install and operate, but the main drawback is & underheating in the cold season, according to the CHP schedule, and overheating in the warm season, which does not have a very good effect on human health and the appearance of indoor plants. The same drawback can be attributed to all other schemes for connecting the heater. But looking at economic indicators, obtained per year when using just such a method of heat transfer, the management of the CHPP is very interested in adjusting the temperature as much as possible to the optimum for a comfortable stay in the room. Every year, such enterprises make changes to the heat supply schemes to the consumer, buying more expensive equipment, so its cost to the consumer increases in direct proportion to their costs.

A dependent heater connection scheme, unlike an independent one, allows you to get a larger temperature difference in the heating system, as well as reduce the coolant consumption. In addition, pipelines for connection are used with a smaller diameter, and the cost of operating the necessary equipment is also significantly reduced. An independent heating connection scheme is more economical and manageable by the end consumer of heat, since it involves automation, which is its main difference from the above type of heating.

Comparison of dependent and independent heating systems

IN apartment buildings Residents mainly use the services of the central heating network for space heating. The quality of these services is influenced by many factors: the age of the house, wear and tear of equipment, the condition of the heating main, etc. Significant importance in heating system It also has a special scheme for connecting to the heating network.

Connection types

Connection schemes can be of two types: dependent and independent. Connecting by dependent method is the simplest and most common option. An independent heating system has gained its popularity in Lately, and is widely used in the construction of new residential areas. What solution is more effective for providing warmth, comfort and coziness to any room?

Such a connection scheme, as a rule, provides for the presence of in-house heating points, often equipped with elevators. In the mixing unit of the heat point, superheated water from the main external network is mixed with the return one, while acquiring a sufficient temperature. Thus, the internal heating system of the house is completely dependent on external heat supply.

Advantages

Main Feature Such a scheme is that it provides for the flow of water into the heating and water supply systems directly from the heating main, while the price pays off rather quickly.

• subscriber input equipment is simple and inexpensive;
• heating systems can withstand large temperature differences;
• the size of the pipeline in diameter is smaller;
• the scheme reduces the flow of coolant;
• low operating costs.

disadvantages

Along with the advantages, this connection also has some disadvantages:

• inefficiency;
• adjustment temperature regime significantly difficult during weather changes;
• overexpenditure of energy resources.

Connection methods

The connection can be made in several ways:

• through direct connection;
• with elevator;
• with jumper pump;
• with a pump on the return or supply lines;
• mixed way.

Water jet pumps or pumps are used for mixing. The most widely used mixing device is the elevator. When using elevators, due to their high resistance, the hydraulic stability of the heating network increases. In addition, the elevator is extremely simple device, having no moving parts, so it is reliable in operation, has a long service life, the cost of its maintenance is minimal. To ensure the design temperature in the heating system, it is necessary to provide design factor mixing, determined by the formula:

where U is the mixing ratio; G2 - consumption of mixed water from the heating system, kg; G1 - consumption of water coming from the heating network, kg, t; T1 - water temperature in the supply pipeline of the heating network, °С; T11 - the same in the supply pipeline of the heating system, ° С; T22 - the same in the return pipeline of the heating system.

a - direct: b - dependent with the help of an elevator;

c - dependent, with a pump on the jumper; g-something with a pump on the supply pipe of the heating system;

e - the same, with a pump on the return pipeline; c - independent;

independent heating system scheme

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Dependent heating system with mixing three-way valve And.

4. Choice of thermostat type ra

What is energy independence, and how do dependent and independent heating systems differ from each other

In multi-apartment buildings, the overwhelming majority use the central heating system for heating. However, the quality of such services depends on many factors, including the condition of the heating main and equipment. The scheme of connecting the house to the heating network is also important. In this case, you will learn about dependent and independent connection methods, as well as how to make the heating in the apartment non-volatile.

Independent and dependent heating system for the home

Connection options

Currently, there are two main connection schemes:

• dependent - is considered the simplest, therefore it is most often used;
• independent - gained popularity relatively recently, it is widely used in the construction of new residential areas.

Below we will take a closer look at each method in order to find out which solution will be the most effective for providing comfort and coziness to your room.

Dependent connection method

This connection option usually requires the creation of in-house heat points, often equipped with elevators. In their mixing unit, superheated water from the external main network is mixed with the return, which makes it possible to reduce its temperature to the required temperature, usually below 100 °C. Thanks to this, the heating system inside the house is completely dependent on external heat supply.

Sources: ultra-term.ru, teplo.kr-company.ru, 1poteply.ru, x-teplo.ru, ros-pipe.ru, lic-met.ru, gidroguru.com

sovet.clan.su

Schemes for connecting heating systems to heat networks

The connection of heat consumption networks to water heating networks is determined by the type of heat load, temperature and piezometric schedule of the heat network. Consumers are connected to heating networks in central and individual heating points.

Distinguish the following types connection of heating systems: direct, dependent, independent.

Direct connection is shown in Figure a. If the parameters of the heating system coincide with the parameters of the heating network, the heating system is connected to the heating network directly, without installing any intermediate device.

dependent connection. If the heating system requires more than low temperature than in the heating network, and the pressure at the connection point is lower than the permissible one, then dependent connection is applied. The coolant temperature is reduced by mixing network water with return water heating systems.

Water jet pumps (elevators) or pumps are used for mixing. The most widespread as a mixing device was the elevator (b). When using elevators, due to their high resistance, the hydraulic stability of the heating network increases. In addition, the elevator is an extremely simple device with no moving parts, so it is reliable in operation, has a long service life, and its maintenance costs are minimal. To ensure the design temperature in the heating system, it is necessary to provide the design mixing ratio, determined by the formula:

U=G2/G1=(T1-T11)/(T11-T22)

where U is the mixing ratio; G2 - consumption of mixed water from the heating system, kg; G1 - consumption of water coming from the heating network, kg, t; T1 - water temperature in the supply pipeline of the heating network, °С; T11 - the same in the supply pipeline of the heating system (after the mixing device), ° С; T22 - the same in the return pipeline of the heating system.

Schemes for connecting heating systems to a heat network

a - direct: b - dependent with the help of an elevator; c - dependent, with a pump on the jumper; g-something with a pump on the supply pipe of the heating system; e - the same, with a pump on the return pipeline; c - independent; 1 - elevator; 2 - sump; 3 - pump; 4 - heater; 5 - water meter; RD - pressure regulator; RR - flow regulator; PC - expansion tank

The values ​​of the mixing coefficients depending on the calculated temperatures of the heating network in the heating system are given in the table below.

Mixing coefficient values

normal operation the elevator occurs at H/h = 8-12 (H is the available pressure at the inlet; h is the resistance of the heating system).

It should be borne in mind that the value of the calculated pressure in front of the elevator is directly proportional to the resistance of the heating system. Therefore, an increase in the resistance of the heating system, for example, by 1.5 times will cause an increase in the calculated pressure R also by 1.5 times.

Connection with a pump on a jumper (c). In the event that water mixing cannot be performed using an elevator, install a pump on the jumper between the supply and return pipelines of the heating system. Mixing with the help of an elevator cannot be performed for the following reasons: the pressure at the connection point is insufficient for its normal operation; required heat output mixing unit is large and goes beyond the capacity of manufactured elevators (usually more than 0.8 MW - 0.7 Gcal / h).

When installing mixing pumps in residential and public buildings, it is recommended to use silent, foundationless pumps. When installing mixing pumps designed for high flow, centrifugal type K and KM are used as mixing pumps. The pump flow is equal to G2=1.1G1, and the head should be equal to H = 1.15h (where h is the resistance of the heating system).

Connection with a pump on the supply pipe of the heating system (d). A supply pipe pump is installed if, in addition to mixing water, it is necessary to increase the pressure in the supply pipe at the connection point of the heating system (the static height of the heating system is higher than the pressure in the supply pipe at the connection point).

The pump flow is G3 = 1.1 (1 + U)G1, and the head should be equal to:

Hus=1.15h+hn

where h is the resistance of the heating system; hn is the difference between the static height of the heating system and the piezometric height in the supply pipeline of the heating network at the point of connection, m.

Connection with a pump on the return pipeline of the heating system (d). The pump on the return pipe is installed if, along with mixing water, it is necessary to reduce the pressure in the return pipe at the point of connection of the heating system (the pressure is higher than that allowed for the heating system). The pump flow in this case is C3 = 1.1 (1 + U)G1 and the pressure must have a value that provides the required pressure in the return pipeline.

Independent connection (e). If the pressure in the return pipeline in the heating network is higher than the allowable pressure for the heating system, and the building has a significant height or is located in a high place in relation to adjacent buildings, then the heating system is connected according to an independent scheme.

According to an independent scheme, it is allowed to attach buildings with a height of 12 floors or more. The independent scheme is based on the separation of the heating system from the heat network using a heat exchanger, as a result of which the pressure in the heat network cannot be transferred to the heat carrier of the heating system. The circulation of the coolant is carried out with the help of circulation pumps of the K and KM types. The pump flow is determined by the formula

where Q is the power of the heating system, kJ/h (Gcal/h); C is the heat capacity of water, J/(kg h); T11, T22 - design water temperature in the supply and return pipelines of the heating system, respectively, °С

The required pressure of the pump should be equal to H = 1DM (psh k-resistance of the heating system). When choosing a pressure, one should strive for a minimum margin in flow and pressure. Otherwise, due to increased costs water in the heating system (speed above the permissible), noise occurs. An independent heating system is usually equipped with an expansion vessel. Leaks of water from the heating system are replenished from the network automatically according to the water level in the expansion tank.

ros-pipe.ru

Dependent and independent heating system - differences in schemes, pros and cons

When arranging heat supply at home, a dependent and independent heating system is used. Their difference lies in different schemes connection to the heating main.

Dependent heat supply scheme

If we imagine the elevator unit of a residential building (you can see how it looks in the photo), then it is arranged as follows:

• the elevator is separated from the heating main by inlet valves;
• behind them, in the place of supply and return, valves or gate valves are located. Through them, hot water supply is connected from the supply or return pipelines. Often in modern elevators there are two tie-ins on the supply and return lines, which are separated by a retaining washer. Their purpose is to ensure constant circulation of hot water;
• after inserting the elements to provide hot water, there is a nozzle with a chamber where mixing is performed. The flow of a hotter liquid coming from a direct pipeline under high pressure heats up part of the water in the return and is sent for recirculation;
• house valves block the heating system of the building - in winter they are open, and in the warm season they are closed.

Dependent and independent heating systems differ in that in the first version, water enters DHW systems and heat supply directly from the heating main.

Independent heating scheme

An independent heating scheme looks like this:

• from the supply pipeline, the liquid enters the return line, at the same time giving thermal energy heat exchanger. Water in this case is not used for hot water supply and space heating;
• in the same heat exchanger, but in its other circuit, drinking water from the water supply enters. After heating, it is fed into the heating system and for domestic use.

It looks like an independent connection of the heating system.

Dependent and independent heating system - comparison

The advantage of a dependent heating connection scheme is that the cost of its implementation is inexpensive. The fact is that with a small area of ​​\u200b\u200bthe house, the elevator unit of the heating system for it can be mounted independently, using ordinary shut-off valves for this. The most expensive is the manufacture of the nozzle, the thermal power of the elevator depends on its diameter.

The advantages that an independent heat supply scheme has:

• it allows you to more flexibly adjust the temperature of the coolant for heating. To do this, it will be enough to reduce the flow of coolant through the heat exchanger and, as a result, the air temperature in the house will drop. You can also press the latches in elevator node and thereby remove the gap. But for these elements, such a situation is considered abnormal, since cheeks may fall and circulation may stop. If the system is independent, the performance is simply regulated - using a circulation pump;
• efficiency is a consequence of the flexible heating settings depending on the needs of residents. In the dependent system, this indicator is at the level of no more than 40%;
• an independent heat supply system allows the use of water purified from impurities as a heat carrier, or antifreeze liquids. It is not difficult to heat drinking water for hot water supply. In turn, in the presence of a dependent system, consumers are forced to use water with large contaminants - sand, scale and mineral salts.

Dependence on electricity supply

A non-volatile heating system means that the heating equipment can operate in the absence of electricity. Some types of heating boilers and heat supply structures cannot work without electricity, while others can function without it.

Solid fuel boilers

The heat generator, which is a boiler (steel or cast iron), having a water jacket in the furnace and mechanical adjustment of the blower with a thermostat, is a completely non-volatile device. True, this design has a serious drawback, which is that a constant reloading of solid fuel is required.

Do independent heating of a private house, that is, without involving people, several technical solutions help:

1. Installation of the bunker and conveyor belt. As the fuel burns out, new portions of pellets or sawdust will be fed. But for the operation of the conveyor, electricity is required.
2. The use of a pyrolysis boiler, in which the combustion process is divided into two stages. The first of them consists in the pyrolysis of firewood with a limited supply of oxygen, and the second in the combustion of the resulting gas. At the top is a pyrolysis chamber, and below it is a compartment where the gas is burned. At the same time, in order for the combustion products to move against the direction of natural draft, an electric fan is needed.
3. The upper combustion boiler can operate on one tab of coal for about five days, since only its upper layer smolders. Air is supplied to the fuel from top to bottom, and the ash is carried away by a hot stream of combustion products. But to ensure air circulation, an electric fan is required.

gas boilers

To make a non-volatile gas boiler work, they use manual ignition using a piezoelectric element and adjusting the burner flame mechanical thermostat. When the main burner high temperature coolant goes out, the pilot remains in working order. Appliances equipped with electronic ignition, in case of downtime, stop the gas supply completely. After the coolant cools down below the critical level, heating resumes, but before the discharge must ignite the main burner. Air is supplied to the burner by an electrically driven forced draft fan.

Which heating scheme is better

If there are frequent power outages in the house, it is preferable to install a non-volatile gas heating boiler, since it can be used without electricity. But it should be noted that these devices do not differ in efficiency: in order to maintain a pilot flame, about 20% of the consumed gas volume is spent.

There is one more drawback of gas-fired non-volatile heating boilers - they do not have the ability to control the weather and control the unit using an external thermostat that determines the temperature regime, for example, in the most remote room. Accordingly, it is not possible to program the temperature for a long period, for example, for two weeks. When you need to make a choice which is the best dependent and independent heating system, it should be noted that the first of them has become unclaimed today.

Heating wooden house solid fuel boiler

What is an independent heating system? Do we have non-volatile heating or something else? What are the advantages and disadvantages of this solution compared to the alternative? Let's try to figure it out.

Terminology

Let's get rid of the confusion first.

Energy independence- this is the ability of heating equipment to work in the absence of electricity. The ability is undoubtedly pleasant, but we are not talking about it now. However, we will also touch on this topic.

What is the difference between independent and dependent heating system? Scheme of connection to the heating main.

dependent schema

Imagine an ordinary residential building. How is it arranged?

• Entrance valves cut off the elevator from the route.
• Behind them, gate valves or valves are embedded in the supply and return, through which hot water supply can be supplied from the supply or return pipeline.

Useful: in modern elevators, you can often find two tie-ins on the supply and return lines, separated by a retaining washer. Their function is to ensure constant circulation in the hot water supply system.

• After the DHW tie-ins, we see the actual elevator - a nozzle with a mixing chamber. A jet of hotter water at high pressure from the direct pipeline heats up part of the return water and recirculates it.
• Finally, house valves cut off the heating system. They are closed in summer and open in winter.

The key feature that a dependent heating scheme has is that water enters the heating and water supply systems directly from the heating main.

independent schema

Now let's imagine another scheme:

• Water from the supply pipeline enters the return pipeline, giving energy to the heat exchanger along the way. Water, we repeat, is not used for heating and hot water needs.
• In the same heat exchanger, but in its other circuit, drinking water from the plumbing. It heats up and enters the heating system. It can also be used for household needs.

Actually, we have exhaustively described an independent scheme for connecting a heating system.

Comparison of solutions

The dependent heating connection scheme has, in essence, only one advantage, but a very important one - the cheapness of implementation. Elevator unit for small cottage can be assembled with your own hands from consumer-grade valves. Noticeable against the background of wiring batteries around the house will be only the price of manufacturing a nozzle - the only exclusive made, the diameter of which determines thermal power elevator.

What is the asset of an independent scheme?

• Incomparably more flexible temperature control. It is enough just to reduce the flow of coolant through the heat exchanger - and the house will become colder.

Please note: yes, in the elevator unit, you can also press the valves by removing the difference. However, for them, this is an abnormal regime, fraught with a fall in the cheeks and a stop in circulation. In the case of an independent system, we simply regulate the performance of the circulation pump.

• The practical consequence of the flexible adjustment of heating to the needs of the house is efficiency. Relative to the dependent system, it is estimated at 10-40 percent.
• Finally, the main thing: in a dependent system, we are forced to use water with big amount pollution. It carries sand, scale and a lot of mineral salts.

We are not talking about the use of water as drinking water, moreover, in some regions hot water from the tap it is undesirable even to wash. An independent circuit makes it possible to use purified water or even non-freezing coolants as a coolant.

For the needs of hot water supply, it is not a problem to heat drinking water.

Dependence on electricity

And now back to energy dependence. When does the heating system need electricity to function, and when can it be dispensed with?

Solid fuel boilers

The canonical solution is an ordinary steel or cast-iron boiler with a water jacket in the furnace and mechanical adjustment of the blower using a thermostat. This unit is completely non-volatile.

In the photo - a classic solid fuel boiler.

However, this design has an important drawback: the boiler requires frequent fuel loading. To make heating as independent as possible from a person, three technical solutions allow:

• Bunker and conveyor belt, as the fuel burns out, it feeds new portions of sawdust or pellets. Electricity is necessary at least for the operation of the conveyor.
• divides combustion into two stages: pyrolysis of firewood with a limited supply of oxygen and combustion of the resulting gas. In this case, the gas combustion chamber is located below the pyrolysis chamber. The movement of combustion products against the vector of natural thrust requires the operation of an electric fan.
• Upper combustion boiler able to work on one tab of coal up to five days. Only the top layer of fuel smolders; air is supplied to it from top to bottom, and the ash is carried away by a stream of hot combustion products. Air circulation is provided by... that's right, an electric fan.

Gas

Non-volatile gas heating boilers use manual ignition with a piezoelectric element and flame adjustment with a mechanical thermostat. When the main burner is extinguished at a high coolant temperature, the pilot continues to operate.

Boilers with electronic ignition stop the gas supply completely when idle. As soon as the coolant cools below the critical temperature, the discharge ignites the main burner, and heating resumes. In addition, the blower fan is often electrically driven to supply air to the burner.

Which scheme is better? If you have frequent power outages, a non-volatile gas heating boiler would be more appropriate. Precisely because he is able to do without electricity in principle. On the other hand, these devices are less economical: up to 20% of the total gas consumed is spent on maintaining the pilot flame.

One more useful feature, which is deprived of gas non-volatile boilers heating - the ability to control the weather and control by an external thermostat that takes the temperature, for example, in a remote room. Of course, we are not talking about programming the temperature regime for a day or a week either.

Useful: in case you have frequent short-term heating outages, it will help simple instruction. Connect the boiler through a UPS with a large battery.

solarium

Everything is simple here: solar boilers are COMPLETELY identical gas boilers with electronic ignition. Only the burners are different. Actually, a lot of dual-fuel installations are produced.

It is clear that without a forced draft fan and electronic ignition, the devices simply cannot work.

Conclusion

You will find some more information about the types of heating systems and equipment for it in the video attached to the article. Warm winters!

When designing heating systems, as a coolant, they use, as a rule, water, the temperature of which is taken in accordance with SNiP. For example, in heating systems of residential and public buildings, the temperature of the coolant (water) should not exceed 95 ° C for two-pipe and 105 ° C for single pipe systems heating.

The determining factor in choosing a heating system connection scheme is temperature and hydraulic conditions operation of heating networks. Depending on this, heating systems are connected to heating networks according to dependent or independent schemes.

IN dependent connection diagrams, the coolant in the heating devices comes directly from the heating networks. Thus, the same coolant circulates both in the heating network and in the heating system.

IN independent In connection schemes, the heat carrier from the heating network enters the heater, in which its heat is used to heat the water that fills the local heating system. In this case, the network water and the water in the local heating system are separated by a heating surface and thus the network and the heating system are completely hydraulically isolated from each other.

With a dependent connection scheme, the hydraulic operating conditions of heat networks have direct influence for heating systems. In this case, either direct (if the temperature schedule of the heat supply system allows) or elevator connection of heating systems of residential and public buildings to the heating network (Fig. 2.9) is used.

Rice. 2.9. Dependent schemes for connecting heating systems to heat networks:
a - direct connection; b - elevator connection; 1 - supply pipeline;
2 - return pipeline; 3 - heating devices; 4 - manometer; 5 - thermometer; 6 - mud collector;
7 – shut-off valves(valve); 8 - air vent; 9 - narrowing device, liquid counter;
10 - elevator (jet pump)

Dependent connection of heating installations according to the scheme of fig. 2.9 but are used, as a rule, in heating systems of industrial enterprises. Such a scheme is also applicable in residential and public buildings, if the water temperature in the heating supply line does not exceed 95 - 105 ° C.

If the temperature of the network water in the supply line of the heating network exceeds 105 ° C and the available pressure at the inlet is sufficient for the operation of the jet pump - elevator (10 - 15 m of water column), then the heating system is connected to the heating network according to the scheme shown in fig. 2.9 b. In this case, the required temperature of the water entering the heating system is achieved by mixing high-temperature network water from the supply line with return water from the heating system in the elevator.

With dependent connection, the quality of heat supply largely depends on the quality of manufacture and installation of the elevator. In the manufacture of elevators, special care should be taken to monitor the alignment of the nozzle and the mixing chamber, the quality of processing internal surfaces nozzles and mixing chambers. Failure to comply with these requirements can lead to a decrease in the efficiency of the jet pump, an increase in pressure losses, clogging of the elevator nozzle and, as a result, to a violation of the circulation in the heating system.

The advantage of the elevator as a mixing device is the simplicity and reliability of operation.

The main characteristic of the elevator is the mixing ratio (injection ratio), which is the ratio of the flow rate of water sucked (injected) by the elevator to the flow rate of water through the elevator nozzle.

The pressure loss in the elevator nozzle is tens of times higher than the pressure loss in the heating system. Therefore, the main resistance of the local system is the resistance of the elevator nozzle, which depends on its geometric dimensions (nozzle cross-sectional diameter); the mixing ratio created by the elevator is a constant value. With a constant mixing ratio, the water flow in the heating system changes in proportion to the flow of network water through the elevator nozzle, i.e. when the supply of network water to the elevator nozzle is interrupted, the circulation of water in the local system will stop.

This can be avoided if a mixing pump is installed at the subscriber input instead of the elevator (Fig. 2.10). In the event of an emergency shutdown of the heating network, such a pump circulates water in the heating system, which prevents it from freezing for quite a long time (8 - 12 hours).

If necessary, the mixing pump can be installed on the supply or return pipelines of the heating system. In the first case, the pump, in addition to mixing, performs the functions of a booster pump, in the second case - a circulation pump.

Mixing pumps are installed, as a rule, in local heating points, therefore, they are subject to increased requirements for vibration and noise characteristics. An important criterion for the selection of mixing pumps is also their overall dimensions.

The advantage of a mixing pump over a jet pump is to increase the reliability of the heating system, ensure the circulation of water in the heating system with insufficient available pressure at the inlet, the possibility of automatic regulation of water flow and hydraulic protection of the heating system.

The advantage of a dependent connection scheme is the simplicity and relatively low cost of subscriber installations compared to an independent scheme. In addition, with dependent connection in a subscriber installation, a larger difference in temperature of network water can be obtained than with independent connection, which helps to reduce water consumption in the heating network and, accordingly, reduce the diameters of heating network pipelines and reduce capital costs in heating networks.

The main disadvantage of dependent schemes for connecting heating installations is the influence hydraulic mode operation of heat networks on the mode of operation of the heating system. Heaters have, as a rule, reduced mechanical strength compared to other elements of the heat supply system. For example, the limit mechanical strength cast iron radiators is 6 kgf / cm 2, steel radiators- 10 kgf / cm 2. Exceeding these limits can lead to accidents in subscriber installations. The low mechanical strength of heating devices significantly reduces the reliability of operation and complicates operation. large systems heat supply, which is explained by the presence a large number subscribers with heterogeneous heat load and extended heat transport systems. A significant disadvantage Dependent connection scheme with elevator mixing is also the impossibility of using local control of the heat load of the heating system, since when the flow of network water through the elevator changes, the water circulation in the heating system may stop, the circulation will be reversed or the heating system will be emptied.

Independent connection of heating systems makes it possible to exclude the influence of the hydraulic regime of the heating system and the influence of the daily uneven load of hot water supply on the operation of heating systems. The use of independent connection schemes is due to increased requirements for the reliability of heat supply, as well as an ever-increasing share of the construction of high-rise buildings. According to regulatory documents, according to an independent scheme, it is allowed to connect heating and ventilation systems of buildings with a number of floors of 12 and above, as well as when justifying the heating and ventilation systems of other heat consumers. An independent scheme for connecting the heating system is shown in fig. 2.11.

The main element of an independent connection scheme is an intermediate heat exchanger - a water-to-water heater, in which the water circulating in the heating system is heated to the required temperature. Network water is used as a heating medium in such a heat exchanger. The circulation of water in the heating system is carried out using a pump.

With independent connection of heating systems, additional investments in heat supply systems are required and the operation of the equipment of heating points and subscriber installations is somewhat more complicated due to the appearance additional elements: intermediate heat exchanger and circulation pump. In addition, with an independent connection scheme, the heat supply system must operate according to an increased temperature schedule to compensate for water undercooling in the intermediate heat exchanger.

Despite the disadvantages, an independent scheme for connecting heating installations has a number of advantages, the main of which is a significant increase in the reliability of the heat supply systems. In the heat supply system, it becomes possible to maintain a pressure level that exceeds the allowable under the conditions of the mechanical strength of heating devices, which is very important for large heat transport systems. The reliability of the heating systems is also increased by eliminating the possibility of emptying. The possibility of using local regulation with independent connection makes it possible to improve the quality of operation of heating installations by eliminating fluctuations in the temperature of the internal air of heated premises relative to the values ​​determined by SNiP and sanitary and hygienic standards.

A significant proportion of the country's housing stock continues to be buildings with outdated utilities. Subscriber units in 4-5-storey buildings, as a rule, are connected to heating networks according to a dependent scheme.

In dependent schemas heat supply, the heat carrier from the heating network enters directly into the heating installations of consumers, in independent - to the intermediate heat exchanger installed in the heating point, where it heats the secondary heat carrier circulating in the house circuit, i.e. consumers' installations are hydraulically isolated from the heating network.

The dependent connection scheme is simpler in design and maintenance due to the exclusion of many structural elements (heat exchangers, circulation pumps, automation).

but dependent schema heat supply has significant disadvantage - the presence of "overshoots" in buildings at the beginning and end of the heating period, when the outdoor temperature does not drop below zero degrees. What is the reason for this?

IN heating season regulation of the heat load of consumers is carried out by the heat supply organization according to the qualitative principle (the lower the outside air temperature, the hotter the coolant (network water) is supplied to the heating system at a constant flow rate). When the outdoor air temperature is close to 0 °C, the temperature of the direct heating water must be lowered and maintained at 30-35 °C. This will be sufficient to ensure comfortable temperature in heated buildings. However, in reality, such a reduction cannot be achieved due to the need for constant heating of water not only for heating, but also for hot water supply, for which the heat supply organization has to maintain the temperature of the network water at a level of 70-75 °C. In turn, maintaining such a temperature in the supply line of the heating network in the autumn-spring periods of the year leads to excessive heat release from heating radiators in buildings, causes discomfort to the population and, as a result, heat loss through open vents and transoms of windows.

According to statistics, winters in Russia are getting warmer, the duration of the period with positive outdoor temperatures is increasing, which means that heat losses with “overheating” are increasing.

During the transition to an independent scheme heat supply, it becomes possible to control the temperature of the secondary coolant entering the heating radiators in accordance with the outdoor temperature. According to experts, the amount of savings in thermal energy during the transition to an independent heat supply scheme can range from 10 to 40%.

Another advantage of independent systems is that it excludes the possibility of penetration of pollutants - sludge (rust, deposits, etc.) into network water from heating devices of subscribers. The ingress of sludge into the return network water is fraught with pollution of boiler plants and their failure.

Independent systems are used mainly in large cities with subscribers with a heterogeneous heat load and with a significant length of the heat network - in order to increase the reliability of heat supply.

When the pressure in the heating network under static conditions exceeds the allowable pressure level in subscriber units, the use of independent schemes for connecting subscribers' heating systems to heating networks is compulsory regardless of the structure, configuration, size of the district heating system.

If the separation of the heat carrier circuits with an independent scheme occurs at the central heating station, then distribution networks(intra-quarter and internal networks of heating systems) operate in a gentle temperature regime (no more than 95 ° C), and it becomes possible to use flexible plastic distribution pipelines with an increased service life.

It is advisable to combine the transition to an independent heat supply scheme with the simultaneous installation of house heat energy meters. When “overheating” is eliminated, residents’ bills for consumed heat will decrease, which will reduce the amount of subsidies from the budget for payment utilities low-income citizens.

In a number of regions, this event is included in the programs for the reconstruction of heat supply systems. However, this measure is not widely used due to significant capital investments.

The application of this method is regulated by SNiP 41-02-2003 "Heat Networks", Rules technical operation thermal installations, Decree of the Government of the Russian Federation of August 28, 2003 No. 1234-R "On the energy strategy of Russia for the period up to 2020" *.

Summary:

When converting to an independent schema:

• “overheating” of consumers in the autumn and spring periods, the consumer receives required amount heat;
• the quality of heat supply to consumers is improved, the cost of water treatment is reduced;
• the cost of heat supply services is reduced;
• the quality of the coolant improves;
• reduced emissions of gases and heat from boilers.

Ways to implement this technology can be both commercial financing and investment project on planning the energy development of the region, city, settlement.

*SNiP 41-02-2003 "Heat networks" were adopted and put into effect on September 1, 2003 by the Decree of the Gosstroy of Russia dated 06/24/2003 No. 110 instead of SNiP 2.04.07-86;
"Rules for the technical operation of thermal installations", approved. by order of the Ministry of Energy of the Russian Federation dated March 24, 2003 No. 115;
Decree of the Government of the Russian Federation of August 28, 2003 No. 1234-R "On the energy strategy of Russia for the period up to 2020".
(Data regulations can be viewed on the RosTeplo portal.en -

The heat supply system is one of the most important components of every residential building. Its main task is to provide thermal comfort for people in the premises. All central heating systems are connected according to a certain scheme - dependent or independent. These heat supply systems differ in the way they are connected and have fundamental differences. An independent heating system is currently gaining more and more popularity.

Independent heating system. Click on the photo to enlarge.

Dependent connection

It can be performed in two versions: directly or using a mixing unit.
If the connection is made according to the first option, then the superheated water from the heating networks is mixed in the boiler (in a certain volume) with the returning water from the heating system. In this way, the water acquires a sufficient temperature, up to approximately 100 0 . Its value depends on the power of the boiler. The temperature may be higher. Then it enters the heating source. Thermal points are supplied with pump mixers and water-jet elevators. To create an optimal indoor air temperature, low-temperature water is added to the pipeline, reducing the temperature regime. The second connection option implies that hot and cold water are mixed, and the coolant liquid with a temperature of 70-80 0 C is sent to the heating radiators of residential buildings.

Dependent wiring diagram. Click on the photo to enlarge.

Direct connection can be used directly in low temperature heating networks, where a two-pipe system with radiator throttling thermostats is made. Here, the parameters of heat carriers are constant throughout the year. Thermal networks reflect changes in consumer demand in terms of heat through instruments showing the pressure drop at the inlets. With their help, electronic regulators change the supply of common pumps of the heating network.

This system can only be regulated quantitatively. The circulation of the heat source of the dependent circuit is carried out through differences in the values ​​of water pressure in the areas of connection to the elements of the external heating system. Dependent connection and its connection scheme with a water mixing unit is structurally simple and easy to maintain.

The cost of the circuit is greatly reduced by eliminating some structural elements. A dependent scheme is selected if the heat-consuming system, including the heating system (according to sanitary and hygienic recommendations) allows an increase in hydraulic pressure to the value of the water pressure outside when it enters the heat pipeline. For some time, the dependent scheme was popular in Russia, due to the ratio of its pros and cons.

Node independent heating system. Click on the photo to enlarge.

Advantages and disadvantages of a dependent heating system

Advantages:

• quick payback;
• easy and inexpensive maintenance.

Disadvantages:

• the inability to adjust the temperature regime in the premises;
• the possibility of using only certain equipment of the system, suitable for the requirements of the plant (systems of this kind must withstand high pressure and water hammer at startup);
• regular measures are required to protect equipment from the hardness of salts dissolved in the coolant and oxygen exposure, in order to avoid corrosion;
• overexpenditure of consumed energy resources.

Connection according to an independent scheme

An independent heating system looks completely different. If the elements are connected according to an independent scheme, then the water in the boiler is heated to approximately 150 0, after which it is sent through special heat exchange equipment to the main coolant. The main coolant is used for circulation in closed circuit heated residential building. In this case, water does not mix.

The heating point is equipped with a circulation pump to provide pressure and water heat exchangers. Application of a set of measures for energy saving of the system: the use of modern, electronic coolant temperature controllers, circulation pumps with adjustable speed, metering devices for consumed thermal energy. Application of a set of measures to ensure the reliability of operation: special design of the heating system of the entire settlement, their loopback with the possibility of emergency switching of consumers to various sources thermal supply.

Schematic diagram of connection by independent system. Click on the photo to enlarge.

An independent connection scheme is used if an increase in hydraulic pressure is unacceptable in the engineering scheme (from the condition of system strength). That is, the water pressure in the outer pipeline must be greater than the pressure in the inner pipeline. In addition to the implementation of an unchanging thermal hydraulic regime under external influences, selected for each building separately, independent heating is characterized by increased reliability.

It is endowed with the ability to maintain circulation with the participation of the content in the water a certain amount heat, for a certain period of time, which is approximately enough to eliminate unforeseen emergencies in case of malfunctions of the external heat pipe.

The hydraulic mode of connection with an independent circuit does not depend on external elements engineering system. IN open systems providing heat, the considered connection of the heating system improves the quality of the water coming through the hot water supply installations. At the same time, the connection scheme is configured so that water does not pass through heating devices that serve as settling tanks for various kinds mud.

The principle of operation of an independent circuit. Click on the photo to enlarge.

Advantages and disadvantages of an independent heating system

Advantages:

• the possibility of flexible adjustment of the temperature regime in the premises (the heat carrier is isolated from the heat carrier boiler of the heating system) by maintaining the required pressure;
• the possibility of using various chemical composition coolant;
• obtaining the effect of energy saving, saving heat from 10 to 40%;
• the possibility of effective organization of the heat supply system with a significant distance and territorial dispersion of consumers;
• heating system shows high level reliability;
• improving the quality of hot water supply.

Disadvantages:

• huge maintenance costs are required;
• laborious and costly repairs.

Elements of an independent heating system. Click on the photo to enlarge.

IN closed systems, made in dependent or independent heating circuits, hot water heaters are connected to the heating network mainly in parallel, mixed and sequential options. When choosing the optimal option, the ratio is taken into account maximum load, calculated for heating, to the load of hot water supply, which is used in some areas. This is done using the temperature chart. centralized regulation release of heat received in subscriber thermal energy-consuming devices.

The heating system, which uses dependent connection, has now lost its distribution. IN modern construction only an independent heating circuit is used. IN modern world they have all the important benefits modern systems heat supply, despite the large financial costs and investments. The transition to independent heating is happening everywhere. Sometimes a combined scheme for connecting a local heating point is used, using both dependent and independent heating systems.