The automated heating point is an important node in the heating system. It is thanks to him that heat from the central networks enters residential buildings. Heating points are individual (ITP), serving MKD and central. From the latter, heat enters entire microdistricts, villages or various groups of objects. In the article, we will dwell in detail on the principle of operation of heat points, tell you how they are mounted, and dwell on the intricacies in the functioning of devices.

How an automated central heating station works

What do heat points do? First of all, they receive electricity from the central network and distribute it to the facilities. As noted above, there is an automated central heating point, the principle of which is to distribute thermal energy in the required ratio. This is necessary so that all objects receive water at the optimum temperature with sufficient pressure. As for individual heating points, they, first of all, rationally distribute heat between apartments in the MKD.

Why are ITPs needed if the district heating units are already provided for by the heat supply system? If we consider MKD, where there are quite a lot of users of utilities, low pressure and low water temperature in them are not uncommon. Individual heat points successfully solve these problems. Heat exchangers, additional pumps and other equipment are installed to ensure the comfort of the residents of the MKD.

The central network is a source of water supply. It is from there, through the inlet pipeline with a steel valve, under a certain pressure that hot water. The inlet water pressure is much higher than necessary internal system. In this regard, the heating point must be installed special device- pressure regulator. To ensure that the consumer receives clean water at the optimum temperature and with the required level of pressure, heating points are equipped with various devices:

• automation and temperature sensors;
• manometers and thermometers;
• actuators and control valves;
• pumps with frequency regulation;
• safety valves.

The automated central heating point operates in a similar way. Central heating stations can be equipped with the most powerful equipment, additional regulators and pumps, which is explained by the amount of energy they process. The automated central heating point should also include modern systems of automatic control and regulation for efficient heat supply of objects.

The heat station passes the treated water through itself, after which it again goes into the system, but already along the path of another pipeline. Automated systems of heat points with competently installed equipment heat is stably supplied, there are no emergencies in them, and energy consumption becomes more efficient.

Sources of heat for TP are enterprises that generate heat. We are talking about thermal power plants, boiler houses. Thermal points are connected to sources and consumers of heat energy using heating networks. They, in turn, are primary (main), which unite TS and enterprises that generate heat, and secondary (distributing), uniting heat points and end consumers. Thermal input is a section of the heating network that connects heating points and main heating networks.

Heat points include a number of systems through which users receive heat energy.

• DHW system. It is necessary for subscribers to receive hot tap water. Often, consumers use heat from the hot water supply system to partially heat rooms, for example, bathrooms in MKD.
• Heating system is needed to heat the premises and maintain the desired temperature in them. Connection schemes for heating systems are dependent and independent.
• Ventilation system is required to heat the air that enters the ventilation of objects from the outside. The system can also be used to interconnect user dependent heating systems.
• HVS system. It is not part of systems that consume heat energy. At the same time, the system is available in all heating points that serve MKD. The cold water supply system exists to provide the required level of pressure in the water supply system.

The scheme of an automated heat point depends both on the characteristics of heat energy users served by the heat point and on the characteristics of the source that supplies thermal energy to the heating substation. The most common is an automated heating point, which has a closed DHW system and an independent heating system connection scheme.

The heat carrier (for example, water with a temperature graph of 150/70), entering the heating point through the supply pipe of the heat input, gives off heat in the heaters of DHW systems, where the temperature graph is 60/40, and heating with a temperature graph of 95/70, and also enters the ventilation system of users. Further, the coolant returns to the return pipeline of the heat input and is sent back through the main networks to the enterprise that generates heat, where it is used again. A certain percentage of the heat carrier can be consumed by the consumer. To make up for losses in the primary heating systems at boiler houses and CHPPs, specialists use make-up systems, the sources of heat carrier for which are the water treatment systems of these enterprises.

Tap water entering the heating point bypasses the cold water pumps. After pumping a certain proportion cold water consumers receive, and the other part is heated by the heater of the first stage of hot water supply. Further, the water is sent to the circulation circuit of the DHW system.

DHW circulation pumps operate in the circulation circuit, which make water move in a circle: from heat points to users and back. Users draw water from the circuit when necessary. During circulation along the circuit, the water is gradually cooled, and in order for its temperature to always be optimal, it needs to be constantly heated in the heater of the second stage of hot water supply.

The heating system is a closed circuit along which the heat carrier moves from the heating points to the heating system of buildings and in the opposite direction. This movement is facilitated by heating circulation pumps. Over time, leakage of coolant from the heating system circuit is not ruled out. To make up for the losses, specialists use the heating point recharge system, in which primary heating networks are used as sources of heat carrier.

What are the advantages of an automated heating point

• The length of the pipes of the heating system as a whole is halved.
• Financial investments in heating networks and the cost of materials for construction and thermal insulation are reduced by 20–25%.
• Electric energy for pumping the heat carrier requires 20–40% less.
• Up to 15% savings in thermal energy for heating are observed, since the heat supply to a certain subscriber is automatically regulated.
• There is a decrease in the loss of thermal energy during the transportation of hot water by 2 times.
• Network accidents are significantly reduced, especially due to the exclusion of hot water pipes from the heating network.
• Since the operation of automated heat points does not require continuously located personnel, in attracting a large number qualified professionals are not needed.
• Maintaining comfortable living conditions due to the control of the parameters of thermal carriers occurs automatically. In particular, the temperature and pressure of network water, water in the heating system, water from the water supply system, as well as air in heated rooms are maintained.
• Each building pays for the actual heat consumed. Keeping track of used resources is convenient thanks to counters.
• It is possible to save heat, and thanks to the complete factory execution, installation costs are reduced.

Expert opinion

Benefits of automatic heating control

K. E. Loginova,

Energy Transfer Specialist

Almost any district heating system has the main problem associated with setting up and adjusting the hydraulic regime. If you do not pay attention to these options, the room either does not heat up to the end, or overheats. To solve the problem, you can use an automated individual heat point (AITP), which provides the user with heat energy in the amount that is needed.

An automated individual heating point limits the flow of network water in the heating systems of users who are located next to the central heating point. Thanks to AITP, this network water is redistributed to remote consumers. In addition, due to AITP, energy is consumed in the optimal amount, and the temperature in the apartments always remains comfortable, regardless of weather conditions.

An automated individual heating point makes it possible to reduce the amount of payment for heat and hot water consumption by about 25%. If the temperature on the street exceeds minus 3 degrees, the owners of apartments in the MKD begin to face overpayment for heating. Only thanks to AITP, thermal energy is consumed in the house in the amount necessary to maintain a comfortable environment. It is in connection with this that many "cold" houses install automated individual heating points in order to avoid low uncomfortable temperatures.

The figure shows how the two buildings of the dormitories consume heat. Building 1 has an automated individual heat point, building 2 does not.

Consumption of thermal energy by two buildings of hostels with AITP (building 1) and without it (building 2)

AITP is installed at the input of the heating system of the building, in basement. Heat generation is not a function of heat points, unlike boiler houses. Thermal points work with a heated carrier of heat, which is supplied by a centralized heating network.

It should be noted that AITP uses frequency regulation of pumps. Thanks to the system, the equipment works more reliably, failures and water hammer do not occur, and the level of electrical energy consumption is significantly reduced.

What do automated heat points include? Saving water and heat in AITP is carried out due to the fact that the parameters of the heat carrier in the heat supply system change quickly, taking into account changing weather conditions or the consumption of a certain service, for example, hot water. This is achieved by using compact, economical equipment. In this case, we are talking about low-noise circulation pumps, compact heat exchangers, modern electronic devices for automatically adjusting the supply and metering of heat energy and other auxiliary elements (photo).

Main and auxiliary elements of AITP:

1 - control panel; 2 - storage tank; 3 - manometer; 4 - bimetallic thermometer; 5 - collector of the supply pipeline of the heating system; 6 - collector of the return pipeline of the heating system; 7 - heat exchanger; 8 - circulation pumps; 9 - pressure sensor; 10 - mechanical filter

Maintenance of automated heat points must be carried out every day, every week, once a month or once a year. It all depends on the regulation.

As part of the daily maintenance, the equipment and components of the heating unit are carefully inspected, identifying problems and promptly eliminating them; control how the heating system and hot water work; check whether the readings of control devices correspond to regime cards, reflect the parameters of work in the AITP log.

Maintenance of automated heat points once a week involves certain activities. In particular, specialists inspect measuring and automatic control devices, identifying possible malfunctions; check how the automation works, look at backup power, bearings, shut-off and control valves of pumping equipment, oil level in thermometer sleeves; clean pump equipment.

As part of the monthly maintenance, specialists check how pumping equipment works, simulating accidents; check how the pumps are fixed, what condition the electric motors, contactors, magnetic starters, contacts and fuses are in; they blow and check pressure gauges, control the automation of heat supply units for heating and hot water supply, test operation in different modes, control the heating replenishment unit, take readings of heat energy consumption from the meter in order to transfer them to the organization supplying heat.

Maintenance of automated heating points once a year involves their inspection and diagnostics. Specialists check open electrical wiring, fuses, insulation, grounding, circuit breakers; inspect and change the thermal insulation of pipelines and water heaters, lubricate the bearings of electric motors, pumps, gears, control valves, pressure gauge sleeves; check how tight connections and pipelines are; look at the bolted connections, the completeness of the heat point with equipment, change the broken components, wash the sump, clean or change the mesh filters, clean the hot water heating surfaces and heating systems, pressurize; hand over an automated individual heat point prepared for the season, drawing up a statement on the suitability of its use in the winter.

The main equipment can be used for 5–7 years. After this period, it is performed overhaul or change some elements. The main parts of AITP do not need verification. Instrumentation, metering unit, sensors are subject to it. Verification, as a rule, is carried out once every 3 years.

On average, the price of a control valve on the market is from 50 to 75 thousand rubles, a pump - from 30 to 100 thousand rubles, a heat exchanger - from 70 to 250 thousand rubles, thermal automation - from 75 to 200 thousand rubles.

Automated block heating points

Automated block heat points, or BTPs, are manufactured in factories. For installation work they are supplied ready blocks. To create a heat point of this type, one block or several can be used. Block equipment is mounted compactly, usually on one frame. As a rule, it is used to save space if conditions are cramped enough.

Automated block heat points simplify the solution of even complex economic and production tasks. If we are talking about a sector of the economy, the following points should be touched upon here:

• the equipment begins to work more reliably, respectively, accidents occur less frequently, and less money is required for liquidation;
• it is possible to regulate the heating network as accurately as possible;
• reducing the cost of water treatment;
• repair areas are reduced;
• a high degree of archiving and dispatching can be achieved.

In the areas of housing and communal services, municipal unitary enterprises, MA (managing organizations):

• maintenance personnel are required in smaller numbers;
• payment for the actually used heat energy is carried out without financial costs;
• system feed losses are reduced;
• free space is released;
• it is possible to achieve durability and a high level of maintainability;
• managing the heat load becomes more comfortable and easier;
• there is no need for constant operator and plumbing intervention in the operation of the heating point.

As for design organizations, here we can talk about:

• strict compliance with the terms of reference;
• a wide choice of circuit solutions;
• high level automation;
• a large selection of engineering equipment for completing heat points;
• high energy efficiency.

For companies operating in the industrial sector, these are:

• redundancy to a high degree, which is especially important if technological processes are carried out continuously;
• strict adherence to high-tech processes and their accounting;
• the ability to use condensate, if any, process steam;
• temperature control by workshop;
• adjustment of the selection of hot water and steam;
• decrease in recharge, etc.

Most facilities typically have shell-and-tube heat exchangers and direct pressure hydraulic regulators. Most often, the resources of this equipment have already been exhausted, in addition, it operates in modes that do not recommend the calculated ones. The last point is due to the fact that now the maintenance of thermal loads is carried out at a level much lower than that envisaged by the project. The control equipment has its own functions, which, however, in case of significant deviations from the design mode, it does not perform.

If the automated systems of heat points are to be reconstructed, it is better to use modern compact equipment that allows you to work automatically and save about 30% of energy compared to the equipment that was used in the 60-70s. At the moment, heat points are equipped, as a rule, with an independent scheme for connecting heating systems and hot water supply, which are based on collapsible plate heat exchangers.

To control thermal processes, specialized controllers and electronic regulators are usually used. The weight and dimensions of modern plate heat exchangers are much smaller than shell-and-tube heat exchangers with the corresponding power. Plate heat exchangers are compact and lightweight, which means they are easy to install, easy to maintain and repair.

Important!

The basis for the calculation of plate-type heat exchangers is a system of criterial controls. Before calculating the heat exchanger, the optimal distribution of the DHW load between the stages of the heaters and the temperature regime of all stages separately are calculated, taking into account the method of adjusting the heat supply from the heat source and the schemes for connecting the DHW heaters.

Individual automated heating point

ITP is a whole complex of devices, which is located on the territory of a separate room and consists, among other things, of elements of heating equipment. Thanks to an individual ATP, these installations are connected to the heating network, transformed, heat consumption modes are controlled, operability is carried out, distribution by types of heat carrier consumption is carried out, and its parameters are regulated.

Thermal installation, serving the object or its individual parts, is an ITP, or an individual heating point. The installation is necessary to supply hot water, ventilation and heat to houses, housing and communal services and industrial complexes. For the operation of the ITP, it is necessary to connect it to the water, heat and power supply system in order to activate the circulation pumping equipment.

A small ITP can be successfully used in a single family home. This option is also suitable for small buildings directly connected to a centralized heating network. Equipment of this type is designed to heat rooms and heat water. Large ITPs with a capacity of 50 kW–2 MW serve large or multi-apartment buildings.

The classic scheme of an automated individual heat point consists of the following units:

• heating network input;
• counter;
• connection of the ventilation system;
• heating connection;
• DHW connection;
• coordination of pressures between heat consumption and heat supply systems;
• make-up of heating and ventilation systems connected according to an independent scheme.

When a TP project is being developed, it should be remembered that the required nodes are:

• counter;
• pressure matching;
• heating input.

The heating point can be equipped with other units. Their number is determined by the design decision in each individual case.

Admission to operation of ITP

To prepare the ITP for use in the MKD, the following documentation must be submitted to Energonadzor:

• The technical conditions for connection that are currently in force, and a certificate that they have been met. The certificate is issued by the energy supply company.
• Project documents, where there are all necessary approvals.
• An act on the responsibility of the parties for the use and separation of balance sheet property, which was drawn up by the consumer and a representative of the energy supply company.
• The act that the subscriber branch of the TP is ready for permanent or temporary use.
• Passport of an individual heat point, which briefly lists the characteristics of heat supply systems.
• Certificate that the heat energy meter is ready for operation.
• Certificate that a contract for the supply of thermal energy with an energy supply company has been concluded.
• Certificate of acceptance of work carried out between the user and the installation company. The document must indicate the license number and the date it was issued.
• Order on the appointment of a responsible specialist for the safe use and normal technical condition of heating networks and thermal installations.
• The list, which reflects operational and operational-repair responsible persons for servicing heating networks and thermal installations.
• A copy of the welder's certificate.
• Certificates for pipelines and electrodes used in the work.
• Acts for carrying out hidden work, an executive diagram of the heating point, where the numbering of the fittings is indicated, as well as diagrams of valves and pipelines.
• Act for flushing and pressure testing of systems (heating networks, heating, hot water supply).
• Job Descriptions, as well as safety instructions and rules of conduct in case of fire.
• Operating Instructions.
• An act that networks and installations are approved for use.
• Journal of instrumentation and automation, issuance of work permits, operational accounting of detected defects during the inspection of installations and networks, inspection of buildings and instructions.
• Outfit from heating networks for connection.

Specialists who service automated heating points must have the appropriate qualifications. In addition, responsible persons are required to immediately familiarize themselves with the technical documents, which indicate how to use the TP.

Types of ITP

Scheme ITP for heating independent. In accordance with it, a plate heat exchanger is installed, designed for one hundred percent load. It is also possible to install a double pump, which compensates for pressure losses. The heating system is fed by the heating return pipeline. TP of this type can be equipped with a DHW unit, a meter and other necessary units and blocks.

Scheme of an automated heat point individual type for domestic hot water also independent. It is parallel and single-stage. Such an IHS contains 2 plate heat exchangers, and each must work with a load of 50%. The complete set of the thermal substation also provides for a group of pumps that are designed to compensate for the decrease in pressure. A heating system block, a meter and other blocks and assemblies are also sometimes installed in the TP.

ITP for heating and hot water. The organization of an automated heat point in this case is organized according to an independent scheme. For the heating system, a plate heat exchanger is provided, designed for one hundred percent load. The DHW circuit is two-stage, independent. It has two plate heat exchangers. To compensate for the decrease in pressure level, the scheme of an automated heat point involves the installation of a group of pumps. To feed the heating system, appropriate pumping equipment is provided from the heating system return pipeline. DHW is fed by the cold water system.

In addition, there is a meter in the ITP (individual heating point).

ITP for heating, hot water supply and ventilation. The thermal installation is connected according to an independent scheme. For the heating and ventilation system, a plate heat exchanger is used that can withstand a load of 100%. The DHW scheme can be described as single-stage, independent and parallel. It has two plate heat exchangers, each designed for a load of 50%.

The decrease in pressure level is compensated by a group of pumps. The heating system is fed by the heating return pipeline. DHW is fed from cold water. ITP in MKD can be additionally equipped with a counter.

Calculation of the thermal loads of the building for the selection of equipment for an automated heating point

The heat load for heating is the amount of heat that all heating devices as a whole, installed in a house or on the territory of another object, give off. Note that before installing all the technical means, everything must be carefully calculated in order to protect yourself from unforeseen situations and unnecessary cash costs. If you correctly calculate the heat loads on the heating system, you can achieve efficient and uninterrupted operation heating systems for a residential building or other building. The calculation contributes to the prompt implementation of absolutely all tasks related to heat supply, and ensuring their work in accordance with the requirements and norms of SNiP.

In general heat load The modern heating system includes certain load parameters:

• for a common central heating system;
• on the floor heating system (if there is one in the room) - underfloor heating;
• ventilation system (natural and forced);
• hot water system;
• for various technological needs: swimming pools, baths and other similar structures.

• Type and purpose of buildings. When calculating, it is important to take into account what type of property belongs to - an apartment, an administrative building or a non-residential building. In addition, the type of building affects the load rate, which, in turn, is determined by organizations supplying heat. The amount of payment for heating services also depends on this.
• architectural component. When calculating, it is important to know the dimensions of various external structures, which include walls, floors, roofs and other fences; the scale of openings - balconies, loggias, windows and doors. They also take into account how many floors the building has, whether it has basements, attics, what features they have.
• Temperature regime for all objects in the building subject to requirements. Here we are talking about temperature conditions in relation to all rooms in a residential building or areas of an administrative building.
• The design and features of fences outside, including the type of materials, thickness and the presence of layers for insulation.
• Purpose of the object. It is usually applied to production facilities, in the workshop or on the site of which the creation of certain temperature conditions is expected.
• Availability and characteristics of premises special purpose (we are talking about swimming pools, saunas and other facilities).
• maintenance level(Is there hot water in the room, ventilation systems and air conditioning, what kind of central heating is there).
• Total number of points from which hot water is taken. This is the first parameter to look at. The more points of intake, the more heat load falls on the entire heating system.
• The number of residents of the house or people staying on the territory of the facility. The indicator affects the requirements for temperature and humidity. These parameters are the factors that the formula for calculating the heat load contains.
• Other indicators. If we are talking about an industrial object, the number of shifts, workers in one shift and working days per year is important here. With regard to private households, it is important how many residents there are, the number of bathrooms, rooms, etc.

Methods for determining thermal loads

1. Aggregated calculation method for the heating system are used in the absence of information about projects or inconsistency of such information with real indicators. An enlarged calculation of the heat load of the heating system is carried out according to a fairly simple formula:

Qmax from. \u003d α * V * q0 * (tv-tn.r.) * 10 - 6,

where α is a correction factor that takes into account the climate in the region in which the object is located (it is used if the calculated temperature differs from minus 30 degrees); q0 is the specific characteristic of the heating system, which is chosen depending on the temperature of the coldest week of the year; V - the outer volume of the building.

2. Within the framework of the integrated heat engineering method surveys must thermograph all structures - walls, doors, ceilings, windows. It should be noted that thanks to such procedures, it is possible to determine and fix the factors that significantly affect the heat loss at the facility.

The results of thermal imaging diagnostics will provide an idea of ​​the real temperature difference when a certain amount of heat passes through 1 m 2 of the fence structures. In addition, this makes it possible to learn about the consumption of thermal energy in the event of a certain temperature difference.

When calculating, special attention is paid to practical measurements, which are an integral part of the work. Thanks to them, you can find out about the heat load and heat losses that will occur at a particular facility over a certain period of time. Thanks to practical calculation, they receive information about indicators that theory does not cover, or, more precisely, they learn about the “bottlenecks” of each of the structures.

Installation of an automated heat point

Suppose, within the framework of the general meeting, the owners of the premises in the MKD decided that the organization of an automated heating point is still needed. Today, such equipment is presented in a wide range, however, not every automated heating point may suit your household.

It is interesting!

99% of users have no idea that the main thing is the initial feasibility study in the MKD. Only after the examination, you need to select an automated individual heating point, consisting either of blocks and modules directly from the factory, or assemble the equipment in the basement of your house, using separate spare parts for this.

AITP, produced at the factory, are easier and faster to install. All that is required is fixing the modular units to the flanges and then connecting the device to the socket. For this reason, most of installation companies prefers such automated heat points.

If an automated heating point is assembled at the factory, the price for it is always higher, but this is compensated good quality. Automated heat points are produced by plants of two categories. The first group includes large enterprises, where serial assembly of heating substations is carried out, the second group includes companies of medium and large scale, manufacturing heating points from blocks in accordance with individual projects.

Only a few companies are engaged in serial production of automated heating points in Russia. Such TPs are assembled very high quality, from reliable parts. However, mass production also has a significant drawback - the impossibility of changing overall dimensions blocks. It is not possible to replace one manufacturer of spare parts with another. The technological scheme of an automated heat point is also not amenable to change, and it cannot be adapted to your needs.

These shortcomings do not have automated block heat points, for which they develop individual projects. Such heat points are produced in every metropolis. However, there are risks here. In particular, you may encounter an unscrupulous manufacturer who assembles TP, roughly speaking, “in a garage”, or you may stumble upon design errors.

During the dismantling of doorways and the reconstruction of walls, an increase in installation work by 2–3 times is often observed. At the same time, no one can guarantee that the manufacturers did not accidentally make a mistake when measuring openings and sent the correct dimensions to production.

The organization of an automated prefabricated heating point is always possible in the house, even if there is not enough space in the basement. Such a TP may include blocks of the factory type. An automated heating point, the price of which is much lower, also has disadvantages.

Factories always cooperate with trusted suppliers and purchase spare parts from them. In addition, there is a factory warranty. Automated block heat points undergo a pressure testing procedure, that is, they are immediately checked for leaks even at the factory. High quality paint is used to paint their pipes.

Control over the teams of workers performing the installation is a rather complicated undertaking. Where and how are pressure gauges and ball valves purchased? These parts are successfully counterfeited in Asian countries, and if these components are inexpensive, it is only because low-quality steel was used in their manufacture. In addition, you need to look at the welds, their quality. The managing directors of apartment buildings, as a rule, do not have the necessary equipment. You should definitely demand installation guarantees from contractors, and, of course, it is better to cooperate with time-tested companies. Specialized enterprises always have the necessary equipment in stock. These organizations have ultrasonic and X-ray flaw detectors.

The installation company must be a member of the SRO. Equally important is the amount of insurance payments. Saving on insurance premiums is not a distinctive feature of large enterprises, since it is important for them to advertise their services and be sure that the client is calm. You should definitely look at how much authorized capital the installation company has. The minimum amount is 10 thousand rubles. If you came across an organization with about this capital, most likely you stumbled upon covens.

The key technical solutions used in AITP can be divided into two groups:

• the connection scheme with the heating network is independent - in this case, the heat carrier of the heating circuit in the house is separated from the heating network by a boiler (heat exchanger) and circulates in a closed cycle directly inside the facility;
• the connection scheme with the heating network is dependent - the heat carrier of the district heating network is used in heating radiators of several objects.

The figures below show the most common connection schemes for heating networks and heating points.

With independent connection schemes, plate or shell-and-tube heat exchange units are used. They come in different types, with their pros and cons. With dependent schemes for connecting to the heating network, mixing units or elevators with a controlled nozzle are used. If we talk about the most optimal option, these are automated heating points, the connection scheme of which is dependent. Such an automated heat point, the price of which is significantly lower, is more reliable. Maintenance of automated heating points of this type can also be called high-quality.

Alas, if it is necessary to organize heat supply at facilities with many floors, they use an exclusively independent connection scheme to comply with the relevant technological rules.

There are many ways to assemble an automated heating point for a specific object using quality spare parts produced by world or domestic producers. The management of the UK is forced to rely on designers, but they are usually affiliated with a specific TP manufacturer or installation company.

Expert opinion

Russia lacks energy service companies - consumer advocates

A. I. Markelov,

CEO of Energy Transfer

There is currently no balance in the market of heat-saving technologies. There is no mechanism by which the consumer can competently and competently choose specialists in design, installation, as well as companies producing AITP. All this leads to the fact that the organization of an automated heat point does not bring the desired results.

As a rule, during the installation of AITP, adjustment (hydraulic balancing) of the heating system of the facility is not performed. However, it is needed, since the quality of heating in the entrances is different. In one entrance of the house it can be very cold, in another hot.

When installing an automated heat point, you can use front-facing regulation, when the adjustment of one side of the MKD does not depend on the other. Thanks to all these procedures, the installation of AITP becomes more efficient.

The developed countries of Europe quite successfully use energy services. Energy service companies exist to protect the interests of consumers. Thanks to them, users never have to deal directly with sellers. In the absence of savings sufficient to pay back the costs, the energy service enterprise may face bankruptcy, since its profit depends on the savings of the user.

It remains to be hoped that adequate legal mechanisms will appear in Russia, through which it will be possible to achieve savings in the payment of CG.

The traditional in our country regulation of heat supply to the consumer today turns out to be costly, in connection with which the qualitative and quantitative regulation of heat supply is becoming more widespread. The article considers both schemes from the point of view of Russian realities.

The structure of modern heat supply systems and proposals for its change

Due to the peculiarities of climatic conditions, the uninterrupted supply of the population and industry with thermal energy in Russia is an urgent social and economic problem.

The use of collapsible heat exchangers

High efficiency and affordable price provide heat exchangers with a priority in the construction market. Due to their low heat loss and high technical performance, heat exchangers are an important part of building equipment.

All about the heat point

Thermal point(TP) is a complex of devices located in a separate room, consisting of elements of thermal power plants that ensure the connection of these plants to the heating network, their operability, control of heat consumption modes, transformation, regulation of coolant parameters and distribution of coolant by type of consumption.

Purpose

The main tasks of the TP are:
Converting the type of coolant
Control and regulation of coolant parameters
Distribution of heat carrier by heat consumption systems
Shutdown of heat consumption systems
Protection of heat consumption systems from an emergency increase in the parameters of the coolant
Accounting for coolant and heat consumption

Types of heat points

Heat points differ in the number and type of heat consumption systems connected to them, individual characteristics which determine the thermal scheme and characteristics of the TS equipment, as well as by the type of installation and features of the placement of equipment in the TS room. There are the following types of heat pumps:
Individual heating point(ETC). It is used to serve one consumer (building or part of it). Usually located in the basement or technical room building, however, due to the characteristics of the serviced building, it can be placed in a separate building.
Central heating point(CTP). It is used to serve a group of consumers (buildings, industrial facilities). Most often located in a separate building, but can be placed in the basement or technical room of one of the buildings.
Block heat point(BTP). It is manufactured in the factory and supplied for installation in the form of ready-made blocks. It may consist of one or more blocks. The equipment of the blocks is mounted very compactly, as a rule, on one frame. Usually used when you need to save space, in cramped conditions. By the nature and number of connected consumers, the BTP can refer to both ITP and CHP.

Heat sources and thermal energy transport systems

The source of heat for TP are heat generating enterprises (boiler houses, combined heat and power plants). TP is connected to sources and consumers of heat through heating networks. Heat networks are subdivided into primary main heat networks connecting heat substation with heat generating enterprises, and secondary (distributing) heat networks connecting heat substation with end consumers. The section of the heating network that directly connects the TP and the main heating networks is called the heat input.

The main heat networks, as a rule, have a large length (the distance from the heat source is up to 10 km or more). For the construction of trunk networks, steel pipelines with a diameter of up to 1400 mm are used. In conditions where there are several heat generating enterprises, loopbacks are made on the main heat pipelines, uniting them into one network. This allows you to increase the reliability of the supply of heat points, and, ultimately, consumers with heat. For example, in cities, in the event of an accident on a highway or a local boiler house, heat supply can be taken over by the boiler house of a neighboring district. Also, in some cases, the common network makes it possible to distribute the load between heat generating enterprises. Specially prepared water is used as a heat carrier in main heating systems. During preparation, the indicators of carbonate hardness, oxygen content, iron content and pH are normalized in it. Unprepared for use in heating networks (including tap water, drinking water) is unsuitable for use as a heat carrier, since at high temperatures, due to the formation of deposits and corrosion, it will cause increased wear of pipelines and equipment. The design of the TP prevents relatively hard tap water from entering the main heating networks.

Secondary heating networks have a relatively small length (remote TS from the consumer up to 500 meters) and in urban conditions are limited to one or a couple of blocks. Diameters of pipelines of secondary networks, as a rule, are in the range from 50 to 150 mm. During the construction of secondary heating networks, both steel and polymer pipelines can be used. The use of polymer pipelines is most preferable, especially for hot water systems, since the rigid tap water in combination with elevated temperature leads to intense corrosion and premature failure of steel pipelines. In the case of an individual heating point, there may be no secondary heating networks.

Water supply networks serve as a source of water for cold and hot water supply systems.

Thermal energy consumption systems

A typical TP has the following heating systems:
Hot water system(DHW). Designed to supply consumers with hot water. Distinguish between closed and open hot water systems. Often, heat from the DHW system is used by consumers for partial space heating, such as bathrooms, in apartment buildings.
Heating system. It is intended for heating rooms in order to maintain the set air temperature in them. There are dependent and independent schemes for connecting heating systems.
Ventilation system. Designed for heating outdoor air, while providing the necessary air exchange to create indoor air conditions. It can also be used to connect dependent consumer heating systems.
Cold water system. Does not apply to systems that consume thermal energy, however, it is present in all heat substations serving multi-storey buildings. Designed to provide the necessary pressure in consumer water supply systems.

circuit diagram heating point

The TP scheme depends, on the one hand, on the characteristics of thermal energy consumers served by the heating point, on the other hand, on the characteristics of the source supplying the TP with thermal energy. Further, as the most common, TP is considered with a closed hot water supply system and an independent scheme for connecting the heating system.
Schematic diagram of a heat point

The coolant entering the TP through the supply pipeline of the heat input gives off its heat in the heaters of the DHW and heating systems, and also enters the consumer ventilation system, after which it returns to the return pipeline of the heat input and is sent back to the heat generating enterprise for reuse through the main networks. Part of the coolant can be consumed by the consumer. To make up for losses in primary heat networks, at boiler houses and CHPPs, there are make-up systems, the sources of heat carrier for which are the water treatment systems of these enterprises.

The tap water entering the TP passes through the cold water pumps, after which part of the cold water is sent to consumers, and the other part is heated in the DHW first stage heater and enters the DHW circulation circuit. In the circulation circuit, water with the help of hot water circulation pumps moves in a circle from the TP to consumers and back, and consumers take water from the circuit as needed. When circulating around the circuit, the water gradually gives off its heat and in order to maintain the water temperature at a given level, it is constantly heated in the heater of the second DHW stage.

The heating system also represents a closed circuit, along which the coolant moves with the help of heating circulation pumps from the heating substation to the heating system of buildings and back. During operation, leakage of the coolant from the circuit of the heating system may occur. To make up for the losses, the heating substation feed system is used, which uses primary heating networks as a source of heat carrier.

Notes
Rules for the technical operation of thermal power plants. Approved by order of the Ministry of Energy of the Russian Federation dated March 24, 2003 No. 115
Safety regulations for the operation of heat-consuming installations and heating networks of consumers
SNiP 2.04.01-85. INTERNAL WATER SUPPLY AND SEWERAGE OF BUILDINGS. Quality and temperature of water in water supply systems.
GOST 30494-96. BUILDINGS RESIDENTIAL AND PUBLIC. The parameters of the microclimate in the premises.

Literature
Sokolov E.Ya. Heat supply and heat networks: a textbook for universities. - 8th ed., stereo. / E.Ya. Sokolov. - M .: MPEI Publishing House, 2006. - 472 p.: ill.
SNiP 41-01-2003. HEATING, VENTILATION AND AIR CONDITIONING.
SNiP 2.04.07-86 Heating networks (ed. 1994 with change 1 BST 3-94, change 2, adopted by the Decree of the Gosstroy of Russia dated 12.10.2001 N116 and with the exception of section 8 and applications 12-19). Thermal points.

Periodicals
Journal “Ventilation, Heating, Air Conditioning, Heat Supply and Building Thermal Physics” (AVOK).

From Wikipedia, the free encyclopedia

Thermal points: device, work, scheme, equipment

A heat substation is a complex of technological equipment used in the process of heat supply, ventilation and hot water supply to consumers (residential and industrial buildings, construction sites, social facilities). The main purpose of heat points is the distribution of heat energy from the heating network between end consumers.

Advantages of installing heat points in the heat supply system of consumers

Among the advantages of thermal points are the following:

• minimization of heat losses
• relatively low operating costs, cost-effectiveness
• the ability to select the mode of heat supply and heat consumption depending on the time of day and season
• silent operation, small dimensions (compared to other equipment of the heat supply system)
• automation and dispatching of the operation process
• Possibility of custom-made

Heating points can have different thermal schemes, types of heat consumption systems and characteristics of the equipment used, which depends on the individual requirements of the Customer. The configuration of the TP is determined on the basis of technical parameters heating network:

• thermal loads on the network
• temperature control of cold and hot water
• pressure of heat and water supply systems
• possible pressure losses
• climatic conditions etc.

Types of heat points

The type of required heating point depends on its purpose, the number of supply heating systems, the number of consumers, the method of placement and installation, and the functions performed by the point. Depending on the type of heat point, its technological scheme and equipment are selected.

Heat points are of the following types:

• individual heating points ITP
• central heating points
• block heat points BTP

Open and closed systems of heat points. Dependent and independent schemes for connecting heat points

V open heating system water for the operation of the heating point comes directly from the heating networks. Water intake can be full or partial. The volume of water taken for the needs of the heating point is replenished by the flow of water into the heating network. It should be noted that water treatment in such systems is carried out only at the entrance to the heating network. Because of this, the quality of water supplied to the consumer leaves much to be desired.

Open systems, in turn, can be dependent and independent.

V dependent scheme of connection of the heat point to the heating network, the heat carrier from the heating networks enters directly into the heating system. Such a system is quite simple, since it does not require the installation of additional equipment. Although the same feature leads to a significant drawback, namely, to the impossibility of regulating the heat supply to the consumer.

Independent schemes for connecting a heat point are characterized by economic benefits (up to 40%), since heat exchangers of heat points are installed in them between the end-user equipment and the heat source, which regulate the amount of heat supplied. Also an indisputable advantage is the improvement in the quality of the water supplied.

Due to the energy efficiency of independent systems, many thermal companies are reconstructing and upgrading their equipment from dependent systems to independent ones.

Closed heating system is a completely isolated system and uses the circulating water in the pipeline without taking it from the heating networks. Such a system uses water only as a heat carrier. A leakage of the coolant is possible, but the water is replenished automatically using the make-up regulator.

The amount of heat carrier in a closed system remains constant, and the generation and distribution of heat to the consumer is regulated by the temperature of the heat carrier. The closed system is characterized high quality water treatment and high energy efficiency.

Ways to provide consumers with thermal energy

According to the method of providing consumers with thermal energy, single-stage and multi-stage heat points are distinguished.

Single stage system characterized by direct connection of consumers to heating networks. The place of connection is called subscriber input. For each object of heat consumption, its own technological equipment (heaters, elevators, pumps, fittings, instrumentation and control equipment, etc.) must be provided.

The disadvantage of a single-stage connection system is the limitation of the permissible maximum pressure in heating networks due to the danger high pressure for heating radiators. In this regard, such systems are mainly used for a small number of consumers and for heating networks of short length.

Multistage systems connections are characterized by the presence of heat points between the heat source and the consumer.

Individual heating points

Individual heating substations serve one small consumer (house, small building or building), which is already connected to the district heating system. The task of such an ITP is to provide the consumer with hot water and heating (up to 40 kW). There are large individual points, the power of which can reach 2 MW. Traditionally, ITPs are placed in the basement or technical room of the building, less often they are located separately. standing premises. Only the coolant is connected to the ITP and tap water is supplied.

ITPs consist of two circuits: the first circuit is a heating circuit for maintaining the set temperature in the heated room using a temperature sensor; the second circuit is a hot water circuit.

Central heating points

The central heating points of the CHP are used to provide heat to a group of buildings and structures. The central heating stations perform the function of providing consumers with hot water, cold water and heat. The degree of automation and dispatching of central heating points (only control over the parameters or control / control of the parameters of the CHP) is determined by the Customer and technological needs. Central heating stations can have both dependent and independent circuits for connecting to the heating network. With a dependent connection scheme, the coolant in the heating point itself is divided into a heating system and a hot water supply system. In an independent connection scheme, the heat carrier is heated in the second circuit of the heating point with incoming water from the heating network.

They are delivered to the installation site in full factory readiness. At the place of subsequent operation, only connection to heating networks and equipment adjustment is carried out.

The equipment of the central heating point (CHP) includes the following elements:

• heaters (heat exchangers) - sectional, multi-pass, block type, plate - depending on the project, for hot water supply, supporting desired temperature and water pressure at water points
• circulating utility, fire-fighting, heating and backup pumps
• mixing devices
• thermal and water meter units
• control and measuring devices for instrumentation and automation
• shut-off and control valves
• expansion membrane tank

Block heat points (modular heat points)

Block (modular) heating point BTP has a block design. The BTP may consist of more than one block (module) mounted, often on one joint frame. Each module is an independent and complete item. At the same time, the regulation of work is general. Blösnche heat points can have both a local control and regulation system, and remote control and dispatching.

A block heat point can include both individual heat points and central heat points.

The main systems of heat supply to consumers as part of a heat substation

• hot water system (open or closed connection scheme)
• heating system (dependent or independent connection scheme)
• ventilation system

Typical schemes for connecting systems in heating points

Typical DHW system connection diagram
Typical scheme for connecting a heating system
Typical diagram for connecting the DHW and heating system
Typical diagram for connecting the DHW, heating and ventilation system

The thermal substation also includes a cold water supply system, but it is not a consumer of thermal energy.

The principle of operation of heat points

Thermal energy is supplied to heating points from heat generating enterprises through heating networks - primary main heating networks. Secondary, or distributing, heating networks connect the heating substation already with the end consumer.

The main heating networks usually have a large length, connecting the heat source and the heat point directly, and the diameter (up to 1400 mm). Often, main heat networks can combine several heat generating enterprises, which increases the reliability of providing consumers with energy.

Before entering the main networks, water undergoes water treatment, which brings the chemical indicators of water (hardness, pH, oxygen content, iron) in accordance with regulatory requirements. This is necessary in order to reduce the level of corrosive effect of water on the inner surface of the pipes.

The distributing pipelines have a relatively short length (up to 500 m), connecting the heating point and the end consumer.

The coolant (cold water) flows through the supply pipeline to the heating point, where it passes through the pumps of the cold water supply system. Further, it (the heat carrier) uses the primary DHW heaters and is fed into the circulation circuit of the hot water supply system, from where it flows to the end consumer and back to the heating substation, constantly circulating. To maintain the required temperature of the heat carrier, it is constantly heated in the heater of the second DHW stage.

The heating system is the same closed circuit as the DHW system. In the event of leakage of the coolant, its volume is replenished from the feed system of the heating point.

Then the coolant enters the return pipeline and goes back to the heat generating enterprise through the main pipelines.

Standard equipment of heating points

To ensure reliable operation of substations, they are supplied with the following minimum technological equipment:

• two plate heat exchangers (brazed or collapsible) for the heating system and the DHW system
• pumping station for pumping the coolant to the consumer, namely, to the heating devices of a building or structure
• automatic control system for the quantity and temperature of the heat carrier (sensors, controllers, flow meters) for monitoring the parameters of the heat carrier, accounting for heat loads and flow control
• water treatment system
• technological equipment - shut-off valves, check valves, instrumentation, regulators

It should be noted that the complete set of the heat point with technological equipment largely depends on the connection scheme of the hot water supply system and the connection scheme of the heating system.

So, for example, in closed systems heat exchangers, pumps and water treatment equipment are installed for further distribution of the coolant between the DHW system and the heating system. And in open systems, mixing pumps are installed (for mixing hot and cold water in the right proportion) and temperature controllers.

Our specialists provide a full range of services, from design, production, supply, and ending with installation and commissioning of heating points of various configurations.

The correct functioning of the heat point equipment determines the efficiency of using both the heat supplied to the consumer and the coolant itself. The heating point is a legal boundary, which implies the need to equip it with a set of control and measuring instruments that allow determining the mutual responsibility of the parties. Schemes and equipment of heat points must be determined in accordance not only with the technical characteristics of local heat consumption systems, but also necessarily with the characteristics of the external heat network, its mode of operation and the heat source.

Section 2 discusses connection schemes for all three main types of local systems. They were considered separately, i.e., it was considered that they were connected, as it were, to a common collector, the coolant pressure in which is constant and does not depend on the flow rate. The total flow rate of the coolant in the collector in this case is equal to the sum branch costs.

However, heat points are not connected to the heat source collector, but to the heat network, and in this case, a change in the coolant flow in one of the systems will inevitably affect the coolant flow in the other.

Fig.4.35. Heat carrier flow charts:

a - when consumers are connected directly to the heat source collector; b - when connecting consumers to the heating network

On fig. 4.35 graphically shows the change in coolant flow rates in both cases: in the diagram of fig. 4.35 a heating and hot water supply systems are connected to the heat source collectors separately, in the diagram of fig. 4.35, b, the same systems (and with the same calculated flow rate of the coolant) are connected to an external heating network with significant pressure losses. If in the first case the total flow rate of the coolant grows synchronously with the flow rate for hot water supply (modes I, II, III), then in the second, although there is an increase in the flow rate of the coolant, the flow rate for heating is automatically reduced at the same time, as a result of which the total flow rate of the coolant (in this example) is when applying the scheme of Fig. 4.35, b 80% of the flow rate when applying the scheme of fig. 4.35 a. The degree of reduction in water flow determines the ratio of available pressures: the larger the ratio, the greater the reduction in total flow.

The main heat networks are calculated for the average daily heat load, which significantly reduces their diameters, and, consequently, the cost of funds and metal. When using increased water temperature schedules in networks, it is also possible to further reduce the estimated water consumption in the heating network and calculate its diameters only for the heating load and supply ventilation.

The maximum hot water supply can be covered by hot water accumulators or by using the storage capacity of heated buildings. Since the use of batteries inevitably causes additional capital and operating costs, their use is still limited. Nevertheless, in some cases, the use of large batteries in networks and at group heating points (GTPs) can be effective.

When using the storage capacity of heated buildings, there are fluctuations in air temperature in rooms (apartments). It is necessary that these fluctuations do not exceed the permissible limit, which can be taken, for example, +0.5°C. The temperature regime of the premises is determined by a number of factors and therefore it is difficult to calculate. The most reliable in this case is the experimental method. In conditions middle lane RF long-term operation shows the possibility of using this method of maximum coverage for the vast majority of operated residential buildings.

The actual use of the storage capacity of heated (mainly residential) buildings began with the appearance of the first hot water heaters in heating networks. So, the adjustment of the heat point with a parallel scheme for switching on hot water heaters (Fig. 4.36) was carried out in such a way that during the hours of maximum water intake, some part of the network water was not supplied to the heating system. Thermal points operate on the same principle with open water intake. Both with open and closed heat supply systems, the greatest decrease in consumption in the heating system takes place at a network water temperature of 70 °C (60 °C) and the smallest (zero) at 150 °C.

Rice. 4.36. Scheme of a heating point of a residential building with a parallel connection of a hot water heater:

1 - hot water heater; 2 - elevator; 3 4 - circulation pump; 5 - temperature controller from the sensor outdoor temperature air

The possibility of organized and pre-calculated use of the storage capacity of residential buildings is implemented in the scheme of a heating point with the so-called upstream hot water heater (Fig. 4.37).

Rice. 4.37. Scheme of a heating point of a residential building with an upstream hot water heater:

1 - heater; 2 - elevator; 3 - water temperature controller; 4 - flow regulator; 5 - circulation pump

The advantage of the upstream scheme is the possibility of operation of the heating point of a residential building (with heating schedule in the heating network) at a constant coolant flow rate throughout the heating season, which makes the hydraulic regime of the heating network stable.

In the absence of automatic control in heating points, the stability of the hydraulic regime was a convincing argument in favor of using a two-stage sequential scheme for switching on hot water heaters. The possibilities of using this scheme (Fig. 4.38) in comparison with the upstream one increase due to covering a certain share of the hot water supply load by using the heat of the return water. However, the use of this scheme is mainly associated with the introduction of the so-called increased temperature schedule in thermal networks, with the help of which an approximate constancy of coolant flow rates at a thermal (for example, for a residential building) point can be achieved.

Rice. 4.38. Scheme of a heating point of a residential building with a two-stage serial connection of hot water heaters:

1,2 - 3 - elevator; 4 - water temperature controller; 5 - flow regulator; 6 - jumper for switching to mixed circuit; 7 - circulation pump; 8 - mixing pump

Both in the scheme with a pre-heater and in the two-stage scheme with the sequential connection of heaters, there is a close relationship between the release of heat for heating and hot water supply, and priority is usually given to the second.

More universal in this regard is the two-stage mixed scheme(Fig. 4.39), which can be used both with normal and with an increased heating schedule and for all consumers, regardless of the ratio of hot water supply and heating loads. A mandatory element of both schemes are mixing pumps.

Rice. 4.39. Scheme of a heating point of a residential building with a two-stage mixed inclusion of hot water heaters:

1,2 - heaters of the first and second stages; 3 - elevator; 4 - water temperature controller; 5 - circulation pump; 6 - mixing pump; 7 - temperature controller

The minimum temperature of the supplied water in a heat network with a mixed heat load is about 70 °C, which requires limiting the supply of coolant for heating during periods of high outdoor temperatures. In the conditions of the central zone of the Russian Federation, these periods are quite long (up to 1000 hours or more) and the excess heat consumption for heating (in relation to the annual one) can reach up to 3% or more because of this. Since modern heating systems are quite sensitive to changes in the temperature and hydraulic regime, in order to eliminate excess heat consumption and maintain normal sanitary conditions in heated rooms, it is necessary to supplement all the mentioned schemes of heating points with devices for controlling the temperature of the water entering the heating systems by installing a mixing pump, which is usually used in group heating points. In local heating substations, in the absence of silent pumps, an elevator with an adjustable nozzle can also be used as an intermediate solution. In this case, it should be taken into account that such a solution is unacceptable for a two-stage sequential scheme. The need to install mixing pumps is eliminated when heating systems are connected through heaters, since in this case their role is played by circulation pumps that ensure a constant flow of water in the heating network.

When designing schemes for heating points in residential areas with a closed heat supply system, the main issue is the choice of a scheme for connecting hot water heaters. The selected scheme determines the estimated flow rates of the coolant, the control mode, etc.

The choice of the connection scheme is primarily determined by the accepted temperature regime of the heating network. When the heat network is operating according to the heating schedule, the choice of connection scheme should be made on the basis of a technical and economic calculation - by comparing parallel and mixed schemes.

The mixed circuit can provide a lower return water temperature from the heat point as a whole compared to the parallel circuit, which, in addition to reducing the estimated water consumption for the heating network, ensures more economical generation of electricity at the CHPP. Based on this, in the design practice for heat supply from a CHP (as well as in the joint operation of boiler houses with a CHP), preference is given to a mixed scheme for the heating temperature curve. With short heat networks from boiler houses (and therefore relatively cheap), the results of a technical and economic comparison may be different, i.e., in favor of using a simpler scheme.

With an increased temperature schedule in closed heat supply systems, the connection scheme can be mixed or sequential two-stage.

A comparison made by various organizations on examples of automation of central heating points shows that both schemes are approximately equally economical under normal operation of a heat supply source.

A small advantage of the sequential scheme is the possibility of working without a mixing pump for 75% of the duration of the heating season, which previously gave some justification to abandon the pumps; with a mixed circuit, the pump must work all season.

The advantage of a mixed circuit is the possibility of a complete automatic shutdown of heating systems, which cannot be obtained in a sequential circuit, since water from the second stage heater enters the heating system. Both of these circumstances are not decisive. An important indicator schemes is their work in critical situations.

Such situations can be a decrease in the temperature of the water in the CHPP against the schedule (for example, due to a temporary lack of fuel) or damage to one of the sections of the main heating network in the presence of reserving jumpers.

In the first case, circuits can react in approximately the same way, in the second - in different ways. There is a possibility of 100% redundancy of consumers up to t n = -15 °С without increasing the diameters of heat mains and jumpers between them. To do this, when the heat carrier supply to the CHP is reduced, the temperature of the supplied water simultaneously increases accordingly. Automated mixed circuits (with the obligatory presence of mixing pumps) will react to this by reducing the consumption of network water, which will ensure the restoration of the normal hydraulic regime throughout the entire network. Such compensation of one parameter by another is also useful in other cases, since it allows, within certain limits, to carry out, for example, repair work on heating mains heating season, as well as to localize known inconsistencies in the temperature of the supplied water to consumers located at different distances from the CHPP.

If the automation of regulation of circuits with sequential switching on of hot water heaters provides for the constancy of the coolant flow from the heating network, the possibility of compensating the coolant flow by its temperature in this case is excluded. It is not necessary to prove the whole expediency (in design, installation and especially in operation) of using a uniform connection scheme. From this point of view, a two-stage mixed scheme has an undoubted advantage, which can be used regardless of the temperature schedule in the heating network and the ratio of hot water supply and heating loads.

Rice. 4.40. Scheme of a heating point of a residential building with an open heat supply system:

1 - regulator (mixer) of water temperature; 2 - elevator; 3 - check valve; 4 - throttle washer

Connection schemes for residential buildings with an open heat supply system are much simpler than those described (Fig. 4.40). The economical and reliable operation of such points can only be ensured if there is and reliable operation automatic water temperature regulator, manual switching of consumers to the supply or return line does not provide the required water temperature. In addition, the hot water supply system, connected to the supply line and disconnected from the return line, operates under the pressure of the supply heat pipe. The above considerations on the choice of schemes of heat points equally apply both to local heat points (LHP) in buildings and to group ones that can provide heat supply to entire microdistricts.

The greater the power of the heat source and the radius of action of heat networks, the more fundamentally the MTP schemes should become, since absolute pressures increase, the hydraulic regime becomes more complicated, and transport delay begins to affect. So, in MTP schemes, it becomes necessary to use pumps, protective equipment and complex automatic control equipment. All this not only increases the cost of the construction of ITPs, but also complicates their maintenance. The most rational way to simplify the MTP schemes is the construction of group heating points (in the form of GTP), in which additional complex equipment and devices should be placed. This method is most applicable in residential areas in which the characteristics of heating and hot water supply systems and, therefore, MTP schemes are of the same type.

S. Deineko

An individual heating point is the most important component of the heat supply systems of buildings. The regulation of heating and hot water systems, as well as the efficiency of using thermal energy, largely depends on its characteristics. Therefore, heat points are given great attention during the thermal modernization of buildings, large-scale projects of which are planned to be implemented in various regions of Ukraine in the near future.

Individual heating point (ITP) - a set of devices located in a separate room (usually in the basement), consisting of elements that ensure the connection of the heating system and hot water supply to the centralized heating network. The supply pipeline supplies the heat carrier to the building. With the help of the second return pipeline, the already cooled coolant from the system enters the boiler room.

The temperature schedule for the operation of the heating network determines the mode in which the heating point will operate in the future and what equipment must be installed in it. There are several temperature schedules for the operation of a heating network:

• 150/70°C;
• 130/70°C;
• 110/70°C;
• 95 (90)/70°C.

If the temperature of the coolant does not exceed 95 ° C, then it remains only to distribute it throughout the entire heating system. In this case, it is possible to use only a manifold with balancing valves for hydraulic balancing of circulation rings. If the temperature of the coolant exceeds 95 ° C, then such a coolant cannot be directly used in the heating system without its temperature regulation. This is precisely the important function of the heat point. At the same time, it is necessary that the temperature of the coolant in the heating system varies depending on the change in the outside air temperature.

In the heat points of the old sample (Fig. 1, 2), an elevator unit was used as a control device. This made it possible to significantly reduce the cost of the equipment, however, with the help of such a thermal converter, it was impossible to accurately control the temperature of the coolant, especially during transient operating modes of the system. The elevator unit provided only "high-quality" adjustment of the coolant, when the temperature in the heating system changes depending on the temperature of the coolant coming from the centralized heating network. This led to the fact that the “adjustment” of the air temperature in the premises was carried out by consumers with the help of an open window and with huge heat costs that go nowhere.

Rice. one.
1 - supply pipeline; 2 - return pipeline; 3 - valves; 4 - water meter; 5 - mud collectors; 6 - manometers; 7 - thermometers; 8 - elevator; 9 - heating appliances heating systems

Therefore, the minimum initial investment resulted in financial losses in long term. Particularly low efficiency of the operation of elevator units manifested itself with an increase in prices for thermal energy, as well as with the impossibility of operating the centralized heating network according to the temperature or hydraulic schedule, for which the previously installed elevator units were designed.

Rice. 2. Elevator node of the "Soviet" era

The principle of operation of the elevator is to mix the heat carrier from the centralized heating network and water from the return pipeline of the heating system to a temperature corresponding to the standard for this system. This happens due to the principle of ejection when a nozzle of a certain diameter is used in the design of the elevator (Fig. 3). After elevator node the mixed heat carrier is fed into the heating system of the building. The elevator simultaneously combines two devices: a circulation pump and a mixing device. The efficiency of mixing and circulation in the heating system is not affected by fluctuations thermal regime in thermal networks. All adjustments are correct selection nozzle diameter and ensuring the required mixing ratio (standard coefficient 2.2). For the operation of the elevator unit, there is no need to supply electric current.

Rice. 3. Schematic diagram of the design of the elevator unit

However, there are numerous disadvantages that negate all the simplicity and unpretentiousness of the maintenance of this device. Fluctuations in the hydraulic regime in heating networks directly affect the efficiency of work. So, for normal mixing, the pressure drop in the supply and return pipelines must be maintained within 0.8 - 2 bar; the temperature at the outlet of the elevator cannot be adjusted and directly depends only on the change in the temperature of the heating network. In this case, if the temperature of the heat carrier coming from the boiler room does not correspond to the temperature schedule, then the temperature at the outlet of the elevator will be lower than necessary, which will directly affect the internal air temperature in the building.

Such devices are widely used in many types of buildings connected to a centralized heating network. However, at present they do not meet the requirements for energy saving, and therefore they must be replaced with modern individual heat points. Their cost is much higher and power supply is required for operation. But, at the same time, these devices are more economical - they can reduce energy consumption by 30 - 50%, which, taking into account the increase in prices for the coolant, will reduce the payback period to 5 - 7 years, and the service life of the ITP directly depends on the quality of the control elements used, materials and the level of training of technical personnel during its maintenance.

Modern ITP

Energy saving is achieved, in particular, by controlling the temperature of the heat carrier, taking into account the correction for changes in the outside air temperature. For these purposes, each heating point uses a set of equipment (Fig. 4) to ensure the necessary circulation in the heating system (circulation pumps) and control the temperature of the coolant (control valves with electric drives, controllers with temperature sensors).

Rice. 4. Schematic diagram of an individual heating point and the use of a controller, a control valve and a circulation pump

Most heat points also include a heat exchanger for connection to an internal hot water supply system (DHW) with a circulation pump. The set of equipment depends on specific tasks and initial data. That is why, because of the different options design, as well as their compactness and portability, modern ITPs are called modular (Fig. 5).

Rice. 5. Modern modular individual heating point assembly

Consider the use of ITP in dependent and independent schemes for connecting a heating system to a centralized heating network.

In ITP with dependent connection of the heating system to external heat networks, the circulation of the coolant in the heating circuit is maintained by a circulation pump. The pump is controlled automatically from the controller or from the corresponding control unit. Automatic maintenance of the required temperature graph in the heating circuit is also carried out by an electronic controller. The controller acts on the control valve located on the supply pipeline on the side of the external heating network ("hot water"). A mixing jumper with a check valve is installed between the supply and return pipelines, due to which the mixture is mixed into the supply pipeline from the coolant return line, with lower temperature parameters (Fig. 6).

Rice. 6. Schematic diagram of a modular heating unit connected according to a dependent scheme:
1 - controller; 2 - two-way control valve with electric drive; 3 - coolant temperature sensors; 4 - outdoor air temperature sensor; 5 - pressure switch to protect pumps from dry running; 6 - filters; 7 - valves; 8 - thermometers; 9 - manometers; 10 - circulation pumps of the heating system; 11 - check valve; 12 - control unit for circulation pumps

In this scheme, the operation of the heating system depends on the pressures in the central heating network. Therefore, in many cases, it will be necessary to install differential pressure regulators, and, if necessary, pressure regulators “downstream” or “downstream” on the supply or return pipelines.

In an independent system, a heat exchanger is used to connect to an external heat source (Fig. 7). The circulation of the coolant in the heating system is carried out by a circulation pump. The pump is controlled automatically by the controller or the appropriate control unit. Automatic maintenance of the required temperature graph in the heated circuit is also carried out by an electronic controller. The controller acts on an adjustable valve located on the supply pipeline on the side of the external heating network ("hot water").

Rice. 7. Schematic diagram of a modular heating unit connected according to an independent scheme:
1 - controller; 2 - two-way control valve with electric drive; 3 - coolant temperature sensors; 4 - outdoor air temperature sensor; 5 - pressure switch to protect pumps from dry running; 6 - filters; 7 - valves; 8 - thermometers; 9 - manometers; 10 - circulation pumps of the heating system; 11 - check valve; 12 - control unit for circulation pumps; 13 - heating system heat exchanger

The advantage of this scheme is that the heating circuit is independent of the hydraulic modes of the centralized heating network. Also, the heating system does not suffer from a mismatch in the quality of the incoming coolant coming from the central heating network (the presence of corrosion products, dirt, sand, etc.), as well as pressure drops in it. At the same time, the cost of capital investments when using an independent scheme is higher - due to the need for installation and subsequent maintenance of the heat exchanger.

As a rule, in modern systems, collapsible plate heat exchangers are used (Fig. 8), which are quite easy to maintain and maintain: in case of loss of tightness or failure of one section, the heat exchanger can be disassembled and the section replaced. Also, if necessary, you can increase the power by increasing the number of heat exchanger plates. In addition, in independent systems, brazed non-separable heat exchangers are used.

Rice. 8. Heat exchangers for independent ITP connection systems

According to DBN V.2.5-39:2008 “ Engineering equipment buildings and structures. External networks and facilities. Heating networks”, in the general case, it is prescribed to connect heating systems according to a dependent scheme. An independent circuit is prescribed for residential buildings with 12 or more floors and other consumers, if this is due to the hydraulic mode of operation of the system or terms of reference customer.

DHW from a heating point

The simplest and most common is the scheme with a single-stage parallel connection of hot water heaters (Fig. 9). They are connected to the same heating network as the building heating systems. Water from the external water supply network is supplied to the DHW heater. In it, it is heated by network water coming from the supply pipeline of the heating network.

Rice. 9. Scheme with dependent connection of the heating system to the heating network and one-stage parallel connection of the DHW heat exchanger

Cooled network water is supplied to the return pipeline of the heating network. After the hot water heater, the heated tap water is supplied to the DHW system. If the devices in this system are closed (for example, at night), then hot water is again supplied through the circulation pipe to the DHW heater.

This scheme with a single-stage parallel connection of hot water heaters is recommended if the ratio of the maximum heat consumption for hot water supply of buildings to the maximum heat consumption for heating buildings is less than 0.2 or more than 1.0. The circuit is used under normal temperature graph network water in thermal networks.

In addition, a two-stage water heating system is used in the DHW system. In it, in winter, cold tap water is first heated in the first stage heat exchanger (from 5 to 30 ˚С) with a coolant from the return pipeline of the heating system, and then for the final heating of the water to the required temperature (60 ˚С), network water from the heating supply pipeline is used. networks (Fig. 10). The idea is to use waste heat energy from the return line from the heating system for heating. At the same time, the consumption of network water for heating water in the DHW system is reduced. V summer period heating occurs in a single-stage scheme.

Rice. 10. Scheme of a heat point with dependent connection of the heating system to the heat network and two-stage water heating

equipment requirements

The most important characteristic of a modern heat point is the presence of heat energy metering devices, which is mandatory provided for by DBN V.2.5-39:2008 “Engineering equipment of buildings and structures. External networks and facilities. Heating network".

According to section 16 of these standards, equipment, fittings, control, management and automation devices should be placed in the heating point, with the help of which they carry out:

• temperature control of the coolant according to weather conditions;
• change and control of coolant parameters;
• accounting for thermal loads, coolant and condensate costs;
• regulation of coolant costs;
• protection of the local system from an emergency increase in the parameters of the coolant;
• post-treatment of the coolant;
• filling and replenishing heating systems;
• combined heat supply using thermal energy from alternative sources.

Connecting consumers to the heating network should be carried out according to schemes with minimal water consumption, as well as saving thermal energy by installing automatic heat flow regulators and limiting network water costs. It is not allowed to connect the heating system to the heating network through an elevator together with an automatic heat flow controller.

It is prescribed to use highly efficient heat exchangers with high thermal and operational characteristics and small dimensions. At the highest points of pipelines of heating points, air vents should be installed, and it is recommended to use automatic devices with check valves. At lower points, fittings with shut-off valves for draining water and condensate should be installed.

At the input to the heating point on the supply pipeline, a sump should be installed, and strainers should be installed in front of pumps, heat exchangers, control valves and water meters. In addition, the mud filter must be installed on the return line in front of control devices and metering devices. Manometers should be provided on both sides of the filters.

To protect the DHW channels from scale, it is prescribed by the standards to use magnetic and ultrasonic water treatment devices. Forced ventilation, which needs to be equipped with an ITP, is calculated for a short-term action and should provide a 10-fold exchange with an unorganized tide fresh air through the front doors.

In order to avoid exceeding the noise level, ITP is not allowed to be located next to, under or above the premises of residential apartments, bedrooms and playrooms of kindergartens, etc. In addition, it is regulated that the installed pumps must be with an acceptable low noise level.

The heating point should be equipped with automation equipment, heat engineering control, accounting and regulation devices, which are installed on site or at the control panel.

ITP automation should provide:

• regulation of the cost of thermal energy in the heating system and limiting the maximum consumption of network water at the consumer;
• the set temperature in the DHW system;
• maintaining static pressure in the systems of heat consumers with their independent connection;
• the specified pressure in the return pipeline or the required water pressure drop in the supply and return pipelines of heating networks;
• protection of heat consumption systems from high blood pressure and temperature;
• switching on the backup pump when the main working one is turned off, etc.

In addition, modern projects provide for the arrangement of remote access to the management of heating points. This allows you to organize a centralized dispatching system and monitor the operation of heating and hot water systems. Suppliers of equipment for ITP are leading manufacturers of the relevant heat engineering equipment, for example: automation systems - Honeywell (USA), Siemens (Germany), Danfoss (Denmark); pumps - Grundfos (Denmark), Wilo (Germany); heat exchangers - Alfa Laval (Sweden), Gea (Germany), etc.

It should also be noted that modern ITPs include rather complex equipment that requires periodic maintenance and after-sales service, which consists, for example, in washing the mesh filters (at least 4 times a year), cleaning the heat exchangers (at least 1 time in 5 years), etc. In the absence of proper Maintenance the equipment of the heating point may become unusable or fail. Unfortunately, there are already examples of this in Ukraine.

At the same time, there are pitfalls in the design of all ITP equipment. The point is that in domestic conditions the temperature in the supply pipeline of the centralized network often does not correspond to the standard, which is indicated by the heat supply organization in specifications issued for design.

At the same time, the difference in official and real data can be quite significant (for example, in reality, a coolant is supplied with a temperature of no more than 100˚С instead of the indicated 150˚С, or there is an uneven temperature of the coolant from the side of the central heating by time of day), which, accordingly, affects on the choice of equipment, its subsequent performance and, as a result, on its cost. For this reason, it is recommended during the reconstruction of ITP at the design stage to measure the actual parameters of heat supply at the facility and take them into account in the future when calculating and choosing equipment. At the same time, due to a possible discrepancy between the parameters, the equipment should be designed with a margin of 5-20%.

Implementation in practice

The first modern energy-efficient modular ITPs in Ukraine were installed in Kiev in 2001-2005. within the framework of the implementation of the World Bank project "Energy saving in administrative and public buildings". A total of 1173 ITPs were installed. To date, due to previously unresolved issues of periodic qualified maintenance, about 200 of them have become unusable or require repair.

Video. Implemented project using an individual heat point in an apartment building, saving up to 30% of heat energy

Modernization of previously installed heat points with the organization of remote access to them is one of the points of the program "Thermosanation in budgetary institutions of Kiev" with the involvement of loans from the Northern Environmental Finance Corporation (NEFCO) and grants from the Eastern Partnership Fund for Energy Efficiency and Environment (E5P ).

In addition, last year the World Bank announced the launch of a large-scale six-year project aimed at improving the energy efficiency of heat supply in 10 cities of Ukraine. The project budget is 382 million US dollars. They will be directed, in particular, to the installation of modular ITP. It is also planned to repair boiler houses, replace pipelines and install heat meters. It is planned that the project will help to reduce costs, improve the reliability of service and improve the overall quality of heat supplied to more than 3 million Ukrainians.

Modernization of the heating point is one of the conditions for improving the energy efficiency of the building as a whole. Currently, a number of Ukrainian banks are engaged in lending for the implementation of these projects, including within the framework of state programs. You can read more about this in the previous issue of our magazine in the article "Thermomodernization: what exactly and for what means".

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