important public service in modern cities is heat supply. The heat supply system serves to meet the needs of the population in heating services for residential and public buildings, hot water supply (water heating) and ventilation.

The modern urban heat supply system includes the following main elements: a heat source, heat transmission networks and devices, as well as heat-consuming equipment and devices - heating, ventilation and hot water supply systems.

City heating systems are classified according to the following criteria:

• - degree of centralization;
• - type of coolant;
• - method of generating thermal energy;
• - method of supplying water for hot water supply and heating;
• - the number of pipelines of heating networks;
• - a way to provide consumers with thermal energy, etc.

By degree of centralization heat supply distinguish two main types:

• 1) centralized heat supply systems, which have been developed in cities and districts with predominantly multi-storey buildings. Among them are: highly organized centralized heat supply based on the combined generation of heat and electricity at CHP - district heating and district heating from district heating and industrial heating boilers;
• 2) decentralized heat supply from small adjoining boiler plants (attached, basement, roof), individual heating devices, etc.; while there are no heating network and associated heat losses.

By coolant type Distinguish between steam and water heating systems. In steam heating systems, superheated steam acts as a heat carrier. These systems are mainly used for technological purposes in industry, power industry. For the needs of communal heat supply of the population due to the increased danger during their operation, they are practically not used.

In water heating systems, the heat carrier is hot water. These systems are mainly used to supply thermal energy to urban consumers, for hot water supply and heating, and in some cases for technological processes. In our country, water heating systems account for more than half of all heating networks.

By method of generating heat energy distinguish:

• - Combined generation of heat and electricity at combined heat and power plants. In this case, the heat of the working thermal steam is used to generate electricity when the steam expands in the turbines, and then the remaining heat of the exhaust steam is used to heat water in the heat exchangers that make up the heating equipment of the CHP. Hot water is used for heating urban consumers. Thus, in a CHP plant, high-potential heat is used to generate electricity, and low-potential heat is used to supply heat. This is the energy meaning of the combined generation of heat and electricity, which provides a significant reduction in the specific fuel consumption in the production of heat and electricity;
• - separate generation of thermal energy, when heating water in boiler plants (thermal power plants) is separated from the generation of electrical energy.

By water supply method for hot water supply, water heating systems are divided into open and closed. In open water heating systems, hot water is supplied to the taps of the local hot water supply system directly from the heating networks. In closed water heating systems, water from heating networks is used only as a heating medium for heating in water heaters - heat exchangers (boilers) of tap water, which then enters the local hot water supply system.

By number of pipelines There are single-pipe, two-pipe and multi-pipe heat supply systems.

By way to provide consumers with thermal energy, single-stage and multi-stage heat supply systems are distinguished - depending on the schemes for connecting subscribers (consumers) to heating networks. The nodes for connecting heat consumers to heating networks are called subscriber inputs. At the subscriber input of each building, hot water heaters, elevators, pumps, fittings, instrumentation are installed to regulate the parameters and flow of the coolant according to local heating and water fittings. Therefore, often a subscriber input is called a local heating point (MTP). If a subscriber input is being constructed for a separate facility, then it is called an individual heating point (ITP).

When organizing single-stage heat supply systems, heat consumers are connected directly to heat networks. Such a direct connection of heating devices limits the limits of permissible pressure in heating networks, since the high pressure required to transport the coolant to end consumers is dangerous for heating radiators. Because of this, single-stage systems are used to supply heat to a limited number of consumers from boiler houses with a short length of heating networks.

In multistage systems, between the heat source and consumers, central heating centers (CHP) or control and distribution points (CDP) are placed, in which the parameters of the coolant can be changed at the request of local consumers. The central heating and distribution centers are equipped with pumping and water heating units, control and safety fittings, instrumentation designed to provide a group of consumers in a quarter or district with thermal energy of the required parameters. With the help of pumping or water heating installations main pipelines(first stage) are partially or completely hydraulically isolated from distribution networks (second stage). From the CHP or KRP, a heat carrier with acceptable or established parameters is supplied through common or separate pipelines of the second stage to the MTP of each building for local consumers. At the same time, only elevator mixing of return water from local heating installations, local regulation of water consumption for hot water supply and accounting for heat consumption are carried out in the MTP.

The organization of complete hydraulic isolation of heat networks of the first and second stages is the most important measure for improving the reliability of heat supply and increasing the range of heat transport. Multi-stage heat supply systems with central heating and distribution centers allow reducing the number of local hot water heaters, circulation pumps and temperature controllers installed in the MTP with a single-stage system by a factor of ten. In the central heating center, it is possible to organize the treatment of local tap water to prevent corrosion of hot water supply systems. Finally, during the construction of the central heating and distribution centers, the unit operating costs and the costs of maintaining personnel for servicing equipment in the MTP are significantly reduced.

Thermal energy in the form of hot water or steam is transported from a CHP or boiler house to consumers (residential buildings, public buildings and industrial enterprises) through special pipelines - heating networks. The route of heat networks in cities and other settlements should be provided in the technical lanes allocated for engineering networks.

Modern heating networks of urban systems are complex engineering structures. Their length from the source to consumers is tens of kilometers, and the diameter of the mains reaches 1400 mm. The structure of thermal networks includes heat pipelines; compensators that perceive temperature elongations; disconnecting, regulating and safety equipment installed in special chambers or pavilions; pumping stations; district heating points (RTP) and heating points (TP).

Heating networks are divided into main, laid in the main directions locality, distribution - within the quarter, microdistrict - and branches to individual buildings and subscribers.

Schemes of thermal networks are used, as a rule, beam. In order to avoid interruptions in the supply of heat to the consumer, individual main networks are connected to each other, as well as the installation of jumpers between branches. In large cities, in the presence of several large heat sources, more complex heat networks are built according to the ring scheme.

To ensure the reliable functioning of such systems, their hierarchical construction is necessary, in which the entire system is divided into a number of levels, each of which has its own task, decreasing in value from the top level to the bottom. The upper hierarchical level is made up of heat sources, the next level is main heating networks with RTP, the lower one is distribution networks with subscriber inputs of consumers. Heat sources supply hot water of a given temperature and a given pressure to the heating networks, ensure the circulation of water in the system and maintain the proper hydrodynamic and static pressure in it. They have special water treatment plants, where chemical purification and deaeration of water is carried out. The main heat carrier flows are transported through the main heat networks to the heat consumption nodes. In the RTP, the coolant is distributed among the districts, autonomous hydraulic and thermal regimes are maintained in the networks of the districts. The organization of the hierarchical construction of heat supply systems ensures their controllability during operation.

To control the hydraulic and thermal modes of the heat supply system, it is automated, and the amount of heat supplied is regulated in accordance with consumption standards and subscriber requirements. The largest number heat is used to heat buildings. The heating load changes with the outside temperature. To maintain the conformity of heat supply to consumers, it uses central regulation on heat sources. achieve High Quality heat supply, using only central regulation, is not possible, therefore, additional automatic regulation is used at heating points and at consumers. The water consumption for hot water supply is constantly changing, and in order to maintain a stable heat supply, the hydraulic mode of heat networks is automatically regulated, and the temperature of hot water is maintained constant and equal to 65 ° C.

The main systemic problems that complicate the organization of an effective mechanism for the functioning of heat supply in modern cities include the following:

• - significant physical and moral wear and tear of equipment of heat supply systems;
• - high level of losses in heat networks;
• - massive lack of heat energy meters and heat supply regulators among residents;
• - overestimated thermal loads of consumers;
• - imperfection of normative-legal and legislative base.

The equipment of thermal power plants and heating networks has a high degree of wear on average in Russia, reaching 70%. The total number of heating boiler houses is dominated by small, inefficient ones, the process of their reconstruction and liquidation proceeds very slowly. The increase in thermal capacities annually lags behind the increasing loads by 2 times or more. Due to systematic interruptions in the provision of boiler fuel in many cities, serious difficulties annually arise in the supply of heat to residential areas and houses. The start-up of heating systems in the fall stretches for several months; winter period become the norm, not the exception; the rate of equipment replacement is declining, the number of equipment in emergency condition is increasing. It has predetermined in recent years a sharp increase accident rate of heat supply systems.

As part of the supply of switchboard equipment, power cabinets and control cabinets for two buildings (ITP) were supplied. For the reception and distribution of electricity in heating points, input-distributing devices are used, consisting of five panels each (10 panels in total). Switching switches, surge arresters, ammeters and voltmeters are installed in the input panels. ATS panels in ITP1 and ITP2 are implemented on the basis of automatic transfer units. Protection and switching devices (contactors, soft starters, buttons and lamps) are installed in the distribution panels of the ASU technological equipment thermal points. All circuit breakers are equipped with status contacts signaling an emergency shutdown. This information is transmitted to the controllers installed in the automation cabinets.

To control and manage the equipment, OWEN PLC110 controllers are used. They are connected to the input / output modules ARIES MV110-224.16DN, MV110-224.8A, MU110-224.6U, as well as operator touch panels.

The coolant is introduced directly into the ITP room. Water supply for hot water supply, heating and heat supply of air heaters of air ventilation systems is carried out with a correction according to the outside air temperature.

The display of technological parameters, accidents, equipment status and dispatch control of the ITP is carried out from the workstation of dispatchers in the integrated central control room of the building. On the dispatching server, the archive of technological parameters, accidents, and the state of the ITP equipment is stored.

Automation of heat points provides for:

• maintaining the temperature of the coolant supplied to the heating and ventilation systems in accordance with the temperature schedule;
• maintaining the temperature of the water in the DHW system at the supply to consumers;
• programming of various temperature conditions by hours of the day, days of the week and public holidays;
• control of compliance with the values ​​of parameters determined by the technological algorithm, support of technological and emergency parameters limits;
• temperature control of the heat carrier returned to the heating network of the heat supply system, according to a given temperature schedule;
• outside air temperature measurement;
• maintaining a given pressure drop between the supply and return pipelines of ventilation and heating systems;
• control of circulation pumps according to a given algorithm:
  • on/off;
  • control of pumping equipment with frequency drives according to signals from PLC installed in automation cabinets;
  • periodic switching main / reserve to ensure the same operating time;
  • automatic emergency transfer to the standby pump according to the control of the differential pressure sensor;
  • automatic maintenance of a given differential pressure in heat consumption systems.
• control of heat carrier control valves in primary consumer circuits;
• control of pumps and valves for feeding circuits of heating and ventilation;
• setting the values ​​of technological and emergency parameters through the dispatching system;
• control of drainage pumps;
• control of the state of electrical inputs by phases;
• synchronization of the controller time with the common time of the dispatching system (SOEV);
• start-up of equipment after restoration of power supply in accordance with a given algorithm;
• sending emergency messages to the dispatching system.

Information exchange between automation controllers and the upper level (workstation with specialized MasterSCADA dispatching software) is carried out using the Modbus/TCP protocol.

V. G. Semenov, Editor-in-Chief, Heat Supply News

The concept of a system

Everyone is used to the expressions “heat supply system”, “control system”, “ automated systems management". One of the simplest definitions of any system: a set of connected operating elements. A more complex definition is given by Academician P. K. Anokhin: “A system can only be called such a complex of selectively involved components, in which the interaction acquires the character of mutual assistance to obtain a focused useful result.” Obtaining such a result is the goal of the system, and the goal is formed on the basis of need. AT market economy technical systems, as well as their management systems, are formed on the basis of demand, i.e., a need for the satisfaction of which someone is willing to pay.

Technical heat supply systems consist of elements (CHP, boiler houses, networks, emergency services, etc.) that have very rigid technological connections. " external environment" for technical system heat supply are consumers of different types; gas, electric, water networks; weather; new developers, etc. They exchange energy, matter and information.

Any system exists within some limits imposed, as a rule, by buyers or authorized bodies. These are the requirements for the quality of heat supply, ecology, labor safety, price restrictions.

There are active systems that can withstand negative environmental impacts (unskilled actions of administrations at different levels, competition from other projects...), and passive systems that do not have this property.

Operational systems technical management heat supply belong to typical human-machine systems, are not very complex and are quite easy to automate. In fact, they are subsystems of a higher level system - heat supply management in a limited area.

Control systems

Management is the process of purposeful influence on the system, providing an increase in its organization, the achievement of one or another useful effect. Any control system is divided into control and controlled subsystems. The connection from the control subsystem to the controlled one is called direct connection. Such a connection always exists. The opposite direction of communication is called feedback. The concept of feedback is fundamental in technology, nature and society. It is believed that control without strong feedback is not effective, because it does not have the ability to self-detect errors, formulate problems, does not allow the use of the system's self-regulation capabilities, as well as the experience and knowledge of specialists.

SA Optner even believes that control is the goal of feedback. “Feedback affects the system. Impact is a means of changing the existing state of the system by excitation of a force that allows this to be done.

In right organized system deviation of its parameters from the norm or deviation from the correct direction of development develops into feedback and initiates the control process. “The very deviation from the norm serves as an incentive to return to the norm” (P.K. Anokhin). It is also very important that one's own goal control system did not contradict the purpose of the managed system, i.e. the purpose for which it was created. It is generally accepted that the requirement of a "superior" organization is unconditional for a "lower" organization and is automatically transformed into a goal for it. This can sometimes lead to a substitution of the target.

The correct goal of the control system is the development of control actions based on the analysis of information about deviations, or, in other words, problem solving.

A problem is a situation of discrepancy between the desired and the existing. The human brain is arranged in such a way that a person begins to think in some direction only when a problem is revealed. Therefore, the correct definition of the problem predetermines the correct managerial decision. There are two categories of problems: stabilization and development.

Stabilization problems are called those, the solution of which is aimed at preventing, eliminating or compensating for disturbances that disrupt the current activity of the system. At the level of an enterprise, region or industry, the solution to these problems is referred to as production management.

The problems of development and improvement of systems are called those, the solution of which is aimed at improving the efficiency of functioning by changing the characteristics of the control object or control system.

From point of view systems approach the problem is the difference between the existing system and the desired system. The system that fills the gap between them is the object of construction and is called the solution to the problem.

Analysis of existing heat supply management systems

A systematic approach is an approach to the study of an object (problem, process) as a system in which elements are identified, internal communications and relationships with the environment that affect the results of functioning, and the goals of each of the elements are determined based on the overall purpose of the system.

The purpose of creating any centralized system heat supply - providing high-quality, reliable heat supply at the lowest price. This goal suits consumers, citizens, administration and politicians. The same goal should be for the heat management system.

Today there is 2 main types of heat supply management systems:

1) administration municipality or region and the heads of state heat supply enterprises subordinate to it;

2) governing bodies of non-municipal heat supply enterprises.

Rice. 1. Generalized scheme existing system heat supply management.

A generalized diagram of the heat supply control system is shown in fig. 1. It presents only those structures (environment) that can actually influence control systems:

Increase or decrease income;

Force to go to additional expenses;

Change the management of enterprises.

For a real analysis, we must start from the premise that only what is paid for or can be fired is performed, and not what is declared. State

There is practically no legislation regulating the activities of heat supply enterprises. Not even procedures state regulation local natural monopolies in heat supply.

Heat supply is the main problem in the reforms of housing and communal services and RAO "UES of Russia", it cannot be solved separately in either one or the other, therefore it is practically not considered, although it is through heat supply that these reforms should have been interconnected. There is not even a government-approved concept for the development of the country's heat supply, let alone a real program of action.

The federal authorities do not regulate the quality of heat supply in any way, there are not even regulatory documents that define the quality criteria. Reliability of heat supply is regulated only through technical supervisory authorities. But since the interaction between them and the tariff authorities is not spelled out in any regulatory document, it is often absent. Enterprises, on the other hand, have the opportunity not to comply with any instructions, justifying this with a lack of funding.

Technical supervision of existing regulatory documents is reduced to the control of individual technical units, and those for which there are more rules. The system in the interaction of all its elements is not considered, the measures that give the greatest system-wide effect are not identified.

The cost of heat supply is regulated only formally. Tariff legislation is so general that almost everything is left to the discretion of the federal and, to a greater extent, regional energy commissions. Heat consumption standards are regulated only for new buildings. There is practically no section on heat supply in state energy saving programs.

As a result, the role of the state was relegated to the collection of taxes and, through supervisory authorities, information local authorities authorities about the shortcomings existing in heat supply.

Responsible to Parliament for the work of natural monopolies, for the functioning of industries that ensure the possibility of the existence of the nation executive branch. The problem is not that the federal bodies are functioning unsatisfactorily, but that there is actually no structure in the structure of the federal bodies, from

Article 18. Distribution of heat load and management of heat supply systems

1. Distribution of the thermal load of consumers of thermal energy in the heat supply system between supplying thermal energy in this heat supply system, is carried out by an authority authorized in accordance with this federal law for approval of the heat supply scheme, by making annual changes to the heat supply scheme.

2. To distribute the heat load of consumers of heat energy, all heat supply organizations that own sources of heat energy in this heat supply system are required to submit to the body authorized in accordance with this Federal Law to approve the heat supply scheme, an application containing information:

1) on the amount of heat energy that the heat supply organization undertakes to supply to consumers and heat supply organizations in this heat supply system;

2) on the amount of capacity of thermal energy sources, which the heat supply organization undertakes to support;

3) on current tariffs in the field of heat supply and predicted specific variable costs for the production of thermal energy, heat carrier and power maintenance.

3. In the heat supply scheme, conditions must be determined under which it is possible to supply thermal energy to consumers from various sources of thermal energy while maintaining the reliability of heat supply. In the presence of such conditions, the distribution of heat load between sources of heat energy is carried out on a competitive basis in accordance with the criterion of minimum specific variable costs for the production of heat energy by sources of heat energy, determined in the manner established by the pricing bases in the field of heat supply, approved by the Government Russian Federation, on the basis of applications from organizations that own sources of thermal energy, and standards taken into account when regulating tariffs in the field of heat supply for the corresponding period of regulation.

4. If the heat supply organization does not agree with the distribution of the heat load carried out in the heat supply scheme, it has the right to appeal against the decision on such distribution, taken by the body authorized in accordance with this Federal Law to approve the heat supply scheme, to the authorized Government of the Russian Federation federal agency executive power.

5. Heat supply organizations and heat network organizations operating in the same heat supply system, annually before the start of the heating period, are required to conclude an agreement between themselves on the management of the heat supply system in accordance with the rules for organizing heat supply, approved by the Government of the Russian Federation.

6. The subject of the agreement specified in part 5 of this article is the procedure for mutual actions to ensure the functioning of the heat supply system in accordance with the requirements of this Federal Law. Mandatory conditions said agreement are:

1) determining the subordination of dispatching services of heat supply organizations and heat network organizations, the procedure for their interaction;

3) the procedure for ensuring access of the parties to the agreement or, by mutual agreement of the parties to the agreement, to another organization to heat networks for the adjustment of heat networks and regulation of the operation of the heat supply system;

4) the procedure for interaction between heat supply organizations and heat network organizations in emergency situations and emergency situations.

7. If the heat supply organizations and heat network organizations have not concluded the agreement specified in this article, the procedure for managing the heat supply system is determined by the agreement concluded for the previous heating period, and if such an agreement has not been concluded earlier, the specified procedure is established by the body authorized in accordance with this Federal law for approval of the heat supply scheme.

Siemens is a recognized world leader in the development of systems for the energy sector, including heating and water supply systems. This is what one of the departments does. Siemens - Building Technologies – “Automation and safety of buildings”. The company offers a full range of equipment and algorithms for the automation of boiler houses, heat points and pumping stations.

1. Structure of the heating system

Siemens offers a complete solution for creating unified system management of urban systems of heat and water supply. The complexity of the approach lies in the fact that everything is offered to customers, starting with hydraulic calculations of heat and water supply systems and ending with communication and dispatching systems. The implementation of this approach is ensured by the accumulated experience of the company's specialists, acquired in different countries around the world during the implementation of various projects in the field of heating systems for large cities in Central and Eastern Europe. This article discusses the structures of heat supply systems, the principles and control algorithms that were implemented in the implementation of these projects.

Heat supply systems are built mainly according to a 3-stage scheme, the parts of which are:

1. Heat sources of different types, interconnected into a single looped system

2. Central heating points (CHP) connected to the main heating networks with a high heat carrier temperature (130 ... 150 ° C). In the central heating center, the temperature gradually decreases to a maximum temperature of 110 ° C, based on the needs of the ITP. For small systems, the level of central heat points may be absent.

3. Individual heating points that receive thermal energy from the central heating station and provide heat supply to the facility.

The principal feature of Siemens solutions is that the whole system is based on the principle of 2-pipe distribution, which is the best technical and economic compromise. This solution makes it possible to reduce heat losses and electricity consumption in comparison with the 4-pipe or 1-pipe systems with open water intake, which are widely used in Russia, investments in the modernization of which without changing their structure are not effective. Maintenance costs for such systems are constantly increasing. Meanwhile, it is the economic effect that is the main criterion for the expediency of development and technical improvement of the system. Obviously, when constructing new systems, optimal solutions that have been tested in practice should be adopted. If we are talking about a major overhaul of a heat supply system of a non-optimal structure, it is economically profitable to switch to a 2-pipe system with individual heating points in each house.

When providing consumers with heat and hot water, the management company bears fixed costs, the structure of which is as follows:

Heat generation costs for consumption;

losses in heat sources due to imperfect methods of heat generation;

heat losses in heating mains;

R electricity costs.

Each of these components can be reduced with optimal control and the use of modern automation tools at every level.

2. Heat sources

It is known that large combined heat and power sources, or those in which heat is a secondary product, such as industrial processes, are preferred for heating systems. It was on the basis of such principles that the idea of ​​district heating was born. Boilers operating on different types of fuel are used as backup heat sources. gas turbines And so on. If gas-fired boilers serve as the main source of heat, they must operate with automatic optimization of the combustion process. This is the only way to achieve savings and reduce emissions compared to distributed heat generation in each house.

3. Pumping stations

Heat from heat sources is transferred to the main heating networks. The heat carrier is pumped over by network pumps which work continuously. Therefore, special attention should be paid to the selection and operation of pumps. The operating mode of the pump depends on the modes of the heating points. A decrease in the flow rate at the CHP entails an undesirable increase in the head of the pump(s). An increase in pressure negatively affects all components of the system. At best, only hydraulic noise increases. In either case, electrical energy is wasted. Under these conditions, an unconditional economic effect is provided with frequency control of pumps. Various control algorithms are used. In the basic scheme, the controller maintains a constant differential pressure across the pump by changing the speed. Due to the fact that with a decrease in the flow rate of the coolant, the pressure losses in the lines are reduced (quadratic dependence), it is also possible to reduce the setpoint (setpoint) of the pressure drop. This control of pumps is called proportional and allows you to further reduce the cost of operating the pump. More efficient control of pumps with correction of the task by the “remote point”. In this case, the pressure drop at the end points of the main networks is measured. The current differential pressure values ​​compensate for the pressures at the pumping station.

4. Central heating points (CHP)

AT modern systems CHP heating supplies play a very important role. An energy-saving heat supply system should work with the use of individual heating points. However, this does not mean that central heating stations will be closed: they act as a hydraulic stabilizer and at the same time divide the heat supply system into separate subsystems. In the case of the use of ITP, systems of central hot water supply are excluded from the central heating station. At the same time, only 2 pipes pass through the central heating station, separated by a heat exchanger, which separates the system of main routes from the ITP system. Thus, the ITP system can operate with other coolant temperatures, as well as with lower dynamic pressures. This guarantees the stable operation of the ITP and at the same time entails a reduction in investments in the ITP. The supply temperature from the CHP is corrected in accordance with the temperature schedule according to the outdoor temperature, taking into account the summer limitation, which depends on the demand of the DHW system in the CHP. We are talking about a preliminary adjustment of the coolant parameters, which makes it possible to reduce heat losses in the secondary routes, as well as increase the service life of the thermal automation components in the ITP.

5. Individual heating points (ITP)

The operation of the ITP affects the efficiency of the entire heat supply system. ITP is a strategically important part of the heat supply system. The transition from a 4-pipe system to a modern 2-pipe system is associated with certain difficulties. Firstly, this entails the need for investment, and secondly, without a certain “know-how”, the introduction of ITP can, on the contrary, increase current costs management company. The principle of operation of the ITP is that the heating point is located directly in the building, which is heated and for which hot water is prepared. At the same time, only 3 pipes are connected to the building: 2 for the coolant and 1 for cold water supply. Thus, the structure of the pipelines of the system is simplified, and during the planned repair of the routes, savings on laying pipes immediately take place.

5.1. Heating circuit control

The ITP controller controls the heat output of the heating system by changing the temperature of the coolant. The heating temperature setpoint is determined from the outdoor temperature and the heating curve (weather-compensated control). The heating curve is determined taking into account the inertia of the building.

5.2. Building inertia

The inertia of buildings has a significant impact on the result of weather-compensated heating control. A modern ITP controller must take into account this influencing factor. The inertia of the building is determined by the value of the time constant of the building, which ranges from 10 hours for panel houses to 35 hours for brick houses. Based on the time constant of the building, the IHS controller determines the so-called "combined" outdoor temperature, which is used as a correction signal in the automatic heating water temperature control system.

5.3. wind force

The wind significantly affects the room temperature, especially in high-rise buildings located in open areas. The algorithm for correcting water temperature for heating, taking into account the influence of wind, provides up to 10% savings in thermal energy.

5.4 Return temperature limitation

All the types of control described above indirectly affect the return water temperature reduction. This temperature is the main indicator of the economical operation of the heating system. With various modes of operation of the IHS, the return water temperature can be reduced using the limitation functions. However, all limiting functions entail deviations from comfort conditions, and their use must be supported by a feasibility study. In independent schemes for connecting the heating circuit, with economical operation of the heat exchanger, the temperature difference between the return water of the primary circuit and the heating circuit should not exceed 5 ° C. Economy is ensured by the function of dynamic limitation of the return water temperature ( DRT – differential of return temperature ): when the set value of the temperature difference between the return water of the primary circuit and the heating circuit is exceeded, the controller reduces the flow of the heating medium in the primary circuit. At the same time, the peak load also decreases (Fig. 1).