"Concretization of indicators of the quantity and quality of communal resources in the modern realities of housing and communal services"

SPECIFICATION OF INDICATORS OF QUANTITY AND QUALITY OF UTILITY RESOURCES IN THE MODERN REALITIES OF HUSAL COMPANY

V.U. Kharitonsky, Head of Engineering Systems Department

A. M. Filippov, Deputy Head of the Department of Engineering Systems,

Moscow State Housing Inspectorate

Documents regulating the indicators of the quantity and quality of communal resources supplied to household consumers at the border of responsibility of the resource supply and housing organizations have not been developed to date. In addition to the existing requirements, specialists of the Moscow Housing Inspection propose to specify the values ​​of the parameters of heat and water supply systems at the entrance to the building, in order to maintain the quality of public services in residential multi-apartment buildings.

A review of the current rules and regulations for the technical operation of the housing stock in the field of housing and communal services showed that at present, construction, sanitary norms and rules, GOST R 51617-2000 * "Housing and communal services", "Rules for the provision of public services to citizens", approved by Decree of the Government of the Russian Federation of May 23, 2006 No. 307, and other current regulatory documents consider and set parameters and modes only at the source (central heating station, boiler house, water booster pumping station) that generates a communal resource (cold, hot water and thermal energy), and directly in the apartment of a resident, where a utility service is provided. However, they do not take into account the modern realities of the division of housing and communal services into residential buildings and public utility facilities and the established limits of responsibility of the resource supply and housing organizations, which are the subject of endless disputes when determining the guilty party for not providing services to the population or providing services of inadequate quality. Thus, today there is no document regulating the indicators of quantity and quality at the entrance to the house, on the border of the responsibility of the resource supply and housing organizations.

Nevertheless, an analysis of the inspections of the quality of supplied communal resources and services conducted by the Moscow Housing Inspectorate showed that the provisions of federal regulatory legal acts in the field of housing and communal services can be detailed and specified in relation to apartment buildings, which will establish the mutual responsibility of resource-supplying and managing housing organizations. It should be noted that the quality and quantity of utility resources supplied to the boundary of operational responsibility of the resource supplying and managing housing organization, and utility services to residents is determined and evaluated based on the readings, first of all, of common house meters installed at the inputs

systems of heat and water supply to residential buildings, and an automated system for monitoring and accounting for energy consumption.

Thus, Moszhilinspektsiya, based on the interests of residents and many years of practice, in addition to the requirements of regulatory documents and in the development of the provisions of SNiP and SanPin in relation to operating conditions, as well as in order to comply with the quality of public services provided to the population in residential multi-apartment buildings, proposed to regulate on entering heat and water supply systems into the house (at the metering and control unit), the following standard values ​​​​of parameters and modes recorded by common house metering devices and an automated system for monitoring and metering energy consumption:

1) for the central heating system (CH):

The deviation of the average daily temperature of the network water supplied to the heating systems must be within ± 3% of the established temperature schedule. The average daily temperature of the return network water should not exceed the temperature specified by the temperature chart by more than 5%;

The pressure of network water in the return pipeline of the central heating system must be at least 0.05 MPa (0.5 kgf / cm 2) higher than the static one (for the system), but not higher than the permissible one (for pipelines, heaters, fittings and other equipment ). If necessary, it is allowed to install backwater regulators on return pipelines in the ITP of heating systems of residential buildings directly connected to the main heating networks;

The network water pressure in the supply pipeline of the CH systems must be higher than the required water pressure in the return pipelines by the amount of available pressure (to ensure the circulation of the heat carrier in the system);

The available pressure (pressure drop between the supply and return pipelines) of the heat carrier at the input of the central heating heating network into the building must be maintained by heat supply organizations within:

a) with dependent connection (with elevator units) - in accordance with the project, but not less than 0.08 MPa (0.8 kgf / cm 2);

b) with independent connection - in accordance with the project, but not less than 0.03 MPa (0.3 kgf / cm2) more than the hydraulic resistance of the central heating system inside the house.

2) For hot water supply system (DHW):

Hot water temperature in the DHW supply pipeline for closed systems within 55-65 °С, for open heat supply systems within 60-75 °С;

Temperature in the DHW circulation pipeline (for closed and open systems) 46-55 °С;

The arithmetic mean of the temperature of hot water in the supply and circulation pipelines at the inlet of the DHW system must in all cases not be lower than 50 °C;

The available pressure (pressure drop between the supply and circulation pipelines) at the estimated circulation flow rate of the DHW system must be at least 0.03-0.06 MPa (0.3-0.6 kgf / cm 2);

The water pressure in the supply pipeline of the DHW system must be higher than the water pressure in the circulation pipeline by the amount of available pressure (to ensure the circulation of hot water in the system);

The water pressure in the circulation pipeline of DHW systems must be at least 0.05 MPa (0.5 kgf / cm 2) higher than the static pressure (for the system), but not exceed the static pressure (for the highest located and high-rise building) by more than by 0.20 MPa (2 kgf/cm2).

With these parameters in apartments near sanitary appliances of residential premises, in accordance with the regulatory legal acts of the Russian Federation, the following values ​​\u200b\u200bmust be provided:

Hot water temperature not lower than 50 °С (optimum - 55 °С);

The minimum free pressure at the sanitary appliances of the residential premises of the upper floors is 0.02-0.05 MPa (0.2-0.5 kgf / cm 2);

The maximum free pressure in hot water supply systems near sanitary appliances on the upper floors should not exceed 0.20 MPa (2 kgf / cm 2);

The maximum free pressure in the water supply systems at the sanitary appliances of the lower floors should not exceed 0.45 MPa (4.5 kgf / cm 2).

3) For cold water supply system (CWS):

The water pressure in the supply pipeline of the cold water system must be at least 0.05 MPa (0.5 kgf / cm 2) higher than the static pressure (for the system), but not exceed the static pressure (for the highest located and high-rise building) by more than 0.20 MPa (2 kgf / cm 2).

With this parameter in apartments, in accordance with the regulatory legal acts of the Russian Federation, the following values ​​\u200b\u200bmust be provided:

a) the minimum free pressure at the sanitary appliances of the residential premises of the upper floors is 0.02-0.05 MPa (0.2-0.5 kgf / cm 2);

b) the minimum pressure in front of the gas water heater of the upper floors is at least 0.10 MPa (1 kgf / cm 2);

c) the maximum free pressure in the water supply systems near the sanitary appliances of the lower floors should not exceed 0.45 MPa (4.5 kgf / cm 2).

4) For all systems:

The static pressure at the inlet to the heat and water supply systems should ensure that the pipelines of the central heating, cold water and hot water systems are filled with water, while the static water pressure should not be higher than that allowed for this system.

The water pressure values ​​in the DHW and cold water systems at the inlet of pipelines into the house must be at the same level (achieved by setting the automatic control devices of the heating point and / or pumping station), while the maximum allowable pressure difference should be no more than 0.10 MPa (1 kgf / cm 2).

These parameters at the entrance to the buildings should be provided by resource supplying organizations by taking measures for automatic regulation, optimization, uniform distribution of heat energy, cold and hot water between consumers, and for return pipelines of systems - also by housing management organizations through inspections, identification and elimination of violations or re-equipment and carrying out adjustment activities of engineering systems of buildings. These measures should be carried out when preparing heat points, pumping stations and intra-quarter networks for seasonal operation, as well as in cases of violations of the specified parameters (indicators of the quantity and quality of communal resources supplied to the boundary of operational responsibility).

If the specified values ​​of parameters and modes are not observed, the resource supplying organization is obliged to immediately take all necessary measures to restore them. In addition, in case of violation of the specified values ​​of the parameters of the delivered communal resources and the quality of the communal services provided, it is necessary to recalculate the payment for the communal services provided in violation of their quality.

Thus, compliance with these indicators will ensure the comfortable living of citizens, the effective functioning of engineering systems, networks, residential buildings and public utilities that provide heat and water supply to the housing stock, as well as the supply of communal resources in the required quantity and standard quality to the boundaries of the operational responsibility of the resource supply and managing housing organization (at the input of engineering communications into the house).

Literature

1. Rules for the technical operation of thermal power plants.

2. MDK 3-02.2001. Rules for the technical operation of systems and structures of public water supply and sewerage.

3. MDK 4-02.2001. Standard instruction for the technical operation of thermal systems of communal heat supply.

4. MDK 2-03.2003. Rules and norms of technical operation of housing stock.

5. Rules for the provision of public services to citizens.

6. ZhNM-2004/01. Regulations for the preparation for winter operation of heat and water supply systems for residential buildings, equipment, networks and structures of the fuel and energy and public utilities in Moscow.

7. GOST R 51617-2000*. Housing and communal services. General specifications.

8. SNiP 2.04.01-85 (2000). Internal plumbing and sewerage of buildings.

9. SNiP 2.04.05-91 (2000). Heating, ventilation and air conditioning.

10. Methodology for checking the violation of the quantity and quality of services provided to the population in terms of accounting for the consumption of thermal energy, the consumption of cold and hot water in Moscow.

(Energy Saving Magazine No. 4, 2007)

The operating pressure in the heating system is the most important parameter on which the functioning of the entire network depends. Deviations in one direction or another from the values ​​provided for by the project not only reduce the efficiency of the heating circuit, but also significantly affect the operation of the equipment, and in special cases can even disable it.

Of course, a certain pressure drop in the heating system is due to the principle of its design, namely the pressure difference in the supply and return pipelines. But if there are larger jumps, immediate action should be taken.

1. static pressure. This component depends on the height of the water column or other coolant in the pipe or container. Static pressure exists even if the working medium is at rest.
2. dynamic pressure. Represents the force that acts on the internal surfaces of the system during the movement of water or other medium.

Allocate the concept of limiting working pressure. This is the maximum allowable value, the excess of which is fraught with the destruction of individual elements of the network.

What pressure in the system should be considered optimal?

Table of maximum pressure in the heating system.

When designing heating, the coolant pressure in the system is calculated based on the number of storeys of the building, the total length of the pipelines and the number of radiators. As a rule, for private houses and cottages, the optimal values ​​\u200b\u200bof the pressure of the medium in the heating circuit are in the range from 1.5 to 2 atm.

For apartment buildings up to five floors high, connected to a central heating system, the pressure in the network is maintained at a level of 2-4 atm. For nine- and ten-story houses, a pressure of 5-7 atm is considered normal, and in higher buildings - 7-10 atm. The maximum pressure is recorded in the heating mains, through which the coolant is transported from boiler houses to consumers. Here it reaches 12 atm.

For consumers located at different heights and at different distances from the boiler house, the pressure in the network has to be adjusted. Pressure regulators are used to lower it, and pumping stations are used to increase it. However, it should be borne in mind that a faulty regulator can cause an increase in pressure in certain parts of the system. In some cases, when the temperature drops, these devices can completely block the shut-off valves on the supply pipeline coming from the boiler plant.

To avoid such situations, the settings of the regulators are corrected in such a way that complete valve overlap is not possible.

Autonomous heating systems

Expansion tank in an autonomous heating system.

In the absence of centralized heat supply in houses, autonomous heating systems are installed in which the coolant is heated by an individual low-power boiler. If the system communicates with the atmosphere through an expansion tank and the coolant circulates in it due to natural convection, it is called open. If there is no communication with the atmosphere, and the working medium circulates thanks to the pump, the system is called closed. As already mentioned, for the normal functioning of such systems, the water pressure in them should be approximately 1.5-2 atm. Such a low figure is due to the relatively short length of pipelines, as well as a small number of devices and fittings, resulting in a relatively low hydraulic resistance. In addition, due to the small height of such houses, the static pressure in the lower sections of the circuit rarely exceeds 0.5 atm.

At the stage of launching an autonomous system, it is filled with a cold coolant, maintaining a minimum pressure in closed heating systems of 1.5 atm. Do not sound the alarm if, after some time after filling, the pressure in the circuit drops. The pressure loss in this case is due to the release of air from the water, which was dissolved in it when the pipelines were filled. The circuit should be vented and completely filled with coolant, bringing its pressure to 1.5 atm.

After heating the coolant in the heating system, its pressure will increase slightly, while reaching the calculated operating values.

Precautionary measures

A device for measuring pressure.

Since when designing autonomous heating systems, in order to save, a small margin of safety is laid down, even a low pressure jump of up to 3 atm can cause depressurization of individual elements or their connections. In order to smooth out pressure drops due to unstable operation of the pump or changes in the temperature of the coolant, an expansion tank is installed in a closed heating system. Unlike a similar device in an open type system, it does not have communication with the atmosphere. One or more of its walls are made of an elastic material, due to which the tank acts as a damper during pressure surges or water hammer.

The presence of an expansion tank does not always guarantee that the pressure is maintained within optimal limits. In some cases, it may exceed the maximum allowable values:

• with incorrect selection of the capacity of the expansion tank;
• in case of malfunction of the circulation pump;
• when the coolant overheats, which happens as a result of violations in the operation of the boiler automation;
• due to incomplete opening of shut-off valves after repair or maintenance work;
• due to the appearance of an air lock (this phenomenon can provoke both an increase in pressure and its fall);
• with a decrease in the throughput of the mud filter due to its excessive clogging.

Therefore, in order to avoid emergency situations when installing closed-type heating systems, it is mandatory to install a safety valve that will discharge excess coolant if the permissible pressure is exceeded.

What to do if the pressure drops in the heating system

Expansion tank pressure.

During the operation of autonomous heating systems, the most frequent are such emergency situations in which the pressure gradually or sharply decreases. They can be caused by two reasons:

• depressurization of system elements or their connections;
• boiler malfunction.

In the first case, the leak should be located and its tightness restored. You can do this in two ways:

1. Visual inspection. This method is used in cases where the heating circuit is laid in an open way (not to be confused with an open type system), that is, all its pipelines, fittings and devices are in sight. First of all, they carefully examine the floor under pipes and radiators, trying to detect puddles of water or traces of them. In addition, the place of leakage can be fixed by traces of corrosion: characteristic rusty streaks form on radiators or at the joints of system elements in case of leakage.
2. With the help of special equipment. If a visual inspection of the radiators did not give anything, and the pipes were laid in a hidden way and cannot be inspected, you should seek the help of specialists. They have special equipment that will help detect the leak and fix it if the owner of the house does not have the opportunity to do it himself. Localization of the depressurization point is quite simple: water is drained from the heating circuit (for such cases, a drain valve is cut into the lower point of the circuit at the installation stage), then air is pumped into it using a compressor. The location of the leak is determined by the characteristic sound that the leaking air makes. Before starting the compressor, use shut-off valves to isolate the boiler and radiators.

If the problem area is one of the joints, it is additionally sealed with tow or FUM tape, and then tightened. The broken pipeline is cut out and a new one is welded in its place. Units that cannot be repaired are simply replaced.

If the tightness of pipelines and other elements is beyond doubt, and the pressure in the closed heating system still drops, you should look for the causes of this phenomenon in the boiler. It is not necessary to carry out diagnostics on your own; this is a job for a specialist with the appropriate education. Most often, the following defects are found in the boiler:

The device of the heating system with a manometer.

• the appearance of microcracks in the heat exchanger due to water hammer;
• manufacturing defects;
• failure of the feed valve.

A very common reason why the pressure in the system drops is the wrong selection of the capacity of the expansion tank.

Although the previous section stated that this could cause pressure to rise, there is no contradiction here. When the pressure in the heating system rises, the safety valve is activated. In this case, the coolant is discharged and its volume in the circuit decreases. As a result, over time, the pressure will decrease.

Pressure control

To visually control the pressure in the heating network, dial gauges with a Bredan tube are most often used. Unlike digital instruments, these pressure gauges do not require an electrical connection. Electrocontact sensors are used in automated systems. A three-way valve must be installed on the outlet to the control and measuring device. It allows you to isolate the pressure gauge from the network during maintenance or repair, and is also used to remove an air lock or reset the device to zero.

Instructions and rules governing the operation of heating systems, both autonomous and centralized, recommend installing pressure gauges at such points:

1. In front of the boiler plant (or boiler) and at its outlet. At this point, the pressure in the boiler is determined.
2. before and after the circulation pump.
3. At the entrance of the heating main to a building or structure.
4. before and after the pressure regulator.
5. At the inlet and outlet of the coarse filter (sump) to control the level of its contamination.

All measuring instruments must be regularly verified to confirm the accuracy of their measurements.

Based on the results of the calculation of water supply networks for various modes of water consumption, the parameters of the water tower and pumping units are determined, which ensure the operability of the system, as well as free pressures in all network nodes.

To determine the pressure at the supply points (at the water tower, at the pumping station), it is necessary to know the required pressure of water consumers. As mentioned above, the minimum free pressure in the water supply network of a settlement with a maximum domestic and drinking water intake at the entrance to the building above the ground in a one-story building should be at least 10 m (0.1 MPa), with a larger number of storeys, 4 m.

During the hours of lowest water consumption, the pressure for each floor, starting from the second, is allowed to be 3 m. For individual multi-storey buildings, as well as groups of buildings located in elevated places, local pumping installations are provided. The free pressure at the standpipes must be at least 10 m (0.1 MPa),

In the external network of industrial water pipelines, free pressure is taken according to the technical characteristics of the equipment. The free pressure in the consumer's drinking water supply network should not exceed 60 m, otherwise, for certain areas or buildings, it is necessary to install pressure regulators or zoning the water supply system. During the operation of the water supply system at all points of the network, a free pressure of at least the normative one must be ensured.

Free heads at any point in the network are defined as the difference between the elevations of the piezometric lines and the ground surface. Piezometric marks for all design cases (during household and drinking water consumption, in case of fire, etc.) are calculated based on the provision of standard free pressure at the dictating point. When determining piezometric marks, they are set by the position of the dictating point, i.e., the point with the minimum free pressure.

Typically, the dictate point is located in the most unfavorable conditions both in terms of geodetic elevations (high geodetic elevations) and in terms of distance from the power source (i.e., the sum of head losses from the power source to the dictate point will be the largest). At the dictating point, they are set by a pressure equal to the standard one. If at any point in the network the pressure is less than the normative one, then the position of the dictating point is set incorrectly. In this case, they find the point that has the smallest free pressure, take it as the dictator, and repeat the calculation of the pressures in the network.

The calculation of the water supply system for work during a fire is carried out on the assumption that it occurs at the highest and most distant points of the territory served by the water supply from the power sources. According to the method of extinguishing a fire, water pipes are of high and low pressure.

As a rule, when designing water supply systems, low-pressure fire-fighting water supply should be taken, with the exception of small settlements (less than 5 thousand people). The installation of a high-pressure fire-fighting water supply system must be economically justified,

In low-pressure water pipes, the pressure increase is carried out only for the duration of the fire extinguishing. The necessary increase in pressure is created by mobile fire pumps, which are brought to the fire site and take water from the water supply network through street hydrants.

According to SNiP, the pressure at any point of the low-pressure fire water pipeline network at the ground level during fire fighting must be at least 10 m. network through leaky joints of soil water.

In addition, a certain supply of pressure in the network is required for the operation of fire pumps in order to overcome significant resistance in the suction lines.

The high-pressure fire extinguishing system (usually adopted at industrial facilities) provides for the supply of water at the fire rate established by the fire standards and the increase in pressure in the water supply network to a value sufficient to create fire jets directly from hydrants. Free pressure in this case should provide a compact jet height of at least 10 m at full fire water flow and the location of the hose barrel at the level of the highest point of the tallest building and water supply through fire hoses 120 m long:

Nsv pzh \u003d N zd + 10 + ∑h ≈ N zd + 28 (m)

where N zd is the height of the building, m; h - pressure loss in the hose and barrel of the hose, m.

In a high-pressure water supply system, stationary fire pumps are equipped with automatic equipment that ensures that the pumps are started no later than 5 minutes after a fire signal is given. The pipes of the network must be selected taking into account the increase in pressure during a fire. The maximum free pressure in the network of the integrated water supply should not exceed 60 m of the water column (0.6 MPa), and in the hour of a fire - 90 m (0.9 MPa).

With significant differences in the geodetic marks of the object supplied with water, a large length of water supply networks, as well as with a large difference in the values ​​\u200b\u200bof the free pressure required by individual consumers (for example, in microdistricts with different building heights), zoning of the water supply network is arranged. It may be due to both technical and economic considerations.

The division into zones is carried out on the basis of the following conditions: at the highest point of the network, the necessary free pressure must be provided, and at its lower (or initial) point, the pressure must not exceed 60 m (0.6 MPa).

According to the types of zoning, water pipelines come with parallel and sequential zoning. Parallel zoning of the water supply system is used for large ranges of geodetic marks within the city area. For this, lower (I) and upper (II) zones are formed, which are provided with water, respectively, by pumping stations of zones I and II with water supply at different pressures through separate conduits. Zoning is carried out in such a way that at the lower boundary of each zone the pressure does not exceed the permissible limit.

Water supply scheme with parallel zoning

1 - pumping station II lift with two groups of pumps; 2 - pumps II (upper) zone; 3 - pumps of the I (lower) zone; 4 - pressure-regulating tanks

The task of hydraulic calculation includes:

Determining the diameter of pipelines;

Determination of pressure drop (pressure);

Determination of pressures (heads) at various points in the network;

Coordination of all network points in static and dynamic modes in order to ensure acceptable pressures and required pressures in the network and subscriber systems.

According to the results of hydraulic calculation, the following tasks can be solved.

1. Determination of capital costs, consumption of metal (pipes) and the main scope of work for laying a heating network.

2. Determination of the characteristics of circulation and make-up pumps.

3. Determination of the operating conditions of the heating network and the choice of schemes for connecting subscribers.

4. The choice of automation for the heating network and subscribers.

5. Development of operating modes.

a. Schemes and configurations of thermal networks.

The scheme of the heat network is determined by the placement of heat sources in relation to the area of ​​consumption, the nature of the heat load and the type of heat carrier.

The specific length of steam networks per unit of calculated heat load is small, since steam consumers - as a rule, industrial consumers - are located at a short distance from the heat source.

A more difficult task is the choice of the scheme of water heating networks due to the large length, a large number of subscribers. Water vehicles are less durable than steam ones due to greater corrosion, more sensitive to accidents due to the high density of water.

Fig.6.1. Single-line communication network of a two-pipe heat network

Water networks are divided into main and distribution networks. Through the main networks, the coolant is supplied from heat sources to the areas of consumption. Through distribution networks, water is supplied to the GTP and MTP and to subscribers. Subscribers rarely connect directly to backbone networks. Sectioning chambers with valves are installed at the distribution network connection points to the main ones. Sectional valves on main networks are usually installed after 2-3 km. Thanks to the installation of sectional valves, water losses during vehicle accidents are reduced. Distribution and main TS with a diameter of less than 700 mm are usually made dead-end. In case of accidents, for most of the country's territory, a break in the heat supply of buildings up to 24 hours is allowed. If a break in heat supply is unacceptable, it is necessary to provide for duplication or loopback of the TS.

Fig.6.2. Ring heating network from three CHPPs Fig.6.3. Radial heating network

When supplying large cities with heat from several CHPs, it is advisable to provide for mutual blocking of CHPs by connecting their mains with blocking connections. In this case, a ring heating network with several power sources is obtained. Such a scheme has a higher reliability, provides the transfer of reserving water flows in case of an accident in any section of the network. With diameters of lines extending from the heat source of 700 mm or less, a radial scheme of the heat network is usually used with a gradual decrease in the diameter of the pipe as it moves away from the source and the connected load decreases. Such a network is the cheapest, but in the event of an accident, heat supply to subscribers is stopped.

b. Main calculated dependencies

On a piezometric graph, the terrain, the height of the attached buildings, and the pressure in the network are plotted on a scale. Using this graph, it is easy to determine the pressure and available pressure at any point in the network and subscriber systems.

The level 1 - 1 is taken as the horizontal plane of pressure reading (see fig. 6.5). Line P1 - P4 - graph of the pressure of the supply line. Line O1 - O4 - graph of the pressure of the return line. H o1 is the total pressure on the return collector of the source; Hсн - pressure of the network pump; H st is the total head of the make-up pump, or the total static head in the heating network; H to- full pressure in t.K on the discharge pipe of the network pump; D H m is the pressure loss in the heat-preparation plant; H p1 - ​​full pressure on the supply manifold, H n1 = H to - D H t. Available pressure of network water at the CHPP collector H 1 =H p1 - H o1 . Pressure at any point in the network i denoted as H n i , H oi - total pressure in the forward and return pipelines. If the geodetic height at a point i there is Z i , then the piezometric pressure at this point is H p i - Z i , H o i – Z i in the forward and reverse pipelines, respectively. Available pressure at the point i is the difference between the piezometric pressures in the forward and return pipelines - H p i - H oi. The available pressure in the heating network at the subscriber's connection point D is H 4 = H p4 - H o4 .

Fig.6.5. Scheme (a) and piezometric graph (b) of a two-pipe heating network

There is a pressure loss in the supply line in section 1 - 4 . There is a pressure loss in the return line in section 1 - 4 . During operation of the network pump, the pressure H st of the feed pump is regulated by a pressure regulator up to H o1 . When the network pump stops, a static head is set in the network H st, developed by the make-up pump.

In the hydraulic calculation of the steam pipeline, the profile of the steam pipeline can be ignored due to the low steam density. Pressure loss at subscribers, for example , depends on the connection scheme of the subscriber. With elevator mixing D H e \u003d 10 ... 15 m, with elevatorless input - D n be =2…5 m, in the presence of surface heaters D H n = 5…10 m, with pump mixing D H ns = 2…4 m.

Requirements for the pressure regime in the heating network:

At any point in the system, the pressure must not exceed the maximum allowable value. Pipelines of the heat supply system are designed for 16 atm, pipelines of local systems - for a pressure of 6 ... 7 atm;

To avoid air leaks at any point in the system, the pressure must be at least 1.5 atm. In addition, this condition is necessary to prevent pump cavitation;

At any point in the system, the pressure must not be less than the saturation pressure at a given temperature in order to prevent water from boiling.