The piezometric graph shows the terrain, the height of attached buildings, and the pressure in the network 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.

Behind horizontal plane The pressure reading level is set to 1 – 1 (see Fig. 6.5). Line P1 – P4 – graph of supply line pressures. Line O1 – O4 – return line pressure graph. N o1 – total pressure on the return collector of the source; Nсн – pressure of the network pump; N st – full pressure of the make-up pump, or full static pressure in the heating network; N to– total pressure in t.K at the discharge pipe of the network pump; D H t – pressure loss in the heat treatment plant; N p1 – total pressure on the supply manifold, N n1 = N k–D H t. Available supply water pressure at the CHP collector N 1 =N p1 - N o1. Pressure at any point in the network i denoted as N p i, H oi – total pressures 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 N p i – Z i , H o i – Z i in the forward and return pipelines, respectively. Available head at point i there is a difference piezometric pressures in forward and return pipelines – N p i – H oi. The available pressure in the heating network at the connection point of subscriber D is N 4 = N p4 – N o4.

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

There is a loss of pressure in the supply line in section 1 - 4 . There is a pressure loss in the return line in section 1 - 4 . When the mains pump is operating, the pressure N The speed of the charging pump is regulated by a pressure regulator to N o1. When the network pump stops, a static pressure is established in the network N st, developed by the make-up pump.

When hydraulically calculating a steam pipeline, the profile of the steam pipeline may not be taken into account due to the low steam density. Pressure losses from subscribers, for example , depends on the subscriber connection scheme. With elevator mixing D N e = 10...15 m, with elevator-free input – D n BE =2...5 m, in the presence of surface heaters D N n =5...10 m, with pump mixing D N ns = 2…4 m.

Requirements for pressure conditions in the heating network:

At any point in the system, the pressure should not exceed the maximum permissible value. The heating system pipelines are designed for 16 ata, pipelines local systems– at a pressure of 6...7 ata;

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 be no less than the saturation pressure at a given temperature to avoid boiling of water.

Warning There is not enough pressure at the source Delta=X m. Where Delta is the required pressure.

WORST CONSUMER: ID=XX.

Figure 283. Message about the worst consumer




This message is displayed when there is a lack of available pressure at the consumer, where DeltaH− the value of the pressure that is not enough, m, a ID (XX)− individual number of the consumer for whom the pressure shortage is maximum.



Figure 284. Message about insufficient pressure




Double-click the left mouse button on the message about the worst consumer: the corresponding consumer will blink on the screen.

This error may be caused by several reasons:

1. Incorrect data. If the amount of pressure shortage goes beyond the actual values ​​for a given network, then there is an error when entering the initial data or an error when plotting the network diagram on the map. You should check whether the following data has been entered correctly:

   

   Hydraulic network mode.

   If there are no errors when entering the initial data, but a lack of pressure exists and is of real significance for a given network, then in this situation the determination of the cause of the shortage and the method for eliminating it is carried out by the specialist working with this heating network.

ID=ХХ "Name of consumer" Emptying the heating system (H, m)

This message is displayed when there is insufficient pressure in the return pipeline to prevent emptying of the heating system of the upper floors of the building; the total pressure in the return pipeline must be at least the sum of the geodetic mark, the height of the building plus 5 meters to fill the system. The head reserve for filling the system can be changed in the calculation settings ().

XX− individual number of the consumer whose heating system is being emptied, N- pressure, in meters of which is not enough;

ID=ХХ "Name of consumer" Pressure in the return pipeline is higher than the geodetic mark by N, m

This message is issued when the pressure in the return pipeline is higher than permissible according to strength conditions cast iron radiators(more than 60 m. water column), where XX- individual consumer number and N- pressure value in the return pipeline exceeding the geodetic mark.

The maximum pressure in the return pipeline can be set independently in calculation settings. ;

ID=XX "Name of consumer" Elevator nozzle cannot be selected. Set the maximum

This message may appear when there is a large heating load or when an incorrect connection diagram is selected that does not correspond to the design parameters. XX- individual number of the consumer for whom the elevator nozzle cannot be selected;

ID=XX "Name of consumer" Elevator nozzle cannot be selected. Set the minimum

This message may appear when there are very small heating loads or when an incorrect connection diagram is selected that does not correspond to the design parameters. XX− individual number of the consumer for whom the elevator nozzle cannot be selected.

Warning Z618: ID=XX "XX" The number of washers on the supply pipe to CO is more than 3 (YY)

This message means that, as a result of the calculation, the number of washers required to adjust the system is more than 3 pieces.

Since the default minimum diameter of the washer is 3 mm (indicated in the calculation settings “Setting up pressure loss calculation”), and the consumption for the consumer’s heating system ID=XX is very small, the calculation results in determining total washers and the diameter of the last washer (in the consumer database).

That is, a message like: The number of washers on the supply pipeline for CO is more than 3 (17) warns that to set up this consumer, you should install 16 washers with a diameter of 3 mm and 1 washer, the diameter of which is determined in the consumer database.

Warning Z642: ID=XX The elevator at the central heating station is not working

This message is displayed as a result of a verification calculation and means that elevator unit does not function.

To task hydraulic calculation includes:

Determination of pipeline diameter;

Determination of pressure drop (pressure);

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

Linking all network points in static and dynamic modes in order to ensure permissible pressures and required pressures in the network and subscriber systems.

Based on the results of hydraulic calculations, the following problems can be solved.

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

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

3. Determination of operating conditions of the heating network and selection of subscriber connection schemes.

4. Selection of automation for the heating network and subscribers.

5. Development of operating modes.

a. Schemes and configurations of heating networks.

The layout of the heating network is determined by the location of heat sources in relation to the area of ​​consumption, the nature of the heat load and the type of coolant.

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

More challenging task is the choice of the scheme of water heating networks due to the large length, large quantity subscribers. Water vehicles are less durable than steam vehicles due to greater corrosion, and are more sensitive to accidents due to the high density of water.

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

Water networks are divided into main and distribution networks. The coolant is supplied through main networks from heat sources to areas of consumption. Through distribution networks, water is supplied to GTP and MTP and to subscribers. Subscribers very rarely connect directly to backbone networks. At the points where distribution networks are connected to the main ones, sectioning chambers with valves are installed. Sectional valves on main networks are usually installed every 2-3 km. Thanks to the installation of sectional valves, water losses during vehicle accidents are reduced. Distribution and main vehicles with a diameter of less than 700 mm are usually made dead-end. In the event of an emergency, a break in the heat supply to buildings for up to 24 hours is acceptable for most of the country. If a break in heat supply is unacceptable, it is necessary to provide for duplication or loopback of the heating system.

Fig.6.2. Ring heating network from three thermal power plants Fig.6.3. Radial heat network

When supplying heat to large cities from several thermal power plants, it is advisable to provide for mutual interlocking of thermal power plants by connecting their mains with interlocking connections. In this case, a ring heat network with several power sources is obtained. Such a scheme has higher reliability and ensures the transmission of redundant water flows in the event of an accident on any part of the network. For pipeline diameters emanating from a heat source of 700 mm or less, it is usually used radial scheme heating network with a gradual decrease in pipe diameter as it moves away from the source and the connected load decreases. This network is the cheapest, but in the event of an accident, the heat supply to subscribers is stopped.

b. Basic calculation dependencies

Working pressure in the heating system - the most important parameter, on which the functioning of the entire network depends. Deviations in one direction or another from the values ​​specified in the design not only reduce the efficiency of the heating circuit, but also significantly affect the operation of the equipment, and in special cases can even cause it to fail.

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

1. Static pressure. This component depends on the height of the column of water 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 internal surfaces systems when water or other medium moves.

The concept of maximum operating pressure is distinguished. This is the maximum permissible value, exceeding which can lead to the destruction of individual network elements.

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 floors of the building, the total length of the pipelines and the number of radiators. As a rule, for private houses and cottages optimal values The medium pressure in the heating circuit is in the range from 1.5 to 2 atm.

For apartment buildings up to five floors high connected to the system central heating, the network pressure is maintained at 2-4 atm. For nine- and ten-story buildings, a pressure of 5-7 atm is considered normal, and in taller 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 on different heights and at different distances from the boiler room, the pressure in the network has to be adjusted. Pressure regulators are used to reduce it, and pumping stations are used to increase it. However, it should be taken into account that a faulty regulator can cause an increase in pressure in certain areas of the system. In some cases, when the temperature drops, these devices can completely shut off the shut-off valves on the supply pipeline coming from the boiler plant.

To avoid similar situations The regulator settings are adjusted so that complete shutoff of the valves is impossible.

Autonomous heating systems

Expansion tank in an autonomous heating system.

In the absence of a centralized heating supply, autonomous heating systems are installed in houses, 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. This low figure is due to the relatively short length of pipelines, as well as a small number of instruments and fittings, which results in relatively low hydraulic resistance. In addition, due to the low height of such houses, the static pressure in the lower sections of the circuit rarely exceeds 0.5 atm.

At the stage of starting the autonomous system, it is filled with cold coolant, maintaining a minimum pressure of closed systems ah heating 1.5 atm. There is no need to sound the alarm if, some time after filling, the pressure in the circuit drops. Pressure losses in this case are caused by the release of air from the water, which dissolved in it when the pipelines were filled. The circuit should be de-aired 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, reaching the calculated operating values.

Precautionary measures

A device for measuring pressure.

Since when designing autonomous systems In heating systems, in order to save money, a small safety margin is laid down; even a small pressure surge of up to 3 atm can cause depressurization of individual elements or their connections. In order to smooth out pressure drops due to unstable pump operation or changes in coolant temperature, an expansion tank is installed in a closed heating system. Unlike a similar device in the system open type, it has no communication with the atmosphere. One or more of its walls are made of elastic material, due to which the tank acts as a damper during pressure surges or water hammer.

Availability expansion tank does not always guarantee maintaining pressure within optimal limits. In some cases it may exceed the maximum permissible values:

• if the expansion tank capacity is incorrectly selected;
• in case of malfunction of the circulation pump;
• when the coolant overheats, which is a consequence of malfunctions in the boiler automation;
• due to incomplete opening shut-off valves after repair or maintenance work;
• due to the appearance air lock(this phenomenon can provoke both an increase in pressure and a drop);
• when the throughput of the dirt filter decreases due to its excessive clogging.

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

What to do if the pressure in the heating system drops

Pressure in the expansion tank.

When operating autonomous heating systems, the most common are the following: emergency situations, in which the pressure decreases smoothly or sharply. They can be caused by two reasons:

• depressurization of system elements or their connections;
• problems with the boiler.

In the first case, the location of 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 open method(not to be confused with an open type system), that is, all its pipelines, fittings and instruments are visible. First of all, carefully inspect the floor under the pipes and radiators, trying to detect puddles of water or traces of them. In addition, the location of the leak can be identified by traces of corrosion: characteristic rusty streaks form on radiators or at the joints of system elements when the seal is broken.
2. Using special equipment. If a visual inspection of the radiators does not yield anything, and the pipes are laid in a hidden way and cannot be examined, you should seek the help of specialists. They have special equipment that will help detect leaks and fix them if the home owner is unable to do this themselves. Localizing the depressurization point is quite simple: water is drained from the heating circuit (for such cases, a drain valve is installed at the lowest point of the circuit during the installation stage), then air is pumped into it using a compressor. The location of the leak is determined by the characteristic sound that leaking air makes. Before starting the compressor, the boiler and radiators should be insulated using shut-off valves.

If problem area is one of the connections; it is additionally sealed with tow or FUM tape, and then tightened. The burst 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 a closed heating system still drops, you should look for the reasons for this phenomenon in the boiler. You should not carry out diagnostics yourself; this is a job for a specialist with the appropriate education. Most often the following defects are found in the boiler:

Installation of a heating system with a pressure gauge.

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

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

Although in previous section it was said that this could cause an increase in pressure, there is no contradiction here. When the pressure in the heating system increases, it triggers safety valve. In this case, the coolant is discharged and its volume in the circuit decreases. As a result, the pressure will decrease over time.

Pressure control

For visual control pressure gauges in the heating network most often use dial gauges with a Bredan tube. Unlike digital instruments, such pressure gauges do not require connection electrical supply. Automated systems use electrical contact sensors. At the outlet to the control and measuring device it is necessary to install three way valve. 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 the following points:

1. Before the boiler installation (or boiler) and at the exit from it. At this point the pressure in the boiler is determined.
2. Before circulation pump and after it.
3. At the entrance of the heating main into a building or structure.
4. Before and after the pressure regulator.
5. At the inlet and outlet of the coarse filter (sludge filter) to control its level of contamination.

All control and measuring instruments must undergo regular verification to confirm the accuracy of the measurements they perform.

“Specification of quantity and quality indicators utility resources V modern realities Housing and communal services"

SPECIFICATION OF INDICATORS OF QUANTITY AND QUALITY OF COMMUNAL RESOURCES IN MODERN REALITIES OF HUSING AND UTILITIES

V.U. Kharitonsky, Head of Department engineering systems

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

State Housing Inspectorate of Moscow

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. Specialists from the Moscow Housing Inspectorate, in addition to the existing requirements, propose to specify the values ​​of the parameters of heat and water supply systems at the entrance to the building, in order to maintain quality in residential apartment buildings utilities.

Review of current rules and regulations for technical operation housing stock in the field of housing and communal services showed that currently construction, sanitary standards and rules, GOST R 51617 -2000* “Housing and communal services”, “Rules for the provision of utility services to citizens”, approved by Decree of the Government of the Russian Federation of May 23, 2006 No. 307, and other valid regulations consider and set parameters and modes only at the source (central heating station, boiler house, water pumping station) that produces communal resources (cold, hot water and thermal energy), and directly in the resident’s apartment, where utilities are 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 boundaries of responsibility of the resource supply and housing organizations, which are the subject of endless disputes when determining the guilty party for the failure to provide services to the population or provide services poor quality. Thus, today there is no document regulating the indicators of quantity and quality at the entrance to the house, at the border of responsibility of the resource supply and housing organizations.

However, an analysis of quality checks of supplied communal resources and services carried out 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 allow establishing mutual responsibility of resource supply and housing management organizations. It should be noted that the quality and quantity of communal resources supplied to the boundary of the operational responsibility of the resource supplying and managing housing organization, and public services to residents, is determined and assessed based on the readings, first of all, of common house metering devices installed at the inputs

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

Thus, the Moscow Housing Inspectorate, based on the interests of residents and many years of practice, in addition to the requirements of regulatory documents and in development of the provisions of SNiP and SanPin in relation to operating conditions, as well as in order to maintain the quality of utility services provided to the population in residential apartment buildings, proposed regulating when introducing 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 automated system control and accounting of energy consumption:

1) for a central heating system (CH):

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

The network water pressure in the return pipeline of the central heating system must be no less than 0.05 MPa (0.5 kgf/cm2) higher than the static pressure (for the system), but not higher than permissible (for pipelines, heating devices, fittings and other equipment ). If necessary, it is allowed to install pressure regulators on the 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 central heating systems must be higher than the required water pressure in the return pipelines by the amount of available pressure (to ensure coolant circulation in the system);

Available pressure (pressure difference between supply and return pipelines) coolant at the input of the central heating network into the building must be maintained by heat supply organizations within the limits of:

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

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

2) For hot water supply system (DHW):

Temperature hot water in the DHW supply pipeline for closed systems within 55-65 °C, for open systems heat supply within 60-75 °C;

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

The arithmetic mean value of the hot water temperature in the supply and circulation pipelines at the inlet of the DHW system in all cases must be at least 50 °C;

The available pressure (pressure difference between the supply and circulation pipelines) at the calculated circulation flow rate of the hot water supply system must be no lower than 0.03-0.06 MPa (0.3-0.6 kgf/cm2);

The water pressure in the supply pipeline of the hot water supply 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 hot water supply systems must be no less than 0.05 MPa (0.5 kgf/cm2) higher than the static pressure (for the system), but not exceed the static pressure (for the highest located and high-rise building) more than by 0.20 MPa (2 kgf/cm2).

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

Hot water temperature is not lower than 50 °C (optimal - 55 °C);

The minimum free pressure for sanitary fixtures in residential premises on 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 at sanitary fixtures on the upper floors should not exceed 0.20 MPa (2 kgf/cm2);

The maximum free pressure in water supply systems at sanitary fixtures on the lower floors should not exceed 0.45 MPa (4.5 kgf/cm2).

3) For a 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/cm2).

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

a) the minimum free pressure for sanitary fixtures in residential premises on 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 on the upper floors is not less than 0.10 MPa (1 kgf/cm2);

c) the maximum free pressure in water supply systems at sanitary fixtures on the lower floors should not exceed 0.45 MPa (4.5 kgf/cm2).

4) For all systems:

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

The water pressure values ​​in the DHW and cold water systems at the entrance of pipelines into the house must be at the same level (achieved by setting automatic devices regulation of a heating point and/or pumping station), while the maximum permissible pressure difference should be no more than 0.10 MPa (1 kgf/cm2).

These parameters at the entrance to buildings must be ensured by resource supplying organizations by implementing measures for automatic regulation, optimization, uniform distribution of thermal 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 adjustment of building engineering systems. These activities should be carried out when preparing heating points, pumping stations and intra-block networks for seasonal operation, as well as in cases of violations of the specified parameters (indicators of the quantity and quality of utility resources supplied to the boundary of operational responsibility).

If the specified parameter values ​​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 supplied utility resources and the quality of the provided utility services, it is necessary to recalculate the payment for the provided utility services with a violation of their quality.

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

Literature

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

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

3. MDK 4-02.2001. Standard instructions on technical operation of thermal systems of municipal heating supply.

4. MDK 2-03.2003. Rules and regulations for the 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 of residential buildings, equipment, networks and structures of fuel, energy and public utilities in Moscow.

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

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

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

10. Methodology for checking violations of the quantity and quality of services provided to the population by accounting for heat energy consumption, cold and hot water consumption in Moscow.

(Energy Saving Magazine No. 4, 2007)