Self-regulation of the heating system: a review of devices and techniques. Adjusting the heating system - details from practice

Starting the heating system. Before starting the heating system, visual inspection equipment, as a result of which the compliance with the project of diameters, slopes, painting, thermal insulation and laying of pipelines, the type and number of heating devices, the correct installation and serviceability of shut-off and control valves, sumps, elevators or mixing pumps, instrumentation, make-up pumps and other equipment are established correct installation of heaters.

The heating system is started only after flushing and pressure testing, as well as checking the quality of the work carried out on the system and the availability of working documents and documentation for the system and its equipment (passports, flushing and testing certificates, work diagrams, instructions for the system equipment).

In case of mass switching on of heating systems in populated areas, it is recommended for quick removal air from systems next order putting the systems into operation: with a flat and decreasing terrain profile from the heat source - in the direction from the source to the end consumers, and with an increasing terrain profile from the heat source - in the direction from the end consumer to the source.

The commissioning of the heating system is a responsible event for the operation of the system, carried out in strict accordance with the schedule by a team of locksmiths, divided into pairs, each of which performs operations when starting the system on 3-4 risers. At the time of filling the system, all air collectors in high points should be open. If the pressure in the return line is higher than possible hydro static pressure in the heating system, the filling of the system is carried out by smoothly opening the valve on the return pipeline so that the pressure drops by no more than 0.03-0.5 MPa. If a water meter is installed on the return pipeline, then the system is filled through the bypass pipeline, and in its absence, the water meter is removed and a branch pipe with a flange is installed in its place.

If the pressure in the return pipeline is lower than the possible hydrostatic pressure in the heating system, then filling is carried out as follows.

In the absence of a pressure regulator "to itself" - initially by supplying water from the return pipeline, and then from the supply pipeline through the suction line to the elevator into the return line, while filling is done slowly, controlling the pressure gauges.

If there is a “to itself” pressure regulator, the system cannot be filled with the usual opening of a valve on the return pipeline: for example, in the absence of water in the heating system and circulation in it, a one-sided force from the spring will act on the regulator valve, tending to close the valve. In this case, for filling, it is necessary to carry out the following operations: open the air collectors in the upper part of the system and the valve on the return pipeline, loosen the valve spring, slightly open the valve on the supply pipeline and start slowly filling the system from the supply pipeline. In this case, it is necessary to observe the pressure gauge on the side of the heating system in thermal node building. As soon as the pressures in front of the valve and behind the valve (on the return pipeline) are equal, the spring is tensioned. It is pulled until all air is removed from the system, and water flows from the air collectors. After that, the air cocks are closed and the spring is further tensioned so that the pressure in front of the regulator is equal to the height of the system plus 3-5 m.

When starting heating systems in winter time in addition to the above operations, it is necessary to perform the following measures to prevent the freezing of the system:
1) the heating system should be filled separate sections(3-5 risers each) starting from the most remote areas from the input; filling and start-up of risers and stairwell devices can be carried out after filling and start-up of the main risers of the building's heating system;
2) risers and devices located in rooms that communicate with outside air (non-insulated rooms, rooms with missing window glazing, non-insulated passages, vestibules, etc.) must be turned off.

Heating systems with bottom wiring and horizontal one-pipe systems are filled with water from the supply pipeline of the heating network through both mains - direct and return. To do this, a jumper is arranged in the thermal input. When filling a horizontal single-pipe system, the riser and appliances of one floor are first filled with coolant, then the second, etc.

In a heating system with natural circulation, as a rule, fill all the risers of the system with water without dividing into parts. With sufficient pressure in the water supply, the heating system is filled with water from the water supply. If there is insufficient pressure, a pump is used to fill the system.
Regulation of the heating system. An important condition Satisfactory operation of the heating system is to achieve hydraulic balance. In an unbalanced system, individual heaters or circuits may be insufficiently supplied with coolant, while others receive it in excess.

After the heating system is put into operation, the consumption of thermal energy used for heating is determined. In case of non-compliance with the required values ​​​​of the heat load, the heating system is regulated.

The heating systems of buildings and structures are subject to adjustment in order to provide the design air temperatures of the premises. To do this, measure the temperature of the surfaces of heating devices using thermoelectric thermometers - temperature probes (thermocouples).

The regulation of heat transfer of heating systems can be carried out in two ways:
1) quality regulation, i.e. change in coolant temperature;
2) quantitative regulation, i.e. change in the amount of coolant.

Quality regulation systems central heating carried out centrally at the boiler house or at another source of heat; quantitative regulation - directly on the heating system of the building.

The regulation of the heating system of a building begins with the determination of the coolant flow rates for water meters and flow meters installed in heating point.
In the absence of control and measuring devices, the regulation of the heating system is based on checking the compliance of the actual water consumption with the calculated ones. In this case, the design flow is understood as the flow of water in the heating system, providing a given heat transfer (consumed thermal energy). The degree of compliance of the actual water flow with the calculated one is determined by the temperature difference of water in the system, while the actual water temperature in the heating network should not deviate from the calculated one by more than 2 °C.

If the difference is below the permissible level, then this indicates an overestimated water flow and, accordingly, an overestimated diameter of the orifice of the throttle diaphragm or nozzle at the inlet to the heating system. If the temperature difference is higher allowable value, then this indicates an underestimated water flow and, accordingly, an underestimated diameter of the throttle diaphragm or nozzle. In both cases, the new diameter of the elevator nozzle is determined.

If it is impossible to determine actual losses pressure in the system, the determination of the new diameter of the throttle or nozzle can be carried out using the calculated value of the pressure loss. If, after replacing the nozzle or throttle plate, the internal temperature of the heated rooms will differ by more than 2 °C compared to the calculated one, then it is necessary to change the diameter of the nozzle or throttle plate again. It should be noted that the regulation of building heating systems using washers is achieved only when the washers are calculated and installed at the inputs of all buildings connected to the heating network.

The internal air temperature in the premises of buildings is measured 3-4 hours after the heating system of the building is switched on, subject to the temperature curve of the water in the supply pipeline. The temperature is measured in at least 15% of heated rooms.

Due to the fact that heating systems are usually not controlled at the design outside temperature, but at comparatively high outside temperatures at the beginning heating season, misalignments occur in the heating system:
- vertical - determined by the discrepancy between the heat transfer of heating devices different floors required values;
- horizontal - is determined by an uneven change in heat transfer from heating devices of one floor.

Vertical misalignment of two-pipe water heating systems with a constant water flow occurs due to unequal changes in gravitational pressure in the heating devices of different floors when changing outdoor temperature. AT single pipe systems vertical misalignment occurs due to changes in water flow in the system. Reducing the flow leads to greater cooling of the water in the appliances of the upper floors; consequently, strongly chilled water will flow into the lower appliances, which will drastically reduce the heat transfer of the lower appliances. To increase the heat transfer of the lower appliances, you can increase the temperature of the network water, but this will lead to increased heat transfer of the upper appliances. In one-pipe systems with closing sections, the vertical misalignment is usually less than in one-pipe flow systems.

Horizontal misalignment of heating systems occurs due to cooling of water in main pipelines and risers. Exceeding the heat transfer through the pipes above the calculated values ​​leads to a decrease in the temperature of the water entering the individual risers. In the risers closest to the heat input, the water temperature will be higher than in the risers remote from the heat input.

Misadjustment of water heating systems is eliminated in the process of operational regulation of systems.

During the entire time of regulation, the temperature of the network water entering the heating system must be maintained constant.

Two-pipe heating systems are subjected to the greatest misalignment. Such systems must be regulated at water temperatures in the system that correspond to the average outdoor temperature of the heating period, adjusted for the temperature difference in appliances located on different floors: for appliances upper floors- 1.5-3°С above normal, for devices on lower floors - HS below normal.

The operational regulation of the systems is carried out according to the required temperature difference in the thermal input by changing the amount of water entering the system according to the above requirements, depending on the type of systems and the thermal input. Since the temperature difference is associated with water flow back proportional dependence, to increase the temperature difference to the required one, it is necessary to reduce the water flow by closing the valve at the inlet or, conversely, increase the flow at an increased temperature difference. The greater the flow of water through the heating devices, the greater the speed of its movement, and therefore, the water in the device will cool less, the average temperature in the device will increase, which will cause its increased heat transfer.
After completing the adjustment in the thermal unit, they begin to adjust the individual risers of the system. In dead-end systems, the adjustment is made by taps on the risers, throttle washers or balancing valves installed on the risers.

If there are only taps on the risers, then first a preliminary adjustment is carried out based on the rule: the closer the riser is located to the input, the more the tap should be covered so that the tap passes the minimum amount of water at the nearest riser; at the farthest riser, the valve must be fully open. After preliminary adjustment, the warming up of each riser is checked and the risers are sequentially adjusted, starting from the farthest and ending with the closest to the input.

If the risers are installed throttle washers, then the distribution of water along the risers is checked according to the calculated temperature difference for the heating system. Having finished setting up the risers, they begin to regulate the heat transfer of heating devices by measuring the temperature difference at the inlet and outlet of water from the device. When regulating the system using temperature probes, a deviation from the calculated value by ± 10% is allowed.

Balancing valves are pipeline throttling valves of variable hydraulic resistance, designed to ensure the calculated flow distribution over the elements of the pipeline network or to stabilize circulation pressures or temperatures in them. Currently, two types of balancing valves are used - manual and automatic.

Manual valves are used instead of throttling diaphragms (washers) to adjust the heating system, in which either there are no automatic control devices, or they do not allow limiting the limiting (calculated) flow rate of the transported medium. The manual balancing valve is a valve-type throttling device. Through manual balancing valves, you can not only regulate the system, but also turn off its individual elements, empty the system through special drain valves. Setting the valve to the required capacity is determined by the height of the spindle. Regulation with manual balancing valves is carried out in the same way as regulation with throttle washers.

Automatic balancing valves are used to 1 maintain a constant pressure difference between the supply and return pipelines of the system, to ensure a constant flow rate of the coolant or stabilize its temperature. Valves are installed on risers or horizontal branches of the heating system. If necessary, the balancing valve is equipped with additional devices that allow you to perform the following additional functions: shutdown of individual risers or branches of the system, measurement of differential pressure and determination of the flow rate of the heat carrier, draining the heat carrier and filling the system, venting air, pre-setting, regulation with an electric temperature sensor, regulation (control) of the pressure difference. The regulation of the automatic balancing valve is carried out in accordance with the operating instructions using an adjusting screw, which allows you to change the valve flow area and, accordingly, the coolant flow rate.

In two-pipe systems, due to the influence of pressure, as a rule, appliances on the upper floors overheat. If there is no overheating in the lower floors, then the heat transfer of the devices of the upper floors is reduced by reducing the cross section of the double adjustment valves. In the absence of such taps, throttle washers are installed in front of the devices, determining the diameter from the condition that the estimated water flow passes through them and assuming the pressure loss in the device is 0.05 m, or reduce the heating surface of the heating device. In case of overheating of devices in the upper floors and underheating in the lower ones, use the double adjustment valves to reduce the flow area on the upper floors and increase it on the lower ones. In the absence of valves on the return pipeline in the riser between overheated and underheated floors, it is allowed to install a throttle washer.

In case of overheating of the devices of the upper floors and underheating of the lower ones in single-pipe systems with closing sections, the following measures can be taken: install throttle washers in front of the devices of the upper floors; reduce the heating surface of devices; dismantle the closing sections at the devices of the lower floors (1st and 2nd) and, if necessary, increase the diameters of the connections.

With uniform underheating of the heating devices of the upper floors and simultaneous overheating of the devices of the lower floors, the mixing ratio of the elevator is reduced.

The water flow in the heating appliances of a single-pipe system is regulated by the difference in water temperature in the appliances.

If there are no taps on the risers, then with the help of taps on the devices it is possible to simultaneously redistribute the water flow both for individual risers and for individual devices. The degree of opening of valves during regulation increases as the devices move away from the thermal input.

In systems with top wiring in addition, the degree of opening of taps within the riser decreases with the movement of water from the upper floor to the lower one, and in systems with lower wiring it is the same.

In two-pipe heating systems, the uniformity of heating of devices increases with an increase in water flow in the system. For single-pipe heating systems, it is not recommended to significantly increase the water flow in the system compared to the calculated one, since this can lead to floor misalignment of the system.

The regulation of the dead-end system requires significant labor and time, as it is carried out in several stages, gradually bringing the heat transfer of the devices closer to the required one.

In a two-pipe system with upper wiring and associated water movement, where the length of all circulation rings is approximately the same, the difference in heating of the devices can only be caused by additional natural pressure (pressure) that occurs at the devices of the upper floors. To do this, when adjusting, the valves are covered at the devices of the upper floors, while the degree of valve cover for the devices of the same floor should be the same, since all risers are in equal conditions. After that, the heat transfer of the devices is finally regulated.

In systems with lower wiring and associated water movement, the additional natural pressure that occurs at the devices of the upper floors has little effect on the operation of the underlying devices due to the large length of the circulation ring. Therefore, in such systems, only slight irregularities in the heating of individual devices are possible, which are easily eliminated by regulation.

In vertical single-pipe systems with associated water movement, all heating devices and risers are in equal conditions, and the regulation of such systems is not difficult.

Operational regulation of heating systems with natural circulation is the simplest, since in such systems there are usually no completely unheated appliances.

Before starting the adjustment, the taps on all risers and appliances must be fully open. Irregularities in heating are eliminated by adjusting the taps.

The water temperature during commissioning should be maintained within 50-60°C.

At the end of the adjustment of the system, the temperature in the boilers of the local heating system is brought to 90 ° C and at this temperature the heating of the devices is checked again.

In operating conditions, no matter how well the operation of the heating system is adjusted, the actual air temperature in the premises may be different. A reliable indicator of the normal heat transfer of heating devices is the temperature of the coolant in the return risers. A low temperature indicates that the heating system does not receive the required amount of coolant from the heating network or its temperature is low.

Elevated temperature indicates an excess consumption of the coolant compared to the calculated value or the inflow of a coolant with a temperature above normal according to the temperature graph.

The operation of heating systems in residential buildings should ensure:

Maintaining the calculated (required by the standards) air temperature in heated rooms according to SNiP 2.08.01 - 89 * (Table 6.1);

tightness of the system;

Noise level in the aisles acceptable standards(30-35 dB).

Maintaining the design air temperature in the heated premises is ensured by regulating the parameters of the coolant: the temperature and pressure of the coolant at the inlet and outlet of the heating system, depending on the outside air temperature, the hydraulic characteristics of the heating system and the heating network.

The maximum operating pressure in the heating system must not exceed: when installing cast iron radiators- 0.6 MPa (6 kgf / sq. cm), with steel heaters - 1 MPa (10 kgf / sq. cm). The heating system must be airtight over the entire pressure range.

There are the following levels of regulation:

Central - in the source of heat supply;

Group - in the central heating station (for a group of buildings);

General house - ITP (for the entire building or facade);

Individual - on heating devices in the room.

AT modern systems heating are widely used various schemes automation of their work (for example, automation of heating systems with an elevator with an adjustable nozzle section; the same with a pump on the return pipeline; the same with a pump on the jumper). Design standards require the installation of devices for regulating, monitoring and accounting for heat consumption for each apartment, and for heating devices to install control valves (usually automatic temperature controllers).

To the main tasks Maintenance and repair of heating systems also include saving heat and ensuring the good condition of the elements of the system.

Maintenance of the heating system includes monitoring its operation and troubleshooting. At the beginning of the heating season, a system bypass schedule is drawn up, which includes following works:

Detailed inspection of distributing pipelines - at least once a month;

Detailed inspection of the most critical elements of the system (pumps, main shut-off valves, instrumentation, automatic devices) - at least once a week;

Removal of air and heating systems through an air collector or air outlet valves on heating appliances when the pressure on the supply pipeline drops below the level of the static pressure of this system, and also after its adjustment;

Control over the temperature and pressure of the coolant;

Replenishment of lubrication of pump bearings;

Flushing of mud collectors, the need for which is determined by the pressure drop on the pressure gauges before and after the mud collectors;

Inspection of in-house devices and devices in technical underground, lofts, stairwells- twice in heating period; during this inspection, the tenants of residential premises are explained the rules for energy saving and the facts of unauthorized conversion of elements of heating systems are established;

Restoration of damaged thermal insulation of pipelines and fittings located in unheated premises;

Checking the performance of gate valves and valves (their control devices are closed to failure, followed by opening to the previous position) - twice a month;

Inspection technical condition heating point equipped with means automatic regulation, and checking the maintenance of the specified parameters of the coolant - at least once a day, etc.

During inspections, all visible water leaks are immediately eliminated, and faulty shut-off or control valves are repaired or replaced. The shutdown time of the entire system or its individual sections when eliminating water leaks or other malfunctions is set depending on the outdoor temperature for up to 2 hours at the estimated outdoor air temperature. At a negative outside temperature, if the circulation of water in the heating system has stopped and the water temperature has dropped to + 5 degrees C, it is necessary to empty the heating system.

Malfunctions that do not significantly affect the operation of the heating and cannot be eliminated immediately are noted in defective statements, are included in the plan for current or major repairs and are eliminated in the summer in preparation for the next heating season.

The plan for the maintenance and overhaul of the heating system includes the actual repair and replacement individual elements systems with inspection of shut-off and control valves, as well as flushing, hydraulic testing, trial run and commissioning work. The schedules for carrying out these works are agreed with the heat supply organization conducting similar works on thermal networks and sources of heat supply.

During repairs, worn-out heating devices, pipelines, shut-off and control valves, air outlets and other equipment, thermal insulation are replaced in accordance with the project or recommendations of the commissioning organization.

During the repair of the system, the fastenings of all equipment are checked and restored, the required equipment slopes are ensured, pumps are cleaned and repaired, instrumentation is removed and handed over for inspection.

Removal of gate valves for internal inspection and repair (scraping of discs, checking the density of rings, pressure testing) is carried out at least once every three years; checking the tightness of the closure and changing the stuffing box seals of the control valves on the heating devices - at least once a year; replacement of sealing gaskets of flange connections - at least once every five years. Setup, cleaning and repair automatic regulators carried out according to the manufacturer's instructions.

After the completion of the repair, as well as the heating season for removal from inner surface pipelines of various deposits, dirt and scale from the system, it is flushed by hydraulic or hydropneumatic methods. Hydraulic flushing provides for the creation of speed tap water 3-5 times higher than the operational one. To do this, a fitting is installed at the lowest point of the system (washed area), through which water is discharged into the sewer through a hose. In some cases, network or circulation pumps. The use of water from compressed air(hydropneumatic flushing) is more efficient, because due to the high turbulence, the movements are better loosened and carried out of the sediment system. Applies also chemical method flushing, which consists in attaching a special installation to the system, having a container for a chemical solution capable of dissolving scale-corrosive deposits on the inner surface of pipelines and heating devices when circulating through a closed office.

The composition of the chemical solution is selected specifically according to the composition of deposits on cuttings taken from pipelines.

With an annual hydropneumatic flushing limited to flushing a group of two to five risers. After acceptance new system in service or after overhaul flushing is carried out in several stages: each riser is blown with compressed air from the bottom up, each riser and distributing pipelines are flushed. Flushing is carried out until the removed air-water mixture is completely clarified, after which the system must be filled network water(or water from the boiler room). Do not keep the heating system empty.

Hydraulic tests carried out after flushing the heating system. With their help, check the tightness of pipelines and connections. Before hydraulic tests, the tested heating point and the heating system are separated from the heating network with steel plugs at least 3 mm thick, installed after the inlet valves. Check the opening of all shut-off and control valves in the circuit of the system under test, including taps for heating appliances. The system is filled with water from the city water supply through the return pipeline of the heating point with open air valves, which are closed after the appearance of water in them. Heating systems with steel radiators(panel heaters, stamped steel radiators) should only be filled with heating water. If the pressure in the water supply is lower than the static pressure in the system, then the systems are filled with a pump. Then, a test pressure test of the system is carried out with a working pressure and the observed shortcomings are eliminated.

Hydraulic tests are carried out at a pressure equal to 1.25 of the operating pressure of the coolant. Basically, the pressure in the system is created due to the actual water pressure in the city water supply. In some cases, the pressure is provided by a hydraulic press. The heating system is considered to have passed the test if no visible water leakage is detected and the pressure drop on the control pressure gauge after five minutes does not exceed 0.02 MPa. Before the heating system is put into operation, it is emptied from tap water, which was pressure tested, and filled with purified water from the heating network.

A trial run of the heating system is carried out after its pressure testing and flushing, bringing the temperature of the coolant to 80-85 degrees C, while air is removed from the system and the heating of all heating devices is checked.

Adjustment of the heating system includes checking and adjusting the distribution of water along the risers and floors, in which temperature differences in the risers and temperatures on the piping and in the middle part of the devices in the premises are measured: when working in apartments, they also determine the air temperatures in the rooms and on the stairwells, relative humidity air in living rooms.

Adjustment is made using valves or taps installed on the risers and connections to the devices. In some cases, adjustment can only be made using throttle diaphragms.

Measures to eliminate noise penetrating into living quarters from operating equipment consist in regular replacement (once every three years) of soft inserts and vibration-isolating nose pads.

When performing maintenance and repair work on residential heating systems, it is recommended to keep the following documentation:

Logbook for registering the operation of the heating system, in which the readings of control and measuring instruments installed at the heating point are entered daily;

Passport of the heating system, which contains specifications systems, layouts of the main units and risers;

Instructions for starting, adjusting and emptying the heating system;

It turns out the order of maintenance of the system, the temperature regime in heated rooms, methods and methods for regulating heat transfer, means and procedure for communication with the dispatcher heat supply organization and emergency services;

Troubleshooting log.

To save the consumption of thermal energy, fuel and water, it is necessary to use means of automatic regulation and control over the operation of the heating system, maintain the design parameters of the temperature and pressure of the coolant in it, reduce heat loss in residential buildings through enclosing structures, to maintain thermal insulation pipelines are in good condition.

THEM. Saprykin, LLC PNTK "Energy Technologies", Nizhny Novgorod

The article proposes a method for determining the coolant flow through heating devices based on the results of measuring three temperatures: the coolant at the inlet and outlet; air temperature in the room. The method can be useful in the design and adjustment of heating systems for buildings and is more accurate than the existing method for practical calculations in off-design modes, especially at low temperature differences and low coolant flow rates.

Introduction

The quality of heat supply (heating) involves ensuring the calculated temperature of the indoor air in the heated room, regardless of fluctuations in outdoor air temperatures. For this, special temperature charts of central or local regulation have been developed.

Any newly installed or reconstructed heating system requires thermal and hydraulic adjustment.

One of the main tasks of setting up heat supply systems is the distribution of the heat carrier among consumers in proportion to their heat loads.

On the method of quality control of adjustment measures in heat supply systems

Earlier, a method was proposed for quality control of adjustment measures in heat supply systems, including a source of thermal energy, heating network and internal systems heating.

The method contains dimensionless indicators that allow monitoring the provision of heat loads and coolant flow rates, which can be obtained from the results of measuring two coolant temperatures before and after the heating system.

If for a separate heated room it is easy to determine qob by measuring the temperature of the indoor air, then for the building as a whole it is quite difficult.

However, information about qabout the building is contained in the "response" of the system - the value of the coolant temperature τ2 in the return pipeline at the outlet of the heating system. This temperature depends on a number of constant and variable parameters, the main of which are the outdoor air temperature tnr, the temperature of the coolant at the inlet to the system τλ, the total heating surface of heating devices F. Since temperatures are relatively easy to measure, information about qabout the building can be obtained, by measuring the actual temperatures of the coolant and the temperature of the outside air. Naturally, in this case, the calculated coolant temperatures and the calculated temperatures of the indoor and outdoor air must be known in advance.

The g parameter has constant value over the entire range of outdoor temperatures. The parameter g can be defined not only for separate system heating, but also for the heating system as a whole.

In well-established heat supply systems (with forced circulation of the coolant), non-observance of the temperature regime at the heat source will lead to a deviation of qrev from the norm qrev ≠ 1, while the coolant flow rate will remain normal g=1. When changing the hydraulic mode at the source, or in case of unauthorized change bandwidth narrowing device (for example, a throttle diaphragm), both parameters qob and g will change at the consumer. The latter circumstance can be revealed by the deviation of g from 1.

In equation (2) there is no value for the temperature of the indoor air, because for heating systems in general, this temperature is unknown. However, the temperature of the internal air averaged over the whole system is determined through qob: t B =t H +Δtp*q TeK * qo6

Based on the indicators qob, g it is possible to determine: the current actual heat consumption separate building; total flow rate of the coolant in the heating system; correction value of the narrowing device.

Using equations (2) and (3), it is quite easy to adjust and control heat supply modes.

This method has been successfully applied since 2001, first for adjustment and then for control of thermal and hydraulic modes in heat supply systems based on 18 hot water boiler houses in the city of Dzerzhinsk, Nizhny Novgorod region.

Adjustment of heating systems

One of the main tasks of adjusting the heating system is the distribution of the coolant along the risers and heaters in proportion to their thermal loads. In case of calculated heat losses through the external fences of the heated room, it is necessary to pass the calculated coolant flow rates through heaters with calculated heating surfaces.

It is not difficult to establish the estimated flow rates through heating devices or risers when setting up the heating system if the design temperature of the coolant is ensured at the system inlet in the supply pipeline. To do this, it is necessary to set the temperature of the coolant at the outlet, corresponding to the temperature graph, by changing the resistance of the throttle device.

If the temperature graph at the inlet is not provided, then it becomes unclear what temperature of the coolant to set at the outlet of the heater or stand.

In the stationary (time-invariant) state of the heating system, sufficiently reliable indicators of the flow distribution of the heat carrier over the heating devices and risers are the temperatures of the heat carrier at the inlet and outlet and the temperature of the indoor air of the room in which the this device(weighted average for the premises in which the riser passes). For a single radiator or heating riser, the influence of the indoor air temperature can be quite significant.

To determine the relative flow rate of the coolant through a separate heater, riser or branch of the heating system, depending on the actual temperatures of the coolant and the temperature of the indoor air, the following equation is proposed:

It follows from equation (4) that the flow rate of the coolant in the heating device (riser) with its known design parameters can be determined by measuring three temperatures: the coolant at the inlet and outlet of the device and the temperature of the indoor air in the room.

Knowledge of the actual coolant flow through the heating device (riser) opens up the possibility of choosing or purposefully correcting narrowing devices (throttle diaphragms, balancing valves, etc.).

For a practical determination of the actual flow rate of the coolant, it is convenient to use a pre-compiled table. 1 calculated by equation (4). Example: T1=43 °C, T2=34 0 C, tB=16 O C - relative flow rate g=0.77.

As the following example, the response to a change in the temperature regimes of heat supply of three heaters belonging to the same heating system is given. The installed heating surfaces of the devices are equal to the calculated f=1. Three temperature conditions: normal (temperature graph) τ1=τΓ; "undertop" τ^<τΓ; «перетоп» τ^>τΓ. Design temperatures: outside air tнр=-30 С; coolant in the supply pipeline τ1ρ=95 °C; in the return pipeline τ2ρ=70 OC. Current temperatures: outdoor air tn=-12 oC; coolant according to the temperature chart in the supply pipeline τ1g = 71.7 °C; in the return pipeline τ2g=55.7 °C.

As a result of measuring the temperatures of device No. 1, it was determined that the calculated flow rate of the coolant q»1 flows through the device. In the "non-heating" mode, when the temperature of the heat carrier at the inlet drops to τ1=60 ° C, the air temperature in the room will decrease to tw = 15.2 ° C, the temperature of the heat carrier at the outlet will decrease to τ2 = 47 ° C, while the "under heat" will be 15% (qrev=0.85). In the "overheating" mode, when the temperature of the heat carrier at the inlet rises to τ^δΟ OC, the air temperature in the room will increase to tb=23.5 °C, the temperature of the heat carrier at the outlet will increase to τ2=62 °C, while the "overheating" will be 11% (qob =1.11).

As a result of measuring the temperatures of devices No. 2, 3, it was determined that: an underestimated flow rate q»0.7 flows through device No. 2; an overestimated flow rate g≈1.42 flows through device No. 3.

The calculation results are summarized in table. 2.

Equation (4) is obtained as follows.

Based on the calculation temperature charts regulation of heat loads of heating systems, an empirical dependence of the heat transfer coefficient of the heater kav on the average temperature difference over the area of ​​the device is assumed: kcp=a-(tcp-tB)n, where a is a constant, depending on the design of the heater and the method of supplying the coolant.

The technique based on the use of tcp shows sufficient accuracy for practical calculations in cases where the coolant temperature is significantly higher than the temperature of the indoor air in the room. In off-design modes, especially at low temperature differences and low coolant flow rates, calculations using this method give overestimated results. The method proposed below in these ranges of modes gives more accurate results, which is essential during adjustment.

Boundary conditions for integrating equation (6): over the surface from 0 to R over temperatures from chl to τ2.

As a result of integration, an equation will be obtained that describes the dependence of the coolant flow rate on the heat exchange surface area and 3 temperatures: the coolant at the inlet and outlet of the device and the indoor air temperature in the room:

G=a-n-F/(c-[(T2-tB)-n-(x1-tB)-n]). (7)

The flow rate of the coolant relative to its calculated value - see equation (4).

Average integral temperature difference:

Q,=(^-T2)/\n[(T,-tB)/(T2-tB)]. (eight)

It can be seen from the last expression (8) that the temperature difference does not depend on the law of change in the heat transfer coefficient along the surface of the device, but depends only on the final temperatures.

Comparison of methods with different laws of formation of heat transfer coefficients, constant k=const and variable k=var along the heater, is given in Table. 3. According to the form of the table. 3 is similar to table. 2, only the cells give the cost ratio gk=const/gk=var.

From Table. 3 it follows that at costs significantly lower than the calculated values ​​g<1, что часто встречается при наладке, метод с постоянным коэффициентом теплопередачи k=const вдоль отопительного прибора дает завышенные результаты.

Table 3. Working table for determining the actual coolant flow rate by two methods (k=const, k=var).

findings

1. A method is proposed for determining the coolant flow through heating devices based on the results of measuring three temperatures: the coolant at the inlet and outlet; air temperature in the room.

2. The method can be useful in the design and commissioning of heating systems.

Literature

1. Saprykin I.M. Quality control method of adjustment in heat supply systems// News of heat supply. No. 1. 2004. S. 21-26.

2. Skanavi A.N. Design and calculation of water and air heating systems for buildings. - M.: Stroyizdat, 1983.

Before putting the heating system into operation, it is necessary to carry out a number of preparatory work, conduct tests and establish the interaction of various units with each other. All this is included in commissioning of the heating system, the purpose of which is to identify and eliminate shortcomings and errors made during installation, as well as bringing the entire system in line with the standards established for it. As a result of these works, the client receives a reliable, productive and efficient system. heating commissioning fully paid off by the subsequent trouble-free operation and safety of the equipment.

Composition of commissioning works

• Commissioning works are carried out after installation. They include:
• Connecting the boiler to the gas main (if a gas boiler is used);
• Setting up security systems;
• Installing a voltage stabilizer and connecting a boiler to it;
• Coordination of the operation of the boiler and indirect heating boiler (if applicable);
• Connection of temperature sensors and their adjustment;
• Test and pressure testing of heating systems;
• Filling the system with coolant;
• Bleeding air from the system and balancing it;
• system start-up;

Upon completion, a heating system commissioning report, which lists the scope of work performed and draws conclusions regarding the further operation and improvement of the equipment.

The essence of the system testing processes and its launch

As you can see, commissioning consists of a large number of operations, the most important of which are related to testing the heating system. Let us consider in more detail one of the important stages of commissioning - pressure testing of the system. It is necessary to perform it to identify all possible leaks. The essence of the procedure is to inject water or air into the system at a pressure several times higher than the working one. During crimping, all connections should be carefully checked. If air is used during the test, the pipe connections must be lubricated with soapy water.

Another stage of verification is a thermal test of the system. Its purpose is to warm up all heating devices with water at a temperature of 60-70 0C for 7 hours. At the same time, the degree of heating of heating devices, the temperature of the coolant at the outlet and inlet to the boiler, and the air temperature are monitored. If all indicators are as close as possible to the design ones, the system has successfully passed the thermal test. If not, then further adjustments are made. Before filling the system with water for testing, it must be flushed to remove equipment preservation agents and other debris from the pipes.

To start the system, it is necessary to fill it with coolant, bleed the air and put the boiler into operation. To fill the system with coolant, a make-up valve is opened, the location of which can be found in the documentation for the boiler equipment. When the pressure in the system reaches the desired value, the valve is closed and the boiler is started for the first time. After turning on the circulation pump, air should be bled from it by slightly unscrewing the screw in the center. When water flows from under the screw, it should be screwed up to the stop. After that, the electronics will start up all the boiler systems, and for some time air will be removed from the system, which will be reported by gurgling sounds. When the operation of the system returns to normal, check the pressure, and, if necessary, bring it to normal by replenishing the amount of coolant.

After the first start-up of the heating, you can adjust the system using the taps for adjusting the radiators. It is necessary to ensure that the energy of the coolant is enough to warm up the last radiator in the circuit. This adjustment can take several days and is done already during operation. You should not worry about this, because in general the system has already been debugged and is working normally.

Modern systems, as a rule, are equipped with highly efficient sources of heat or cold, expensive radiators or fan coil units, copper pipes, high-quality fittings, microprocessor control systems. Although heating and cooling systems are made up of the best components, problems are constantly being identified:

Insufficient or excessive heating;

Low cooling efficiency;

Uneven "warming up" of devices after a decrease in temperature;

Too large fluctuations in air temperature;

High fuel/electricity consumption;

Incorrect functioning of control valves (for example, proportional regulators operate in open-closed mode) and, in general, all automation;

Frequent occurrence of accidents or emergency conditions, etc.

The above problems cannot be blamed on the individual components, since their operating conditions are often not met and it is technically impossible to ensure their correct functioning. Three basic hydraulic conditions must be met for the entire system to work well:

1. Nominal flow must be ensured in all parts of the system

2. The differential pressure across the valves must not change significantly

3. The flow must be consistent at all nodal points in the system

The solution to these problems is simple - you need to balance the flow.

Is it necessary to balance the wheels of the car?

Strange question, you say. Obviously yes.

But why is hydraulic balancing (adjustment) of heating, ventilation, air conditioning and water supply systems still not considered necessary? After all, incorrect consumption of heat or coolant leads to incorrect air temperature in the premises, poor operation of automation, noise, rapid failure of pumps, boilers, pipes, uneconomical operation of the entire system.

It seems that the main reason lies in the underestimation of the importance of balancing hydraulics and simply in the absence of the necessary knowledge and experience.

It is often believed that it is enough to carry out a hydraulic calculation with the selection of pipes and, if necessary, washers, and the problem is solved. But it's not. Firstly, the calculation is approximate, and secondly, during installation, a lot of additional uncontrollable factors arise. It is believed that hydraulics can be linked by calculating the settings of thermostatic valves. This is also not the case, since the accuracy of such linkage will be low, up to ± 40% at low settings, the settings of thermostatic valves close to the pump will be small, which is fraught with the risk of clogging, the possibility of noise. Also, if for some reason not enough water flows through the riser, the thermostatic valves will simply open and the room temperature will be low. On the other hand, if the coolant is overused, there may be a situation when the vents and thermostatic valves are open. The foregoing does not at all detract from the need and importance of installing thermostatic valves on radiators, but only emphasizes that hydraulic balancing is also necessary for their good operation.

Balancing refers to the adjustment of hydraulics, so that each element of the system: radiator, heater, branch, shoulder, riser, line have project costs.

The tables show that the imbalance of water flow leads to significant deviations in the indoor air temperature from comfortable. With insufficient water flow, the air temperature in the room is lower than comfortable. To maintain the room temperature in the range of +/- 1 C, the flow must not differ by - 10% and + 15% from the nominal value, the return temperature must lie in the range of +/-1.5 C from the nominal value.

Moreover, if desired, the temperature can be reduced, for example, at night to 14-16 C for better sleep and to save energy. Savings are also achieved with the appearance of additional energy sources, such as the sun, electrical appliances, people, etc.

Independent performance of work on the hydraulic adjustment of the heating system in EnergoStroyTechService LLC is trusted only by masters who have mastered this responsible business to perfection. This is explained by the fact, first of all, that the company is striving in every possible way to strengthen its reputation as a reliable service provider in the market for servicing thermal equipment. In addition, the social significance of thermal facilities plays an important role. This will help to avoid accidents and waste of energy resources, and, accordingly, save money for the owners of the premises.

When concluding an agreement with EnergoStroyTechService, we carefully check the condition of your equipment, prepare a defective report if necessary, draw up a list of necessary work and agree with the client on a schedule for their implementation. With our specialists, you can be sure that the maintenance of the gas boiler house at home will be carried out at the highest professional level.

Professionally organized hydraulic adjustment is a guarantee of long and correct operation of the equipment, ensures high-quality and uninterrupted supply of heat and hot water to the premises.

Many people know about our work firsthand, and customer reviews are always positive. We regularly retrain our employees and improve their skills, teach them how to work with new equipment offered by world leaders in the production of heating installations. The flow charts for maintenance of boiler installations used by us in our work are developed taking into account the latest requirements and guarantee the most effective service technical support for fuel installations, both in houses and cottages, and at industrial facilities.

Flushing the heating system is the process of flushing the pipes and pipelines of the heating system by various methods, with the aim of ridding the inner walls of the heating system of scale formed during operation, consisting of salts of calcium, magnesium, sodium and other non-metals, various organic and inorganic products.

Usually in the composition of deposits on the walls of pipes are found:

• iron oxide (II) from 15 to 35%;
• oxides of magnesium and calcium from 35 to 65%;
• oxides of copper and zinc from 2 to 6%;
• trivalent sulfur oxide from 2.5 to 4%.

As a rule, flushing of heating pipelines is required for any heating system that has worked without flushing for more than 5-10 years. Practice shows that during this time the efficiency of the heating system is significantly reduced; most of the diameter of the heating system pipe is clogged with deposits, which can lead to various accidents in the heating system, as well as to a decrease in the quality of heat supply and hot water supply.

The procedure for hydropneumatic flushing and pressure testing of the heating system in residential buildings

After the end of the heating season, all heating system equipment must be flushed and tested with hydraulic pressure in accordance with SNiP 3.05.01-85 "Internal sanitary systems", SNiP 3.05.03-85 "Heat networks". Tests of the heating system must be carried out according to the technological schemes in compliance with the safety precautions for the work.

Before hydraulic testing, the heating system is flushed.
Flushing of heating systems during the preparation of houses for winter should be carried out in a hydropneumatic way. Flushing with domestic and drinking water is allowed.
For hydropneumatic flushing of the heating system, an air compressor is used with a connection to a cold water supply system.
Diaphragms and nozzles of hydraulic elevators must be removed during flushing of the heating system. The water pressure in the pipelines during flushing should not be higher than the working one, and the air pressure should not exceed 0.6 MPa (6 kgf / cm²). Water velocities must exceed the calculated coolant velocities by at least 0.5 m / s.
Hydropneumatic flushing is carried out until the flushing water at the outlet of the heating system drains is completely clarified.
After flushing, the system must immediately be filled with coolant or water; it is not allowed to keep the heating system empty.
A hydraulic test should be carried out after flushing the heating system. Hydraulic tests of the equipment of heat points and heating systems should be carried out separately.
Thermal points and heating systems should be tested at least once a year, with a test pressure equal to 1.25 working pressure at the heating network inlet, but not less than 0.2 MPa (2 kgf / cm 2).

For heating systems with cast-iron heaters, steel stamped radiators, 0.6 MPa (6 kgf / cm²) should be taken, panel and convector heating systems - 1.0 MPa (10 kgf / cm 2).
Piping tests should be carried out in compliance with the following basic requirements:

• test pressure must be provided at the top point (mark) of the pipelines; the water temperature during testing should not be higher than 45 ° C, air is completely removed through air vents at the highest points;
• the pressure is brought to the operating pressure and maintained for the time necessary to inspect all welded and flanged joints, fittings, equipment, instruments, but not less than 10 minutes;
• if no defects are detected within 10 minutes, the pressure is brought to the test pressure.

The pressure must be maintained for 15 minutes and then reduced to working pressure. The pressure drop is recorded on the control pressure gauge.
The results of hydraulic tests for the tightness of the pipeline are considered satisfactory if: during their conduct, there was no pressure drop of more than 0.01 MPa (0.1 kgf / cm 2), no signs of rupture, leakage or fogging in the welds, as well as leaks were found in the base metal, flange connections, fittings, compensators and other pipeline elements, there are no signs of shear or deformation of pipelines and fixed supports.
The defects identified during the tests must be eliminated, after which the equipment is tested again. The test results are documented in an act.
After the hydraulic test, the system must immediately be filled with coolant or water.
When testing for strength and density, spring pressure gauges of an accuracy class of at least 1.5 are used with a body diameter of at least 160 mm, a scale for a nominal pressure of about 4/3 of the measured pressure, a division value of 0.01 MPa (0.1 kgf / cm 2), verified and sealed by the state trustee.