A thermal unit is a set of devices and instruments that record energy, volume (mass) of coolant, as well as register and control its parameters. The metering unit is structurally a set of modules (elements) connected to the pipeline system.

Purpose

A thermal energy metering unit is being organized for the following purposes:

• Controlling the rational use of coolant and thermal energy.
• Control of thermal and hydraulic modes heat consumption and heat supply systems.
• Documentation of coolant parameters: pressure, temperature and volume (mass).
• Carrying out mutual financial settlements between the consumer and the organization engaged in the supply of thermal energy.

Essential elements

The thermal unit consists of a set of devices and metering devices that provide the performance of one or several functions at the same time: storage, accumulation, measurement, display of information about mass (volume), amount of thermal energy, pressure, temperature of the circulating fluid, as well as operating time .

As a rule, a heat meter is used as a metering device, which includes a resistance thermal converter, a heat calculator and a primary flow converter. Additionally, the heat meter can be equipped with filters and pressure sensors (depending on the model of the primary converter). Heat meters can use primary transducers with the following measurement options: vortex, ultrasonic, electromagnetic and tachometer.

Metering unit device

The thermal energy metering unit consists of the following main elements:

• Shut-off valves.
• Heat meter.
• Thermal converter.
• Sump.
• Flow meter.
• Return temperature sensor.
• Optional equipment.

Heat meter

The heat meter is the main element of which the thermal energy unit should consist. It is installed at the heat input into the heating system in close proximity to the balance sheet boundary of the heating network.

When installed remotely from this boundary, in addition to the meter readings, losses are added (to take into account the heat that is released by the surface of the pipelines in the area from the balance separation boundary to the heat meter).

Heat meter functions

Any type of device must perform the following tasks:

1. Automatic measurement:

• Duration of work in the error zone.
• Operating time with supply voltage applied.
• Excessive pressure of liquid circulating in the pipeline system.
• Water temperatures in pipelines of hot, cold water supply and heat supply systems.
• Coolant flow in pipelines and heat supply.

2. Calculation:

• The amount of heat consumed.
• The volume of coolant flowing through the pipelines.
• Thermal power consumption.
• Differences in the temperature of the circulating fluid in the supply and return pipelines (cold water supply pipeline).

Shut-off valves and sump

Shut-off devices cut off the heating system of the house from the heating network. At the same time, the mudguard protects the elements of the heat meter and the heating network from dirt that is present in the coolant.

Thermal converter

This device is installed after the mud trap and shut-off valves in an oil-filled sleeve. The sleeve is either fixed to the pipeline using a threaded connection or welded into it.

Flow meter

The flow meter installed in the thermal unit performs the function of a flow converter. It is recommended to install special valves in the measurement area (before and after the flow meter), which will simplify service and repair work.

Having entered the supply pipeline, the coolant is directed to the flow meter, and then goes into the heating system of the house. Next, the cooled liquid is returned in the opposite direction through the pipeline.

Thermal sensor

This device is mounted on the return pipeline together with shut-off valves and a flow meter. This arrangement allows not only to measure the temperature of the circulating fluid, but also its flow rate at the inlet and outlet.

Flow meters and temperature sensors are connected to heat meters, which allow calculation of consumed heat, storage and archiving of data, registration of parameters, as well as their visual display.

As a rule, the heat meter is located in a separate cabinet with free access. In addition, the cabinet can be installed additional elements: source uninterruptible power supply or modem. Additional devices allow you to process and control data that is transmitted by the metering unit remotely.

Basic diagrams of heating systems

So, before considering the diagrams of thermal units, it is necessary to consider what types of heating system diagrams there are. Among them, the most popular is the top distribution design, in which the coolant flows through the main riser and is directed into the main pipeline of the top distribution. In most cases, the main riser is located in the attic, from where it branches into secondary risers and is then distributed throughout heating elements. It is advisable to use a similar scheme in one-story buildings in order to save free space.

There are also diagrams of heating systems with bottom wiring. In this case, the heating unit is located in the basement, from where it comes out warm water. It is worth noting that, regardless of the type of circuit, it is recommended to also place an expansion tank in the attic of the building.

Diagrams of thermal units

If we talk about the schemes of heating points, it should be noted that the most common types are the following:

• Thermal unit - a circuit with a parallel single-stage hot water connection. This scheme is the most common and simple. In this case, the hot water supply is connected in parallel to the same network as the heating system of the building. The coolant is supplied to the heater from external network, then cooled liquid into reverse order flows directly into the heat pipe. The main disadvantage of such a system, compared to other types, is the high consumption network water, which is used to organize hot water supply.

• Scheme heating point with consistent two-stage connection hot water. This scheme can be divided into two stages. The first stage is responsible for the return pipeline heating system, the second - for the supply pipeline. The main advantage of thermal units connected according to this scheme is the absence of a special supply of network water, which significantly reduces its consumption. As for the disadvantages - this is the need to install the system automatic regulation for setting and adjusting heat distribution. This connection is recommended to be used in the case of a relationship maximum flow heat for heating and hot water supply, ranging from 0.2 to 1.

• Thermal unit - a diagram with a mixed two-stage connection of a hot water heater. This is the most universal and flexible connection scheme. It can be used not only for normal temperature chart, but also for increased. Basic distinctive feature It is worth mentioning the point that the connection of the heat exchanger to the supply pipeline is carried out not in parallel, but in series. The further principle of the structure is similar to the second scheme of the heating point. Thermal units connected according to the third scheme require additional consumption of network water for the heating element.

The procedure for installing the metering unit

Before installing a thermal energy metering unit, it is important to conduct a site survey and develop design documentation. Specialists who design heating systems make all the necessary calculations, select instrumentation, equipment and a suitable heat meter.

After documentation, it is necessary to obtain approval from the organization that supplies thermal energy. This is required by the current thermal energy accounting rules and design standards.

Only after approval can you safely install thermal metering units. Installation consists of inserting shut-off devices, modules into pipelines and electrical installation work. Electrical installation work is completed by connecting sensors and flow meters to the computer and then starting the computer to record heat energy.

After this, thermal energy accounting is carried out, which consists of checking the operability of the system and programming the computer, and then the object is handed over to the approving parties for commercial accounting, which is carried out by a special commission represented by the heat supply company. It is worth noting that such an accounting unit must function for some time, which for different organizations ranges from 72 hours to 7 days.

To combine several metering nodes into a single dispatch network, it will be necessary to organize remote recording and monitoring of metering information from heat meters.

Permission to operate

Upon admission thermal unit Before operation, the compliance of the serial number of the metering device, which is indicated in its passport, and the measurement range of the established parameters of the heat meter with the range of measured readings, as well as the presence of seals and the quality of installation are checked.

Operation of the heating unit is prohibited in the following situations:

• Presence of tie-ins in pipelines that are not provided for project documentation.
• The operation of the meter is outside the accuracy standards.
• Presence of mechanical damage to the device and its elements.
• Broken seals on the device.
• Unauthorized interference with the operation of a heating unit.

To meet the heating needs of residents of high-rise buildings, they are well suited centralized systems heat supply. District heating involves the transfer of heated coolant from the boiler room through a network connected to a multi-story building insulated pipes. Centralized boiler houses have sufficient efficiency and make it possible to combine low operating costs and acceptable heat supply efficiency indicators multi-storey buildings.

But in order for efficiency district heating was at the proper level, the heating circuit was in apartment building compiled by professionals in their field - heating engineers. The fundamental principles by which a home heating scheme is designed are to achieve maximum efficiency heating with minimal resource consumption.

Contractors and builders are interested in providing apartment owners with a reliable and efficient heating system, so the heating scheme multi-storey building is developed taking into account the current cost of heat resources, the thermal output of heating devices, their energy efficiency and the optimal sequence of connection to the circuit.

Any heating scheme apartment building is radically different from the method and sequence of connecting heating appliances in private homes. It has a more complex structure and guarantees that even in severe frosts, residents of apartments on all floors will be provided with heat and will not encounter such troubles as airy radiators, cold spots, leaks, water hammer and frozen walls.

A well-designed heating system for an apartment building, the scheme for which is developed individually, guarantees that optimal conditions will be maintained inside the apartments.

In particular, the temperature in winter will be at 20-22 degrees, and the relative humidity will be about 40%. To achieve such indicators, it is important not only the basic heating scheme, but also high-quality insulation of apartments, which prevents heat from escaping into the street through cracks in the walls, roof and window openings.

Scheme development

On initial stage Heating engineers work on the development of a heating scheme, carry out a series of calculations and achieve the same efficiency indicators of the heating system on all floors of the building. They draw up an axonometric diagram of the heating system, which is subsequently used by installers. Calculations carried out correctly by specialists guarantee that the designed heating system will be characterized by optimal pressure coolant that will not lead to water hammer and operational interruptions.

Inclusion of an elevator unit in the heating scheme

The central heating scheme for an apartment building, prepared by heating engineers, assumes that the radiators located in the apartment will receive coolant at an acceptable temperature. However, at the exit from the boiler room, the water temperature can exceed 100 degrees. To achieve coolant cooling by mixing cold water, the return and supply lines are connected by an elevator unit.

A reasonable heating elevator design allows the unit to perform a number of functions. The main function of the unit is direct participation in the heat exchange process, since hot coolant, entering it, is dosed and mixed with the injected coolant from the return. As a result, the unit allows you to achieve optimal results in matters of mixing hot coolant from the boiler room and cooled water from the return. After this, the prepared coolant optimal temperature delivered to apartments.

Design features of the circuit

An effective heating system in an apartment building, the design of which requires competent calculations, also implies the use of many other structural elements. Right after elevator unit Special valves are integrated into the heating system to regulate the flow of coolant. They help control the heating process of the entire house and individual entrances, but only employees of service utility companies have access to these devices.

In the heating circuit, in addition to thermal valves, more sensitive devices are used to regulate and adjust the heating.

We are talking about devices that increase the performance of the heating system and allow for maximum automation of the home heating process. These are devices such as collectors, thermostats, automation, heat meters, etc.

Pipeline layout

While heating engineers are discussing optimal scheme heating a house with central heating, the issue of proper piping in the house is raised. In modern multi-storey buildings The heating wiring diagram can be implemented according to one of two possible patterns.

Single pipe connection

The first template provides for a single-pipe connection with upper or lower wiring and is the most used option when equipping heating appliances in multi-storey buildings. At the same time, the location of the return and supply is not strictly regulated and may vary depending on external conditions– the region in which the house was built, its layout, number of floors and design. The direct direction of movement of the coolant along the risers can also change. There is an option for the heated water to move in the direction from bottom to top or from top to bottom.

It is distinguished by simple installation, affordable cost, reliability and long service life, but it also has a number of shortcomings. Among them are the loss of coolant temperature while moving along the circuit and low efficiency indicators.

In practice, various devices can be used to compensate for the disadvantages that characterize a single-pipe heating scheme beam system it may become effective solution Problems. It is designed to use a collector that helps regulate temperature conditions.

Two-pipe connection

A two-pipe connection is the second version of the template. A two-pipe heating scheme for a five-story building (as an example) is devoid of the disadvantages described above and has a completely different design than a single-pipe one. When implementing this scheme, the heated water from the radiator does not move to the next heating device in the circuit, but immediately enters check valve and goes to the boiler room for heating. Thus, it is possible to avoid loss of temperature of the coolant circulating along the contour of a multi-story building.

The complexity of the connection, which heating radiators in an apartment require, makes the implementation of this type of heating a long and labor-intensive process, requiring large material and physical costs. Maintenance of the system is also not cheap, but the high cost is offset by high-quality and uniform heating of the house on all floors.

Among the advantages provided by the two-pipe scheme for connecting heating batteries, it is worth highlighting the possibility of installation on each radiator in the circuit special device– heat meter. It allows you to control the temperature of the coolant in the battery, and by using it in the apartment, the owner will achieve significant results in terms of saving money on payments utilities, because he will be able to independently regulate the heating if necessary.

Connecting radiators to the system

After the pipe routing method has been chosen, heating batteries are connected to the circuit; the circuit also regulates the connection order and the type of radiators used. At this stage, the heating scheme for a three-story building will not differ radically from the heating scheme for a high-rise building.

Since the central heating system is characterized by stable operation, versatility and has an acceptable ratio of temperature and pressure of the coolant, the connection diagram for heating radiators in an apartment may involve the use of batteries made of various metals. In multi-storey buildings, cast iron, bimetallic, aluminum and steel can be used, which will complement the central heating system and provide apartment owners with the opportunity to live in comfortable temperature conditions.

The final stage of work

At the last stage, the radiators are connected, and their internal diameter and volume of sections are calculated taking into account the type of supply and cooling rate of the coolant. Because the central heating represents complex system interconnected components, it is quite difficult to replace radiators or repair jumpers in a particular apartment, because dismantling any element can cause interruptions in the heating supply of the entire house.

Therefore, apartment owners who use central heating for heating are not recommended to independently carry out any manipulations with radiators and the piping system, since the slightest intervention can turn into a serious problem.

In general, a well-designed, efficient heating scheme for a residential apartment building allows one to achieve good performance in matters of heat supply and heating.

Residents of city apartments are usually not interested in how the heating works in their home. The need for such knowledge may arise when the owners want to increase the comfort in the house or improve the aesthetic appearance of engineering equipment. For those who are planning to start a renovation, we will briefly tell you about the heating systems of an apartment building.

Types of heating systems for apartment buildings

Depending on the structure, characteristics of the coolant and piping layouts, heating of an apartment building is divided into the following types:

By location of the heat source

• Apartment system heating, in which a gas boiler is installed in the kitchen or separate room. Some inconveniences and investments in equipment are more than compensated by the ability to turn on and regulate heating at your discretion, as well as low operating costs due to the absence of losses in heating mains. If you have your own boiler, there are practically no restrictions on system reconstruction. If, for example, the owners wish to replace the batteries with warm water floors, there are no technical obstacles to this.
• Individual heating, in which one house or residential complex has its own boiler room. Such solutions are found both in the old housing stock (stokers) and in new luxury housing, where the community of residents decides for itself when to start heating season.
• Central heating in an apartment building it is most common in standard housing.

The installation of central heating in an apartment building, heat transfer from the thermal power plant is carried out through a local heating point.

According to coolant characteristics

• Water heating, water is used as a coolant. In modern housing with apartment or individual heating, there are economical low-temperature (low-potential) systems where the coolant temperature does not exceed 65 ºС. But in most cases and in all standard houses the coolant has design temperature within 85-105 ºС.
• Steam heating apartments in an apartment building (water vapor circulates in the system) has a number significant shortcomings, has not been used in new houses for a long time; old housing stock is being transferred to water systems everywhere.

According to the wiring diagram

Basic heating schemes in apartment buildings:

• Single-pipe - both the supply and return of coolant to the heating devices are carried out through one line. Such a system is found in “Stalin” and “Khrushchev” buildings. It has a serious drawback: the radiators are located in series and, due to the cooling of the coolant in them, the heating temperature of the batteries drops as they move away from the heating station. In order to maintain heat transfer, the number of sections increases as the coolant moves. In a pure one-pipe circuit, it is impossible to install control devices. It is not recommended to change the configuration of the pipes or install radiators of a different type and size, otherwise the operation of the system may be seriously disrupted.
• “Leningradka” is an improved version of the single-pipe system, which, thanks to the connection of heating devices via a bypass, reduces their mutual influence. You can install regulating (not automatic) devices on radiators, or replace the radiator with a different type, but of similar capacity and power.

• The two-pipe heating scheme for an apartment building became widely used in Brezhnevkas and is still popular to this day. The supply and return lines are separated, so the coolant at the entrances to all apartments and radiators has almost the same temperature; replacing radiators with a different type and even volume does not have a significant effect on the operation of other devices. Control devices, including automatic ones, can be installed on batteries.

On the left is an improved version of the single-pipe circuit (analogous to the Leningrad circuit), on the right is the two-pipe version. The latter provides more comfortable conditions, precise regulation and provides greater opportunities for replacing the radiator

• The beam scheme is used in modern atypical housing. The devices are connected in parallel, their mutual influence is minimal. The wiring is usually done in the floor, which allows you to free the walls from pipes. When installing control devices, including automatic ones, accurate dosing of the amount of heat throughout the rooms is ensured. It is technically possible to have both partial and complete replacement heating systems in an apartment building with a radial circuit within the apartment with a significant change in its configuration.

With a radial scheme, the supply and return lines enter the apartment, and the wiring is carried out in parallel with separate circuits through the collector. Pipes are usually placed in the floor, radiators are neatly and discreetly connected from below

Replacement, relocation and selection of radiators in an apartment building

Let’s make a reservation that any changes to apartment heating in an apartment building must be agreed upon with executive bodies and operating organizations.

We have already mentioned that the fundamental possibility of replacing and moving radiators is determined by the circuit. How to choose the right radiator for an apartment building? Please note the following:

• First of all, the radiator must withstand pressure, which is higher in an apartment building than in a private one. The greater the number of floors, the higher the test pressure can be, it can reach 10 atm, and in high-rise buildings even 15 atm. The exact value can be obtained from your local operating service. Not all radiators sold on the market have the appropriate characteristics. A significant part of aluminum and many steel radiators are not suitable for an apartment building.
• Is it possible and how much to change? thermal power radiator, depends on the circuit used. But in any case, the heat transfer of the device must be calculated. One typical section of a cast iron battery has a heat transfer of 0.16 kW at a coolant temperature of 85 ºС. Multiplying the number of sections by this value, we obtain the thermal power of the existing battery. Characteristics of the new heating device can be found in its technical data sheet. Panel radiators are not assembled from sections and have fixed dimensions and power.

Averaged heat transfer data various types radiators may vary depending on the specific model

• The material also matters. Central heating in an apartment building is often characterized by low quality coolant. Traditional ones are the least sensitive to contamination. cast iron batteries, aluminum react the worst to aggressive environments. Bimetallic radiators performed well.

Installation of a heat meter

A heat meter can be installed without problems using a radial wiring diagram in an apartment. As a rule, in modern houses There are already metering devices. As for the existing housing stock with standard systems heating, this possibility is not always available. This depends on the specific piping layout and configuration; advice can be obtained from your local operating organization.

An apartment heat meter can be installed with a radial and two-pipe wiring diagram, if there is a separate branch to the apartment

If it is not possible to install a meter throughout the entire apartment, you can place compact heat meters on each of the radiators.

An alternative to an apartment meter is heat metering devices placed directly on each radiator

Please note that the installation of metering devices, replacement of radiators, and other changes to the heating system in an apartment building require prior approval and must be carried out by specialists representing an organization licensed to carry out the relevant work.

Video: how to supply heating in an apartment building

The design of heating systems in multi-story, multi-apartment buildings is carried out by special design organizations, which in their project work are guided by such regulatory documents, such as GOSTs, OST, TU, SNIPs and sanitary standards.

According to the requirements of some of them, the temperature in residential premises should be stable within twenty to twenty-two degrees Celsius. And the relative air humidity is 40-30%. Only if such parameters are observed can comfortable living conditions for people be ensured.

The design and adjustment is based on the choice of coolant, which is determined by a number of factors, including availability and the ability to connect to it the heating system of the housing construction in the area where the facility is located.

Types of adjustment of heating systems

Adjustment of the heating system of an apartment building can be carried out by using pipes of different diameters in the system. As is known, the flow rate and pressure of liquid and steam in a pipeline depend on the diameter of the pipe opening. This allows you to regulate the pressure in the system by combining pipes with different diameters with each other.

Pipes with a diameter of 100 mm are usually placed at the entrance to basements houses.

This is the maximum pipe diameter used in the heating system. In the entrances, pipes with a diameter of 76-50 mm are used for heat distribution. The choice depends on the size of the building. Installation of risers is made from pipes with a diameter of 20 mm. The end caps of the “beds” are closed with ball valves with a diameter of 32 mm, which are usually installed at a distance of 30 cm from the outer riser.

However, such a building does not allow effective equalization of flexible pressure in the system. Thus, the temperature in the living quarters of the upper floors decreases noticeably. Therefore it is used hydraulic system heating system, which includes circulation vacuum pumps and automatic systems pressure regulation.

They are installed in the collector of each building. At the same time, the layout of the coolant distribution along the entrances and floors changes.

When the number of floors in a building is higher than two floors, the use of a system with pumping for water circulation is mandatory. Heating system adjustment apartment buildings carried out most often vertical systems water heating, which are called single-pipe.

Disadvantages of a one-pipe system

The disadvantages include the fact that with such a system it is impossible to take into account the heat consumption in each apartment. And, therefore, make an individual calculation of payment for the actual consumption of thermal energy. In addition, with such a system it is difficult to maintain the same air temperature in all living areas of the building.

That is why other apartment heating systems are used, which are designed differently and provide thermal energy in each apartment.

Currently, there are various apartment heating systems. However, for now they are settling in multi-storey buildings rarely. This is due to a number of reasons. In particular, due to the fact that such systems have low hydraulic and thermal stability.

Most often, in multi-storey residential buildings, so-called central heating is used.

The coolant for such heating is supplied to the housing construction from the city thermal power plant.

In recent years, in the construction of new residential buildings, it has been used heating system. With this method individual heating, the boiler room is installed directly in the basement or attic high-rise buildings. In turn, heating systems are divided into open and closed. The first provide for the division of hot water supply for residents for heating and other needs, and in the other - only for heating.

Requirements for adjusting the heating system

Requirements for heating systems are determined by design documentation. The heating system of an apartment building is adjusted in accordance with the parameters defined by this documentation. It is not particularly complex. Heating systems are equipped with thermostats on radiators, as well as heat meters, balancing valves for both automatic and manual control.

Adjustment does not require the use of special tools.

Produced directly by residents. All other adjustments are made by system maintenance personnel.

When new Vacation home has already been built and all the necessary communications, in particular the pipeline system, are connected, it is still too early to talk about the building’s full readiness for operation....

If air accumulates in the heating system, it can become an obstacle to its normal operation. This problem most often occurs among residents of apartments and houses...

The heating point of a heating system is the place where the hot water supplier's main line is connected to the heating system of a residential building, and the consumed thermal energy is also calculated.

The nodes connecting the system to a source of thermal energy are of two types:

1. Single-circuit;
2. Dual-circuit.

A single-circuit heating point is the most common type of consumer connection to a source of thermal energy. In this case, a direct connection to the hot water supply line is used for the heating system of the house.

A single-circuit heating point has one characteristic detail - its design includes a pipeline connecting the direct and return lines, which is called an elevator. The purpose of the elevator in the heating system is worth considering in more detail.

Boiler heating systems have three standard operating modes, differing in coolant temperature (direct/return):

• 150/70;
• 130/70;
• 90–95/70.

The use of superheated steam as a coolant for the heating system of a residential building is not permitted. Therefore, if due to weather conditions the boiler room supplies hot water temperature of 150 °C, it must be cooled before being supplied to the heating risers of a residential building. For this purpose, an elevator is used, through which the “return” enters the direct line.

The elevator opens manually or electrically (automatically). Its main line may include an additional circulation pump, but usually this device is made of a special shape - with a section of sharp narrowing of the highway, after which there is a cone-shaped expansion. Due to this, it works like an injection pump, pumping water from the return line.

Double-circuit heating point

In this case, the coolants of the two circuits of the system do not mix. To transfer heat from one circuit to another, a heat exchanger, usually a plate one, is used. The diagram of a double-circuit heating point is shown below.

A plate heat exchanger is a device consisting of a number of hollow plates, through some of which the heating liquid is pumped, and through the others - the heated liquid. They have a very high ratio useful action, they are reliable and unpretentious. The amount of heat removed is regulated by changing the number of plates interacting with each other, so taking cooled water from the return line is not required.

How to equip a heating point

H2_2

The numbers here indicate the following nodes and elements:

• 1 - three-way valve;
• 2 - valve;
• 3 - plug valve;
• 4, 12 - mud collectors;
• 5 - check valve;
• 6 - throttle washer;
• 7 - V-fitting for thermometer;
• 8 - thermometer;
• 9 - pressure gauge;
• 10 - elevator;
• 11 - heat meter;
• 13 - water meter;
• 14 - water flow regulator;
• 15 - sub-steam regulator;
• 16 - valves;
• 17 - bypass line.

Installation of heat metering devices

Thermal metering equipment includes:

• Thermal sensors (installed in the forward and return lines);
• Flow meters;
• Heat calculator.

Heat metering devices are installed as close as possible to the departmental border so that the supplier company does not calculate heat loss using incorrect methods. It is best that thermal units and flow meters have gate valves or valves at their inputs and outputs, then their repair and maintenance will not cause difficulties.

Advice! There must be a section of the pipeline in front of the flow meter without changing the diameters, additional inserts and devices to reduce flow turbulence. This will increase the measurement accuracy and simplify the operation of the unit.

The thermal computer, which receives data from temperature sensors and flow meters, is installed in a separate locked cabinet. Modern models These devices are equipped with modems and can connect via Wi-Fi and Bluetooth to a local network, providing the opportunity to receive data remotely, without a personal visit to heat metering centers.