Today it is impossible to imagine a comfortable apartment nice house no hot water. High-quality organization of a hot water supply system is necessary both for domestic needs and for compliance with hygiene measures. Evening relaxing bath or morning warm shower have become habitual daily procedures for many residents.

However, few people understand and understand how hot water supply is organized. To understand this issue, it is necessary to consider the important requirements when creating a system design and methods for monitoring its condition. To do this, you need to understand the main principles of the functioning of hot water supply.

Video: Hot water supply with recirculation

The most popular method of obtaining hot water today is the use of a heating network system. There are two types of heat generation – closed and open. Before the consumer hot water supplied through a dead-end and circular pipeline.

Methods for obtaining hot water

Heated water can be obtained from a centralized mains or an individual source. According to the first method, hot water is supplied to residential premises and organizations through a central pipeline, and when in an individual way personal water heaters are used for a separate apartment, country house or entrance.

The source of heat for heating water in the main is boiler houses or thermal stations. In this way, a large volume of water can be driven through. The central highway is used for supply multi-storey buildings, and even microdistricts. According to the method of obtaining heat in a centralized way, systems are divided into:

• open;
• closed.

The main task DHW systems is the provision hot water with the required temperature parameter for industrial and residential premises. In this case, it is necessary to take into account the quality of the water, its pressure parameters and the method of heating to the required value. Depending on the heating method, the DHW system is divided into two types:

1. Central system. Water is heated at substations and then supplied through pipes to the consumer.
2. Standalone or local. To heat to the required value, special heating devices- boilers, geysers, storage or flow boilers. This type of creation of a hot water supply system is used for small spaces - a house or apartment.

Let's look at these systems in more detail to understand how they differ and how they function.

Open system

You can often see on city streets big pipes, insulated with special material, and components heating network. Hot water passes through them, which received heat at the thermal station. Water comes to residential buildings and other objects from such a large pipeline through a substation and forms a branch. Through it, water flows into heating system and heating radiators installed in residential premises.

In an open system, heated water enters the kitchen faucet or bathroom from the same place as the heating radiator. The temperature in the line can vary from +50 to +75 degrees. But in the central pipeline it is most often much higher. Therefore it can be mixed with cold water. This possibility is not always available for technical reasons, so winter period The temperature of the water in the kitchen faucet reaches its limit.

The open method is the simplest, since no auxiliary heating devices are required. To comply sanitary rules for hot water supply to joint ventures (to view the Code of Practice, you can follow the link) it is often necessary to organize water purification from impurities that are noticeable when heating is initially started: the same water that goes into the kitchen mixer as into the heating radiators.

The quality of hot water depends on the wear and tear of heating structures and the presence of filters. But, even taking these features into account, the open system has become popular since the times of the Soviet Union.

Closed system

This method also uses a thermal central system, like the one discussed above. The difference is in the heating method. If with an open system the water is heated at a thermal station and directly enters the residential building, then with a closed system the water flows through a separate circuit. It receives cold purified water passing through special heat exchangers. They receive heat from a centralized system, which is heated at a thermal station, the same one from which it is supplied when the hot water supply system is open.

It is possible to use other heat sources. However, convection and heat supply from the system have become the most popular open view. At closed type systems water quality is not affected by pipelines central system. For the closed method, you need to have heat exchangers, auxiliary pumping stations, which increases the cost when changing from open to closed.

However, in the future it is possible to save due to the stability of temperature regimes: in an open system it is often necessary to heat centralized water due to its separation for heating and domestic needs. The closed method also has advantages in terms of bacteriological and organoleptic indicators.

Therefore, the temperature of hot water in a living room is always stable. It is not affected by winter air temperature, unlike open method obtaining hot water. But heating water is not enough; it must be delivered without loss to residential premises and organizations. Today there are two ways to supply water:

1. Circular method.
2. Dead end method.

Circulation method

Using this method, hot water constantly circulates through a closed system: thermal station– central system – substation – water supply – and returns back. This is done due to several reasons:

• a large number of consumers;
• water cooling when the system is idle;
• other possible reasons.

Practice shows that this method makes it possible to quickly obtain hot water from a kitchen faucet. It is always hot and ready for use. When the system stops, the water will cool, which will lead to large heat losses. IN multi-storey buildings For this purpose, branching the riser into additional pumps or blocks is used.

With this method, some difficulties are possible: everyone knows the problem that in the bathroom heated towel rails heat up summer time, and there is no way to reduce their temperature. Hot water is constantly available in them at any time. You can adjust the heating by installing a control tap and adding a pipe through which water will flow when the tap is closed.

Dead end method

With this method, the DHW system operates with less efficiency, since the consumer is provided with a final dead-end water supply system. It contains only supply pipes, not equipped with a return circuit. Hot water flows when the faucet is opened. When it is closed, the water in the pipelines stops and slowly cools.

In practice, it looks like if the tap is inactive for a long time, for example at night, cold water will flow first, and after a while hot water will flow. The dead-end feeding method is most often used in own homes which are connected to the water supply. Today, it is the dead-end method that has become the most common due to the popularity of individual electric boiler heaters.

Central and autonomous hot water supply

Each type has its own advantages and disadvantages. The central system is more convenient for the consumer if its operation is constant and meets the temperature and water quality standards. But such conditions are not always observed in our country, and are more like an exception than natural conditions.

The central system does not always provide reliable comfort in a living space, and is often a “headache” for residents. To a greater extent, this depends on the diligence of local bosses, supervisory and regulatory authorities.

The offline method requires high expenses, since it is necessary to install special structures and lay water pipes. But its performance and degree of comfort are much greater than the central system. The consumer can independently set the temperature level and control coolant consumption.

Requirements for hot water

Frequent planned shutdowns and low temperature conditions are the main negative factors in the central hot water supply. Such cases occur frequently, but their frequency is regulated by law. The following standards exist:

1. The hot water temperature should not decrease below +40 degrees, with an accuracy of 5 degrees.
2. The total time when hot water is turned off should not exceed eight hours per month.
3. The longest period of work to prevent the system in the summer is 14 days.

The composition of the water must necessarily comply with SanPiN 2. 1. 4. 2496 - 09. To monitor coolant consumption, special devices are installed. They can only be installed by employees management company, with which an agreement was concluded for the supply of hot water to residential premises.

Types of local systems

The practical implementation of such systems is possible only with a professional approach to the stages of work. To create a project, you need to know the main types of local systems, their operating efficiency, and the influence of technical parameters.

Accumulation system

The storage type boiler takes water from an external source and further heats it to the required temperature. A diagram of a heated water supply system of this type is used for cottages and country houses.

Modern boiler devices are equipped with auxiliary options:

• several operating modes – the most economical, optimal and “maximum”. You can also adjust the delay for the start of heating;
• the thermal insulation material of the housing guarantees heat retention, which directly affects the consumption of electrical energy;
• a wide range of models that differ in volume, functionality and operational parameters.

To achieve the required temperature value, electric heaters are used - heating elements.

Flow system

In large residential buildings The use of instantaneous boilers is common. Depending on the type of equipment, there are the following types of such water heaters:

• flow heaters;
• double-circuit boilers.

Instead of coolant, electric or thermal energy, appearing during combustion gas fuel. The last method is the most suitable, since it is not too expensive in terms of finances and is effective due to its low inertia.

Hot water supply metering

Commercial accounting of hot water is carried out on the basis legislative documents. Government Decree No. 1034 of November 18, 2013 provides for the organization of coolant metering by heat supply organizations and heat consumers.

Such accounting must be carried out using special meters. At the same time, the legislation allows the installation of meters to control the coolant at the site. In particular, meters are installed to remotely determine indicators that do not affect commercial heat metering and the accuracy and quality of measurements.

When installing remote control equipment, access to such a system can be obtained by the heat supply organization or residents under the terms of a contract. Commercial heat metering includes the procedure for periodically taking meter readings. According to the law, if the technical parameters of metering units make it possible to use telemetric systems, then special systems are installed that transmit meter readings remotely.

In this case, it is permitted that heat meters equipped with standard protocols be equipped with auxiliary devices that make it possible to perform remote readings in automatic mode.

Which DHW system to choose?

Regardless of the type of DHW system, it must comply with standards, perform immediate tasks and be safe for the consumer. Each of them has advantages and negative points. The quality of hot water depends not only on the water pressure in the system, but also on the presence of a dead-end water supply.

When the pressure increases and the mixer is not operating sufficiently, it is difficult to achieve the required balance of hot and cold water on the way out. If there are frequent hot water outages in a residential area, then it is advisable to buy and install a water heater. If you have it, you can comfortably survive the period of repair of the heating network.

We are often asked the question: “Which hot water supply system is better: open or closed?” The truth is that there are no closed and open hot water systems; in fact, it is correct to talk about Closed and Open heat supply systems, where hot water systems are only part of them. On the other hand, how the water supply to the hot water supply is organized in the heating system determines its type. It sounds a little confusing, but then everything will fall into place.

Types of heat supply systems

Heat supply systems are classified according to various parameters:

• Depending on the location of the heat source: Centralized And Decentralized;
• By temperature conditions: Low potential, Medium potential And High potential;
• By coolant type: Mermen And Steam;
• By connection method to the consumer: Single stage And Multistage;
• By number of pipelines: Monotube, Double pipe And Multi-pipe;
• According to the method of supplying water to hot water supply: Open And Closed.

For the purposes of this article, the latter classification will be considered.

Open system heat supply- this is a system in which hot water is heated in a thermal power plant, state district power station, boiler room and is taken from the same pipes through which water flows to heating devices: steel registers, convectors and radiators.

Closed heating system- a system in which hot water is prepared at the heat consumption facility (apartment building, business center or production premises) from cold water using plate heat exchangers.

Fig.1. Difference between closed and open heat supply systems

In Figure 1, both on the left and on the right are heat supply systems, but in the open one (on the right) it can be seen that the water for the hot water supply and the water for the heating devices are the same. At the same time, both heat supply systems have their advantages and disadvantages.

Open heating system

An open system has a simpler structure than a closed one. It includes the following equipment:

• pipes of various sections (with a nominal diameter from 20 to 200 mm inclusive);
• valves;
• pressure gauges;
• thermometers;
• check valves;
• ball valves;
• temperature regulators (with and without controller);
• thermal insulation.

A schematic diagram of an open heat supply system (implemented in Surgut) is shown in Fig. 2.

Rice. 2. Open heat supply system (Surgut)

1a, 2a Ball valves;

4. Pressure gauge;

5. Thermometer;

Maintenance of this system is carried out by one plumber or a team of several people.

Pros of an open system:

• Easy installation;
• Easy to maintain.

Disadvantages of an open system:

• The presence of harmful chemical impurities in hot water: they can dry the skin, cause irritation, hot water is not of potable quality;
• High cost of water preparation in centralized conditions;
• Hot water emits intermittently bad smell;
• The water periodically has an orange tint due to rust;
• It is necessary to pay for more expensive chemically desalinated water;
• If the system is used incorrectly, a short-term flow of water from the water taps may exceed 100 degrees, which can lead to burns.

From 2022, an open heat supply system is PROHIBITED on the territory of the Russian Federation. The transition from an open to a closed system is mandatory for apartment buildings (apartment buildings) and organizations of any type of property.

Closed heating system

A closed system has a more complex structure. In addition to the equipment that is present in the open system, it also uses:

• Pumps;
• Controllers;
• Control panels.

A schematic diagram of a closed system is shown in Figure 3.

Rice. 3. Scheme of a closed heat supply system

1a and 2a. Ball valve;

3. Three-way valve for pressure gauge;

4. Pressure gauge;

5. Thermometer;

6a. Expansion tank of the domestic hot water system;

7a. Control valve;

13, 13a, 13b. Mechanical filters of various sizes;

10. Ball valve DN 15 (air discharge);

11. Automatic air collector;

12. Ball valve DN 25 (drainage);

14a. Steel pipe of the appropriate standard size;

17a, 17b. Heat exchangers for hot water supply - first and second stage;

26. Pressure regulator after itself;

27. Direct-acting temperature controller.

Maintenance of this system is carried out comprehensively by personnel of various qualifications:

• Pipes of various sections, valves, pressure gauges, thermometers, check valves, ball valves and temperature regulators (with and without controller), thermal insulation, as in an open system, they are served by a plumber or a team of mechanics.
• Controllers and thermal automation served by employees of a specialized organization.
• To service electrical components, an electrician is required on staff of the operating organization.

Pros of a closed system:

• No unpleasant odor from water;
• Hot water level corresponds to water drinking quality;
• Lower cost of preparing water;
• Savings due to no need to pay for chemically demineralized water.
• Water with a temperature of no more than 60 degrees will flow from the tap, which prevents severe burns.

Disadvantages of a closed system:

• The use of expensive equipment, as a result, higher capital costs during the construction phase;
• More expensive maintenance (compared to an open heating system).

Conclusions:

When wondering about providing hot water supply at a facility, it is worth remembering that closed and open is the principle of organizing heat supply systems, and not the hot water supply itself.

At the same time, an open system is simpler and cheaper, but the quality of hot water in it leaves much to be desired. A closed system, on the contrary, is more expensive and requires more attention, but the water in it is of better quality.

On the other hand, the question “Which type of heating system to choose? Open or closed? will lose its relevance from 2022 thanks to Part 9 of Article 29 of Federal Law No. 190 of July 27, 2010 “On Heat Supply”:

“From January 1, 2022, the use of centralized open heat supply systems (hot water supply) for hot water supply needs, carried out by selecting coolant for hot water supply needs, is not allowed.”

The full text of Article 29 of Federal Law No. 190-FZ is available at the link.

In addition, according to Article 8 of the same Law, it is already prohibited to connect new capital construction projects to open heat supply systems:

“From January 1, 2013, connection ( technological connection) capital construction projects for consumers to centralized open heat supply systems (hot water supply) for the needs of hot water supply, carried out by selecting coolant for the needs of hot water supply, is not allowed.”

Hot water supply in modern world is an integral part of comfort. Proper organization water supply systems will not only provide comfort, but also save money on installation and operation.

Hot water systems

When arranging a water supply system, it is necessary to take into account that there are two completely opposite connection methods. This is an open (open, dead-end) and closed (closed, ring) layout of pipelines and equipment. Moreover, the second option is much more popular than the first. This is due to the possibility of adjustment and complete control over the condition of the water and its temperature.

The open circuit in recent years is used less and less. The reason was its complete organizational lag behind advanced technologies and user needs. Although, it is worth recognizing that in terms of the cost of direct installation, an open system is much cheaper.

When choosing open circuit A detailed technically and economically sound design should be followed. In addition, the arrangement of such systems has high requirements for technical specifications coolant, which will also be used as hot water. An open hot water supply system has proven itself best in small networks, or under conditions where the resource is constantly being dismantled.

When installing such a system, you should first of all take into account the principle of operation. In fact, the water that is heated for the heating system is supplied to dismountable points (mixers). This results in one general outline. Technologically, it looks like supply and return pipelines with the arrangement of any type of water heater (electric, solid fuel, gas). Constant pressure in such a network is achieved exclusively hydraulically(hot water squeezes out cold water, gradually cools down, becomes cold and is itself squeezed out with a new volume of hot water).

This simplicity is considered one of the advantages of an open circuit. An open hot water supply system is beneficial due to the maximum level of thermal energy transfer at very low coolant costs. Also, such equipment has a low price, because there is no need to install additional pumps, heat exchangers, expansion tanks and so on. And the absence of all this makes for easy operation during the winter and inter-heating periods.

Besides, an important factor is a lower level of final costs for operating the system. In addition, an open hot water supply system has increased safety and reliability indicators, and if used drinking water as a coolant, significant improvements in network efficiency are possible in the future.

But, undoubtedly, there are a lot of disadvantages to an open hot water supply system. Firstly, in the absence of frequent analysis, hot water cools faster and warms up worse, which disrupts natural circulation (in areas connected to mixers). Due to such moments, the heating system may also “suffer”. But in winter, when outside severe frost, the heating warms up more strongly, which increases the temperature of the supplied hot water. Therefore, there is a clear negative relationship in the general contour.

Secondly, the quality of the water itself. Again, due to dependency, you have to use either too clean water for heating, or coolant for hot water supply, whose sanitary parameters are far from the required standards. Accordingly, an open water supply system leads to additional costs in connection with the use deaeration and chemical cleaning water. Carrying out these works is necessary in any case, as they eliminate the formation of scale and corrosion.

And thirdly, the lack of hot water in summer period. At a time when it is quite warm outside, it is very unprofitable to operate the circuit. After all, both heating and hot water supply will work actively in this case.

Open circuit optimization.

To optimize the use of an open system, some sections of the mains are closed with shut-off valves, which facilitates preventive and renovation work and allows you to drain water from a small section of the pipeline, instead of draining the entire volume. For additional protection open hot water systems are supplied float sensors and relay for measuring pressure in pipes.

Heating and hot water supply systems include a set of devices that provide heating of cold water and distribute it to the required water distribution elements. Water is heated in water heating equipment to the required temperature, after which it is supplied through pipelines to the building using a pump.

Closed and open DHW system

Heating and hot water supply systems are divided into open and closed, depending on the method of heating the water. An open hot water supply system contains a coolant circulating in the system. An open water supply system is also used for heating buildings. A closed hot water supply system has the following operating principle: water from the water supply enters water heating devices or heating points, where it is heated.

An open water supply scheme excludes water heaters, as a result of which it costs much less than a closed hot water supply system. Open and closed water supply systems can be used in both multi-apartment and private buildings. For cottages and dachas, an open hot water supply system is not optimal, due to the high costs of its installation. For multi-apartment buildings or large houses the best option is an open water supply scheme.

Differences between closed and open water supply systems

An open and closed water supply system can be centralized or autonomous, depending on the location of the water heating equipment and its thermal power. The pressure in centralized water supply pipes significantly exceeds the level of water pressure in the water supply pipes of an autonomous system. IN autonomous systems A pressure switch is often used for water supply, which allows you to monitor and, if necessary, equalize the water pressure level. The pressure switch for centralized water supply is installed in heating point, it regulates the pressure in water supply pipes or in its individual sections.

Cold water supply systems are classified according to the territorial coverage of their consumers, the method of water supply, the type of water supply source and the types of consumers or purpose.
There are circulating and direct-flow cold water supply systems. The second type is easier to use and design. The recirculating system makes it easier to protect water bodies, as well as reduce the cost of pipelines and treatment facilities.

Circulation system water supply

Where a continuous supply of hot water to points of consumption is preferable, but draining water is undesirable, circulation systems are used. The water in the pipeline of such a system does not stop or cool, but is continuously pumped through water heating installation, which allows you to maintain its temperature at a given level at each individual point of water consumption.

In buildings up to 4 floors high, water circulates only in the distribution pipes, and in buildings over 4 floors - also in riser pipes. At the same time, the water temperature in water points where the centralized heating system is connected to the local system is not lower than 60 degrees (for open water supply systems) or 50 degrees (for closed water supply systems). In both cases, the water temperature should be up to 75 degrees.

Figure 2. Hot water circulation system

Differences between open and closed water supply systems

There are two completely opposite connection methods. This is an open (open, dead-end) and closed (closed, ring) layout of pipelines and equipment. The fundamental difference between these two systems is that with an open DHW circuit, hot water is drawn directly from the heating network, that is, the hot water flowing from the mixer tap is the same as in the heating radiators.

The choice of a DHW scheme depends on several factors - these are the conditions under which the water supply is made, the source of energy for heating the water, and the quality of both the water and the plumbing. The use of an open water supply system must be justified in terms of economy and technology.

Considering the choice from the point of view of sanitary standards, a closed system that is connected to the central city heating network looks more reliable.

But if we talk about local network, then everything is decided by the quality of water and the economic benefit of each system in each particular case.

In a closed system, water from heating networks is used as an energy carrier to heat cold water coming from the water supply system to the hot water supply system in a heat exchanger. In open systems, hot water is supplied directly from the heating network. The temperature of such water is up to 75 degrees, and it is intended to satisfy the hygienic and domestic needs of the population (bathing, washing, etc.). Therefore, open and closed water supply systems are different and classified depending on the method of water supply. Water taken directly from the heating network is called domestic water.

Figure 3. Closed hot water system

A closed DHW system is characterized by the fact that the hot water circuit is separated from the heating circuit. That is, water enters through the supply heating circuit, passes through the internal heating system of the building (pipes, radiators) and returns to the return line, along the way through a heat exchanger, heating the hot water supply circuit in the heating point of the building. Hot water (drinking) circulates separately along its own circuit, and water withdrawal in the building is compensated by replenishment from the cold water supply line.

There are variations for the open DHW circuit: circulation and dead-end. In the first case, hot water circulates in internal system hot water supply and when the hot water tap is opened, hot water should run almost immediately desired temperature, but this is ideal. In a dead-end circuit, hot water does not circulate in the system, and in order to obtain water at the desired temperature, it must be discharged through the tap, i.e. drain the cooled liquid in the pipes.

Maintenance of open water supply systems includes disinfection, and, in agreement with state supervision authorities, it can be carried out not only by chlorination, but also by simply washing with hot water at a temperature of about 90 degrees.

The water heating device also needs to be cleaned periodically, because under the influence high temperatures conditions unfavorable for water quality may be created.

Figure 4. Open hot water system

The efficiency of the system is determined by the maximum transfer of thermal energy to the consumer with minimal coolant consumption. The water supply system is open and closed; in the absence of water intake for hot water supply, the efficiency indicators will not differ, with the exception of the option with a heat pump (which is the most effective in any conditions).

Closed and open systems have different advantages. In a closed system, it is possible to provide hydraulic isolation of heating networks, and in an open system, the cost of hot water supply for the end consumer is much lower. In addition, it is characterized by more high level reliability and increased efficiency in the long term (provided that the coolant is drinking water).