Pipeline for hot centralized water supply cannot be done according to the cold water supply scheme. These pipelines are dead-end, that is, they end at the last water withdrawal point. If you make a hot water supply in an apartment building using the same scheme, then the water will cool down in the pipeline at night, when it is used little. In addition, there may be such a situation, for example, the residents of a five-story building located on the same riser went to work during the day, the water in the riser was cooling down, and suddenly one of the residents on the fifth floor needed hot water. After turning on the tap, you will first have to drain all cold water, wait until warm, and then hot water- this is an excessively high expense. Therefore, hot water supply pipelines are made in a loop: the water is heated in the boiler room, thermal unit or boiler room and is supplied through the supply pipeline to consumers and returns back to the boiler room through another pipeline, which in this case is called circulation.

IN centralized system For hot water supply, pipelines in the house are laid with two-pipe and single-pipe risers (Fig. 111).

Rice. 111.Distribution diagrams for hot water supply in centralized systems

A two-pipe hot water supply system consists of two risers, one of which supplies water, the other drains it. Place on the outlet circulation riser heating devices- heated towel rails. The water was still heated and served to consumers, but whether they will use it or not and at what time is unknown, so why waste it, let this water warm the heated towel rails and the air in damp, by definition, bathrooms. In addition, heated towel rails serve as a U-shaped compensator for thermal expansion of pipes.

A single-pipe hot water supply system differs from a two-pipe system in that all circulation risers (within one section of the house) were combined into one and this riser was called “idle” (it has no consumers). For better water distribution to individual points of water consumption, as well as in order to maintain the same diameters along the entire height of the building in single-pipe hot water supply systems, the risers are looped. With a ring scheme, for buildings up to 5 floors high inclusive, the diameters of the risers are 25 mm, and for buildings from 6 floors and above - 32 mm in diameter. Heated towel rails in single-pipe installations are placed on supply risers, which means that when the water in boiler rooms is weakly heated, it can reach distant consumers cold. Hot water will not only be supplied to nearby consumers, but it will also cool in their heated towel rails. To ensure that the water does not cool down and reaches hot water to distant consumers, a bypass is installed in the heated towel rails.

Two- and one-pipe hot water supply systems can be made without heated towel rails, but then these devices must be connected to the heating system. At the same time, in summer period heated towel rails will not work, and in winter the overall costs for hot water supply and heating will increase.

To ensure air removal from the system, pipes are laid with a slope of at least 0.002 to the pipeline entrance. In systems with bottom wiring, air is removed through the top tap. With overhead wiring, air is removed through automatic air vents installed at the highest points of the systems.

Whoever gets up first... has to drain the hot water for a long time to wash himself. We learned this simple truth thanks to houses built in the mid-20th century.

Heated towel rails cooling down in the absence of water supply and, as a result, a damp and cool bathroom complete the dull picture. Not everyone knows that both problems have long been solved by engineers. Meet: hot water supply with recirculation!

Traditional DHW wiring

The installation of a hot water supply system in Stalinist and early Khrushchev buildings is no different from the distribution of cold water. The only bottling ends with dead-end risers, from which the apartment wiring departs. IN elevator unit, the bottling branches into two connections - into the supply and return threads.

DHW switching from supply to return is carried out manually in accordance with temperature chart heating:

• At a temperature process water at the output of the thermal power plant up to 80-90 degrees hot water is supplied from the supply;
• If 90°C is exceeded, the water supply switches to return water supply.

Why is this bad?

The advantages of this scheme are low cost of implementation and extremely simple maintenance. There are downsides too.

We have already mentioned two of them:

1. Without water tapping, the water in the risers and connections cools down. To wash or take a shower, you have to pour it down the drain for a long time (up to several minutes). For apartment residents, this means not only a loss of time, but also significant costs: in fact, you drain cold water, but if you have a water meter, you pay for it as for hot water;

Reference: the cost of a cubic meter of hot water in mid-2017 for Moscow residents is 163 rubles. It is estimated that per year a family of 3-4 people drains at least 10-12 cubic meters into the sewer while waiting for the water to heat up.

1. Heated towel rails that disconnect internal hot water supply lines are heated only by the water supply in your apartment. About high-quality heating You can forget the bathroom.

Let's throw another handful of little things into the general treasury of shortcomings of the solution:

• Cold and dampness in the bathroom contribute to the appearance of fungus;

• Towels hung on a cold drying rack quickly become musty;
• Cyclic heating and cooling of hot water risers are accompanied by cycles of their lengthening and reduction in size. As a result, the sealing of the risers in the ceiling with cement mortar is gradually destroyed.

Please note: the elongation of pipes when heated, if they touch the ceiling reinforcement, can be accompanied by quite loud sounds. In the author's memory, the friction of the riser against the fittings led to a comical situation: residents accused their neighbors in the riser of... underground money printing.

All in white and on a white horse

How does a hot water supply system with recirculation differ from the one described above? It's not hard to guess. In it, hot water continuously circulates through the taps and (in the case of multi-storey building) hot water risers.

As a result:

• Instant supply of hot water to the water collection point at any part of the circuit is ensured;
• Heated towel rails are transferred from the in-house supply to the hot water riser (or, in the case of a private house, bottling). Thanks to continuous circulation, they remain hot around the clock, provide heating for bathrooms and toilets, and at the same time quickly dry towels;

• The temperature regime of the DHW system remains stable, without cyclic cooling and heating.

Implementation

What hot water supply schemes with recirculation are possible in apartment buildings and private buildings?

Apartment buildings

To create continuous circulation of water, the DHW system needs to be looped.

IN apartment buildings this is achieved as follows:

Image	Description
	There are two hot water dispensers throughout the house. The risers are connected to them one by one. As an option, only DHW risers are connected to one of the bottlings, and only risers with heated towel rails are connected to the second.
	DHW risers (optional - DHW and heated towel rails) are connected by jumpers on the upper floor. A group can consist of 2-4 risers. An air vent (Maevsky valve) is mounted at the top point of the jumper, allowing the air to bleed off that is preventing circulation.

It’s interesting: in some houses built in the late 80s, the author observed jumpers between the hot water supply risers, placed in a cold attic. The solution raises doubts about the adequacy of the authors: at street temperatures of -30°C and below, they freeze within an hour after stopping circulation in DHW system(for example, for emergency repair of a valve in an elevator unit).

It is clear that the described water supply scheme with recirculation will not work without a pressure difference.

How it is provided:

• Outside heating season DHW is switched on between the supply and return lines;

• During heating operation with this connection, the hot water supply system will act as a bypass for heating system, catastrophically reducing the difference by water jet elevator. Therefore, the DHW is connected depending on the temperature of the water from supply to supply or from return to return, and the difference is ensured by retaining washers installed on the flanges between the taps.

Reference: a retaining washer is a steel plate with a hole in the middle. The hole diameter is usually 1 mm larger than the elevator nozzle diameter. When water moves through the washer, a difference of 0.1 - 0.3 kgf/cm is created on it, which is quite sufficient for circulation in the hot water system.

If the risers are airy

What should I do if, after resetting the hot water supply system, the air pocket remaining in the risers prevents circulation and the heated towel rails remain cold?

To bleed air, use the Mayevsky valve at the top point of the jumper. However, to access it you need to get into the upper apartment via the riser, which is not always possible.

Here's a simple one step-by-step instruction, which will help you fix the problem yourself:

1. We block any of the hot water supply risers connected by a jumper;
2. We open one, or better yet, two hot water taps in any apartment along this riser all the way. The air plug flies out through the mixer at the front of the water flow;

1. We start the risers in normal mode.

Private houses

What hot water recycling schemes can be implemented in a private house with autonomous hot water preparation? Quite predictably, a minimum power circulation pump (from 25 watts) will be responsible for creating circulation pressure in such a system.

The DHW circuit must be looped along its entire length: after the plumbing fixture farthest from the water heater, the filling returns to the starting point. But the connection diagram for the water heater depends on whether it has an additional outlet for recirculation.

Boiler with additional outlet for recirculation

The closed circuit is supplied only circulation pump: since the water temperature in the circuit is constant after it starts, problems thermal expansion there is no need to decide on water, but if so - safety valve and an expansion tank is not required.

Is it possible to use a regular boiler with two outlets (for DHW and cold water) in such a scheme? Yes, but in this case the wiring will be noticeably more complicated.

• A three-way thermostatic mixer is responsible for maintaining a constant water temperature in the recirculation circuit. As it cools, he mixes in hot water from the boiler;

• To compensate for the flow of hot water, cold water is supplied to the three-way mixer;
• Check valves limit the movement of water in the circuit in one direction, regardless of its flow.

Useful: it makes sense to install an automatic air vent at the top point of the DHW circuit. Air jams if there is a pump, they will not interfere with circulation, but they can become a source of annoying hydraulic noise.

Conclusion

As you can see, hot water recirculation systems for a private home have quite convincing advantages over the usual dead-end circuits and are quite easy to install. The video in this article will help you learn more about them. Good luck!

In order for any residential building to function normally, it is necessary to install a water supply system. Its proper design will ensure timely supply and sufficient water pressure. This article will discuss in detail the hot water supply scheme, types of connection and its features in an apartment building.

What is special about the water supply of an apartment building?

It is very difficult to provide water to a building with a large number of storeys. After all, the house consists of many apartments with separate bathrooms and plumbing fixtures. In other words, water supply schemes in apartment buildings are a kind of complex with separate pipe distributions, pressure regulators, filters and metering equipment.

Most often, residents of high-rise buildings use water from the central water supply. With the help of a water supply, it is supplied to individual plumbing fixtures under a certain pressure. Often water is purified using chlorination.

Composition of the central water supply system

Centralized water supply schemes in multi-storey buildings consist of a distribution network, water intake structures and treatment plants. Before entering the apartment, the water passes long haul from pumping station to the pond. Only after purification and disinfection is water sent to the distribution network. With the help of the latter, water is supplied to appliances and equipment. Pipes for the central hot water supply circuit of a multi-storey building can be made of copper, metal-plastic and steel.

The latter type of material is practically not used in modern buildings.

Types of water supply schemes

There are three types of water supply system:

• collector;
• sequential;
• combined (mixed).

Recently, when it is becoming more common in apartments a large number of plumbing equipment, use collector wiring diagram . She happens to be the best option normal functioning of all devices. The collector-type hot water supply scheme eliminates pressure drops at different connection points. This is the main advantage of this system.

If we consider the diagram in more detail, we can conclude that there will be no problems with using the plumbing equipment for its intended purpose at the same time. The essence of the connection is that each individual water consumer is connected to the cold and hot water supply riser collectors separately. The pipes do not have many branches, so the likelihood of leakage is very low. Such water supply schemes in multi-storey buildings are easy to maintain, but the cost of the equipment is quite high.

According to experts, the collector hot water supply system requires the installation of a more complex installation of plumbing fixtures. However, these negative aspects are not so critical, especially considering the fact that the collector circuit has many advantages, for example, hidden installation of pipes and accounting individual characteristics equipment.

Series circuit hot water supply multi-storey building - this is the easiest way to wire. This system is time-tested; it was put into operation during the Soviet era. The essence of its device is that the cold and hot water supply pipelines are parallel to each other. Engineers advise using this system in apartments with one bathroom and a small amount of plumbing equipment.

Popularly, such a hot water supply scheme for a multi-storey building is called a tee scheme. That is, from the main highways there are branches that are connected to each other by tees. Despite the ease of installation and savings consumables, this scheme has several main disadvantages:

1. In the event of a leak, it is difficult to look for damaged areas.
2. Inability to supply water to a separate plumbing fixture.
3. Difficulty in accessing pipes in case of breakdown.

Hot water supply for an apartment building. Scheme

Pipe connections are divided into two types: to the hot and cold water supply riser. Briefly they are called cold water and hot water. Special attention hot water system deserves apartment building. Scheme DHW networks consists of two types of wiring - lower and upper. To save high temperature Looped wires are often used in pipelines. The gravitational pressure forces the water to circulate in the ring, despite the absence of water intake. In the riser it cools and enters the heater. Water with a higher temperature is supplied to the pipes. This is how continuous circulation of the coolant occurs.

Dead-end highways are also not uncommon, but most often they can be found in utility rooms industrial facilities and in small residential buildings with low number of floors. If water selection is planned intermittently, then a circulation pipeline is used. Engineers advise using hot water supply in apartment buildings (the diagram was discussed above) with a number of floors of no more than 4. A pipeline with a dead-end riser is also found in dormitories, sanatoriums and hotels. Dead-end network pipes have a lower metal consumption and therefore cool faster.

DHW networks include a horizontal main pipeline and distribution risers. The latter provide pipe distribution to individual objects - apartments. DHW is installed as close as possible to plumbing equipment.

For buildings with a large length of main pipes, schemes with circulation and looped supply pipelines are used. Required condition is to install a pump to maintain circulation and constant water exchange.

Two-pipe DHW circuit - Photo 07

Modern builders and engineers are increasingly resorting to the use of two-pipe hot water systems. The principle of operation is that the pump takes water from the return line and supplies it to the heater. This pipeline has a higher metal consumption and is considered the most reliable for consumers.

The schematic diagram of a hot water supply system includes an installation for heating cold water to a temperature not exceeding 75 ° C and a network of distribution pipelines. For this purpose, high-speed buses are used. instantaneous water heaters. In such water heaters, water flows at a significant speed through the heating tubes, which in turn are heated by water from the heating network passing inside the body of the water heater and washing them.

When preparing hot water in the central heating station according to closed scheme use high-speed water heaters OCT 34-588-68 (coolant - water), OCT 34-531-68 and OCT 34-532-68 (coolant - steam).

Rice. 174. High-speed water heaters: a - sectional OST-34-588-68, b - steam; 1 - body, 2 - lens compensator, 3 - grille, 4 - brass tubes, 5 - pipe system, 6 - rear water chamber, 7 - cap, 8 - front water chamber

Water heaters OST 34-588-68 ( , a) are designed for a pressure of 1 MPa and a coolant temperature of 150 ° C. They are produced in separate sections with an outer diameter of 57 to 325 mm with a heating surface of each section from 0.37 to 28 m2. The required heating surface of the water heater is made up of similar sections connected to each other by rolls. The section consists of a body 1 with steel tube sheets 3 welded to it and a bundle of brass tubes 4 with a diameter of 16X1 mm. Nozzles with flanges are welded to the body to connect the sections in the interpipe space. Hot water from the heating network is directed into the interpipe space, and the heated water moves through the tubes of the water heater.

Steam water heaters (OST 34-531-68 and OST 34-532-68) (,6) are designed for heating water with steam in heating and hot water supply systems. Maximum operating steam pressure 1 MPa. Water heaters are produced as two-pass (OST 34-531-68) and four-pass (OST 34-532-68). The heating surface can be from 6.3 to 224 m2.

The water heater consists of housing 1, pipe system 5, front 8 and rear 6 water chambers. The pipe system includes steel gratings and a bundle of brass tubes with a diameter of 16X1 mm. Heated water enters through the lower pipe of the front inlet chamber, passes through brass tubes, is heated and goes into the network through the upper pipe. The steam that heats the water enters the interpipe space.

The water heated in the water heater enters the hot water supply system through the supply pipeline, from which consumers use it for domestic and industrial purposes. The water taken from the system is replenished from the water supply.

To heat the water that has cooled in the system, a circulation pipeline is laid that connects the hot water supply system to the water heater.

To maintain a constant flow of water coming from the heating network, a flow regulator is installed, and a water meter is installed on the pipeline supplying cold water to the water heater, which takes into account the water flow. At the control unit of water heaters, valves are installed to shut off the pipeline of the hot water supply and heating system and individual parts of the unit. The pressure and temperature of water at individual points of the control unit are measured with pressure gauges and thermometers.

Depending on the purpose, hot water supply systems are made with two-pipe risers, one of which is circulation, and single-pipe.

Two-pipe hot water supply systems with circulation risers() are used where cooling of water in pipes is not allowed, for example in multi-storey residential buildings, hotels, hospitals and other buildings.

Rice. 175. Two-pipe hot water supply system with circulation risers

Rice. 176. Single-pipe hot water supply circuit: 1 - diaphragm, 2 - plug valve, 3 - supply transit line, 4 - circulation transit line

In single-pipe centralized hot water supply systems used in residential buildings(), the risers within one section at the top are connected to each other, and all risers, except one, are connected to the supply line 3, and one idle riser is connected to the circulation line 4. To ensure uniform circulation of water in the hot water supply systems of buildings connected to one central heating point, a diaphragm is installed on the idle riser.

For better water distribution to individual points of water consumption, as well as in order to maintain the same diameters along the entire height of the building in single-pipe hot water supply systems, the risers are looped. With a ring scheme, for buildings up to 5 floors high inclusive, the diameters of the risers are 25 mm, and for buildings from 6 floors and above - 32 mm in diameter. Temperature extensions in the risers of hot water supply systems of high-rise buildings are compensated by installing single-turn heated towel rails, and in double-pipe hot water supply systems by installing U-shaped compensators on the risers.

Heated towel rails made of galvanized pipes are connected to the hot water supply system using a flow-through circuit. Hot water supply pipelines, in order to protect against corrosion, should be made of galvanized steel pipes.

To ensure air removal from the system, pipes are laid with a slope to the input of at least 0.002. In systems with bottom wiring, air is removed through the top tap. With overhead wiring, air is removed through automatic air vents installed at the highest points of the systems.

Page 5 of 18

Schemes for connecting hot water supply to heating networks.

· IN closed systems heat supply The coolant is completely returned to

source of heat supply (except for leaks). The coolant is used as a heating medium in heat exchangers. Closed systems are hydraulically isolated from heating networks, which ensures stable water quality in the hot water supply, because there is no removal of slag deposits into the hot water supply system (this is a plus). However, water enters the hot water supply system (pipes) from a cold water supply system, which is not subject to deaeration (removal of oxygen and carbon dioxide), heats up and aggravates corrosion activity, therefore, pipes are destroyed faster by corrosion than in open circuits. Therefore, in closed systems it is recommended to use non-metallic, plastic pipes.

Closed circuits distinguish between single-stage and multi-stage. The choice of scheme depends on the ratio of heat consumption for heating and domestic hot water. The choice of connection scheme is made based on calculations.

· IN open systems DHW uses not only the heat supplied

coolant from the heating network to the local network, but also the coolant itself. In open circuits DHW pipes corrode to a lesser extent than in closed systems, because water comes from the heating network after chemical water treatment (CWT), but stability may be disrupted sanitary standards water indicators. Open circuits cheaper. Than closed, because no costs for heat exchangers and pumping equipment are required.

Schemes for connecting hot water supply systems of buildings to heating networks.

· Single-stage circuits (Fig. 7, 8):

One heat exchanger and heating for DHW occurs before the MOS).

Rice. 7. Single stage pre-connected

Rice. 8. Single stage parallel

· Multi-stage schemes (Fig. 9, 10):

Т = 30˚С Т = 5˚С

Rice. 9. Sequential two-stage

Rice. 10. Mixed two-stage

Two-stage schemes are effective in application because there is a deep decrease in the temperature of the return water, and there is also an independent heat consumption for heating and hot water supply, i.e. fluctuations in flow rate in the DHW system do not affect the operation of the MOS, which can occur in open circuits.