Schemes for connecting hot water supply to heating networks. Centralized hot water systems

Our topic today is the hot water system apartment building: diagrams, basic elements and typical problems that a homeowner may face. So let's get started.

DHW and heat supply scheme

The hot water supply scheme in an apartment building can be implemented in two fundamentally different ways:

It uses water from the cold water supply and heats it with heat from an autonomous source. It can be a boiler installed in the apartment, geyser or a heat exchanger using a heat carrier from a local boiler house or CHP for heating;

Please note: the advantage of such a scheme is more high quality water. It must comply with the requirements of GOST R 51232-98 (" Drinking water"). In addition, the parameters of hot water supply (temperature and pressure) rarely deviate from the nominal values; in particular, the DHW pressure is always equal to the cold water pressure, taking into account the head loss during draw-off.

It supplies the consumer with water directly from the heating main. This is exactly what is implemented in the vast majority of residential and administrative buildings Soviet-built, constituting 90% of the housing stock in the vastness of our great and immense. In what follows, we will focus our attention on it.

Dear reader can find additional information in the video in this article.

Elements

So, what elements does the water supply scheme of an apartment building include?

Water meter assembly

He is responsible for supplying cold water to the house.

The water meter performs several functions:

Provides accounting for water consumption (as its name unambiguously reminds);
Allows you to disable cold water for the whole house to repair shut-off valves or eliminate spill leaks;
Provides coarse filtration of water at the entrance to the house. To do this, the water meter is equipped with a sump.

The composition of the water meter includes:

Entrance and house shut-off valves(gate valves or ball valves located on the side of the input of cold water and the intra-house water supply system);
Water meter (usually mechanical);
Mud tank (a tank with a drain cock, in which, due to the slow movement of water through its volume, sand, large particles of rust and other debris settle). Often, instead of a sump, the water meter unit is equipped with a coarse filter, in which a stainless mesh is responsible for cleaning the water from debris;
Pressure gauge or control valve for its installation;
Optionally, the water meter can be equipped with a bypass line with its own valve or a ball valve on it. The bypass opens when the water meter is dismantled for the period of repair or verification. At other times, it is closed and sealed by a representative of the organization - the water supplier.

It is curious: "Vodoset", or the organization replacing it, is responsible for the state of input of cold water up to the first flange of the inlet valve. The water meter is the responsibility of the organization serving the house.

Elevator node

The elevator unit, or heating point, also combines a number of functions:

Responsible for the operation and regulation of the heating system;
Provides a home hot water. Water (it is also the heat carrier of the heating system) is supplied to the domestic hot water system directly from the heating main;
Allows, if necessary, to switch the hot water supply between the supply and return threads of the heating main. The changeover is necessary because in winter the flow temperature can reach an impressive 150°C, while the permissible maximum hot water temperature is only 75°C.

A short lecture on physics: water is heated above the boiling point without evaporating, thanks to overpressure in the heat pipe. The higher the pressure, the higher the boiling point of liquids.

The heart of the elevator unit is a water jet elevator, through the nozzle of which hot and more high pressure supply water is injected into the mixing chamber filled with return water. Thanks to the operation of the elevator, a large volume of water with a relatively low temperature passes through the heating system of the house; at the same time, the consumption of water from the supply is relatively small.

DHW tie-ins are located between the inlet valves and the elevator. There can be two of these tie-ins (one for supply and return) and four (two for each thread). The first scheme is typical for houses built in the 70s of the last century and older buildings, the second - for more or less modern buildings.

Why are additional inserts needed?

To answer this question, we need to jump ahead and look at water supply patterns in apartment buildings.

On cold water, a dead-end scheme is always used: the water meter goes into a single filling, that one - into risers that end with intra-apartment connections. Water moves in such a water supply circuit only during drawdown.

What's going on in the GVS?

In houses with two DHW tie-ins to the elevator unit, the same scheme is used.

However, it has two rather annoying drawbacks:

If the water intake for your riser long time was not, the water has to be drained for a long time before it heats up;

Note: if you have mechanical meters on your pipes, they will register the flow of water, ignoring its temperature. As a result, you will overpay a hundred or two rubles a month for a service that you actually did not use.

Towel dryers installed on the hot water pipes, which are also responsible for heating the bathroom, will only heat up when hot water is drawn in your apartment. And, accordingly, most of the time will remain cold. Hence - the cold and dampness in the bathrooms, often becoming the cause of the appearance of the fungus.

Elevator unit with four DHW tie-ins provides continuous circulation of hot water through two bottlings and risers connected by jumpers.

DHW operation is possible according to one of three schemes:

From the supply to the return pipeline. This hot water supply high-rise building used only in summer when the heating is off: a bypass between the heating mains would reduce the pressure drop across the elevator;
From feed to feed. This scheme is for autumn and spring with their relatively low supply temperature;
From back to back. So DHW is turned on for the period of cold weather, when the supply temperature exceeds the threshold 75 degrees.

Readers who have not forgotten the basics of physics will have a reasonable question: how is the pressure difference necessary for continuous circulation between two tie-ins in one thread provided?

Remember: water is constantly moving through the pipes between the inlet valves and the elevator. To create a pressure difference, it is only necessary to restrict the flow by an obstacle installed between the tie-ins. This role is performed by a retaining washer - a metal pancake with a hole in it.

Captain Evidence suggests: a significant restriction of the patency of any pipeline would interfere with the operation of the elevator unit, so the diameter of the retaining washers is a millimeter larger than the diameter of the elevator nozzle. That, in turn, is calculated by the organization (heat supplier) in such a way that the return temperature at the outlet of the heating point corresponds to the temperature schedule.

Bottling

Water supply spills are called horizontal pipes, passing through the basement or subfloor of the house, and connecting the risers with the elevator and water metering units. There is always one bottling of cold water, there are two bottlings of hot water in the circulating hot water supply system.

The filling diameter, depending on its material and the number of water consumers, varies from 32 to 100 millimeters. The latter value is clearly redundant; however, the project for the water supply of an apartment building had to take into account not only the current condition of the pipelines, but also their inevitable overgrowth with deposits and rust. After 20-25 years of operation, the clearance of the pipe in cold water decreases by 2-3 times.

Risers

Each riser is responsible for the vertical distribution of water in the apartments located one above the other.

The most typical scheme is one group of risers (cold water and hot water, optionally heated towel rails) per apartment; however, other options are also possible:

Two groups of risers can pass through the apartment, supplying water to a bathroom and kitchen spaced over a long distance;
Risers in one apartment can supply water not only to its residents, but also to neighbors behind the wall;
On DHW, circulation jumpers can combine up to 7 risers from several apartments.

The typical diameter of cold water and hot water risers is 25-40 mm. The diameter of risers for heated towel rails and idle (without plumbing fixtures) circulation risers is usually smaller: they are mounted with a DN20 pipe.

In the circulation scheme of hot water supply, the jumpers between the risers can be located in the apartment on the top floor or taken out to the attic. Jumpers are equipped with air vents (Maevsky taps or ordinary taps), which allow bleed air that prevents circulation.

Eyeliners

Their function is to distribute water to plumbing fixtures inside the apartment. What is useful to know about water supply lines?

Their typical size (for steel water and gas pipes) - DN15 (which approximately corresponds to an inner diameter of 15 mm). When replacing eyeliners with your own hands, it is advisable not to reduce them inner diameter- this will lead to a drop in pressure on all plumbing fixtures when parsing water on one of them;

Since Soviet times, simple and cheap serial (tee) wiring has traditionally been used in apartments. A more material-intensive collector requires, among other things, hidden installation of connections, which greatly complicates their further maintenance;

With time throughput steel eyeliners drops noticeably, due to the notorious overgrowing with deposits. In such cases, the pipes are cleaned with a thin steel string or, quite simply, they are changed to new ones.

If you decide to replace eyeliners, we strongly advise you to opt for metal pipes. The instruction is associated with a fairly high probability of water hammer and deviations from the standard temperature in the DHW system: for example, if a forgetful locksmith does not switch the water supply from supply to return at the first frost, the water temperature can significantly exceed the maximum for any polymer pipes 90-95 degrees.

Which pipes can be used for water supply:

Image	Description
	have been used for water distribution since the time of stalinok. Unlike black steel, galvanizing is not afraid of deposits and rust. Important point: galvanized only mounted on threaded connections, because during welding, the zinc in the weld area completely evaporates.
	have long proved their reliability and durability: the oldest operating copper water pipes are over a century old, and they are in excellent condition. Soldered connections of copper pipes are maintenance-free, and can be mounted hidden, in a screed or strobes.
	Corrugated stainless steel pipes compare favorably with competitors simple installation. For their connection, compression fittings are used, for the assembly of which only two adjustable wrenches are needed. The service life of the pipes themselves is characterized by manufacturers as unlimited; however, after 30 years, you, or more likely your children, will have to change the silicone o-rings in the fittings.

Faults

What violations in the operation of the water supply system can the owner of the apartment eliminate on his own? Here are some of the most typical situations.

Leaking valves

Description: leak on the stem of screw valves.

Reason: partial wear of the oil seal or wear of the rubber sealing ring.
Solution: open the valve knob as far as it will go. In this case, the thread on the rod will press the stuffing box from below, and the flow will stop.

Noise of cranes

Description: when opening a hot or (more rarely) cold water tap, a loud noise is heard and the mixer is vibrating. Alternatively, your neighbor's faucet may be the source of the noise.

Cause: a deformed and crushed gasket on a screw valve box in a half-open position causes a continuous series of water hammers. Its valve closes the seat in the mixer body with a frequency of fractions of a second. On hot water, the pressure, as a rule, is noticeably greater, so the effect is more pronounced on it.

Decision:

Turn off the water to the apartment;
Unscrew the problematic crankbox;
Replace the gasket with a new one;
Remove the chamfer from the new gasket with scissors. The chamfered face will prevent the valve from beating in the turbulent water jet in the future.

By the way: ceramic crankboxes are fully compatible with screw threads, and are devoid of the described problem.

Cold towel warmer

Description: The heated towel rail in your bathroom is cold and does not heat up.
Cause: if the water supply scheme of a residential apartment building uses continuous circulation of hot water, the air remaining in the jumper between the risers after the water is discharged is to blame (for example, for revision and repair of valves).
Decision: go up to the top floor and ask your neighbors to bleed air from the jumper between the hot water risers and heated towel rails.

If for some reason this is not possible, the problem can be solved from the basement:

Shut off the DHW riser passing through your apartment, to which your connections are connected;
Climb into the apartment and open the hot water taps to failure;
After all the air comes out of the riser through them, close the taps and open the tap on the riser.

Nuance: immediately after the end of the heating season, there may be no pressure difference between the heating mains. In this case, the heated towel rails will be cold even if there are no air pockets in the risers.

Conclusion

We hope that our material has helped you to study the water supply of an apartment building: the water supply scheme described by us is the most common. Good luck!

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Types and advantages of DHW flow circuits
DHW using a flow circuit and plate heat exchangers is the most efficient and hygienic way to prepare hot water. Compared to battery circuits, it has significant advantages.

For flowing hot water, a parallel single-stage scheme, sequential and mixed two-stage schemes are used.

Parallel one-stage circuit with one heat exchanger connected to the supply pipeline of the heating network in parallel with the heating system ( rice. one) is simple and inexpensive.

The two-stage DHW scheme is used to reduce the water temperature in the return pipeline and the total water flow from the heating network. To do this, the heat exchange surface of the DHW heat exchanger is divided into two sections, called steps. Cold in the first stage tap water heated by water leaving the heating system. Then, the water heated in the first stage of the heat exchanger is heated together with the recirculation water to the required temperature (55-60 °C) by heating water from the supply pipeline of the heating network.

With a sequential DHW scheme, the second stage is connected before the heating system to the supply pipeline ( rice. 2). First, hot network water passes through the second stage of the DHW, then enters the heating system. Thus, it may turn out that the temperature of the heat carrier will not be sufficient to cover the heat losses of the building. Then during the selection a large number hot water during peak hours, the building connected to the IHS may not heat up enough. Because of the storage capacity building structure this does not affect the comfort in the rooms if the period of insufficient heat supply does not exceed approx. 20 minutes. For the summer non-heating period, there is a switchable bypass, through which the network water after the second stage enters the first stage of the DHW, bypassing the heating system.

The mixed two-stage DHW scheme is distinguished by the fact that its second stage is connected to the supply pipeline of the heating network in parallel to the heating system, and the first stage is connected in series ( rice. 3). The network water leaving the second stage of the hot water supply is mixed with the return water from the heating system and also passes through the first stage.

Thus, the comfort in the premises of a building with a mixed two-stage DHW scheme does not decrease, however, more network water is consumed than with a sequential DHW scheme ( rice. 4).

* Based on the book by N.M. Singer and others. "Improving the efficiency of heat points." M., 1990.

The two-stage scheme is most widely used in residential buildings with significant in relation to heating loads on hot water supply. In buildings with very low or high heat loads, DHW compared to heating (1< Q ГВС /Q О < 5), по действующим нормам, применяется параллельная одноступенчатая схема ГВС.

AT Western countries Recently, more and more people are thinking about the use of a flow-through method of hot water supply, especially after the recognition of the serious danger of infection with legionella - bacteria that multiply in a stagnant warm water. Strict regulations already adopted in European countries provide for regular thermal disinfection of storage tanks and hot water pipes connected to them, including recirculation pipes. Disinfection is carried out by raising the temperature in the entire system by certain time up to 70 °C and above. The complication of accumulator circuits necessary for this especially reveals the advantages of DHW flow systems with plate heat exchangers. They are simple and compact, require less investment, while providing lower return temperatures and lower heating water costs.

More low temperature water in the return pipeline of heating networks reduces heat losses and increases the efficiency of electricity generation at a combined heat and power plant. Lower consumption of network water requires smaller diameters of pipelines of heating networks and lower consumption of electricity for its pumping.

Control options
Many firms are currently working on automatic regulators that would provide comfortable temperature hot water with an accuracy of 1-2 °C or less. In accumulator tanks, the uniformity of heating is achieved by natural or artificial mixing of the incoming water with the water in the tank.

For this purpose, in DHW flow systems, especially with low and rapidly changing flow rates, when regulating the temperature of hot water, it is necessary to take into account, in addition to temperature, as a second value, the flow rate. Leading manufacturing companies have developed regulators for a small - for one consumer - consumption, operating without auxiliary energy. These controllers take into account both the flow and the temperature of the hot water. Unlike conventional thermostatic regulators, in the absence of hot water flow, these devices can generally stop the supply of heating coolant, which protects the DHW heat exchanger from the formation of lime deposits.

In systems of flowing hot water with a large consumption of hot water, flow fluctuations, compared with its general meaning, less, and satisfactory temperature control accuracy can be achieved by using both thermostatic and electronic controllers. However, in electronic controllers it is necessary to smooth the control curve the right choice the control law and the characteristics of the control valve itself - the stroke speed of the regulator drive, the diameter of the valve Du, its hydraulic resistance k VS - in order to exclude oscillation phenomena in the entire range of its operation. The constant opening and closing of the regulator at a high frequency exposes the DHW plate heat exchanger to high thermal and hydraulic loads, which will lead to its premature failure due to the occurrence of external or internal leaks.

In order to prevent fluctuations with large differences in hot water flow or with significant fluctuations in the temperature of the heating water, for example 150-70 °C, it is advisable to install two parallel regulators of different diameters, which - by themselves - optimally provide a certain range of heating water flow ( rice. 5).

As noted above, in the absence of hot water analysis, for example in systems without recirculation or with regular shutdowns of the water supply, it is necessary to protect the heat exchanger from carbonate deposits by stopping the supply of heating water. At high flow rates, this can be achieved using combined regulators with two temperature sensors - heated and heating water - at the heat exchanger outlets ( rice. 6). The second sensor, set, for example, to 55 °C, stops the supply of coolant to the heat exchanger even if the hot water temperature sensor is installed far from the heat exchanger and is not affected by the heating medium due to the lack of water intake. At a temperature in the heat exchanger of 55 °C, the process of deposition of hardness salts slows down significantly.

The closer the sensors are installed to the environment, the parameters of which are subjected to regulation, the more quality regulation can be achieved. Therefore, it is desirable to install temperature sensors, if possible, deeper into the corresponding fittings of the heat exchanger. To do this, you can use plate heat exchangers with fittings on both sides of the plate pack, where a temperature sensor is inserted into one of the fittings, and the other serves to select the coolant. Then the sensor is washed by the coolant even before it exits the heat exchanger, and in the absence of coolant circulation, the sensor records the temperature of the medium under the influence of thermal conductivity and natural convection, which would not have occurred if it was installed outside the heat exchanger.

Two-stage DHW schemes are distinguished by the fact that in the first stage of heating, heat is taken from the return water of the heating system. Due to the discrepancy between the heat loads of heating and hot water in winter or night mode, it may turn out that hot water heated above the required 55-60 °C. For example, with a heat carrier with a temperature of 70 ° C (calculated point), DHW water can be heated up to 67-69 ° C even in the first stage. To exclude overheating and intensive deposits of carbonates at these temperatures, it is possible to install a regulating three-way valve at the inlet or outlet of the heat exchanger ( rice. 7). Its task, depending on the temperature of the coolant at the outlet of the heat exchanger, is to pass heating water through the heat exchanger or past it - along the bypass. The three-way valve sensor is installed in the return pipe. It simultaneously with the regulation of the temperature of the heating medium indirectly limits the temperature of hot water. At the same time, heat extraction from the return pipeline is not limited, but optimized, increasing the reliability and comfort of hot water supply.

In favor of a brazed heat exchanger
In Western countries, in the vast majority (over 90%) of cases, brazed plate heat exchangers are used for hot water purposes. This is due to the relative cheapness and ease of maintenance of these devices.

As a rule, Russian and Ukrainian customers who have experience in operating high-speed shell-and-tube heat exchangers, which often require cleaning, prefer gasketed plate heat exchangers. However, it should be taken into account that these devices are equipped with gaskets made of polymer (rubber) materials, which are subject to aging - crack, become brittle. After five years of operation, when repairing a gasketed plate heat exchanger, it is often no longer possible to ensure its satisfactory density. And the purchase of a new set of seals comes at a price, sometimes almost comparable to the price of a new heat exchanger.

If the seals are attached to the plates with adhesive, then replacing them involves such work as destroying the existing seals in liquid nitrogen and gluing new ones. For their implementation, special devices and highly qualified personnel are required. Heat exchanger manufacturers provide customer service, but the heat exchanger often needs to be sent to a specialized facility. All this led to the widespread use in Western countries of brazed plate heat exchangers for hot water purposes.

Note: doubts about the possibility of using brazed heat exchangers in the countries of the post-Soviet space, associated with bad quality coolant are not justified - hard water is found all over the world. It is only necessary to correctly adjust the DHW and limit the temperature of the heat exchanger walls, as described in the previous section.

Brazed plate heat exchangers are chemically washed. If insufficient heating of hot water or return cooling is noticed, and chemical composition water is characterized by a high content of hardness salts, it is necessary to regularly flush the heat exchanger with special solutions that do not destroy either the walls of the heat exchanger or the copper solder. The customer can carry out flushing on his own: this work is simple, flushing units and reagents are affordable and pay for themselves quickly.

At ultra-high heating water temperatures (for example, if temperature graph 150/70 °C), when it is not excluded that the temperature of the heat exchanger wall exceeds the temperature at which intensive scale formation occurs, a preliminary decrease in the temperature of the heat carrier before the heat exchanger is required. There are two ways to do this - pumping scheme injection or elevator scheme. In the first case, a separate sensor is required to turn on the pump, a significant amount of electricity is consumed; the equipment used is subject to wear and tear. elevator scheme extremely simple, thermostatic drive does not depend on electrical network and more economical in implementation and operation ( rice. eight). Connecting the suction pipe of the elevator to the return pipeline of the heating system gives an additional effect of lowering the temperature in the return pipeline of heating networks.

Point solution
A two-stage DHW scheme requires two heat exchangers - for the first and second stages. The choice of heat exchangers by power, that is, the division of the total power into steps, - not an easy task, requiring several iterations in the calculations (their implementation is the responsibility of the supplier). The absence of mass-produced DHW units with a two-stage scheme is due to certain deadlines supplies.

Two brazed heat exchangers need to be tied together with pipelines. The piping takes up space and accounts for a significant part of the cost of a two-stage DHW module. Therefore, manufacturers began to produce brazed heat exchangers with an intermediate dividing wall and six fittings.

The piping of heat points based on them is simplified, but problems with the calculation and the lack of mass production remain.

In addition, during operation, there are periods when the first or second stages of the system are not loaded at all. Yes, in summer period the second stage would be enough, and at the calculated heating point - the first.

The author of this article has developed and patented a solution for a mixed two-stage DHW scheme, including one commercially available brazed plate heat exchanger ( rice. nine). Its essence lies in the use of a special fitting inserted into one of the serial fittings. Through this fitting, both return water from the heating system and hot network water from the heating network are supplied. The heat exchange surface is fully engaged in any mode.

The hot water system has much in common with the cold one. So network hot water supply can be:

with bottom and top wiring;

dead end or ring.

But unlike a cold water supply, the ring network is performed for a different purpose - maintaining a high temperature at the consumer.

The dead-end scheme has the lowest metal consumption, but due to the fact that there is no circulation here, there is a significant discharge of water into the sewer (due to cooling of the water in the risers).

Such a scheme is used in buildings with a height of up to four floors or if heated towel rails are not provided on the risers, and the length of the network is quite small (Fig. 4.4).

Hot water supply schemes with a circulation pipeline are different. If the length of the main pipelines is large, then apply top wiring diagram, and the circulation pipeline closes only the circulation network (Fig. 4.5).

In the diagram in fig. 4.6. circulation pipeline is being laid with lower line wiring. In this case, water circulation in the absence of water intake is carried out under the action of gravitational pressure, which occurs in the circuit due to the difference in densities of cooling and hot water. Cooled water flows down and is fed into the water heater. The water released from it has a higher temperature, thus there is a constant water exchange.

If the length of the main pipelines is large, and the height of the risers is limited, then apply a circuit looped with the supply and circulating lines.(The circulating water is supplied by a pump). In this scheme, some cooling of water can also be observed, but its volume is insignificant, and therefore the length of the network can be increased.

The most widespread in the hot water supply system are two-pipe schemes, in which circulation through risers and mains is carried out using a pump that takes water from the return line and supplies it to the water heater (Fig. 4.7).

The scheme with one-sided connection of water points to the supply riser and with the installation of heated towel rails on the return riser is the most common. This scheme the most reliable in operation, but its disadvantage is a large metal consumption.

To reduce the metal consumption (Fig. 4.8), the supply risers are combined by a jumper with one circulation riser. This scheme is used in public buildings where there are no heated towel rails.

There are three main schemes for connecting heat exchangers: parallel, mixed, serial. The decision to apply this or that scheme is made by the design organization based on the requirements of SNiP and the supplier of heat coming from their energy capacities. In the diagrams, the arrows show the passage of heating and heated water. In the operating mode, the valves located in the jumpers of the heat exchangers must be closed.

1. Parallel circuit

2. Mixed scheme

3. Sequential (universal) circuit

When the DHW load significantly exceeds the heating load, hot water heaters are installed on heating point according to the so-called one-step parallel circuit, at which the hot water heater is connected to the heating network in parallel with the heating system. The constancy of the temperature of tap water in the hot water supply system at the level of 55-60 ºС is maintained by the RPD direct-acting temperature controller, which affects the flow of heating network water through the heater. When connected in parallel, the consumption of network water is equal to the sum of its costs for heating and hot water supply.

In a mixed two-stage scheme, the first stage of the DHW heater is connected in series with the heating system on the heating water return line, and the second stage is connected to the heating network in parallel with the heating system. At the same time, tap water is preheated by cooling the network water after the heating system, which reduces heat load second stage and reduces the total consumption of network water for hot water supply.

In a two-stage sequential (universal) scheme, both stages of the DHW heater are connected in series with the heating system: the first stage - after the heating system, the second - before the heating system. The flow regulator, installed in parallel with the second stage of the heater, maintains a constant total flow of network water to the subscriber input, regardless of the flow of network water to the second stage of the heater. At hours maximum loads DHW all or most of the network water passes through the second stage of the heater, cools in it and enters the heating system with a temperature below the required one. In this case, the heating system receives less heat. This undersupply of heat to the heating system is compensated during hours of low loads of hot water supply, when the temperature of the network water entering the heating system is higher than required at this outdoor temperature. In a two-stage sequential scheme, the total consumption of network water is less than in a mixed scheme, due to the fact that it uses not only the heat of network water after the heating system, but also the heat storage capacity of buildings. Reducing network water costs helps to reduce the unit cost of external heating networks.

The scheme for connecting hot water heaters in closed heat supply systems is selected depending on the ratio maximum flow heat for hot water supply Qh max and maximum heat flow for heating Qo max:

0,2 ≥	Qhmax	≥ 1 - single-stage scheme
	Qomax

0,2 <	Qhmax	< 1 - two-stage scheme
	Qo ma

Providing hot water to a multi-storey building is not easy, because the DHW system must have water under a certain pressure and at a certain temperature. This is the first. Second: the hot water supply of an apartment building is a long way of the water itself from the boiler house to consumers, in which there is a huge amount of various equipment, devices and appliances. In this case, the connection can be made according to two schemes: with upper or lower wiring.

Network diagrams

So, let's start with the question of how water enters our homes, I mean hot. It moves from the boiler house to the house, and is distilled by pumps installed as boiler equipment. Heated water moves through pipes called heating mains. They can be laid above or below ground. And they must be thermally insulated in order to reduce the heat loss of the coolant itself.

Ring connection diagram

The pipe is brought to apartment buildings, from where the route is branched into smaller sections that supply the coolant to each building. A pipe of smaller diameter enters the basement of the house, where it is divided into sections that deliver water to each floor, and already on the floor to each apartment. It is clear that such an amount of water cannot be consumed. That is, all the water pumped into the hot water supply cannot be consumed, especially at night. Therefore, another route is being laid, which is called the return line. Through it, water moves from the apartments to the basement, and from there to the boiler room through a separately laid pipeline. True, it should be noted that all pipes (both return and supply) are laid along the same route.

That is, it turns out that the hot water itself inside the house moves along the ring. And she is constantly on the move. In this case, the circulation of hot water in an apartment building is carried out precisely from the bottom up and back. But in order for the temperature of the liquid itself to be constant on all floors (with a slight deviation), it is necessary to create conditions under which its speed is optimal, and it does not affect the decrease in the temperature itself.

It should be noted that today separate routes for hot water supply and for heating can approach apartment buildings. Or one pipe with a certain temperature (up to + 95C) will be supplied, which in the basement of the house will be divided into heating and hot water supply.

DHW wiring diagram

By the way, look at the photo above. A heat exchanger is installed in the basement of the house according to this scheme. That is, water from the route is not used in the hot water supply system. It only heats the cold water coming from the water supply network. And the DHW system at home is a separate route, unrelated to the route from the boiler room.

The house network is circulating. And the water supply to the apartments is produced by a pump installed in it. This is by far the most modern scheme. Its positive feature is the ability to control temperature regime liquids. By the way, there are strict norms for the temperature of hot water in an apartment building. That is, it should not be lower than +65C, but not higher than +75C. In this case, small deviations in one direction or another are allowed, but not more than 3C. At night, deviations can be 5C.

Why is this temperature

There are two reasons.

The higher the water temperature, the faster pathogenic bacteria die in it.
But you have to take into account the fact that the high temperature in the DHW system is burns when in contact with water or metal parts of pipes or mixers. For example, at a temperature of +65C, a burn can be obtained in 2 seconds.

Water temperature

By the way, it should be noted that the water temperature in the heating system of an apartment building can be different, it all depends on various factors. But it should not exceed + 95C for two-pipe systems, and + 105C for single-pipe systems.

Attention! According to the legislation, it is determined that if the temperature of the water in the DHW system is 10 degrees below the norm, then the payment is also reduced by 10%. If it is with a temperature of +40 or +45C, then the payment is reduced to 30%.

That is, it turns out that the water supply system of an apartment building is available in type of DHW, This individual approach payable, depending on the temperature of the coolant itself. True, as practice shows, few people know about this, therefore disputes usually never arise on this issue.

Dead End Schemes

There are also so-called dead-end schemes in the DHW system. That is, water enters consumers, where it cools down if it is not used. Therefore, in such systems there is a very large overrun of the coolant. Such wiring is used either in office premises or in small houses - no more than 4 floors. Although all this is already in the past.

The best option is circulation. And the simplest thing is to enter the pipe into the basement, and from there through the apartments through the riser, which runs through all floors. Each entrance has its own stand. Reaching the top floor, the riser makes a U-turn and, past all the apartments, descends into basement, through which it is output and connected to the return pipeline.

dead end scheme

Wiring in the apartment

So, consider the water supply scheme (HW) in the apartment. In principle, it is no different from cold water. And most often, hot water pipes are laid next to the cold water elements. True, there are some consumers who do not need hot water. For example, a toilet, washing machine or dishwasher. The last two themselves heat the water to the required temperature.

Wiring diagram for hot water and cold water pipes

The most important thing is that the distribution of water supply in the apartment (both hot water supply and cold water) is a certain norm for laying the pipes themselves. For example, if the pipes of two systems are laid one above the other, then the top one should be from hot water supply. If they are laid in a horizontal plane, then the right one should be from the DHW system. In this case, on one wall it may be in the depth of the strobe, and on the other, on the contrary, closer to the surface. In this case, the laying of the pipeline can be hidden (in strobes) or open, laid on the surface of walls or floors.

Conclusion on the topic

The seeming simplicity of hot water supply in apartment buildings is determined by the inhabitants by piping inside the apartments. Actually it's enough big variety various schemes in which pipes are stretched for several kilometers, starting from the boiler room and ending with a mixer in the apartment. And, as practice shows, even in old houses today the hot water supply is being reconstructed for new improved technologies that provide hot water and reduce the loss of heat itself.

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