Circulation riser

The pipeline for hot centralized water supply cannot be made 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 hot water in apartment building according to the same scheme, 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 the cold water from the riser, wait for warm, and then hot water - this is an excessively high consumption. 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 a centralized hot water supply system, 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 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.

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.

The circulation riser is laid to the right of the hot riser.
Connecting the risers to the supply pipeline at the lower (a, b and upper distributions (c). The circulation risers and the prefabricated circulation pipeline are used to transport the water cooled in the system back to the water heater (or boiler) for heating to the required temperature.
Diagrams of circulation flow rates in the upper and lower zones of the hot water supply system of the Salute Hotel in Moscow with open (a and closed jumpers (b). The circulation risers of both zones of the system are connected to the elevator as follows: the riser of the upper zone is connected to the nozzle, and the riser of the lower zone of the system is connected to the expansion chamber By dampening the excess pressure of the upper zone, the elevator creates a pressure difference in the lower zone of the system, under the influence of which water circulates in it. This difference is relatively small in magnitude, therefore, to maintain water circulation during water collection, when in the water heater and the supply pipeline of the lower zone. pressure losses increase, the supply and circulation pipelines of the system are connected by a jumper pipeline. In the hot water supply system of the hotel, one common elevator was installed at the heating point, serving four sectional units simultaneously.
Diagram of a hot water supply system with risers connected at the top. With the latter, the circulation riser is mounted in front of the risers (counting along the flow of water in the main); all valves on risers, connections and jumpers are replaced with straight-through taps, in which water movement in both directions is possible; the circulation line is dismantled.
We find the diameters of the circulation riser 14 in a 12-story building.
Changing the resistance of circulation risers can be done by changing their diameters, including the height of the riser, using throttling diaphragms and control valves. However, the use of such measures in systems large radius This action is impractical, since this will require the use of diaphragms with small hole diameters or tightly covered control valves, which is undesirable due to the possibility of frequent blockages. In addition, in many cities the commissioning of the first and last houses connected to common system hot water supply, separated by a large period of time (one to three years), which greatly complicates the implementation commissioning work.
The diameter of the circulation riser pipeline is selected according to the nomogram of the recommended appendix.
In this case, the smaller diameter of the circulation riser is connected to the ring jumper of the unit, and the larger diameter is connected to the circulation pipeline of the quarterly network.
Elementary diagram of a hot water system with paired risers.| Schematic diagrams ringing and combining water distribution units. Water distribution units consist of supply and circulation risers, heated towel rails and connections to water distribution devices. In addition to their direct purpose, they also serve as heating devices, providing these rooms with elevated temperature air. In cases where the systems do not have circulation pipelines, the standards allow the connection of heated towel rails to the heating system, with the installation of a separate branch and ensuring year-round circulation of water in this branch.
Scheme of hot water supply with circulation risers. Hot water supply schemes with circulation risers (Fig. 265) are used where cooling of the water in the pipes is not allowed, for example in multi-storey residential buildings and hotels.

Hot water supply schemes with circulation risers (Fig. 200) are used where cooling of the water in the pipes is not allowed, for example in multi-storey residential buildings, hotels, hospitals and other buildings. Hot water supply systems come with an upper or lower distribution line.
Two-pipe hot water supply systems with circulation risers (Fig. 175) are used where cooling of the water in the pipes is allowed, for example in multi-storey residential buildings, hotels, hospitals and other buildings.
The hot water supply system is designed without the installation of circulation risers; but with ringing of risers in the upper floors. Heated towel rails in in this case installed directly on the riser - rather than the riser using a flow-through design, which ensures compensation of the risers.
Schematic diagram of hot water in tall buildings. In this case, it is allowed to install heated towel rails on the circulation riser.
The hot water supply system was designed according to a new scheme without the installation of circulation risers, but with ring risers in the upper floors.
HTU dependency. In this case, we will assume that there is no water flow in the circulation riser of the sectional unit in water withdrawal mode. To take into account the uneven application of drainage, we assume that in half of the water draw-off risers of the sectional unit there is no draw-off, and in the other half of the risers, water draw-off points are evenly distributed throughout the risers every three floors.
In this scheme, circulation risers are laid from the last water withdrawal point of each riser, which are then combined into a collection circulation line, which is connected to the bottom of the water heater.
What requirements must be met when installing hot water supply systems without circulation risers.
If circulation through risers is provided, then the connection of the circulation riser to the supply pipe should be made below the highest water intake.
In hot water networks shut-off valves installed: at the base of supply and circulation risers in buildings and structures 3 floors high; on pipeline branches to sectional units.
If it is necessary to connect water-circulation risers to the supply pipeline and lay additional circulation risers, the diameters of the latter are recommended to be determined based on the condition of increased pressure loss in the sectional unit in order to increase the hydraulic stability of the system.
Some buildings still use hot water supply systems with individual circulation risers at each water riser. This scheme of intra-house systems can have satisfactory quality indicators only in small systems servicing one building or a very small group of compactly located buildings. There are also projects for hot water supply systems in which heated towel rails on each floor are connected to both the water supply and circulation risers. The use of such schemes leads to significant complications for the operation service, since it is impossible to organize in them a more or less uniform distribution of circulation along the risers.

The scheme with sectional units (Fig. 6.4, b) makes it possible to reduce the length of the circulation risers, since one circulation riser is laid for 3 to 8 supply risers. This system widely used in residential sectional buildings.
Schematic diagrams of hot water supply systems. Shut-off valves are installed: on all branches from main pipelines; at the bases of supply and circulation risers in buildings of three floors or more; on branches to each apartment and on branches feeding five or more water points.
The risers of hot water supply systems are usually located to the right of the cold water supply risers, the circulation riser is located to the right of the hot water supply riser. The distance between the axes of risers with a diameter of up to 32 mm is taken equal to 80 mm; for larger diameters it can be increased based on the convenience of pipeline assembly. When laying pipelines in parallel horizontally hot pipe located above the cold one.
Shut-off valves are installed on branches to sectional units, individual buildings or structures, at the base of supply and circulation risers in buildings with a height of three floors or more, also on branches to each apartment or room in which there are water dispensing devices. To prevent the movement of water in the opposite direction through the circulation pipeline, there is a check valve.
In bathrooms, provision should be made for the installation of constantly heated heated towel rails, usually connected to circulation risers. In buildings up to 4 floors high, inclusive, in the absence of circulation units, and in other individual cases, depending on local conditions, heated towel rails may be attached to the heating system.
Numerical analysis of the resulting formula showed that the parameters a to p have little effect on the accuracy of the results for isolated circulation risers of sectional units.
Shut-off valves for hot water supply systems are valves installed on all branches from the main pipelines, at the bases of supply and circulation risers (in buildings three floors or more high), on branches to each apartment or feeding five or more water points. The sealing gasket in the valves of these valves is made of heat-resistant material - fiber.
Shut-off valves for hot water supply systems are valves installed on all branches from the main pipelines, at the bases of supply and circulation risers (in buildings three floors or more high), on branches to each apartment or feeding five or more water points. The sealing gasket in the valves of these valves is made of heat-resistant material - fiber.
In hot water supply systems, shut-off valves should be installed: on all branches from the main pipelines; at the bases of supply and circulation risers in buildings three or more floors high; on branches to each apartment; on branches feeding five or more water points. In hot water supply systems, install automatic regulators temperature of hot water, and in places where water is drawn - mixers that mix hot and cold water to a given temperature.
Compensators and their installation diagrams. If it is planned to connect heated towel rails to the hot water supply system, then they should, as a rule, be connected to the circulation risers.
For buildings with a height of nine floors or more, the pipelines of the water risers must be looped at the top with jumpers and connected to a common circulation riser. In shower rooms (the number of shower nets is more than three), the distribution pipeline must also be looped.
Currently, hot water supply systems serving residential and public buildings are usually installed with circulation risers.
Modern large systems hot water supply, serving a group of buildings from a single thermal center, almost completely eliminate the possibility of differentiated changes in the resistance of the circulation risers. In-house systems are made from standard unified pipeline units with a significant part of the installation operations transferred from construction site onto the factory assembly line.

Ringing of water risers into sectional units is not carried out in cases where the total length of the individual (for each water riser) circulation risers is less than the length of the ring lintel, if it is not possible to lay the ring lintel in the attic of the building or under the ceiling of the upper floor.
Temperature the system is regulated by temperature regulators, which are located after the water heater, as well as on the circulation lines of individual buildings, at the base of the circulation risers.
To reduce metal consumption, in recent years they have begun to use a scheme (Fig. 12.5), in which several supply risers are combined by a jumper with one circulation riser. This solution to the hot water supply scheme is most often used for public buildings, where installation of heated towel rails is not provided. The scheme is characterized by low performance indicators, since the upper jumper is made of pipes of the same diameter as the supply risers; its resistance exceeds the resistance of the mains, so water moves only in risers close to the circulation one.
The hot water supply system consists of the following elements (Fig. 1.14): hot water heater; distribution pipelines (main and risers); circulation risers and mains; storage tanks; circulation pumps; water fittings. Heat exchangers are used as a heater in both group and house hot water supply systems (if connected heating point to a centralized heating system) or boilers. In water heating systems for heating tap water Tubular high-speed sectional water heaters with brass tubes are used. In recent years, due to the shortcomings of tubular sectional water heaters, it has been proposed to use plate water heaters to heat water for hot water supply, which are installed at a number of central heating points in Moscow, Kharkov and the Moscow region.
These costs are determined total losses pressure through each water riser from the point(s) of connection of the sectional unit to the supply main to the point of connection of the circulation riser to the ring jumper.
Reduced temperature for consumers it is possible: due to the absence or insufficient circulation in the hot water supply system; malfunction or lack of thermal insulation of pipelines; blockage in the supply or circulation riser; cross-flow cold water into the pipelines of the hot water supply system through faulty fittings. To reduce the discharge of chilled water, it is recommended to turn on the circulation pump 0 5 - 1 hour before the start of morning water collection.
In the circulation mode (in the absence of water withdrawal, equal water flow rates, values of k0 and F in all sections of the sectional unit), the final temperature of the water entering the circulation riser can be determined by formula (6.6), in which the value of F is the total area of the heat transfer surface of all water risers of the sectional unit.
In centralized hot water supply systems serving a group of buildings, it is possible to combine the pipelines of draw-off and circulation drains into sectional units, and also to connect groups of pipelines of circulation risers to the circulation pipeline at one point.
A decrease in temperature is possible for various reasons: insufficient heating from the coolant - it is necessary to check the operation of the flow regulator by increasing the flow network water from thermal power plant; violation or absence of thermal insulation of main pipelines - it is necessary to inspect the network and perform thermal insulation work; scale deposits, overgrowth of supply pipelines or blockages in circulation risers - it is necessary to carry out hydropneumatic cleaning of pipes with compressed air and water under a pressure of 0 7 MPa and at a speed of 3 m / s or washing of pipes with a 20% solution of inhibited acid to dissolve the formed scale, followed by washing clean water; flow of cold water into the hot water pipe riser through a faulty mixing water fitting - it is necessary to replace the mixer with a working one.
Hot water supply risers are mounted to the right in relation to cold water supply risers. The circulation riser is laid to the right of the hot riser.
Diameters of circulation risers in the same type in-house systems remain unchanged regardless of their location. There are no adjustment diaphragms in these risers. Therefore, as you approach the beginning of the system (heating point), the circulation flow in the risers increases. In systems of this type, the largest temperature drop occurs only in the last riser. Therefore, the total circulation flow is determined taking into account the uneven distribution of flows along the risers and is checked for the permissible amount of water cooling in the last riser of the system.
Therefore, tanks are heated with a steam coil circulation system. It consists of a circulation riser 3, a steam piston pump 4, 5 heat exchangers for steam pressure up to 12 atm and piping systems. Steam circulation is carried out after preliminary local heating of the material by means of a small steam coil, which is lowered into the neck of the tank by blocks and a winch. Local heating of softeners is necessary to ensure initial absorption of the product. The jumper system makes it possible to drain the product through the neck using the circulation pump 4 in the event that the tank supplied to the plant does not have a bottom drain.

The pipeline for hot centralized water supply cannot be made 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 the cold water from the riser, wait for warm, and then hot water - this is an excessively high consumption. Therefore, hot water supply pipelines are made in a loop: water is heated in a boiler room, heating unit or boiler room and supplied through the supply pipeline to consumers and returned back to the boiler room through another pipeline, which in this case is called circulation.

In a centralized hot water supply system, 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. Heating devices - heated towel rails - are placed on the outlet circulation riser. 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.

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.

Hot water supply system (DHW) is a set of devices that provide heating of cold water and its distribution to water distribution devices.

DHW systems are divided into centralized and local (decentralized).

In centralized systems, one water heating unit in the boiler room or central heating station serves hot water one or more large buildings within a residential microdistrict, block or village. All centralized systems DHW systems are designed with circulation pipelines to provide consumers with hot water, since without them, in the absence of water tapping, the water in the supply lines quickly cools down and the consumer is forced to drain it, losing water and heat. In addition, heated hot water systems are equipped with heated towel rails, which are necessary for drying clothes and heating bathrooms and cannot work in the absence of circulation.

Circulation pipelines and circulation pumps create a continuous movement of water (circulation) along a closed circuit: heat exchanger - supply pipeline - water tap - circulation pipeline - heat exchanger, maintaining the temperature of hot water at the water tap at 50-60 ° C. At this temperature, most of the pathogenic bacteria contained in the water die (pasteurization effect), food fats, oils and household contaminants emulsify well - they dissolve in water and are washed away by its flow when washing dishes and washing clothes. To enhance these processes, the industry produces a variety of soaps, synthetic detergents, cleaning powders and emulsifiers.

To wash the body, people usually use hot water at a temperature of 35-40 °C in bathtubs and up to 45 °C during bathing procedures, diluting the hot primary water with cold water using mixing taps and devices.

In recent years, in buildings with a height of 5 floors or more, part of the supply risers (for example, from 3 to 7 risers of one section of a residential building) are combined into one water distribution unit, called a sectional unit, with a single circulation pipe. In buildings with a height of more than 50 m (over 16 floors), the hot water system is divided vertically into separate zones with independent distributions and separate risers for each zone, sometimes even with the construction of special technical floors. This is due to the limitation of the permissible pressure in front of the water supply and water shut-off valves to 0.6 MPa.

Local (dead-end) hot water systems are installed in individual houses (country houses, cottages, semi-detached houses) or apartments. Their range of action is small; hot water is prepared in small heat generators (electric, gas water heaters, small boilers, etc.). Often such a heat generator is common to both the heating system and the DHW system; they are called double-circuit. Double-circuit boiler it is often enough to prepare hot water for a family of 3-4 people. For large families, sometimes a capacitive boiler is attached to the hot water boiler.

At industrial and municipal enterprises (baths, laundries, dry cleaners, swimming pools), along with high-speed water supply installations, steam-water hot water heaters are widely used.

For internal pipelines of cold and hot water, SNiP 2.04.01-85* recommends the use of plastic pipes and fittings made of polyethylene, polypropylene, polyvinyl chloride, polybutylene, metal-polymer, fiberglass and other plastic materials for all water supply networks, except for an independent network fire-fighting water supply.

The laying of plastic pipes is carried out mainly hidden - in baseboards, grooves, shafts and channels in the floor pouring. Open laying of connections to sanitary fixtures is allowed, as well as in places where mechanical damage to plastic pipelines is excluded. For all internal water supply networks, it is allowed to use copper, bronze and brass pipes, fittings, as well as steel pipes with internal and external protective coating from corrosion.

To avoid rapid destruction from internal corrosion, hot water supply systems are made of galvanized pipes with a slope of the distribution pipes to the risers of at least 0.002. For pipe diameters of more than 150 mm in open systems for heat supply, the use of non-galvanized black pipes is allowed.

For agricultural enterprises it is allowed to use asbestos cement pipes. In DHW and cold water systems, fittings for ordinary general industrial purposes are used, designed for operating pressure up to 0.6 MPa. Pipes are connected by threading or welding in a carbon dioxide gas environment. To compensate for thermal elongation, either natural pipe turns or special compensators are used.

Shut-off valves are installed on branches to individual buildings and structures, on branches to sectional units and on branches from risers to each apartment. To repair individual risers, shut-off valves with plugs are installed at their upper and lower points to drain water from the risers and let air into them.

Water consumption rates, l, per 1 resident of residential buildings

Water consumption time	In an apartment-type residential building		In a residential building with a high level of amenities
Water consumption time	Total cold water flow	Including hot water supply	Total cold water flow	Including hot water supply
On an average day
On the day of greatest water consumption
At the hour of greatest consumption

All pipelines of the DHW system, with the exception of apartment connections and heated towel rails, must have thermal insulation. The thickness of the thermal insulation layer of the structure must be at least 10 mm, and its thermal conductivity must be at least 0.05 W/(m °C).

Water consumption rate (in liters per inhabitant), for example, in an apartment-type residential building with centralized hot water supply (with bathtubs 1500-1700 mm long, equipped with showers) and in a residential building with increased requirements for improvement (with a building height of 12 floors and above) ranges from 250 to 400 liters per day (table above).

The physiological (drinking) need of a person ranges from 5 l/day (at rest) to 10 l/day (during heavy physical work).

Determination of heat flows for hot water supply is carried out according to SNiP 2.04.02-84.

Basic heating devices. In centralized hot water supply systems, water is heated in hot water boilers, open tanks or closed water heaters equipped with coils.

The most commonly used hot water supply system is from a steam boiler and a system from the heating network.

The hot water supply system of a residential building with a steam boiler and a horizontal water heater functions as follows. From the steam collector, steam flows through a steam line into the coil of a horizontal capacitive water heater, where it condenses, heating the water in the water heater. The condensate from the coil flows back into the boiler through the condensation pipe. The water in the water heater is under pressure from the city water supply and is heated to 70 °C. Through the supply pipeline it enters the upper filling, from where it is supplied through hot water supply risers through hot water supply lines to sanitary fixtures. Part of the water is returned through the return pipeline to the water heater through the lower fitting, which prevents the water in the supply line from cooling. As hot water is dispensed, cold water from the water line enters the water heater. A safety device is installed on the water heater lever valve with a drain pipe and a thermometer, and on the boiler - a safety discharge device, a pressure gauge, a thermometer and a water meter glass.

Domestic industry produces steam-water high-speed water heaters MVN-1436 and MVN-1437 and water-water sectional MVN-2052-62, designed for heating water in heating and hot water supply systems.

Water heaters MVN-1436 and MVN-1437 consist of a body, a pipe system, front and rear water chambers and a cap. The body, chambers and cap are made of steel. The pipe system consists of steel support grids and a bundle of brass tubes with a diameter of 16x1 mm or 16x0.75 mm. Heaters are manufactured short - 2040 mm and long - 4080 mm. Water heaters with a diameter of 273 and 325 mm are two-pass, with a diameter of 377 mm and more - four-pass

Water heaters work as follows. Heated water enters through the lower pipe of the front inlet chamber, passes through brass tubes, is heated and through the upper pipe enters the network at the required temperature. The steam that heats the water is supplied to the interpipe space.

Water-to-water water heaters MVN-2052-62 are manufactured in collapsible single and multi-section, long and short. The sections are connected to each other by bolted rollers. The section consists of a body (seamless pipe) with steel tube sheets welded to it and a bundle of brass tubes with a diameter of 16x0.75 mm. Nozzles with flanges are welded to the body to connect the sections along the interpipe space. Water heaters are designed for maximum temperature network water 150 °C and operating pressure of heating and heated water up to 1 MPa.

The circuit with a steam-water high-speed water heater is used for hot water supply systems of large residential buildings, bathhouses, laundries and other large consumers of hot water. In a water heater, the water entering the house network through the inlet is heated to the required temperature. A high-speed water heater is instantaneous, the consumed water flows at a significant speed through the heating tubes - tubular heating elements, which in turn are heated by water from the heating network passing inside the body of the water heater and washing them. From the water heater, hot water is supplied to the hot water supply system through a pipeline. A regulator is installed on the supply pipeline of the heating network, which automatically maintains a constant flow of water from the heating network, and an air vent. Cold water enters the water heater from the water supply. At the control unit at the input there are valves for disconnecting the heating system pipeline and individual parts node. Water flow in the network is measured using a water meter.

To prevent water from the heating system from entering the heating network pipeline, check valves are installed. To measure water pressure and temperature, pressure gauges and thermometers are installed at individual points of the control unit. Three-way control valves are installed under the pressure gauges, which are screwed into the pipe fittings. High-temperature water from the heating network from the input is mixed with part of the cooled water from the return line of the heating system by an elevator, which has valves installed that regulate the temperature of the mixed water. The mixed water enters the main riser into the heating system and returns to the return pipeline of the heating system through the return pipeline from the heating system. The mud trap is used to catch dirt from the return pipe of the heating system. A heat meter is used to take into account the heat consumed. A pressure regulator is installed on this line.

Hot water supply systems are:

with a dead-end pipeline, where, with little or no hot water being drawn, the water quickly cools down. Therefore, such a scheme is used in low-rise residential buildings with a short network, or in systems where water is constantly dispensed (baths, laundries, etc.);

with circulation risers; Such schemes are used where cooling of water in pipes is not allowed, for example in multi-storey residential buildings and hotels.

Single-pipe centralized hot water supply systems are currently widely used in residential buildings (figure below). In these systems for buildings of 5-9 floors, the risers within the section at the top are connected to each other, and all risers, except one, are connected to the supply line 2, and one lower riser is connected to the circulation main 3. The same goes for the lower riser , like the supply, devices for drawing hot water are connected. To ensure uniform circulation of water in the hot water supply systems of buildings connected to one central heating point, a diaphragm 1 is installed on the downpipe.

Sectional unit of a single-pipe hot water supply system

1 - diaphragm; 2 - supply transit line; 3 - circulation transit Mainline; 4 - plug valve; CV - centralized water supply; GW - hot water supply; i - pipe slope

For residential buildings with more than 9 floors, all hot water supply risers are connected to the supply line and an independent circulation riser is laid, which is connected at the top to the jumper between all supply risers, and at the bottom to the circulation line. In single-pipe systems, the supply line is calculated based on the condition for supplying the estimated amount of hot water. Air removal from hot water supply systems is carried out through an air collector or by connecting a branch to the devices of the top floor to the top level of the riser. At the base of each riser and on the jumpers between the risers, shut-off valves are installed.

With a ring scheme, the risers are assumed to be of the same diameter along the entire height of the building and are usually equal to 25 mm for buildings up to five floors high, and 32 mm for buildings with more floors.

Water heating devices that heat water for domestic needs are: electric, gas, solid fuel, indirect heating of hot water from the coolant of the heating system.

Water heaters are divided into:

flow-through, where water is heated as it moves past heat transfer elements (electric heating elements, copper pipes, plate heat exchangers);

storage, where water is heated in the storage parts of the device using heat transfer elements.

All water heaters can be divided into the following types: gas instantaneous ( geysers), gas storage, electric flow-through, electric storage (with and without a built-in coil), electric storage with a firebox for solid fuel, indirect heating.

The installation of the DHW pipeline is carried out from components and parts prepared at the CZM according to measured sketches or installation projects (figure below).

Installation diagram of a water riser

1 - liner to the washbasin; 2 - connection to the tank; 3 - coupling; 4 - lock nut; 5 - long thread; 6, 9 - tees; 7 - plug; 8 - valve

Hot water supply risers are mounted to the right in relation to cold water supply risers. The circulation riser is laid to the right of the hot riser. The distance between the axes of the risers is 80 mm.

Horizontal piping from risers to appliances should be carried out near the floor: the cold water pipeline is 100 mm above the clean floor, and the hot water pipeline is 200 mm above. Vertical connections to devices must be routed in the same way as risers: hot - on the right, cold - on the left. The pipeline is secured to the wall using clamps.

Hot water supply pipelines with a diameter of up to 70 mm are made from galvanized water and gas pipes. Linen strands impregnated with red lead mixed with natural linseed oil are used as a sealing material. DHW pipes with a diameter of up to 32 mm, they are laid at a distance of 35 mm from the surface of the plaster to the axis of the pipe. Galvanized pipes are assembled on threads using fittings made of malleable cast iron or galvanized steel. Electric welding of galvanized pipes in an environment is allowed carbon dioxide. When welding pipes with a diameter of up to 32 mm, push-in couplings are used (to preserve the live cross-section of the pipes); pipes with a diameter of more than 32 mm are butt welded. Gas welding is not allowed due to significant burnout of zinc. Non-galvanized pipes are connected mainly by welding.

Turns of main pipelines are performed by bending. On small cross-section pipes, it is allowed to install angles at an angle of 90°. In areas of overlap, interior walls and partitions, the pipelines are enclosed in sleeves.

DHW pipelines are laid above cold water supply pipelines. To drain water from the system and vent air, pipes are laid with a slope of 0.002-0.005.

Water heaters horizontal type installed on a metal frame or on brick pillars with a rise of 10-15 mm towards the upper fitting. Between the water heater and brick supports lay asbestos cardboard 5 mm thick so that the metal in places of contact with brickwork did not rust and the water heater could freely expand when heated without destroying the masonry of the columns. A thermometer and a safety valve are installed on the water heater.

Steam hot water boilers mounted, installing additional steam collectors and steam fittings on them.

Hydraulic and thermal tests of the hot water supply network are carried out upon completion of installation. The network is tested for hydraulic pressure higher than the working pressure by 0.5 MPa, but not more than 1 MPa. Before testing, remove air from the system. The test lasts 10 minutes, during which the pressure should not drop by more than 0.05 MPa. At thermal test Hot water supply systems heat water to a temperature of 50-60 °C and check the operation of the system with the number of operating devices provided for in the working documentation. The temperature deviation from the calculated temperature should not exceed 5 °C.

Heat exchangers are tested hydraulic pressure, exceeding 1.5 times the highest working pressure, but not less than 0.3 MPa for the steam part and not less than 0.4 MPa for the water part. The pressure should not drop during testing for 5 minutes. After checking and testing the water supply system, heat exchanger tanks and hot water supply pipelines are insulated to reduce heat loss.

Let’s imagine an ordinary morning in one of the high-rise buildings in a residential area of our beloved city: toilet, shower, shave, tea, brush your teeth, water for the cat (or in any other order) - and off to work... Everything is automatic and without thinking. As long as cold water flows from the cold water tap, and hot water flows from the hot water tap. And sometimes you open a cold one, and from there comes boiling water!!11#^*¿>.

Let's figure it out.

Cold water supply or cold water supply

Local pumping station supplies water to the main line from the water utility network. A large supply pipe enters the house and ends with a valve, after which there is a water metering unit.

In short, the water metering unit consists of two valves, a strainer and a meter.

Some have an additional check valve

and water meter bypass.

The water meter bypass is an additional meter with valves that can feed the system if the main water meter is being serviced. After the meters, water is supplied to the house mains

where it is distributed over risers that lead water to apartments on floors.

What is the pressure in the system?

9 floors

Houses up to 9 floors high have bottom filling from bottom to top. Those. From the water meter, water flows through a large pipe through risers to the 9th floor. If the water utility is in a good mood, then at the input of the lower zone there should be approximately 4 kg/cm2. Taking into account a pressure drop of one kilogram for every 10 meters of water column, residents of the 9th floor will receive approximately 1 kg of pressure, which is considered normal. In practice, in old houses the inlet pressure is only 3.6 kg. And residents of the 9th floor are content with even less pressure than 1 kg/cm2

12-20 floors

If the house is higher than 9 floors, for example 16 floors, then such a system is divided into 2 zones. Top and bottom. Where the same conditions are maintained for the lower zone, and for the upper zone the pressure is raised to approximately 6 kg. In order to raise the water to the very top into the supply main, and with it the water goes in risers to the 10th floor. In buildings above 20 floors, the water supply can be divided into 3 zones. With this supply scheme, water does not circulate in the system, it stands on a backwater. In a high-rise apartment, on average we get pressure from 1 to 4 kg. There are other meanings, but we will not consider them now.

Hot water supply or DHW

In some low-rise buildings The hot water is connected in the same way, it stands on a backwater without circulation, this explains the fact that when you open a hot water tap, cold, cooled water flows for some time. If you take the same house with 16 floors, then in such a house DHW system arranged differently. Hot water, like cold water, is also supplied to the house through a large pipe, and after the meter it goes into the house mains

which lifts the water into the attic where it is distributed along the risers and goes down to the very bottom into the return line. By the way, hot water meters count not only the volume of lost (consumed) water in the house. These counters also count temperature losses (gigocolors)

Temperature is lost when water passes through apartment heated towel rails, which act as risers.

With this scheme, hot water always circulates. As soon as you open the tap, the hot water is already there. The pressure in such a system is approximately 6-7 kg. on the supply and slightly lower on the return to ensure circulation.

Due to circulation, we get pressure in the riser in the apartment of 5-6 kg. and immediately we see the difference in pressure between cold and hot water, from 2 kg. This is precisely the essence of pressing hot water into cold water when plumbing fixtures malfunction. If you noticed that on hot water if your pressure is still higher than on the cold one, then be sure to install a check valve at the cold inlet, and at the hot inlet you can include control valves in the system, which will help equalize the pressure to approximately the same figure as the cold one. Pressure regulator installation example