Hot water heating schemes. Schemes of hot water supply networks

In some cases, it is necessary to install storage tanks to equalize the load of hot water supply, and also, as a reserve, in case of a break in the supply of coolant. Reserve tanks are installed in hotels with restaurants, baths, laundries, for shower nets in production, etc. That's why parallel circuit can be without a battery, with a lower tank-accumulator and with an upper tank-accumulator.

Parallel scheme for switching on a hot water heater

The scheme is used when Q max hot water / Q o ?1. The consumption of network water for subscriber input is determined by the sum of expenses for heating and hot water supply. The water consumption for heating is a constant value and is maintained by the flow regulator RR. The consumption of network water for hot water supply is a variable value. The constant temperature of the hot water at the outlet of the heater is maintained by the temperature controller RT, depending on its consumption.

The circuit has simple switching and one temperature controller. heater and heating network calculated for the maximum DHW consumption. In this scheme, the heat of network water is used insufficiently rationally. The heat of return network water, which has a temperature of 40 - 60 ° C, is not used, although it allows covering a significant share of the DHW load, and therefore there is an overestimated consumption of network water for subscriber input.

Scheme with an upstream hot water heater

In this scheme, the heater is switched on in series with respect to the supply line of the heating network. The scheme is applied when Q max hot water / Q o< 0,2 и DHW load small.

Dignity of this scheme is the constant flow rate of the heat carrier at the heat point during the entire heating season, which is supported by the flow regulator PP. It does hydraulic mode thermal network stable. Underheating of the premises during periods of maximum DHW load is compensated by the supply of network water elevated temperature into the heating system during periods of minimum water intake or in its absence at night. The use of the heat storage capacity of buildings virtually eliminates fluctuations in indoor air temperature. Such compensation of heat for heating is possible if the heating network operates at an increased temperature chart. When the heating network is regulated according to the heating schedule, there is an underheating of the premises, so the scheme is recommended for use at very low DHW loads. This scheme also does not use the heat of the return network water.

With single-stage heating of hot water, a parallel circuit for switching on heaters is more often used.

Two-stage mixed hot water supply scheme

The estimated consumption of network water for hot water supply is somewhat reduced compared to a parallel single-stage scheme. The 1st stage heater is connected sequentially to the return line through the network water, and the 2nd stage heater is connected in parallel with respect to the heating system.

In the first step tap water is heated by return network water after the heating system, which reduces the thermal performance of the heater of the second stage and reduces the consumption of network water to cover the load of hot water supply. The total flow of network water to the heating point is the sum of the flow of water to the heating system and the flow of network water to the second stage of the heater.

According to this scheme, join public buildings having a large ventilation load of more than 15% heating load. Dignity scheme is an independent heat consumption for heating from the heat demand for hot water supply. At the same time, there are fluctuations in the consumption of network water at the subscriber input, associated with uneven water consumption for hot water supply, therefore, a PP flow regulator is installed that maintains a constant water flow in the heating system.

Two stage sequential circuit

The network water branches into two streams: one passes through the RR flow regulator, and the second through the second stage heater, then these streams are mixed and fed into the heating system.

At maximum temperature return water after heating 70?С and the average load of hot water supply, tap water is practically heated to the norm in the first stage, and the second stage is completely unloaded, because. the temperature controller RT closes the valve to the heater, and all the network water flows through the flow controller PP into the heating system, and the heating system receives heat more than the calculated value.

If the return water has a temperature after the heating system 30-40?С, for example, at a positive outside air temperature, then the heating of water in the first stage is not enough, and it is heated up in the second stage. Another feature of the scheme is the principle of coupled regulation. Its essence lies in setting the flow controller to maintain a constant flow of network water to the subscriber input as a whole, regardless of the load of hot water supply and the position of the temperature controller. If the load on the hot water supply increases, then the temperature controller opens and passes more network water or all the network water through the heater, while the water flow through the flow controller decreases, as a result, the temperature of the network water at the inlet to the elevator decreases, although the coolant flow remains constant. The heat that is not supplied during the period of high load of hot water supply is compensated during periods of low load, when the elevator receives a flow of increased temperature. There is no decrease in the air temperature in the rooms, because the heat storage capacity of building envelopes is used. This is called coupled regulation, which serves to equalize the daily uneven load of hot water supply. AT summer period when the heating is turned off, the heaters are switched on sequentially using a special jumper. This scheme is used in residential, public and industrial buildings with a load ratio Q max hot water / Q o ? 0.6. The choice of scheme depends on the schedule of central regulation of heat supply: increased or heating.

advantage sequential scheme compared to a two-stage mixed one is the alignment of the daily heat load schedule, best use coolant, which leads to a decrease in water consumption in the network. The return of network water with a low temperature improves the effect of district heating, because. steam extraction can be used to heat water reduced pressure. The reduction in network water consumption under this scheme is (per heating point) 40% compared to parallel and 25% compared to mixed water.

Flaw- inability to complete automatic regulation thermal point.

Two-stage mixed scheme with limitation of the maximum input water flow

It has been applied and also makes it possible to use the heat storage capacity of buildings. Unlike the usual mixed scheme The flow regulator is installed not in front of the heating system, but at the inlet to the point of delivery of network water to the second stage of the heater.

It maintains the flow rate below the set value. With an increase in water intake, the RT temperature controller will open, increasing the flow of network water through the second stage of the hot water heater, while reducing the flow of network water for heating, which makes this scheme equivalent to a sequential circuit in terms of the estimated flow of network water. But the second stage heater is connected in parallel, so maintaining a constant water flow in the heating system is ensured circulation pump(an elevator cannot be used), and the pressure regulator RD will maintain a constant flow of mixed water in the heating system.

Open heating networks

Schemes for connecting DHW systems are much simpler. Economical and reliable operation of DHW systems can only be ensured with the availability and reliable operation water temperature controller. Heating installations are connected to the heating network according to the same schemes as in closed systems.

a) Scheme with a thermostat (typical)

Water from the supply and return pipelines is mixed in the thermostat. The pressure behind the thermostat is close to the pressure in the return pipeline, so the DHW circulation line is connected after the water withdrawal point after throttle washer. The washer diameter is selected based on the creation of resistance corresponding to the pressure drop in the hot water supply system. Max Flow water in the supply pipeline, which determines the estimated flow rate for subscriber input, takes place at maximum load DHW and minimum temperature water in the heating network, i.e. in a mode where the DHW load is entirely provided from the supply pipeline.

b) Combined scheme with water intake from the return line

The scheme was proposed and implemented in Volgograd. Used to reduce fluctuations variable flow water in the network and pressure fluctuations. The heater is connected to the supply line in series.

Water for hot water supply is taken from the return line and, if necessary, is heated in the heater. At the same time, the adverse effect of water intake from the heating network on the operation of heating systems is minimized, and the decrease in the temperature of the water entering the heating system must be compensated by an increase in the temperature of the water in the supply pipeline of the heating network in relation to the heating schedule. Applies to load ratio? cf \u003d Q cf hot water /Q o\u003e 0.3

c) Combined circuit with water withdrawal from the supply line

With insufficient power of the water supply source at the boiler house and to reduce the temperature of the return water returned to the station, this scheme is used. When the return water temperature after the heating system is approximately equal to 70?С, there is no water intake from the supply line, hot water supply is provided by tap water. This scheme is used in the city of Yekaterinburg. According to them, the scheme makes it possible to reduce the amount of water treatment by 35 - 40% and reduce the consumption of electricity for pumping the coolant by 20%. The cost of such a heat point is more than with the scheme a), but less than for a closed system. In this case, the main advantage of open systems is lost - the protection of hot water systems from internal corrosion.

The addition of tap water will cause corrosion, therefore the circulation line of the DHW system must not be connected to the return pipe of the heating network. With significant water withdrawals from the supply pipeline, the consumption of network water entering the heating system is reduced, which can lead to underheating of individual rooms. It doesn't happen in the schema. b) which is its advantage.

Connection of two types of load in open systems

Connection of two types of load according to the principle unrelated regulation shown in figure A).

In the scheme unrelated regulation(Fig. A) heating and hot water installations operate independently of each other. The consumption of network water in the heating system is maintained constant by means of the flow regulator PP and does not depend on the load of hot water supply. The consumption of water for hot water supply varies in a very wide range from the maximum value during the hours of the greatest water intake to zero during the period when there is no water intake. The temperature regulator RT regulates the ratio of water flow from the supply and return lines, maintaining a constant temperature of the water for hot water supply. The total consumption of network water for the heating point is equal to the sum water consumption for heating and hot water supply. The maximum consumption of network water occurs during periods of maximum drawdown and at a minimum water temperature in the supply line. In this scheme, there is an overestimated flow of water from the supply line, which leads to an increase in the diameters of the heating network, an increase in initial costs and increases the cost of heat transport. Estimated consumption can be reduced by installing hot water accumulators, but this complicates and increases the cost of equipment for subscriber inputs. AT residential buildings Batteries are usually not included.

In the scheme related regulation(Fig. B) the flow regulator is installed before connecting the hot water supply system and maintains a constant total water flow for the subscriber input as a whole. During the hours of maximum water intake, the supply of network water for heating is reduced, and, consequently, the heat consumption. To avoid hydraulic misalignment heating system, on the elevator jumper is switched on centrifugal pump, maintaining a constant flow of water in the heating system. The undelivered heat for heating is compensated during the hours of minimum drawdown, when most of network water is sent to the heating system. In this scheme building construction buildings are used as a heat accumulator, leveling the heat load curve.

With an increased hydraulic load of hot water supply, most subscribers, which is typical for new residential areas, often refuse to install flow controllers at subscriber inputs, limiting themselves only to installing a temperature controller in the hot water supply connection unit. The role of flow regulators is performed by constant hydraulic resistances (washers) installed at the heating point during the initial adjustment. These constant resistances are calculated in such a way as to obtain the same law of change in the consumption of network water for all subscribers when the load of hot water supply changes.

Pipeline for hot centralized water supply cannot be done according to the cold water supply scheme. These pipelines are dead ends, that is, they end at last point drawdown. If done hot plumbing in an apartment building according to the same scheme, then the water at night, when it is little used, will cool down in the pipeline. In addition, there may be such a situation, for example, residents of a five-story building located on the same riser went to work during the day, the water in the riser cools 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 from the riser, wait for warm, and then hot water - this is excessive high flow. Therefore, hot water pipelines are made looped: water is heated in the boiler room, thermal node or boiler room and is fed 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, piping in the house is carried out with two-pipe and one-pipe risers (Fig. 111).

Rice. 111. Schemes of hot water distribution in centralized systems

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

A single-pipe hot water supply system differs from a two-pipe one in that in it 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 over the entire height of the building in single-pipe hot water supply systems, the risers are looped. At ring pattern for buildings with a height of up to 5 floors, inclusive, the diameters of the risers are 25 mm, and for buildings from 6 floors and above - with a diameter of 32 mm. Heated towel rails in single-pipe wiring are placed on supply risers, which means that with weak heating of water in boiler rooms, it can reach distant consumers cooled down. Hot water will not only be disassembled by nearby consumers, but it will also cool down in their heated towel rails. In order for the water not to cool down and reach hot to remote consumers, a bypass is cut into the heated towel rails.

Double and single pipe systems hot water supply can be made without heated towel rails, but then these devices must be connected to the heating system. At the same time, heated towel rails will not work in summer, and in winter - total 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 entry. In systems with lower wiring, air is removed through the upper tap. At top wiring air is removed through automatic air vents installed in high points systems.

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Scheme DHW connections to heating networks.

· In closed heating systems the coolant is completely returned to

source of heat supply (excluding 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 hot water supply, as there is no removal of slag deposits into the hot water supply system (this is a plus). However, the DHW system (pipes) receives water from a cold water supply, which is not subjected to deaeration (removal of oxygen and carbon dioxide), heats up and exacerbates corrosive activity, therefore, the destruction of pipes from corrosion occurs faster 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 hot water. The choice of the connection scheme is made on the basis of the calculation.

· In open systems DHW use 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 disturbed sanitary norms water indicators. Open circuits are cheaper. Than closed, because no costs for heat exchangers and pumping equipment are required.

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

· Single stage schemes(Fig. 7, 8):

One heat exchanger and DHW heating takes place before the WTP).

Rice. 7. Single stage upstream

Rice. 8. Single stage parallel

· Multistage 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 in that there is a deep decrease in the return water temperature, and there is also an independent heat consumption for heating and hot water supply, i.e. flow fluctuations in the DHW system do not affect the operation of the MOS, which can occur in open circuits.

Provide hot water multi-storey building not easy, because in the DHW system there must be water under a certain pressure and at a certain temperature. This is the first. Second: hot water supply apartment building- this 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 devices. 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 insulated to reduce heat loss 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 water supply network. And herself DHW system at home is a separate route, unconnected with 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 one must also take into account the fact that heat in the DHW system, these are burns 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, meaning hot water supply, is an individual approach to payment, 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 up to top floor, the riser makes a U-turn and already by 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 determined by the townsfolk by piping inside the apartments. It's actually quite a 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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Imagine an ordinary morning in one of the high-rise buildings of the sleeping area of ​​our beloved city: toilet, shower, shave, tea, brush your teeth, water for the cat (or in any other order) - and go to work ... Everything is automatic and without hesitation. Until the faucet cold water- cold water flows, and hot water flows out of hot water. And sometimes you open a cold one, and from there - boiling water!! 11#^*¿>.

Let's figure it out.

Cold water supply or cold water

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

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

Some have 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 serviced. After the meters, water is supplied to the house main

where it is distributed along 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 pouring from bottom to top. Those. from the water meter through a large pipe, water leaves through the risers to the 9th floor. If the vodokanal is in a good mood, then at the input of the lower zone there should be approximately 4 kg/cm2. Given a pressure drop of one kilogram, for every 10 meters of water column, residents on the 9th floor will receive approximately 1 kg of pressure, which is considered normal. In practice, in old houses, the input pressure is only 3.6 kg. And the inhabitants of the 9th floor are content with even less pressure than 1kg / 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. Upper and lower. Where the same conditions remain for the lower zone, and for the upper zone the pressure is raised to about 6 kg. In order to raise the water to the very top into the supply line, and with it the water rises up to the 10th floor. In houses above 20 floors, the water supply can be divided into 3 zones. With such a supply scheme, the water in the system does not circulate, it stands on a backwater. In a high-rise apartment, on average, we get pressure from 1 to 4 kg. There are other values, but we will not consider them now.

Hot water supply or DHW

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

which raises the water to the attic where it is distributed along the risers and descends to the very bottom into the return line. By the way, DHW meters consider not only the volume of lost (consumed) water in the house. These counters also count the temperature loss (hygocalories)

The temperature is lost when water passes through apartment heated towel rails, which play the role of risers.

With this scheme, hot water always circulates. As soon as you turn on the faucet, 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 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 squeezing hot water into cold water in the event of a malfunction of plumbing fixtures. If you have noticed that hot water if your pressure is still higher than at the cold one, then be sure to install a check valve at the cold inlet, and at the hot inlet, control valves can be included in the system, which will help equalize the pressure by about one digit with the cold one. Pressure regulator installation example