The pressure in the cold water system is normal. At what values does household appliances work? Classification of circulation pumps
Considering that most cases of organizing water supply in a house or apartment involve the use of plastic pipes, the causes of problems in the system can be either salt deposits or increased water pressure in the water supply system. Both problems can stimulate the failure of the entire structure.
The technical passport, which is necessary when purchasing pipes, must have information on the recommended pressure in the system, which the purchased products are guaranteed to withstand.
Water pressure - features
When performing work on the installation of a water supply system or entrusting this work to professionals, you should make sure that the company is experienced by first knowing the rating of this organization and customer reviews.
An indicator of paramount importance is the value of the working pressure in the pipeline. This parameter depends on several indicators, including the material from which the pipes are made, the type of pipeline.
In a particular section of the system, the pressure may have a deviation from the average. When monitoring the work performed, attention should be paid to the compliance of the working pressure with the requirements.
Planning independent work on the organization of water supply in the house should be accompanied by familiarization with all the requirements for such systems. Properly performed installation will ensure that these conditions are met at the proper level.
Expansion tanks and accumulators
Typically, arrangement suburban area or a private house provides for the presence of other water systems, in addition to water supply.
These include a fire extinguishing system and hot water supply, as well as a wastewater filtration system. Possibly and the device of watering of the territory and system of heating.
Water supply, fire extinguishing and filtration systems provide for a hydraulic accumulator. Other systems must be equipped expansion tanks. Besides, necessary measure is the installation of expansion tanks at the intake stage hot water from the tank heating system. Such measures will create fluid compensation in the event of a water hammer.
The task of the expansion tank when organizing the supply of hot water is to protect the heater from high pressure. Hydraulic accumulators are used to form a reserve of fluid in the fire safety system.
The water supply of houses, as a rule, provides for the pressure in the tank, which ensures the transport of water for 60m. This lift provides a pressure of 6 bar.
An expansion tank is used to ensure a safe level of pressure in the heating system. This is due to the constant increase in the volume of water with a change in temperature that occurs as a result of its movement through the system. Compensation of this pressure is necessary to prevent destruction or damage to the pipeline.
It is recommended to apply closed tanks only. This type of device will make the system more manageable than with an open tank, allowing the liquid to evaporate and the system to operate at low pressure.
Besides, closed design saves pipes from corrosion. Another advantage of a closed tank is the possibility of its installation in the place where it is convenient for the consumer, and not only in the upper part of the system.
Hydraulic accumulators are necessary to form a reserve of water with the possibility of its launch into the water supply system. By analogy with expansion tanks, they have open and closed forms.
The negative features characteristic of compensation products are valid for hydraulic accumulators. The main function of this unit is to prevent water hammer, which can cause irreparable damage to the system.
Causes of water hammer
- power failure of the pump motor associated with emergency situations;
- abrupt opening and closing of valves at water intake points.
Such actions lead to a significant increase in the load that is not characteristic of this system, which it may not endure. Places for fluid intake are recommended to be equipped with tanks with a capacity of 0.2 liters.
The membrane cylinder located in the tank is filled with air space. The flow of liquid into the device stimulates a decrease in the volume of air in the balloon and an increase in pressure inside. When the pressure increases, a relay is activated that reacts to a change in the pressure itself and turns off the pump.
Further intake of liquid from the tank stimulates the normalization of pressure and the relay gives a signal to start the pump. A decrease in pressure inside the system, which may occur due to depressurization of the structure, will also cause the compressor to turn off.
Based on an understanding of the principle of operation of a hydraulic accumulator, it is clear that the correct choice of its volume affects the number of operations of the membrane relay, and hence its service life.
For a water supply system with three points of water distribution, a hydraulic accumulator with a volume of 24 liters is acceptable, and a larger number of points assumes a capacity of 50 liters. Sometimes a large number of devices requires an individual calculation of the tank capacity.
Pressure in the water supply system
The pressure maintained in the cylinder by membranes is designed to ensure the delivery of water to the highest point of the water supply system of the room.
For example, to raise water to a height of 10 meters, the system must be provided with a pressure of 1 bar. The pump is started by a pressure exceeding the minimum by 0.2 bar. In this example it will be 1.2 bar.
Delivery of water to the highest point of the structure provides for a pressure of 0.5 bar above the minimum. Given the example data, it will be 1.5 bar.
The calculation of the maximum pressure value is a rather laborious process. This indicator depends on the characteristics and parameters of the pump itself, the resistance of the system, and possible changes in the voltage in the network.
Given the complexity of such a calculation, systems do not industrial use take the value of the maximum pressure obtained by adding the results of the pressure required to start the pump and the indicator required to deliver water to the highest point in the system. For this example this will be the value equal to the sum 1.2 bar and 1.5 bar, i.e. 2.7 bar.
Based on the value of the maximum pressure, you need to choose the pump itself. It is recommended that the head of this product be 30% greater than the maximum water head.
The performance of the system elements should be checked at least once a year. First of all, such a check is aimed at detecting leaks.
Having eliminated them, you should check the pressure on the lower accumulator, which must correspond to minimum value. Pressure deviations in the direction of decrease by more than 10% must be eliminated with a compressor.
The pressure in the water supply system is the most important characteristic, the correct choice of which determines the comfort of using it and the duration of operation of various hydraulic, plumbing and household appliances.
The logic of choosing the optimal pressure in the water supply system at home
Immediately, we note that the water pressure should be as low as possible, allowing plumbing fixtures (faucets, shower) and household appliances (washing machines, dishwashers, boilers of the heating system) to function normally. For example, for plumbing, dishwashers and washing machines, the minimum allowable overpressure is 0.5 atm., That is, the system must have at least 1.5 atm. If you have heating system, then the pressure must be increased to 2 atm. And if a hydromassage device (without its own pump), then up to 4 atm. For normal irrigation, 3 atm is enough. Then you should add another 0.5 atm., So that plumbing fixtures and Appliances did not work at minimum pressure.
Be sure to consider the location of points of consumption of water. A height difference of 10 m between the diaphragm accumulator (the area of maximum pressure in the system) and the point of water consumption adds one atmosphere to the system. In other words, if you have a two-story private house, in which the accumulator is located in the caisson at a mark of minus 2 m, and the shower in the bathroom on the second floor (the highest point of water consumption) at a mark of + 6 m, then the pressure in the water supply system of your house should be 1.5 + 0.5 + 0.8 = 2.8 atm. This is the optimum water pressure in your home.
It is not worth increasing the pressure beyond what is necessary. First, it will require more energy to maintain it. And secondly, the elements of the hydraulic system will wear out faster.
Setting the upper and lower pressure values in the diaphragm accumulator
Having defined required pressure in the hydraulic system, it is necessary to set the accumulator pressure switch. There are two pressure values - the pressure to turn on the well pump and the pressure to turn it off. The cut-in pressure is equal to the optimum system pressure plus 10%. That is, in our example, it is 2.8 + 0.1x2.8 ≈ 3 atm. Ten percent is given to ensure that the pressure in the system is guaranteed not to fall below the permissible level. The cut-off pressure is equal to the turn-on pressure plus 1 - 1.2 atm. Of course, the greater the difference between these pressures, the less often it will turn on borehole pump(and, consequently) his resource of work will be greater. But on the other hand, a large difference leads to an uncomfortable change in water pressure and an increase in the likelihood of water hammer.Causes of a drop in water pressure in the water supply system
The pressure in the system creates a downhole pump. Therefore, problems with it can automatically lead to a decrease in pressure. It can be:
- Voltage drop in the network - it is necessary to install a voltage stabilizer.
- Incorrect connection of the phases to the three-phase electric motor of the pump, which will cause the rotation of its rotor in the opposite direction - re-switch the connection.
- Wear of the working element of the pump - wheel or screw - replace the working element or the entire pump.
- Sand or dirt entering the pump - clean the pump and well.
In addition, the pressure drop in the water supply system of a private house may be due to malfunctions in the system itself:
- Clogged pipes, filter and other hydraulic elements - flush or change them.
- Violation of the tightness of the system - find a leak and fix it.
- Air pressure drop in membrane accumulator due to a malfunction of the air nipple or a violation of the tightness of the membrane - eliminate the malfunction.
It often happens that water from the tap flows with little pressure. In this case, various devices may not work at all or work incorrectly ( washing machines, water heating boilers etc.), and in general, using water for bathing, washing something is quite inconvenient. So how much pressure tap water should go to the consumer?
Head norms
The required pressure is normalized by several documents at once. SNiP 2.04.02-84 defines the minimum pressure at the entrance to the building. For a one-story building, this figure is 10 m (1 atm.), 4 meters are added to each floor. The same SNiP indicates the maximum pressure already at the entrance to the apartment - no more than 60 m (6 atm.), If the value is higher, then the installation of regulatory mechanisms is necessary.
Directly at plumbing fixtures, according to SNiP 2.04.01-85, the pressure in hot water pipes should not exceed 45 m (4.5 atm or 0.45 MPa).
Decree of the Government of Russia No. 307, describing the procedure for providing utilities citizens, indicates that in cold water supply systems at the point of water dispensing, i.e. in each specific device (faucet in the bathroom, kitchen, etc.), the pressure should be in the range of 0.3-0.6 MPa. For hot water, this indicator is in the range of 0.3 - 0.45 MPa.
Causes of insufficient pressure
- Emergencies in the central water supply, as a result of which water is already supplied to the house with insufficient pressure;
- Leaks and other malfunctions inside the house;
- Unregulated water supply system in the house;
- Old clogged pipes;
- Significant modifications to the water supply system made by one of the residents. The water supply is calculated based on the configuration of the system, the number and types of plumbing fixtures used. And if, for example, in a residential building someone arranges a car wash, a bathhouse or some other institution with a high water consumption that was not originally intended, then naturally the residents will experience problems with pressure in the taps.
In case of insufficient pressure, contact management company and a public utility responsible for water supply. Their representatives conduct an audit, according to the results of which they are obliged to eliminate the existing violations. During the period when the pressure in the pipes did not meet the standards, i.e. water service was inadequate quality, according to the already mentioned Government Decree, a decrease in utility bills is provided for.
The familiar system central water supply is a very complex structure. Many consumers often have to deal with deviations in water pressure.
This is caused by pressure changes in the pipeline. But is it permissible and how to avoid the unpleasant consequences of such a phenomenon?
To do this, you must first study the regulatory documentation, according to which any water supply system is designed.
The organization of any uninterrupted water supply complex should be based on current regulatory documents.
They regulate the main indicators and specifications which are observed in without fail, indicating how much water pressure should be in the water supply.
The basis is, according to which the design of central water supply systems for utilities and household services takes place. However, for consumers, first of all, indicators of water pressure in the system are important.
According to the norms, there are several indicators:
Water pressure. With the maximum water consumption in the building at the entrance to it (before distribution to consumer points), it must be at least 10 m.
It concerns one-story houses. With an increase in the number of storeys, 4 m must be added for each additional level.
As an example, consider a standard 9-storey building. For him, the input water column is equal to:
10+(4*9)=46 m, or 4.6 atm.
It is worth noting that this is the value of the input stream. Before sending it to specific consumers, the pressure indicators should be reduced to normal.
It should not exceed 6 atm. For hot water supply (DHW), data must be taken from, which regulates the organization of internal water supply in residential buildings.
According to the calculated indicators, the DHW pressure should be within:
From 0.3 to 6 atm.
In this case, it is necessary to take into account the nominal values \u200b\u200bfor each plumbing fixture, for which the minimum free pressure should not be less than the following figures:
- washbasin with mixer - 0.2 atm.;
- bathroom and faucet - 0.3 atm.;
- shower cabin - 0.3 atm.;
- toilet flush tank - 0.2 atm.
Utilities take into account the average daily water consumption as calculated data. The table shows the specific indicators for the well-maintained housing stock:
Photo: table of indicators of daily water consumption, l-person.
It is worth noting that these figures have decreased significantly - until 2000. They amounted to 600 liters per 1 person. In addition to the documents, the data from which are taken as calculated, there is one more - Decree of the Government of the Russian Federation of 05.23.2006 N 307.
These data apply not only to the central, but also to the autonomous water supply of houses. Therefore, when designing such a system, the above indicators should be taken as a basis.
When using a well, when calculating pumping equipment take into account its depth. Those. for two-story house, the water for which is supplied from a well with a depth of 30 m. The pumping equipment must create a pressure in the system not lower than the following indicator:
10+(4*2)+30= 48 m or 4.8 atm.
If this indicator is higher than 6 atm. - a pressure compensation (reduction) system should be provided.
In what units is it measured
Standard physical quantities are used as indicators of pressure in the water supply system.
The size of the water column
This characteristic does not apply to system ones, but it is used for many hydraulic calculations. She matches hydrostatic pressure column of water in 1 m at normal density.
For example, if pumping equipment with a water column of 20 m is required, then it must provide water to rise to the same height.
Bar
Also a non-systemic unit of pressure. Its value is approximately equal to 1 atmosphere or 10 meters of water column.
technical atmosphere
The value of atmospheric pressure at the level of the World Ocean is taken as the initial reference point. It corresponds to the pressure that occurs when a force of 1 kg is applied to an area of 1 cm².
There is also an indicator of the Physical Atmosphere, but it is not common on the territory of the Russian Federation.
Pascal
The only system unit that is similar to the technical atmosphere. The difference lies only in the definition. It is equal to the pressure that occurs with a force of 1 newton on an area of 1 m².
Each of the above values is applicable to the characteristics of water pressure in the plumbing system. To move from one to the other, you can use the following table:
Photo: characteristics of water pressure in the plumbing system Despite current rules and regulations, utilities do not always comply optimal value pressure in the plumbing. In order to reach best score several pressure stabilization methods should be used.
How to increase the pressure
Before proceeding with the independent design of a pressure normalization system, it is imperative to contact the housing office service.
Its representatives, according to the received complaint, are obliged to carry out measuring work and draw up an appropriate document.
If the minimum water pressure in the water supply really differs from normal, then the housing office must take measures to stabilize it.
But in practice, this scheme practically does not work. What to do in such cases, and are any independent actions needed?
Negative factors:
- with an unstable pressure indicator, water hammer may occur. Its consequences are often very detrimental - violation of the integrity of the pipeline, failure of plumbing fixtures;
- operation of household appliances that consume water. This applies to washing machines and dishwashers. For their normal functioning, the pressure in the water supply should not be less than 0.4 atm. Otherwise, failures and breakdowns occur;
- comfort level. At weak pressure it is rather problematic to take a shower or simply wash the dishes.
Consider the most common case when the pressure is significantly below normal. The following methods can be taken for normalization.
Video: pumps for increasing water pressure GIDROSNAB TOP 12
Installing a hydraulic accumulator and a centrifugal pump
A hydraulic accumulator is a metal tank that is divided into two parts.
Photo: hydraulic accumulator They are separated from each other by a plastic membrane. One of the chambers is filled with water from the system, and the second serves as a limiter.
When a certain indicator of water pressure is reached, the membrane does not allow the system to fill further. To regulate the pressure in the air chamber, the design provides a fitting for injection (bleeding) of air.
The hydraulic accumulator is installed with centrifugal pump, which produces forced water intake from the system.
To automate the control of this system, the following components are required:
- pressure switch. It is connected to the pump and works when a certain level of water pressure is reached;
- manometer - allows you to visually monitor the current indicators.
For the installation of this system, it is necessary to carry out consumption calculations, since in the event of a decrease in pressure in central system below 0.2 atm. the pump stops automatically.
Important! The relatively small capacity of the accumulator should also be taken into account. In most cases, it does not exceed 100 liters.
As an alternative to this scheme, one can consider a complex method - pumping station with storage capacity. A pumping station is a hydraulic accumulator and a pump already assembled in one design. In the vast majority of cases, all protective and control equipment is already installed in it.
Photo: pumping station The pumping station is connected to central water supply and already from it there is a highway to the storage tank.
In the event of a complete shutdown of water, you can use the reserves from the tank. Some prefer to save money and install only the pump, connecting it to a common system.
But this approach is accompanied by the following unpleasant factors:
- rapid wear of pumping equipment. With uneven pressure, the automation will soon fail;
- water will be supplied in shocks, which will lead to water hammer;
- if all residents of the house install such pumps, then a “struggle” for pressure will begin, which will lead to wear common system water supply.
How to reduce water pressure
An increase in water pressure in the water supply is very dangerous for local pipelines and plumbing equipment. When it constant value pipe breakage may occur, deterioration of instrumentation.
Several methods can be used to solve this problem. The most effective is the installation of a pressure reducer at the point of connection to the public water supply.
Photo: pressure reducer Its principle of operation is based on the interaction of two forces - the pressure of water and springs. The spring presses on the water intake chamber, thereby regulating its pressure. In this case, the spring force compensates for the excess pressure. A typical water reducer circuit is shown below.
Photo: water reducer diagram Adjustment takes place with the help of a rod. At the same time, it is important to maintain normal pressure indicators. To do this, it is recommended to install a pressure gauge, which should be located immediately after the gearbox.
Before starting work on designing a pressure normalization system in hot or cold water pipes, it is necessary to know the current indicators.
Important! It must be taken into account that the pressure may change over time. This is clearly seen in the morning and evening hours, when the water intake is apartment buildings the most active.
To accomplish this task, you will need statistics, which are best obtained as follows:
- create a measurement schedule. It is best to do this 4 times a day - morning, afternoon, evening and night. Readings must be taken within a week;
- determine the minimum and maximum performance pressure;
- compare the results obtained with the above standards.
According to the received data, you can choose best way regulation of water pressure.
Photo: water pressure gauge The installation of the device must be carried out in close proximity to the place of connection to the common central water supply.
In addition to this method, there is folk method". To do this, you need to take a standard plastic liter bottle. Install a tube in the cover, which is installed in flexible hose soul. detailed instructions on this species pressure measurement is shown in the video.
Formula
There is a certain formula that allows you to calculate the indicators of water pressure in the system. Its full part, with all the introductory parts, is quite difficult for practical application.
Therefore, it is customary to use a simplified version, which is calculated for a standard section of nozzles in a mixer of 0.85 cm.
For the calculation, a 3-liter jar is required, which will be filled with the tap fully open. At the same time, it is important to note exact time filling it out.
The formula looks like this:
P=21.22/t²,
where R- pressure indicator (kg / cm²), t- time filling s-x liter jar, sec. The following results were determined empirically:
Photo: calculation of water pressure in the pipeline pressure regulator
The water pressure regulator for plumbing systems has an almost identical design with a water reducer. The only difference is a more advanced security system - an emergency valve that opens when the water pressure is exceeded.
Photo: water pressure regulator for plumbing systems Important! When this situation occurs, the excess pressure is absorbed by the membrane. If there is a discrepancy between the parameters of the water pressure in the central water supply system, it is necessary to take measures to normalize them.
Otherwise, with connivance, not only plumbing equipment, but also the entire internal piping may suffer.
Video: crazy hands - homemade water pressure gauge
Today we have to find out what pressure should be in the water supply system, and what to do if its values deviate from the norm. For the convenience of readers, we will build our material in the form of answers to the most frequently asked questions. So let's get started.
Norm
- What should be the water pressure in the drinking water supply system? cold water(HVS)?
A typical norm is 2.5-5 kgf / cm2, depending on the number of storeys in the building of the city area and on the terrain. Each atmosphere (or 1 kgf/cm2) overpressure corresponds to a water column of 10 meters. More exact values cites SNiP 2.04.02-84:
- The minimum value at the entrance to the house with a building height of 1 floor is 1 atmosphere (or a head of 10 meters);
- At more floors, 0.4 atmospheres, or 4 meters of head, are added to each of them;
- At the same time, the maximum pressure at the consumer (that is, in front of plumbing fixtures, at the entrance to the apartment) cannot be higher than 60 meters.
- How is the significant height of residential buildings or uneven terrain compensated?
Curious: according to paragraph 5.12 of SNiP 2.04.01-85, allowable pressure in the hot water supply system - no higher than 4.5 atmospheres. Alas, this is one of those cases where the requirement normative document is not always observed. By the time the DHW is switched to the return line, the supply is usually at least 5-5.5 kgf / cm2, and this value increases as the house approaches the CHP or boiler house due to the reduction of hydraulic losses in the heating main with a decrease in its length.
- What is the minimum pressure allowed on hot water?
According to Government Decree No. 307 on the procedure for the provision of public services, it is equal to 0.3 atmospheres.
Autonomous water supply
- What should be the pressure in autonomous system water supply?
The normal range is from 1.5 to 4.5 atmospheres. Minimum (for a gravity water supply system with water supply from an attic or other elevation storage capacity) - 0.3 kgf / cm2: with a further decrease in pressure, it is impossible normal work filling valves of some drain cisterns and parts of water-using household appliances (washing and dishwashers, instantaneous water heaters etc.).
- How to adjust this setting?
For maintaining pressure in the water supply system from offline source the automatic control of the pump is responsible (for it, the limits for turning on and off the pumping of water are set) and the pumping pressure (it should be approximately 0.2 kgf / cm2 lower than the value at which the pump turns on).
Note: if the accumulator is pumped up to a pressure exceeding the turn-on limit of the pump, the water supply will also work. However, the pump will turn on only after the accumulator and water supply are completely empty, which will create short-term interruptions in the water supply.
Deviations
Now let's turn to the problems and their solutions.
Centralized water supply
- Who is to blame, and what to do if there is no pressure in the city water supply system?
The cause of this problem may be:
- Insufficient capacity or insufficient outlet head, mounted without taking into account the further development of the microdistrict;
- Malfunction of swap stations;
To clarify: booster pumps should be backed up in case one of them fails. However, the installation of a backup pump is possible only with sufficient funding, which often causes problems with large debts on rent and utility bills.
- Overgrowing with deposits and/or rust steel and (to a lesser extent) cast-iron main water pipes.
None of these problems can be fixed by the homeowner on their own. Help speed up the work of specialized organizations simple instruction: every time when you have no water at the peaks of water intake (usually in the morning and evening), call the emergency service and draw up an act indicating the current pressure in the cold water system at home.
- How to measure the current pressure on the cold water?
The water pressure gauge in the water supply system is usually located in the water meter unit.
If it is necessary to take a measurement on the riser, the laboratory pressure gauge is screwed in instead of the plug or into the thread of the vent.
- What can you do yourself if there is no pressure in the water supply system of an apartment building?
Check that the valves on your water lines and cold water riser are fully open. Visit the water meter and make sure that the valves or Ball Valves not covered. If you have filters on your eyeliners coarse cleaning- open them and wash the nets.
Often the reason for the drop in pressure on the riser or cold water supply is garbage accumulated in the narrow place of the water supply - under the saddle of the screw valve. To clean it, just unscrew the valve head (of course, after turning off the water) and remove scale, rust and sand with a screwdriver or any other suitable object.
Bottlenecks in an overgrown riser or bottling can be indicated by the characteristic hiss of water during drawdown. By partnering with your neighbors, you can replace the riser from bottling to top floor without waiting for the house to be refurbished.
- How to lower the pressure in the taps?
And in this case, it all depends on what kind of problem you want to solve:
- If you are worried that as the pressure increases, the water flow increases - teach family members not to open the taps completely or, if this is problematic, install needle throttles on the connections to each mixer to forcefully limit the flow;
- If you are afraid that the water supply system itself may be damaged by high pressure, the pressure reduction will be provided by the reducer installed at the inlet;
- If increased pressure is dangerous for individual plumbing fixtures, filters or household appliances, the same gearboxes are placed on their connections.
Autonomous water supply
- How to increase the pressure in the water supply system of a private house?
It all depends on the symptoms of your problem:
- If you observe short-term drops in pressure during active drawdown through several taps, a capacious hydraulic accumulator connected to any point of the water supply system will save the situation. Within its effective capacity, it compensates for the excess flow over water flow. Don't forget to install on the water supply input check valve that won't let the water out membrane tank merge back into the water supply line;
- How to increase steadily low head? This can only be achieved by installing a storage tank for water and a pumping station. A container installed in a basement or other room with a year-round positive temperature creates a supply of water at the time of its peak consumption; a pumping station with a hydraulic accumulator provides an acceptable pressure in the water supply.
- How to reduce the pressure drop in the water supply system of a private house between the moments when the pump is turned on and off?
By adjusting the pressure switch for the water supply system - by reducing the pressure at which the pump turns off, or by increasing the threshold for turning it on. In the second case, do not forget to raise the accumulator pump pressure to the appropriate value. Please note that this will cause the pump to start up more often, which will significantly reduce its service life.
Conclusion
We hope that we were able to answer all the questions of the reader. To learn more about how you can increase the pressure of the water supply system, the video in this article will help you. Good luck!