No matter how trite the phrase may sound that you get used to good things quickly, it is true. And indeed, what was considered unattainable yesterday is now accepted as a given. This is especially obvious in our Everyday life, or rather in the process of arranging our life. So, some 15-20 years ago, autonomous hot water supply for many owners of private houses, especially in rural areas, was considered as something not exclusive and expensive. At the moment, consumers have one problem: how to understand this variety of market offers. After all, hot water supply for general household needs must be arranged not only efficiently, but also economically.

Hot water supply country house can be done in many ways. The main thing is to choose the right water heating equipment. Water heaters vary in design, power source, and power. You can find a huge number of models of these devices on the market, but they are all divided into two categories:

• flow-through;
• cumulative.

Already, judging by the names, you can understand the functional features of each of these types.

Important! The most practical are considered gas water heaters both capacitive and flow type. There are also indirect heating devices that operate on the heat given off by the heating boiler and electric water heaters.

Flow heaters

They heat constantly flowing water and have no reserve. This circumstance places very high demands on them. Everyone knows that water is an extremely heat-intensive substance. To heat it in real time, a huge consumption of thermal energy per unit of time is required. In addition, flow-through water heating equipment must be brought into working condition almost instantly: when turned on, hot water flows; when turned off, heating stops.

Scheme of operation of a conventional instantaneous water heater

By the way: the gas water heater familiar to many is the clearest example of a flow-through gas water heater.

Storage heaters

They heat a given volume of water very slowly, while consuming only 1 kW/hour. Heated water is used as needed. They also respond instantly when the tap is opened, but at this time the power indicator will have a minimum value. The only drawback storage water heaters- dimensions. If large volumes of water are needed, then the heating tank must be of impressive size.

Heating water with heating boilers

This is an extremely common way to secure a home. hot water. Heating boilers come in 2 types:

1. Single-circuit - heats only tap water.
2. Double-circuit - used for both water heating and heating.

Types of hot water supply systems

Any hot water supply system involves the inclusion of a set of devices designed to heat cold water with its subsequent distribution among specified water intake elements. In water heating equipment, water is heated to desired temperature. After this, using a pump, it is supplied to the building through pipelines. Water supply systems, depending on the method of heating water, can be open or closed.

Open system

Open system hot water supply

An open hot water supply system in its design has a coolant that circulates in the system. Consumer uses hot water, coming directly from centralized system heat supply. IN in this case The quality of the water in the tap and inside the heating radiator will be the same. In other words, people consume coolant. Such a system is called open because hot water flows to the consumer through open taps from the heating network. Hot water supply diagram apartment building in most cases it implies the installation of an open hot water supply system. While in private buildings it will not be optimal due to the high costs of its installation.

Important! This method of providing hot water to your home apartment buildings does not provide for the operation of water heating devices, which means its design is relatively economical.

Closed system

A closed hot water supply system is built on the principle that when drinking water taken from the water supply is cold, it is heated in an additional heat exchanger network water, and only then goes to the consumer. The coolant and hot water are separated from each other. The hot water people use has similar characteristics to the cold water from the tap. Hot water pipes corrode more quickly than cold water pipes. Such a system is called closed because the consumer receives only heat, but not coolant.

How much hot water do you need?

The calculation of hot water supply depends on many factors, which are determined by the lifestyle and the number of residents in a particular room or building. Both in apartments and residential buildings hot water supply is loaded in a short period of time.

Moreover, there are standards for hot water supply according to which about 10 minutes are allotted for a full load. In other words, within 10 minutes hot water should be available in the required quantity, and it can be used simultaneously in several places. For example, in the kitchen the housewife washes the dishes, and at the same time another family member is taking a shower in the bathroom. Thus, when calculating hot water supply, it is imperative to take into account the following nuances:

• number of residents;
• frequency of use of the bath, shower;
• number of bathrooms where hot water is used;
• specifications plumbing elements (for example, the volume of a bathroom);
• expected temperature of heated water.

Hot water consumption - approximate calculation

Calculation of the required amount of hot water is possible using measuring instruments

For calculations, let's take a standard family of 4 people. Let’s also agree that in 10 minutes a bathtub with a volume of 140 liters is filled, and at this time a shower is used in another bathroom, consuming about 30 liters of hot water, and finally, the dishes are washed in the kitchen - that’s another 30 liters. By simple addition we calculate that in 10 minutes the water heater should provide 200 liters of water heated to a given temperature.

Of course, this calculation takes into account ideal conditions hot water consumption. In real life, the value may be less. After all, such an amount of hot water may not be essential: you can wait until the water is heated further by the heater or use it alternately in different places. Now, after reading our article, realistically assess your needs, make calculations, and you can safely begin creating a hot water supply system in your home, if you don’t have one.

Heating and hot water supply systems include a set of devices that provide heating of cold water and distribute it to the required water distribution elements. Water is heated in water heating equipment to the required temperature, after which it is supplied through pipelines to the building using a pump.

Closed and open hot water system

Heating and hot water supply systems are divided into open and closed, depending on the method of heating water. An open hot water supply system contains a coolant circulating in the system. An open water supply system is also used for heating buildings. The closed hot water supply system has next principle work: water from the water supply goes to water heating devices or heating points, where it is heated.

An open water supply scheme excludes water heaters, as a result of which it costs much less than closed system hot water supply. Open and closed water supply systems can be used in both multi-apartment and private buildings. For cottages and dachas, an open hot water supply system is not optimal, due to the high costs of its installation. For apartment buildings or houses large area the best option is an open water supply scheme.

Differences between closed and open water supply systems

An open and closed water supply system can be centralized or autonomous, depending on the location of the water heating equipment and its thermal power. The pressure in centralized water supply pipes significantly exceeds the level of water pressure in the water supply pipes of an autonomous system. IN autonomous systems A pressure switch is often used for water supply, which allows you to monitor and, if necessary, equalize the water pressure level. A pressure switch for centralized water supply is installed at a heating point; it regulates the pressure in the water supply pipes or in its individual sections.

Cold water supply systems are classified according to the territorial coverage of their consumers, the method of water supply, the type of water supply source and the types of consumers or purpose.
There are circulating and direct-flow cold water supply systems. The second type is easier to use and design. The recirculating system makes it easier to protect water bodies, as well as reduce the cost of pipelines and treatment facilities.

Hot water supply system (DHW) - a set of devices that provide heating of cold water and its distribution to water distribution devices.DHW systems divided into centralized and local (decentralized).

In centralized systems, one heating installation in a boiler room or central heating station supplies hot water to one or more large buildings within a residential neighborhood, block or village. All centralized hot water systems are designed with circulation pipelines to provide consumers with hot water, since without them, in the absence of water supply, 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 hot water temperature at the water tap at 50-60 degrees C. At this temperature, most of the pathogenic bacteria contained in the water die (the effect of pasteurization), 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 in bathing procedures at a temperature of 35-40 degrees C in bathrooms and up to 45 degrees C when washing in baths, diluting the hot primary water with cold water using mixing taps and devices.
In recent years, in buildings with a height of five floors or more, part of the supply risers (for example, from 3 to 7 risers of one section of a residential building) have been combined into one water distribution unit, called a sectional unit, with a single circulation pipeline. In buildings taller 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) DHW systems arranged in individual houses(dacha, cottage, semi-detached)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.
On industrial and municipal enterprises (baths, laundry rooms, dry cleaners, swimming pools), along with high-speed water supply installations, steam-water hot water heaters have found their application.
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 fire-fighting water supply network.
The laying of plastic pipes is carried out mainly hidden - in baseboards, grooves, shafts and channels in the floor pouring. Open installation of connections to sanitary fixtures is allowed, as well as in places where mechanical damage to plastic pipelines is prevented. For all internal water supply networks, it is allowed to use copper, bronze and brass pipes, fittings, as well as 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 greater than 150 mm In open heat supply systems, 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. The 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, a shut-off valves with plugs for draining water from risers and letting air into them.
All pipelines of the hot water 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 is not less than 0.05 W (m x deg. C).
Water consumption rate (in liters per inhabitant), for example, in an apartment-type residential building with centralized hot water supply (with bathrooms 1500-long 1700 mm 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 l per day.
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.
Most A hot water supply system from a steam boiler and from a heating network is often used.
Hot water supply system for a residential building with a steam boiler and a horizontal water heater operates 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 pipeline. The water in the water heater is under pressure from the city water supply and is heated to 70 degrees Celsius. 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 valve 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 measuring glass.
The domestic industry produces steam-water high-speed water heaters MVN - 1436 and MVN - 1437 and sectional water-water heaters 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 made short - 2040 mm and long - 4080 mm . Water heaters with a diameter of 273 and 325 mm - two-way, with a diameter of 377 mm and more - four-way.
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 with outside temperature. Steam that heats the water is supplied to the interpipe space.
Water-to-water water heaters MVN-2052-62 They produce collapsible single- and multi-sectional, 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 tubesdiameter 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 water 150 degrees C and operating pressure of heating and heated water up to 1 MPa.
Scheme with steam high-speed water heater used for hot water supply systems of large residential buildings, baths, 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. High speed water heater is flow-through, 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 duct. Cold water enters the water heater from the water supply. The control unit at the inlet has valves to shut off the heating system pipeline and individual parts node. Water consumption in the network is measured using a water meter.
To prevent water from the heating system from entering the heating network pipeline, stand check valves. 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 inlet 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 flows to the main riser of the heating system and returns to the return pipeline of the heating network through the return pipeline from the heating system. The dirt 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, this 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 Currently widely used in residential buildings. In these systems for buildings of 5-9 floors, the risers within the section at the top are connected to each other, with all but one of the risers connected to the supply line, and one release riser to the circulation line. Devices for drawing hot water are connected to the outlet riser, as well as to the supply riser. To ensure uniform water circulation in hot water supply systems of buildings connected to one central heating point, a diaphragm is provided for installation on the release riser.
For residential buildings with more than 9 floors, all hot water supply risers are connected to the supply main and laid independently circulation riser, which at the top is connected to the jumper between all supply risers, and at the bottom to the circulation line. In supply systems, the circulation line is calculated based on the condition of supplying the calculated 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 on the top floor at the top level of the riser. At the base of each riser and on the jumpers between the risers, shut-off valves are installed.
At ring pattern risers are assumed to be of the same diameter along the entire height of the building and are usually equal for buildings up to 5 floors high 25 mm , and for buildings with higher storeys - 32 mm.

Water heating devices, heating water for domestic needs, there 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.

02.10.2013

Open hot water system

This article describes in detail an open hot water supply system, its advantages and disadvantages over a closed system. The elements of the system under consideration and the principles of its use are named.

Providing hot water is possible thanks to a set of devices that are designed and installed to supply process water and water for personal use.

Which hot water supply system you need to choose depends on several factors - these are the conditions under which the water supply is produced, the source of energy for heating the water, and the quality of both the water and the plumbing. The use of an open water supply system must be justified in terms of economy and technology.

Looking at the choice from the outside sanitary standards, then a closed system that is connected to the central city heating network looks more reliable.

But if we talk about the local network, then everything is decided by the quality of water and the economic benefit of each system in each specific case.

Types of open systems

The system can have two versions: centralized or decentralized. The difference is that the centralized system provides several consumers (from one building to an entire village). Decentralized system prepares water directly at the point of use, using small heating devices.

To supply hot water, one of two types of schemes can be used: with circulation pipelines, or a non-circulation scheme. The non-circulation hot water supply scheme is characterized by its structural simplicity and low starting cost.

Consider a non-circulating water supply system

When using a non-circulation circuit, there is no need to purchase a circulation pump, but at the same time, if you do not use water for some time, it cools quickly. This means that by opening the tap, the consumer will not receive hot water, but already cooled water, and to obtain hot water, it is necessary to drain a certain amount of cool water.

Which is only an inconvenience, increases the waste of water, adds burden to the drainage system and wastes energy.

An open system of this type will be suitable for use only in a network with a continuous supply of hot water, or in short individual networks.

Circulating water supply system

In places where a constant supply of hot water is necessary, and it is undesirable to drain the water before intake, circulation systems are used. In this system, water continuously passes through the water heater without stopping or cooling, maintaining the temperature at the selected level at all points of water consumption.

For buildings with no more than 4 floors, it is necessary to arrange water circulation only in separated pipes. For taller buildings, water must also circulate through risers. Moreover, in the places where the centralized system is connected to the local branch, the water must have a temperature of at least 60˚C for open systems, and at least 50˚C for closed ones. And, in both cases, it should not exceed 75˚C.

What is the difference between open and closed water supply method

A closed system is more energy efficient by using the heat from the outgoing water to heat the incoming cold water. This process of thermal energy exchange occurs in a heat exchanger. Conversely, in open systems, hot water comes directly from the heating network. In this regard, systems differ and are classified according to the method of water supply.

The use of open systems requires disinfection of the network with chlorine, as well as flushing the system with 90 degree hot water.

Any water heating device must be cleaned periodically, because when high temperatures are being created unfavourable conditions, greatly affecting water quality.

The composition of an open hot water supply system is simple. The system consists of equipment that heats water, a pump that circulates water in the system and pipelines through which water is directly supplied to each intake point. The distribution line can be designed in two versions:

1. With overhead wiring - when water heaters and tanks are located on top, which requires a technical floor in the building. The circulation line itself, in this case, is located in the basement.

2. With bottom wiring - when the heating equipment is located in the basement, which is more convenient for servicing such a system.

Required water quality

Water in an open system has the same quality as water in heating radiators. In this connection, the requirements prescribed for the quality of water in an open system are much higher than for water in closed systems, where hot water is almost no different in quality from the cold water supplied.

Open system design

All equipment for an open system must be selected taking into account the operating principle of the system. In other words, the water pressure in the taps of all floors must be absolutely sufficient and practically the same. This is not even always achievable when using a pump with the required performance.

You should take into account the friction force of water against the walls of the pipes, which acts as some kind of barrier to the movement of water. At first this seems insignificant, but, as practice shows, an open system works effectively when even the smallest influencing factors are taken into account.

The following factors influence water pressure:

Geodetic height of water injection;

Dynamic pressure in the pipeline;

Pressure losses in networks.

In such a system, it is convenient to use cranes to cut off individual sections when it is necessary to carry out scheduled maintenance or repairs. It is also advisable to use other protective devices, such as float sensors in tanks and pressure switches in pipes.

System efficiency

As in the general case, the efficiency of the system can be determined by the level of thermal energy output with the least energy consumption. Both systems, with zero water intake, will not differ in their efficiency (except that it will be more efficient when using a heat pump).

A closed system can provide hydraulic isolation of heating networks, while an open system supplies consumers with hot water at a lower cost. Also, it has greater reliability and the ability to improve operating efficiency in the future (when using high-quality water).

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Currently, hot water supply is an integral part of the lives of most people on the planet. No apartment or residential building can live without it. Arranging a hot water supply system is a complex process; moreover, there are several types of connecting systems. In this article we will look at all hot water supply systems, calculations and types of water heaters.

Regardless of the type of hot water supply, a set of equipment is connected, which are designed to heat water and distribute it to various water intake points. In this equipment, water is heated to the required temperature, after which it is supplied into the house and through the pipeline using a pump. There are open and closed hot water supply systems.

Open system

Open DHW system characterized by the presence of coolant circulating in the system. Hot water comes directly from the centralized heating system. The quality of tap water and heating equipment no different. The result is that people use coolant.

The open system is so named because hot water is supplied from the open taps of the heating system. DHW scheme multi-storey building provides for the use of an open type. For private homes this type is too expensive.

You should know that the cost savings of an open system occur due to the no need for water heating devices to heat the liquid.

Features of open hot water supply

During installation open DHW the principle of operation must be taken into account. There are two types of open hot water supply depending on the type of circulation and transportation of coolant to the radiators. There are open systems with natural circulation and those using pumping equipment for these purposes.

Natural circulation is carried out in this way: an open system eliminates the presence of excess pressure, so at the highest point it corresponds to atmospheric pressure, and at the lowest point it is slightly higher due to the hydrostatic action of the liquid column. Thanks to a small pressure, it occurs natural circulation coolant.

The principle of natural circulation is quite simple, due to the different temperatures of the coolant and, accordingly, different densities and masses, cooled water with a low temperature and greater mass displaces hot water with less mass. This simply explains the existence of a gravity system, which is also called gravitational. The main advantage of such a system is absolute energy independence, if parallel heating boilers do not use electricity.

It is important to know! Gravity pipelines are made with a large slope and diameter.

If natural circulation is not possible, use pump equipment, which increases the rate of coolant flow through the pipeline and reduces the time it takes to warm up the room. Circulation pump produces coolant movement at a speed of 0.3 - 0.7 m/s.

Advantages and disadvantages of an open system

Open hot water supply is still relevant, thanks primarily to energy independence and other advantages:

1. Easy to fill open hot water and vent. No need for control high pressure and release additional air, since the release is carried out automatically when filling through an open expansion tank.
2. Easy to recharge. Because there is no need to monitor the maximum pressure. It is also possible to add water to the tank even with a bucket.
3. The system functions properly, regardless of leaks, since the operating pressure is not high and the presence of such problems does not affect it.

Among the disadvantages is the need to control the water level in the tank and its constant replenishment.

Closed hot water system

A closed system is based on the following principle: cold drinking water is taken from the central water supply and heated in an additional heat exchanger. After heating, it is supplied to water intake points.

A closed system implies separate operation of the coolant and hot water; it is also distinguished by the presence of a return and supply pipeline, which are used for circular circulation of water.

Such a system will ensure normal pressure even when using a shower and sink at the same time. Among the advantages of the system, the ease of regulating the temperature of hot liquid is also noted.

DHW can be circulation or dead-end. A dead-end system consists only of water supply pipes, the connection method of which is the same as in the first case.

The advantage of a closed hot water supply is the reduction of costs by ensuring a stable temperature. It is possible to install a heated towel rail. A closed hot water system requires water heaters, the types of which we will consider below.

Types of water heaters

1. All water heaters are classified as follows: Flow devices. Such heaters heat water continuously, leaving no reserve. Since water has a high heat capacity, constant heating requires increased energy consumption. In addition to this factor, the flow-through heater must be immediately brought into working condition: when turned on, supply hot water, and when turned off, stop heating. To traditional flow heaters
2. include a gas water heater. Storage devices. They are characterized by slow heating of a certain volume of water, which often consumes 1 kW/hour. Hot liquid is used as needed. Storage heaters

They operate instantly after opening the tap, but the power is much less. Among the disadvantages of such devices, large sizes are also noted; the larger the volume, the larger the device.

Calculation and recirculation of hot water supply

The calculation of hot water supply systems depends on the following factors: the number of consumers, the approximate frequency of shower use, the number of bathrooms with hot water supply, some technical characteristics of plumbing equipment, and the required water temperature. By calculating all these indicators, you can determine the required daily volume of hot water.

The hot water supply system can be of two types, which are used depending on the specified parameters.