The difference between a closed hot water supply system and an open one. What types of hot water supply systems are there? Disadvantages of a loop network

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.

Security hot water This is possible thanks to a set of devices that are designed and installed for the purpose of supplying 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. Usage open system water supply must be justified in terms of economy and technology.

Considering the choice from the point of view of sanitary standards, a closed system that is connected to the central city heating network looks more reliable.

But if we talk about local network, then everything is decided by the quality of water and the economic benefit of each system in each particular 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). The 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 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 periodically cleaned, because high temperatures create unfavorable conditions that greatly affect the quality of water.

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).

Note: Quality plastic window depends on the type of glass unit used. They are single-chamber, double-chamber, heat-saving, sound-insulating, sun-protective and impact-resistant. The price of the window will differ from all this. In addition, you need to carefully choose stores and familiarize yourself with possible discounts.

The hot water supply scheme includes a system of pipelines, fittings and devices that either supply already heated water or themselves ensure its heating before supplying it to the consumer. Depending on the heat source, there are open and closed hot water supply schemes. They represent two systems that are opposite in action, each of which has its own positive and negative sides.

What are they, and how are they different? We will talk about this in our material, reinforcing the video theory in this article.

Dependence of the system on the heat source

If we consider hot water supply schemes on a large scale, they can be divided into two groups:

1. Centralized, when water heating is provided by boiler houses or thermal power plants.
2. Local, which serve only one object.

In centralized systems, briefly called TsSGV, both closed and open hot water supply systems can be used. To provide warm water to the civilian population and organizations, the same water is used as a coolant, only highly overheated.

On industrial enterprises Waste (secondary) steam is often used as a coolant. But we won’t delve into these jungles - let’s talk about the most common option.

The difference between the two schemes and their applicability

So, let's figure out what an open and closed water supply system is.

1. In open, or as they are also called, dead-end schemes, during the water treatment process, boiling water is diluted to the desired temperature cold water, and is served to the consumer. That is, the water that needs to be heated is in direct contact with the coolant.
2. This does not happen in closed circuits - in them heating occurs due to heat exchange. This is the main difference between open and closed system hot water supply.

Note: Open way It’s easier to get hot water, but at the same time it loses quality and cools faster. To save longer high temperature, the system needs to be looped. It is the circular circulation of water that is the distinctive feature of closed circuits.

Open (dead-end)

A dead-end network is a very convenient option for buildings with a small number of floors and short risers. They are often designed for domestic (non-industrial) water supply systems of industrial enterprises and for any buildings with stable or long-term consumption of hot water (residential buildings, catering establishments, baths and health institutions).

In the photo - a dead-end (open) network

• In terms of metal consumption, an open scheme is more profitable. However, due to rapid cooling, in order to wait for hot water in the tap, you have to drain the cooled water - and this is already an irrational use of water resources. Therefore, in high-rise buildings this scheme is not used at all.
• In terms of maximum heat transfer, which determines the efficiency of the system as a whole, open and closed hot water supply systems are approximately the same. Their performance will differ only if one of these systems has a heat pump, which significantly increases the efficiency.

Note: Both schemes have advantages, but they are different. In particular, the open one has a lower price. It is also important that in these systems water most often corresponds drinking quality- but for this it must be constantly deaerated.

Open circuit structure

This system is the simplest.

• If we talk on the scale of a private home, then it contains a device that heats the water, a pipeline through which it moves to the distribution points, and which, in fact, ensures transportation.
• If we talk about installation options, then there are schemes with upper and lower wiring. The first can only be implemented in buildings where it is possible to install water heating tanks on the under-roof technical floors.
• With lower wiring, all equipment is installed in the basement, where it is much easier to maintain it. However, the pressure in such a system is practically never the same for all floors, so to maintain it, booster pumps are installed in houses with lower distribution.

There are three factors that influence the speed of water movement.

This:

1. Dynamic pressure;
2. The height to which water is pumped;
3. Inevitable losses.

Therefore, float sensors are installed in the tanks from which water enters the pipeline, and pressure switches are installed on the pipes themselves. And so that in order to carry out repairs it is not necessary to drain water from the entire system, all branches of the pipeline are equipped with a device that allows the section to be temporarily cut off from the system.

Operating principle, pros and cons

In general, the system looks like this: two pipes - supply and return - are connected in an elevator unit or heating point, where the water is brought to the required 60 degrees Celsius. Then hot water is supplied to the internal pipeline of the building, to dismountable points.

• The stability of the pressure in such a network is maintained hydraulically, when cooling water is squeezed out by hotter water. Wherein thermal energy is transmitted to the maximum, without requiring high coolant costs.
• A minimum of equipment in the system facilitates its operation, and, accordingly, makes the scheme the most economical. But all the benefits from the design are “eaten up” by the costs of water purification.
• The main disadvantage of a dead-end circuit is the fact that when there is no stable supply of hot water, it quickly cools down. Many people know firsthand how long it takes to turn on the tap early in the morning for hot water to come out. It turns out that residents who have water meters simply pour their money down the drain.

• Due to the rapidly cooling water, the temperature in the heating radiators is also not very stable. Another significant drawback is the inability to heat bathrooms, since heated towel rails only heat up when the hot water supply is open.
• However, most older residential buildings receive water according to this scheme. This means that water is actually taken from the heating system - which is why it is, in fact, called open.

Note: In new buildings, a newer, closed scheme has long been used, which contains special equipment that heats the water. And according to Federal Law 190, from January 2022, coolant selection from heating systems will be prohibited, and all capital construction projects will switch to closed schemes.

How does a closed system work?

We have figured out one heat supply scheme, now let’s consider the second option - after all, closed and open water supply systems function completely differently. In a closed network, in contrast to a dead-end circuit, the water for the plumbing is not mixed with the coolant, but is heated from water from the heating network. That is, heat exchange occurs.

Open circuits have significant drawbacks, as described in the instructions in the previous chapter. But since they want to abolish dead-end systems at the legislative level in favor of ring (closed) systems, it means that the latter have undeniable advantages over the former. What are they?

This:

1. Stable quality of heated water;
2. Constant temperature, for which the minimum is +70 degrees;
3. Sanitary and other control of systems is carried out more simply.

Disadvantages of a loop network

As usual, positive characteristics entail an increase in the cost of the system, which is a significant disadvantage of closed schemes. They become more technically complex, and the price increases due to the introduction of individual water heaters with a corresponding arsenal of communications.

Note: When connecting such a system to the heating network, you also have to use brass tubes, which are also not cheap. The thing is that polymer tubes cannot withstand intense heat. Ferrous metal is highly susceptible to corrosion due to increased oxygen release. Brass in this regard is more stable, and allowing you to do without expansion joints on the body, it simplifies the design of the tube sheets.

The disadvantages of a looped network include the difficulty of regulating water flow. A storage tank must be installed near each boiler, which is not always technically possible.

Even with proper operation, heating networks operating in a closed circuit suffer water losses and have to be regularly recharged using a booster pump. Normally, these losses account for 0.5% of the total volume of water in the network. Its quality is ensured by vacuum deaerators installed in the central heating substation.

All this equipment operates from the mains, which means that electricity costs also increase, which also cannot be considered an advantage.

Conclusion

In the article, we briefly described what closed and open hot water supply is - the difference between these schemes is significant, each of them has its own advantages and disadvantages. It is, of course, up to you to decide which option to choose for installation in a private home.

But let us give you some advice: when the water supply is central, you have to pay for water - and in order to save money, it is better to make a loop network, even if its installation is more expensive. Well, for those who are supplied from an underground water intake, it is easier to make a dead-end system, which is much more economical.

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 the 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 enters 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 a closed hot water supply system. 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 multi-apartment buildings or large houses 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.

Just 20 years ago, hot water supply in a private house was just a dream of its owner.

Today it is a reality accessible to everyone. The question is only one thing - which system saves water consumption enough?

The correct choice of a hot water supply system will help not only effectively heat a country house, but also significantly save on costs. Sources of hot water supply vary in operating power, energy consumption and design solutions.

Gas-powered water heaters can use both stored water and running water, and are considered the most practical. However, there is an alternative in the form of electric heaters. Only by considering the advantages and disadvantages of a particular heating system can you make the right choice.

All water heaters are divided into instantaneous and storage.

Flow and storage heaters

The principle of their operation is as follows. Heated running water transfers heat to the room.

A simple example - standard geyser, installed in the private sector of the city.

In its previous versions, there is a significant drawback - a lot of water will leak before it heats up.

However, current gas heating systems make it possible to minimize consumption. (As you know, it is the most optimal heat transferr.) Having spent money on gas heating, you only have to calculate the cost of electricity.

Storage heaters work by storing water. The volume of liquid already in the tank is heated. Electricity consumption is 1 kW per hour. The advantages of this heater are that when you turn it on, hot water comes out of the tap.

The disadvantage is the large size of the tank for its accumulation. Here, owners of small-sized housing are unlikely to be delighted.

You can also provide hot water to your home with a heating boiler. Existing types boilers allow you not only to have hot water, but also to use it for heating the house. Single-circuit boilers are used only for heating, double-circuit boilers are used for heating.

Each system includes devices that evenly distribute heated water along given coordinates. These include temperature sensors and a water supply device. The pump supplies a measured amount of it through pipelines, which can also heat the building.

Water supply systems are divided into open and closed.

Open and closed systems - diagrams

In open hot water supply at home, the coolant is located directly in the system itself.

Here the water from the tap and in the radiator are the same in temperature.

And it is called “open” because the water flows directly through the open taps of the heating network.

An apartment building is supplied with hot water through an open water supply system. Here it is the best option, since there is no need to install and operate water heating equipment.

However, it is practically not suitable for the private sector, since the high costs of its installation do not pay off soon.

A closed supply system is a means of obtaining clean hot water. Simply put, drinking cold water is heated in the boiler, which enters the house.

You can even use it in cooking, since there are no obvious disadvantages of open supply (debris from radiators, chemical additives, etc.) here. Closed is good because it does not contain elements harmful to human health.

Calculation of hot water consumption using an example

Consumption calculation

When calculating hot water consumption, you need to take into account the number of residents in the house and their lifestyle.

After all, the main requirement for hot water is its minimum time of appearance from the tap.

In addition, according to the existing supply standards (within 10 minutes), it is supposed to be used not only at several points, but also in unlimited quantities.

Suppose that at the same time in the apartment they wash dishes in the kitchen and use the shower in the bathroom. Therefore, when calculating the supply of hot water, you need to consider the following points:

• Number of water consumers;
• How often do residents use the bath or shower?
• Number of bathrooms and toilet rooms;
• Volumetric costs of plumbing fixtures (for example, the volume of a bathtub);
• What temperature of hot water is needed.

The most optimal calculation option is to use special measuring instruments.

However, this is not yet possible for everyone. For an approximate calculation without flow sensors, let's take a family of four people.

In the current situation, when the father fills a 140 liter bathtub within 10 minutes, the son takes a shower in another bathroom, using 30 liters of water. At the same time, mom washes dishes in the kitchen - plus 30 liters.

Adding up all the data, you can understand that 200 liters of hot water were consumed in 10 minutes.

Of course, the situation is exaggerated and can only be ideal. In reality, consumption is much less.

Only by assessing the needs of all family members can you choose the most optimal system supplying the house with hot water.