The water heating system, which uses a membrane expansion tank and the coolant does not come into contact with atmospheric air in any way, is considered closed and operates under pressure. This scheme is the most common this moment because it has many advantages. In this article, we will analyze what a closed heating system of a private house is, its pros and cons, as well as service features.

What is a closed heating system?

An important feature of such a system is the absence of contact with the outside air and the presence of a small overpressure. As a rule, the circuit works with artificial stimulation of the circulation of the coolant using a pump. This allows you not to worry about observing large slopes of highways, as well as to accept smaller pipe diameters and lay them in the most convenient way.

Typically, a gravity heating system with natural circulation coolant is made with an open expansion tank installed at the highest point. The closed system is traditionally supplied with circulation pump, which increases the efficiency of its work and reduces material consumption.

Due to their characteristics, systems closed type have a lot of advantages:

• pressurized coolant heats up faster;
• the probability of airing the network of pipelines and radiators is very low;
• the coolant is not saturated with oxygen and does not evaporate into the atmosphere, which is very important when filling the system with antifreeze;
• installation expansion tank in a closed heating system, it is produced on the return pipeline near the boiler, which is very convenient in terms of maintenance;
• there is no need to use pipelines of large diameters and lay them in plain sight, in this respect a closed system with forced circulation - optimal choice for a private house.

There is only one significant drawback - dependence on the reliability of power supply, a closed heating system without a pump powered by the mains will not work. Fortunately, circulation units for individual systems have a small power consumption, and therefore, during a power outage, they will be able to function from an uninterruptible power supply sufficiently for a long time.

Some experts argue that a closed system with natural circulation will help solve the problem of power outages. Recall that in this case the movement of the coolant occurs due to the difference in density and mass of hot and chilled water. The first, heating up in the boiler, as a lighter one, is displaced upwards by the cooled coolant coming from the radiators, which has a large mass.

Despite the fact that the pressure in a closed heating system (1.5-2 Bar) does not prevent the gravitational movement of hot and cold water its effectiveness is questionable. The fact is that the difference in convective forces is already small, and here you still need to overcome the resistance of the tank membrane, which stretches when the water expands. In order not to mess with these slippery moments, it is better to always put a pump on a closed system. If there is a need to mount a gravity circuit, then it must be made open.

Scheme of a closed heating system

In private housing construction, 2 types of schemes are traditionally used:

• single-pipe;
• two-pipe.

One-pipe, better known as "Leningrad", works satisfactorily in one - and two-storey houses a small area, when no more than 5 radiators are installed on each floor. The implementation of the scheme requires an accurate calculation of the pipe diameters and the number of battery sections, since the coolant cools down significantly after passing through each subsequent radiator. These requirements also need to be met by a single-pipe scheme of a closed-type heating system with top wiring which is shown in the figure below:

Note. Regardless of the type of scheme chosen, a closed system must contain a security group, sometimes it comes with a boiler. The group consists of a manometer for pressure control, an air vent and a safety valve for emergency water release. The unit is installed on the supply pipeline leaving the boiler, and without any shut-off valves.

Two-pipe scheme closed system easier to calculate and install, is famous for its good performance. After all, the coolant is delivered to all radiators with the same temperature, and when implementing a passing scheme, it also travels the same distance. An example of a two-pipe system is shown in the figure:

Some additions have a closed heating system with solid fuel boiler. To avoid the formation of condensate in the furnace of the heat generator, the circuit is supplemented with a mixing unit with three-way valve and bypass line. The valve forces the water to turn around along the bypass until it is heated to set temperature, and only then it launches the coolant from the main into the boiler.

How to fill the system with coolant?

When the make-up connection is connected to the water mains via ball valve, then filling a closed-type heating system with a coolant is quite simple. For this case, it makes sense to attract an assistant, especially if the house has several floors. One person operates the make-up valve, and the second is responsible for the release of air from the batteries. The faucet opens about a third so that the pressure is not strong.

The person in the boiler room monitors the readings of the pressure gauge, the recharge of the closed heating system is closed when the pressure reaches 2 bar. Now the assistant bleeds air from the radiators by means of Maevsky's taps, after which the pressure drops. The goal is to reach the design pressure by removing all air from the pipelines by gradually replacing it with tap water.

It is more difficult to pump the coolant into a closed system when there is no make-up from the water supply or it is necessary to fill in an antifreeze liquid. To do this, you need a special manual or electric pump and a container for the coolant from which it will be pumped into the system. First you need to open all the air valves on the radiators, and then fill the pipes through the drain fitting by connecting a pump with a check valve to it.

As the liquid is pumped in, it is necessary to close the Mayevsky taps, from which the coolant will flow. Having pumped up the system to 1.5 bar, it is necessary to remove the air, after which the pressure is brought to the working one. At the end, a trial run of the boiler and pressure adjustment are carried out, and, if necessary, air is bled.

Why does pressure drop in a closed heating system?

There is only one reason why the pressure drops - the lack of tightness, that is, leakage. The question is to find it. A characteristic sign of a leak is a puddle in a certain place or a brown spot when the water has time to dry. During the search, you should inspect the following nodes and elements:

• pipe connections and fittings: it happens that cracks occur in the latter;
• automatic air vents: a defective element with a stuck float will let water through;
• shut-off and control valves, safety valve;
• expansion tank: a crack in the membrane will cause a pressure drop, air in the system and frequent shutdowns of the boiler.

To eliminate leakage, one cannot do without partial or complete emptying of pipelines. At the end of the work, you will have to refill the water into the system, create required pressure and follow the pressure gauge for several days.

Conclusion

A closed heating system has a lot of advantages, hence its popularity. If the installation and commissioning is carried out correctly, then it does not require intervention in its work for a long time. Most of the malfunctions that occur can be easily fixed with your own hands, as well as system maintenance. It is advisable to check the performance of elements such as air vents, valves and an expansion tank annually.

Closed heating system mandatory installation expansion tank of membrane type. In addition, with this scheme, the contact of atmospheric air with the coolant is excluded.

1

Such options for organizing the heating of a private house are very popular these days. They are relatively easy to install with your own hands and have many operational advantages, which will be discussed below. A closed heating system consists of several main elements:

• circulation pump;
• heating unit (gas,);
• pipes;
• membrane expansion tank;
• batteries.

Such systems operate understandable principle. Heat carrier heating up to set temperature carried out in a heating boiler. At the same time, the volume hot water increases, which initiates its entry into heating batteries through the pipes.

Excess heated liquid passes through the return line into the expansion tank. This part of the system is made in the form of a closed-type capsule, which is divided into two separate compartments by a special membrane.

The principle of operation of the expansion tank

Nitrogen is pumped into one section of the expansion tank, the second is necessary for the passage of hot water. In the compartment where the gas is located, when the boiler is started, the pressure is identical to the pressure of the system. The coolant upon admission to expansion device equalizes the pressure. Water is pumped out and sent back to the heating unit by a special circulation pump.

The systems under consideration are necessarily equipped with additional control equipment. These include:

• drain valve;
• security group (it protects the system from excessive pressure);
• make-up valve;
• valves;
• valve to remove excess pressure;
• manometer.

These elements provide reliable control of the functioning of the heating complex and make its operation easier.

2

Such equipment has many advantages, which determines its popularity today. The main advantages of closed-type heating systems are as follows:

1. Ability to perform all installation work with your own hands.
2. High heat dissipation.
3. No need for additional thermal protection of the line and for setting clearly calibrated angles of its inclination.
4. It is not necessary to regularly add water to the system, as it does not evaporate when long-term operation equipment.
5. Uniform distribution of the coolant over all, regardless of which wiring diagram was chosen to build the system.
6. Minimal corrosion provided by increased tightness of the equipment used.
7. Rapid heating of the coolant.
8. Increasing the time of trouble-free operation of a closed-type system due to a significant reduction in the temperature difference between hot water in the return and direct lines.
9. Possibility of using small heating pipes.
10. If desired, instead of water, antifreeze can be used as a coolant. Its use allows you to stop the boiler in winter for long time. In this case, the antifreeze will definitely not freeze.

Closed heating system

The disadvantages of closed systems include the need to purchase a sufficiently large expansion tank (its cost is high) and the need for a constant supply of electricity. The circulation pump will not work without electricity.

3

The expansion tank may be installed next to the circulation pump. At the same time, both of these elements of the system can be placed with a heating boiler in the same room. This means that you will achieve a reduction in the footage of the main and save on the purchase of additional pipes. And the need to install fewer tubular products will please anyone home master who is accustomed to doing home repairs with his own hands.

A closed heating system is equally effective for a private house with small area, and for spacious cottages. It can be installed even in very spacious industrial and special facilities. This distinguishes closed systems from open ones, which function effectively only in buildings with a small area.

Closed heating system in the cottage

Note! In most cases, the circulation unit and the expansion tank are placed on the return line, thereby increasing the time of its use (the cooled coolant brings less operational harm to the pump).

But there are also devices that can be placed on the supply pipe. Such pumps are treated with a special lubricant that perfectly protects them from negative impact hot water.

4

For a private house, both two-pipe and one-pipe heating systems are suitable. The scheme with two pipes (with supply and return lines) is considered by experts to be more modern and efficient in operation. It guarantees the same temperature of the coolant supplied to all heating radiators(no matter how far they are from the boiler).

The one-pipe scheme also has its supporters. The arrangement of such a system requires less financial investments. But its calculation must be carried out very carefully. The main thing is to correctly determine the number of heating batteries and the number of their sections. Professionals recommend using single pipe systems exclusively in small houses, for heating all rooms of which 4-5 radiators are enough.

Heating batteries in a single-pipe scheme

It is optimal to create closed-type heating systems using metal-plastic pipes. They do not rust and are long term operation. It is recommended to purchase pipes with a cross section of 2–2.5 cm. In this case, products with a diameter of 2.5 cm should be connected to the heating unit. And then smoothly switch to pipes with a cross section of 2 cm.

Batteries for the systems we are interested in take aluminum, steel or cast iron. You choose. If you plan to install the system yourself, it is better to buy lighter and at the same time quite reliable aluminum radiators. They are easier to transport and install. It is advisable to place the batteries under window openings. In this case, they will form an excellent barrier to air seeping through windows from a cold street.

Strictly follow the installation order and you will not have any problems.

Remember that you need to equip a closed system in such a way that at any time you can turn off the failed element without stopping the operation of the entire heating complex. To drain water from individual radiators, ball or other shut-off valves are installed at their outlet and inlet. Be sure to install a bypass (spare) line. It makes it possible to direct the coolant directly to the battery.

Shut-off valves for draining water from the radiator

Also, do not forget about the need to install a security group. It is located at the exit heating installation. This group, when pressure increases, automatically resets it to acceptable limits, thereby protecting the system from breakdown.

Seal all joints between pipes and individual parts of the heating complex with sealant or sanitary flax. Choose fittings carefully to create a complete system. Connecting products made of brass and bronze have maximum resistance to pressure surges.

When designing the heat supply of a private house today, a closed heating system is mainly chosen due to its numerous benefits which we will consider below. Heating systems open type are already becoming archaic, although they can still be used for heat supply small spaces.

Features of open heating systems

Device and operation

The open heating system got its name because of its leakage - it freely communicates with air through an open expansion tank. It is a stainless steel box where excess water merges when it heats up and, accordingly, expands. As it cools, the water decreases in volume and returns from the tank to the pipeline.

Open-type heating systems are distinguished by the natural circulation of the coolant: water moves in pipes without the use of pumps, so such systems do not depend on electricity. To achieve this, several rules are followed during design and installation:

1. The heating boiler is placed at the lowest point, for example, in the basement.
2. An expansion tank is installed at the very top, for example, in the attic of a house.
3. Pipes throughout from the top to the bottom should be sloped so that water flows through them without delay.

Water is heated in the boiler, expands and naturally rises up the riser to the highest point, from where it is diluted down the radiators and, cooled down, returns to the boiler. If during installation the pipe was raised too high in any place, the angle of inclination was not maintained, then an air bubble forms in this place, which slows down the flow of water and subsequent batteries remain cold. The speed of movement of the coolant is low, so it is necessary to install pipes large diameter, especially on the supply riser - 40-50 mm in diameter.

Advantages and disadvantages

• Ease of operation.
• Independence from the presence of electricity.
• Noiseless operation due to the lack of a pump.
• Low cost of equipment and components.

• From an open expansion tank, air enters the system, which leads to air locks, intense corrosion of metal parts, and cavitation.
• The tank must be insulated so that the water does not freeze.
• It is necessary to control the water level in the tank.
• It is impossible to use antifreeze instead of water - it evaporates from the expansion tank.
• Due to the lack of a pump, the total length of the pipeline is limited, so open heating systems are suitable for heating only small rooms.
• Due to the weak circulation of the coolant, it is necessary to heat it up to more high temperature, and this is an extra waste, especially since the volume of the coolant here is greater than in closed heating systems.
• Also, extra costs for the pipeline due to the larger diameter of the pipes and the need to bring them to the attic to the expansion tank.
• The pipes are all in sight, usually they cannot be covered with finishing panels.

Features of closed heating systems

The specifics of the arrangement and performance

Closed-type heating systems are hermetic: the expansion tank in them is a closed container, which is internally divided by a heat-resistant rubber membrane into two compartments. Excess heated water is drained into one compartment, and air (or nitrogen) under pressure is in the other, which squeezes the water back when it cools.

Important: volume membrane tank choose at the rate of 10% of the total volume of the coolant in the system.

Closed heating systems of a private house are systems with artificial forced circulation of the coolant. The circulation pump can be built into the heating boiler or installed separately - usually on the return line, where the water is cooler. Thanks to forced circulation it is much easier to install the entire heating system: you do not need to withstand the slope of the pipes, pipes of smaller diameter can be used, an expansion membrane tank can be placed anywhere for ease of maintenance. On the other hand, because of the pump, the heating system becomes dependent on electricity. To compensate for this dependence, it is necessary to provide backup power sources: UPS, gas generator, etc.

Advantages and disadvantages

• Easy installation.
• The evaporation of the coolant is excluded, so antifreeze can be used.
• The absence of air in the system eliminates oxygen corrosion, as well as air locks.
• Lower pipeline costs. Pipes can be laid so as to hide them under the finish.
• It is possible to connect additional heating circuits, such as underfloor heating (with a separate pump).
• Due to the higher speed of the coolant, the system has better heat transfer and heats up faster when turned on.

• Equipment for a closed system is more expensive than for an open system.
• Dependence on power supply.
• High demands on the tightness of the joints, especially when using antifreeze.

Filling a closed heating system with water

Proper filling of a closed-type heating system is carried out in several stages. The hose is connected at one end to a filling tap, and at the other end to a water supply system, or to a pump that will pump prepared water from an appropriate container. First, water is supplied until the pressure reaches 0.5 bar. At this stage, all joints should be checked for leaks. Then the pressure is raised to 2 bar and air is removed from the heating system: Mayevsky taps and other air vents are opened on the radiators. The pressure drops and additional replenishment is needed. When the equipment is filled with water, all taps are closed and again check for leaks at the joints. After that, the coolant is lowered to a pressure of 1.5 bar - this is the optimal indicator for cold water. When heated, the pressure will increase.

It is quite possible to mount an open or closed heating system yourself. But it is important not to make mistakes in the calculations when choosing the appropriate pipe diameter, expansion tank volume, boiler power and other characteristics of the heating system. Such mistakes can be very costly. Therefore, for the calculation and installation of the heating system, it is better to contact the professionals of a specialized company.

Video: one-pipe and two-pipe heating systems

The creation of a water heating system by unknown inventors, no doubt an ingenious solution that uses change physical properties water when heated. The water heated in the boiler moves up and creates a certain head (pressure). Under its action, water moves by gravity through the pipes of the circuit, gives off heat to the radiators and returns to the boiler through the "return". The first working heating system was, of course, open. After the advent of new technologies, materials and equipment, closed circuits heating, but there are still disputes about which heating system, closed or open, is better for heating homes.

There are only two options to choose from - a closed or open heating system at home. Has anyone wondered why the first systems created were only open? And they were open for one simple reason - the boilers that heated water were solid fuel. When the circulation stops, the water in the boiler boils, the explosion of the boiler is prevented by a safety valve, but it is impossible to extinguish it quickly. Therefore, closed heating systems with forced circulation began to be used for electric and gas boilers, which can be turned off automatically at any time.

Open heating system

The open heating system is now considered obsolete and is used in small private houses and country cottages. In this case, an expansion tank must be installed in open system heating in the highest point accelerating manifold, to ensure circulation under the influence of gravity.

Modern open circuit heating systems from a closed system borrowed the most important unit - a circulation pump. It is usually used during system start-up to reduce its inertia. Then, during operation, the pump turns off and the bypass opens. Knowing where to put the pump in the heating system is necessary for its reliable and long work. The pump is placed at the point with the lowest coolant temperature, usually in the "return" near the boiler.

The system is called "open" because atmospheric air constantly in contact with water in an open expansion tank.

The open system is simple, reliable, and its cost is minimal. There is an erroneous opinion that its installation is more expensive, because such systems require pipes of a larger diameter. If we take into account the cost of the circulation pump, the expansion membrane tank and the cost of electricity for a closed heating system, then the installation will obviously not be cheaper. In some cases, there is no alternative to using an open heating system. For example, if there is no power supply.

The main advantages of open heating systems:

Of course, a simple and reliable open heating system, its scheme is usually two-pipe, is not without drawbacks:

Closed heating system

If a closed-type heating system is chosen, the scheme of which can be any - one-pipe or two-pipe, with warm floors or without, then its main feature is the absence of contact between the coolant and air, i.e., it is completely sealed. The movement of the coolant in the circuit provides, and the thermal expansion of the liquid is compensated in a sealed membrane expansion tank. The use of forced circulation facilitates installation, because it is not necessary to strictly maintain the slope of pipes, which may be of a smaller diameter. The presence of a pump makes the system volatile.

With an increase in the number of storeys of private houses and the complexity of heating circuits, a closed-type heating system is mainly used, which may include several circulation pumps, collector beam wiring and automated electronic temperature control different rooms. In a closed circuit, the scheme for installing an expansion tank in a heating system differs from its placement in an open system. The best option is to place the membrane tank in the "return" near the boiler.

The popular closed heating system has both advantages and some disadvantages:

Commissioning of a closed heating system

After installation is completed, the system must be filled with water and tested. The initial filling of the closed-type heating system is carried out according to certain rules. The design of the heating circuit must provide for drain valves located at the lowest point of the system and valves for filling the system with water.

The sequence of actions when filling the circuit with coolant is as follows:

If leaks appear during the filling process, then the filling process of the system must be stopped and the problems eliminated. After eliminating the shortcomings, work can be continued.

If, after carrying out all the above operations, the system does not work well, some batteries do not warm up well, circulation is disturbed, then this indicates the presence of air in the system. In such cases, the heating system is purged, which consists in carefully removing air. The Mayevsky tap opens and not only air is removed, but also a certain amount of water. At the same time, it is desirable to provide increased pressure by opening the make-up from the water supply in the heating system. Usually, repeating the procedure leads to the complete removal of air bubbles from the circuit.

What is the need for recharge in a closed system

For effective work closed heating system, it is necessary that it constantly maintain operating pressure. Despite the fact that the system is sealed, there are leaks that are imperceptible at first glance and insignificant. Water from the system is lost when air is removed through the Mayevsky tap, seeps through glands, through various joints of the circuit. These losses are cumulative and after some time affect the performance of the system. To compensate for these losses, it is necessary to feed the closed heating system from the water main.

Manual or automatic make-up

For simple and small systems heating, a mechanically controlled tap is usually used. It is installed at the point of least pressure, which is in front of the circulation pump. At this point, a pressure gauge is installed to control the make-up process.

A shut-off valve is used to prevent the ingress of coolant into the water main.

In complex and branched systems, automatic make-up heating systems, the price of the make-up valve depends on the brand of the manufacturer. Sometimes automatic make-up valves are part of the boiler equipment. If the make-up is carried out from the water supply, in which the pressure is usually 3 - 4 bar, then everything happens quite simply. factory setting valve - 1.5 bar.

If the pressure in the heating system falls below 1.5 bar, the valve will open and remain open until the set pressure is reached. If the automatic make-up will use the coolant from other sources, then a pump is needed, which will be turned on by a signal from the valve and supply the coolant at a certain pressure to the heating system.

Automatic temperature control

How to automate and select optimal mode in the premises of the house, especially with frequent absence in the apartment or in private country house. Very simply, you need to buy a controller for the heating system - a device that allows you to program and control the temperature in the house. Before buying a controller for heating, you need to make sure that the boiler has an appropriate control unit. Most the best option- expert advice.

One of the most best options automation is obtained by using . Special valves are installed on the comb, which are controlled by the control unit of the multi-channel controller. The same control unit issues a signal to turn on the boiler.

A separate thermostat is installed in each room, which is set to a certain temperature. The multi-channel controller of the heating system is radiant, it processes data from thermostats and, when the temperature drops in any room, turns on the boiler and opens the valve of this room on the comb. In any case, the boiler will work until the temperature in all rooms reaches the programmed value.

It is impossible to say unequivocally which heating system is better - open or closed. The application of a particular system depends on many factors, such as the size and number of storeys of the house, its location, the availability of financial resources and the region. Only a reasonable approach will allow you to choose a home heating system that will provide comfort and coziness in the house at optimal installation and operation costs.