A heating system with natural circulation of coolant is often used for heating dachas and private houses that are located far from city communications. Such a system works without a pump, which means, regardless of electricity, so preference is given to it.

The principle of operation of a heating system with natural circulation

The main task of a water heating system- this is to force the coolant to circulate through the pipes. In order for the house to warm up, hot water from the boiler must flow into the pipes and radiators. The natural circulation heating system works on the principle of gravity. The liquid moves through the pipes by gravity without the use of a pump. The density and weight of the liquid becomes less when heated, and after cooling it returns to its primary state.

In such a device there is virtually no pressure. According to calculations, you can see that with a pressure of a 10-meter water column there is a pressure of 1 atmosphere. It turns out that in a heating device for a one-story house the pressure will be from 0.5 to 0.7 atm., and in a two-story house - no more than 1 atm.

Advantages and disadvantages of heating with natural circulation

Like any device, water heating with natural circulation has its advantages, but also disadvantages. What's good about the system?

Disadvantages of the system:

Types of natural circulation systems

Before creating a scheme for heating a private house, first calculate the amount of heat required for the premises. The calculation includes boiler data, placement and diameter of pipes, as well as the level of thermal insulation of external walls. Even the smallest errors in calculations can affect the quality of home heating. Therefore, it is better if all calculations are carried out by specialists. Heating systems come in several types:

• Open and closed type (differing in expansion tanks).
• Single-pipe and two-pipe type (heating radiators are connected in different ways).

Open system

The open device includes a reservoir (open tank), which is equipped with a pipe (emergency overflow). The pipe is connected to the sewer system or taken to the street. The tank is installed under the ceiling, sometimes in the attic. An open-type tank can be made of any size with your own hands, which is its main advantage. Has an affordable price. Disadvantages of the device:

• An open-type tank needs to be constantly refilled with water, as it evaporates quickly. To avoid constantly adding water manually, you can connect a water pipe to the tank.
• Often, corrosion forms on the metal elements of the circuit. Due to the fact that oxygen constantly flows into the open tank.
• Air enters the pipeline. By securing the radiators at a slight angle and installing automatic air vents, you can get rid of the problem.

Closed system

Natural circulation system Closed-type coolant is well suited for both one-story and two-story houses. A membrane tank is built into the heating circuit. Thanks to the tank, the metal parts of the device are less susceptible to corrosion. The closed device works as follows:

If you choose between an open system and a closed one, it is cheaper to purchase or create an open tank with your own hands. A membrane tank costs several times more, so is rarely used.

Single pipe system

For one-story houses with a small area, single-pipe heating is suitable. In a two-story house, this type of heating will be ineffective. The advantages of the system are cheap installation, simple design, pipes are not installed under the ceiling, which means the overall interior of the room will not deteriorate. Single-pipe heating works according to the following principle:

• The liquid rises along the vertical section of the pipe.
• Then the coolant moves into a pipe located horizontally. This pipe connects heating radiators.
• The cooled liquid is returned back to the boiler from the outer radiator.

Such a system has its drawbacks. The further away the supply riser, the lower the temperature of the radiators. Bypasses will help increase productivity. To establish uniform heating of the house, jumpers are placed in the places where the radiators are connected. Even after making accurate calculations, a single-pipe type of system will be ineffective if a one-story house has more than three rooms. The problem can be solved by upgrading the system with a circular pump.

Scheme of two-pipe water heating for a private house with natural circulation

The two-pipe type of heating is suitable for heating a two-story house. If we compare a one-pipe and two-pipe system, then in the second, the liquid is supplied to all radiators hot. The two-pipe circuit has a special design consisting of two pipes. One for supply, the other for return. A supply pipe is connected to each heating device. The connection is made through a separate input tap. And the return pipe is connected separately. The advantages of a heating system with top and bottom wiring are that its installation is very simple and its performance characteristics are effective. With this system:

1. You don't have to add additional sections to the radiator to improve heating.
2. Unlike a single-pipe circuit, smaller diameter pipes are used to lay the pipeline in this system.
3. Easy system adjustment.
4. There is an even distribution of heat.

Currently, it is possible to create a two-pipe type of heating with natural circulation with your own hands . For its manufacture, steel or polymer pipes are used..

Calculation diagram for a heating system with natural circulation

The most difficult thing in designing a heating system is the correct calculation. How well the device will work depends on the length and angle of the pipes, as well as the number of turns on it. You need to know this because there is no pressure in the circuit. What you need to consider when drawing up a diagram and calculation:

1. What is the diameter of the pipes and the material from which they are made.
2. Pipe angle.
3. Types of coolants.

Which pipe material is better?

The method of installing the circuit, corrosion protection and hydraulic resistance, all these indicators will depend on the material from which the pipeline is made. For the heating system you can use polypropylene, steel, metal-plastic and copper pipes.

To determine what pipe diameter suitable for warming up your home, you need to know that:

1. The diameter of the pipe is selected according to the material from which the pipes are made and the thermal calculations made.
2. Calculate the amount of heat required for the room and add 20% to the result obtained.
3. Using the values ​​​​indicated in the SNiP tables, the cross-section of the pipeline is calculated. For the calculation, heat capacity readings and pipe size (internal cross-section) are taken.

If after each branch you install a supply pipe 1 size smaller than the previous one, then the circulation of the heat exchanger will become several times more intense. The return pipe is installed with an extension. This is how the minimum diameter of two pipes is calculated. Adhering to the obtained values, each pipe section is set to its own size.

Angle of inclination of heating pipes

In sections of the pipe with corners and turns, the coolant will move weakly. Here, its movement is negatively affected by hydraulic resistance. Therefore, when drawing up a diagram and making calculations, you need to adhere to the building codes that are specified in SNiP 41-01-2003. To prevent air from entering the system, and to ensure that distant radiators warm up well, the pipes must be installed with an inclination: per 1 meter of length, an inclination of at least 10 mm is made.

Types of coolant

Water or antifreeze can be used as a coolant. Since antifreeze has a high density and low heat transfer, it will take a lot of fuel to heat it. Therefore, for a system with natural circulation it is more profitable to use water. In addition, when heated, antifreeze expands more strongly, Therefore, choosing such a coolant membrane tank should be larger.

The coolant can circulate from the boiler to the heating device in two ways. Through bottom or top filling.

Conclusion

A natural circulation heating system can be connected to a simple solid fuel stove or to a heating boiler. Thanks to a pumpless heating system, heating your home will not depend on electricity.

A heating system with natural circulation of water coolant was patented in 1832 by the Russian metallurgist P.G. Sobolevsky. In our age of rapidly changing technologies, this scheme (also called gravity or gravity) for heating a private home could be considered obsolete if not for its simplicity, reliability and efficiency. The gravity heating system is still widely used in DIY home construction and is considered the optimal technical and economic solution. Low pressure in the network limits its scope of application, but for a one-story residential building this scheme is very effective and is often considered as an alternative to heating using pumping units.

Heating system for a private house with natural circulation

Heating scheme with natural circulation

Scheme of the movement of coolant water in a heating system with natural circulation

The following designations are used in the diagram:

• pos. 1 – heating boiler;
• pos. 2 – expansion tank;
• pos. 3 – heating radiators;
• T1 – heated coolant, red arrows show the direction of its movement;
• T2 – cooled coolant, blue arrows indicate its movement in the circuit.

In autonomous heating of a one-story or two-story private house, the use of special antifreeze compounds is allowed, but in systems with natural coolant circulation, the use of antifreeze is not recommended.

The main disadvantages of antifreeze for use in a natural circulation heating circuit:

• In a heating scheme with natural circulation, the designs of the expansion tanks provide contact with the surrounding atmospheric air. Antifreeze quickly evaporates, polluting the surrounding environment;
• The need for constant monitoring of the volume of coolant and its periodic replenishment;
• Antifreezes have low heat transfer, which contributes to low heat removal by radiators from the coolant during its circulation. This leads to overheating of the antifreeze in the circuit and the boiler itself;
• The use of overheated antifreeze in a closed circuit contributes to the abundant formation of deposits inside the heat exchanger, clogging the flow area in the tubes.

The most optimal heat carrier in a gravity-type circuit for heating a one-story or two-story residential building is a water coolant due to its low cost and availability.

Natural circulation in heating circuits

The main functional elements of a heating system with natural circulation of a residential building are:

• Boiler heating water coolant;
• An expansion tank, which is a container for discharging excess water that appears when the volume of coolant water in the circuit increases when it is heated;
• Pipelines for supplying hot water from the boiler to heating radiators and returning cooled liquid from the radiators back to the boiler (for which the return part of the heating network is commonly called return). Together they form a closed coolant circulation loop;
• Heating radiators.

Diagram of a heating network with natural circulation for heating a private house

When the coolant heats up, its volume increases, excess heated water rises vertically upward to the expansion tank, hydrostatic pressure is created in the system, depending on the difference in the weights of the water columns of hot (supply line) and cold (return line) water.

Under this pressure, hot water flows from the top point of the heating main (red line in the diagram) to the heating radiators. The water cooled in the radiators flows through the return line (blue line) to the boiler inlet. A gravity heating system in a one-story or two-story house is operational only if during installation the slopes of the horizontal sections of the heating pipeline in the direction of fluid movement are ensured. Then the coolant will be able to move downward under its own weight with the least hydraulic resistance.

Another factor influencing the movement of liquid is the circulation pressure, indicated in the figure by the letter H. The higher the difference in the levels of the placement of radiators and the boiler, the faster the movement of water in the circuit.

In gravity heating systems, the expansion tank is not closed with a lid, so this system is often called open. All air pockets from the heating main are forced into the upper part of the circuit, where a tank is installed, open to contact with the atmosphere. A system using sealed tanks is called closed. It uses a pump; its operating principle is of a forced nature.

Water speed

With cyclical temperature changes, hot water is in the upper part of the heating network, cold moisture moves in the lower pipes. The main driving force for the natural (without coercion from the pump) movement of liquid in the circuit is the circulation pressure, which depends on the ratio of the heights of the boiler and the lowest radiator. The figure below shows a graphical diagram of the occurrence of circulation pressure h. The parameter h has a constant value for this circuit and does not change during operation of the heating system.

Scheme of the occurrence of circulation pressure

To create optimal pressure, the heating boiler is installed at a maximum depth, for example, in the basement. In turn, the expansion tank must be installed higher. Quite often it is placed in the attic of a house.

The speed of water circulation in the circuit when installing a gravity heating system in a private house with your own hands is determined by the following factors:

1. The magnitude of the circulation pressure. The larger it is, the higher the speed of water flow in the heating main;
2. Diameters of heating pipes. Small internal pipe dimensions will provide greater resistance to water flow than pipes with a larger diameter. For one-pipe or two-pipe gravity flow systems for wiring, the dimensions of the pipes are deliberately increased to D 32-40 mm;
3. Materials for manufacturing circuit pipes. Modern polypropylene pipes have a flow resistance that is several times lower than that of steel pipelines damaged by corrosion and covered with deposits;
4. The presence of turns in the heating main network. The ideal option is a straight pipeline;
5. An abundance of fittings, adapters, retaining washers. Each valve reduces the amount of pressure.

Natural circulation processes are very inert and proceed slowly. The time between firing the boiler and completely stabilizing the temperature in the rooms is several hours.

Circuit wiring diagrams

According to the method of connecting heating radiators, it is customary to distinguish two schemes for installing heating system circuits: one-pipe and two-pipe.

A do-it-yourself single-pipe assembly assembly is characterized by a sequential arrangement of heating devices on the supply circuit. Having passed from the top point through all the radiators (red line), the water returns through the return line (blue line) to the boiler.

Single-pipe diagram of a gravity heating system

In a two-pipe scheme, two separate circulation circuits are installed. Hot coolant flows through one circuit, supplying heat to the radiators, and through the other circuit, cooled water is sent from the radiators to the boiler.

The figure below shows a two-pipe heating system for a two-story house. The distribution of coolant (red line) through the radiators begins from the maximum height H, which provides the required circulation pressure. The cooled coolant (blue line) is collected in the return line and sent to the boiler inlet.

Two-pipe diagram of a gravity heating system

Circulation diagram. Video

You can find out what a heating scheme with natural coolant circulation is like in the video below.

Gravity heating systems for a private home impress with their simplicity of design, ease of maintenance and energy independence. They do not have pumping units, which create discomfort for residents with their noise, and there are no vibrations that accompany their operation. The trouble-free service life of natural circulation systems is estimated at half a century, since they do not have electric pumps or automation equipment. In general, gravity schemes are inferior to forced heating systems on a number of points:

• excessive inertia forces you to wait several hours until the circuit reaches the required thermal conditions;

In contact with

The use of natural circulation heating systems goes back many decades. Their introduction began almost simultaneously with the advent of steam heating. There are several current heating schemes with natural circulation for a private home, and each of them can be successfully used with high efficiency in the most comfortable conditions for it.

Design features

The main difference between the gravity heating scheme is that in the circuit through which the coolant moves, there is no circulation pump forcibly pushing the water.



Popular arguments given in favor of a gravity heating system are the following:

• complete independence from the availability of electricity in the room;
• high degree of inertia, which minimizes the impact of external factors on heat redistribution.

It must be taken into account that increasing the diameter of the heating pipes in such a situation has a positive effect on the operation of the system. However, it is worth adhering to certain restrictions in dimensions.

Operating principle

During heating operation with natural circulation, physical principles are used in which the warmer liquid rises, moving from the highest point along the installation slope created for it from the main pipes.



1. With this scheme, it is necessary to install the boiler below the level of the sections with radiators.
2. When moving from the top point, water moves towards the sections. The pipes connecting the radiators to the main line should be significantly smaller in diameter than the main line. This heating scheme for a private house with natural circulation will be in demand with the top type of distribution.
3. For lower distribution, you will need to provide some kind of acceleration circuit. It is formed when installing a pipeline going up to the expansion tank installed there. After this, the window is lowered horizontally, from which further wiring is carried out.



Heating systems without a pump have reduced efficiency in rooms with low ceilings, since it is advisable to install a pipe with the highest point of the system line 1.5-1.6 m above the boiler, and an expansion tank should also be mounted above it.

Due to the fact that movement in heating is carried out without a pump, during the time it reaches distant sections of the main line, the coolant manages to release a sufficient amount of thermal energy. This principle of operation involves working in small spaces. It is believed that for highways with a circuit length of more than 30 m, a scheme with a gravity heating system for a private house loses its effectiveness.

VIDEO: Calculation of heating with natural circulation

Installation features

Boilers with natural circulation can have two types of mains connections:

• single-pipe;
• two-pipe.

Both wiring options have individual installation features, but in terms of efficiency of use with a gravity heating system they differ slightly. It is important to observe the slope of the heating pipes during natural circulation to ensure uninterrupted movement and the absence of airy areas. In open systems, gas formations exit naturally through the expansion tank.

When installing heating lines with natural circulation with your own hands, a slope is maintained, ensuring a drop in height of 5-10 mm for every meter of length.

The hydrodynamic forces developed under system conditions, which determine the speed of flow movement, directly depend on the level of lift of the circuit. It is important to install radiators above the boiler installation level, and the pipeline resistance depends on the diameters of the lines.

When the installation of a heating system with natural circulation is carried out with numerous branches and frequent refractions, this helps to increase the hydraulic resistance. In addition, an unreasonably high number of installed shut-off valves also increases this value. Minimizing such areas plus increasing the reasonable diameter of the lines helps to increase the pressure in the system.

Installation of a two-pipe system

Natural circulation in the heating system can be provided in two-pipe circuits. The first pipe (supply) directs the flow of hot coolant from the boiler, and the second pipe (cold) returns cooled water to the boiler. During installation, the following actions are carried out:

• a branch is drawn upward from the heat generator, which goes to the expansion tank;
• installation of the barrel can be carried out both under the ceiling and at the level of the insulated attic;
• a pipeline is mounted to the bottom of the tank, going into the room, descending to a level of 2/3 of the height from the ceiling;
• wiring is carried out to the nearest section of radiators;
• the second branch pipe of the section is mounted to the return;
• The return line is mounted parallel to the supply, but the slope is provided towards the boiler.

How to determine the volume of the expansion tank



The volume of an open type expansion tank is determined very simply - 10% of the total volume of coolant circulating through the water circuit. Determining the tenth part is considered a universal way to calculate the volume of the expansion chamber at which it works ideally.

Determining the volume of a closed-type tank is somewhat more difficult, but it is also quite easy for a non-specialist to overcome. To calculate, you need to know the following input data:

• percentage increase in coolant volume when heated (HW) - standard 5% for water and 10% for antifreeze;
• the total amount of water or antifreeze in the water circuit (WC) - if there is no such data, you will have to drain all the coolant and measure it with buckets or other devices. The task is to determine the most accurate volume;
• circuit and boiler pressure (DC) - this information is reflected in the technical passport for the boiler. If it is not there, the Internet will save you;
• maximum pressure in the expansion chamber (DB) - all information is also reflected in the data sheet.

We apply the formula:

OV x VK x (DK + 1) / DK - DB

We round the resulting value to a whole number and obtain the estimated volume of the expansion tank.

This value is always greater than the “by eye - 10%” method, but this is not a violation. If the volume of the expansion tank is larger than required for the water circuit, it must be configured correctly.



Installation of a one-pipe system

This type of water circulation in the heating system, unlike the two-pipe scheme, does not depend on the level of the radiator sections. The expansion barrel is selected with a volume of 25-32 liters. Its filling should be 2/3 of the volume.

The location of the boiler, as in a single-pipe boiler, should be below the level of the radiators to ensure natural outflow. An installation slope for highways of 5-70 is provided. Radiators are powered by pipes with a diameter of at least 32 mm. The preferred material for wiring is a polymer pipeline. For connections to the radiator pipes, pipe diameters of up to 20 mm are used.

If the diameters are selected correctly, then balancing is not required. However, it is advisable to install shut-off valves on the coolant inlet/outlet to the radiators. This will ensure ease of dismantling the sections for maintenance or repair work.

A two-pipe system is more expensive, since you have to use double the main line. In this regard, it is often important to use single-pipe circuits for small rooms with natural heating.

VIDEO: Heating scheme with natural circulation

Heating systems (HS) of private houses are carried out according to two main operating schemes: heating a one-story house with natural circulation (NC) and forced circulation (FC).
Despite the fact that the second is more efficient, the EC system is still quite often used in private housing construction, especially in small one-story houses.

If we talk about how this system works, without using technical terms, then it looks like this.

A certain volume of water is heated in a heating boiler, as a result of which it increases in volume and its density decreases. Due to this, cold water entering from below squeezes it into the upper part of the heating system. From here, the water begins to move by gravity through the CO, gradually cooling and giving off heat to radiators and heating pipes. Having completed a full circle, it returns to the lower part of the cauldron. This cycle then repeats.

The heating system with natural circulation of a one-story house has operating features that are often used to back up the operation of the system with a PC. The pump installed in it operates in normal mode, and if the power supply is lost, the system switches to operation according to the EC option.

General information.

The fact that the heating scheme of a one-story house with natural circulation has practically no moving elements allows it to be operated without major repairs for a long time. If the CO distribution is carried out using galvanized or polymer pipes, then the terms can reach fifty years.

EC automatically implies a low pressure difference between the inlet and outlet. Naturally, the coolant experiences a certain resistance to its movement as it passes through heating devices and pipes. Taking this into account, the optimal radius for normal operation of the SO with the EC was determined to be thirty meters. But we must understand that the figure is quite arbitrary and may fluctuate.

Due to the design features, the heating system with natural circulation of a one-story house has high inertia. From the moment the boiler is ignited until the temperature in the premises of the building stabilizes, at least several hours pass. The reason is simple. First, the boiler heat exchanger warms up and only then the slow movement of the coolant begins.



It is important that in those places where CO pipes are laid horizontally, they must have a mandatory slope in the direction of coolant flow. This ensures the movement of water in the system without stagnation and the automatic removal of air from the system to its highest point, which is located in the expansion tank. It is made in one of three options: open, with a built-in air vent, or sealed.

Wiring diagrams

Water heating of a one-story house with natural circulation can be performed according to several different schemes.



The work, regardless of the chosen scheme, begins with the creation of a heating plan for a one-story house with natural circulation.

The mentioned scheme provides for the laying of two pipelines along the perimeter of the building. It is used when it is necessary to heat fairly large areas. The upper one is used to supply hot water to the CO, the lower one is used to return the cooled coolant to the boiler. Radiators are mounted between them. If possible, the boiler is installed below the latter. Pipes are laid with a slope along the water flow of at least 5 degrees.

Bottling, especially in places where several radiators are fed at once, must be carried out using a pipe with a diameter of ≥ 32 mm. A metal-plastic or polymer pipe is best suited. The connection directly to each radiator should be made with a pipe with a diameter of 20 mm.

If the pipe diameters are selected correctly, such CO does not need balancing. Despite this, chokes should be installed on the lines going to the radiators.

Heating a one-story house with natural circulation, made using a two-pipe scheme, is the most expensive option in terms of its execution (materials, work), and therefore is used quite rarely.



The simplest system that allows you to provide heating for a one-story private house with your own hands, made according to the specified scheme, is “Leningradka”.
Installation conditions (angle of inclination and pipe diameters) are similar to the previous option.

The specificity is that the radiators, in this case, cut into the main heating ring (parallel to the main pipe).

In addition to the expansion tank, valves for bleeding air must be installed on each radiator. Thermal heads or chokes are installed on the radiators closest to the boiler and on the radiators farthest from it, which helps to equalize the temperature in them.



When choosing this option, the scheme for heating a one-story house with natural circulation looks like this.

In sections of the pipe that supply hot water to the CO and return cold water to the boiler, special manifolds are installed, which are combs, on each outlet of which a choke is installed. Each radiator has two pipes, one for supply and return.

This version is the most convenient in terms of adjustment capabilities. But its installation is quite complicated, there are too many pipes, which, in order to maintain an acceptable design of the premises, will have to be removed into the floors or behind false walls, which automatically leads to a significant increase in the cost of work and purchased materials. It’s easy to verify this, just look at the pre-drafted heating plan for a one-story house with natural circulation.

Advantages and disadvantages

The main advantages of COs that use natural circulation for operation are ease of installation and long service life.

However, there are no pros without cons. The main disadvantages of these RMs include:

• Short working distance (range of action). Acceptable characteristics are achieved only when the pipeline length is ≤ 30 linear meters.
• It is not technically possible to regulate the temperature in each room of the house separately.
• Water circulates in the CO under low pressure, which leads to different temperatures in different rooms (the lower the further from the boiler).
• The long period of time required for the system to reach operating mode and completely warm up all rooms of the house.

The advantage of a natural circulation heating system is that it operates independently of electricity. However, it is very difficult to obtain comfortable conditions with such a scheme, and sometimes it is simply impossible. Therefore, a pump is most often used to ensure circulation of the coolant. But sometimes, for example, in summer cottages where there is no electricity, a heating system without a pump is the only possible version.

A system with natural circulation (NC) or forced movement of fluid is also called gravitational due to the fact that it operates on the principle of gravity. It is also called gravity flow. All these names mean that the heating system operates without the use of a pump.

How does the natural circulation scheme work?

As a coolant, ordinary water is most often used, which moves along circuits from the boiler to the batteries and back due to changes in its thermodynamic properties. That is, when heated, the density of the liquid decreases and the volume increases; it is squeezed out by a cold flow, which goes back and rises through the pipes. While the coolant disperses along the horizontal branches, its temperature decreases and it returns to the boiler. So the circle closes.

If heating with natural circulation water was selected for a private house, then all horizontal pipes are laid with a slope in the direction of flow of the coolant. This makes it possible for the radiators not to “air up”. Air is lighter than liquid, so it goes up through the pipes, enters the expansion tank, and then, accordingly, into the air.

Liquid is poured into the tank, the volume of which increases with increasing temperature, and creates continuous pressure.

To create the necessary circulation pressure, it is necessary to calculate the entire heating system when designing a private house. It depends on boiler middle level and the lowest battery. The greater the height difference, the better the fluid moves through the system. It is also influenced by the difference in densities of hot and cooled liquids.

A heating system with natural circulation is characterized by a change in temperature in the radiators and in the boiler, which occurs along the central axis of the devices. Hot water is at the top, cold water is at the bottom. Under the influence of gravity, the cooled liquid moves down the pipes.

Movement directly depends on the installation height of the radiators. Its increase is facilitated by the angle of inclination of the supply line, which is directed towards the batteries, and the slope of the return line, directed towards the boiler. This makes it easier for the liquid to overcome the local resistance of the pipes.

When installing a heating system in a private house with natural circulation, the boiler is placed at the lowest point so that all the batteries are located above.

Heating system diagrams

Heating system diagram depends on several criteria:

• method of connecting batteries to supply risers. There are one-pipe and two-pipe systems;
• the location of the line that supplies hot water. You need to choose between upper and lower wiring;
• line laying schemes: dead-end system or associated movement of water in routes;
• risers can be located horizontally or vertically.

What is the difference between forced and natural circulation?

Forced movement of the coolant implies the circulation of liquid along the line due to the working force of the pump. The natural system does not require the use of any equipment; here the coolant moves due to the difference in the weight of the hot and already cooled liquid.

Single-pipe circuit: how to regulate the temperature?

A single-pipe heating system with natural circulation can have only one wiring option - the top one. There is no return riser, so the liquid cooled in the radiators returns to the supply line. Coolant movement provides temperature difference water in the lower and upper batteries.

To ensure the same temperature in rooms on different floors, the surface of heating devices on the lower floor should be slightly larger than on the upper floors. The liquid that is hot and cooled in the upper heating devices enters the lower radiators.

In a single-pipe system, there can be two versions of fluid movement: in the first case, part goes to the battery, the other part goes further along the riser to the lower radiators.

In the second case, the entire coolant passes through each device, starting from the top. The peculiarity of this wiring is that the batteries on the lower floors receive only cooled coolant.

And if in the first option you can regulate the temperature in the rooms using taps, then in the second you cannot use them, since this will lead to to reduce coolant supply to all subsequent batteries. In addition, completely shutting off the tap will stop the circulation of liquid in the system.

When installing a single-pipe system, it is better to choose a wiring that makes it possible to regulate the water supply to each battery. This will allow you to adjust the temperature in individual rooms and make the heating system more flexible, and therefore more efficient.

Since a single-pipe system can only be top-mounted, its installation is only possible in buildings with an attic. This is where the supply pipeline should be located. The main disadvantage is that heating can only be started throughout the entire house at once. The main advantages of the system are ease of installation and lower cost.

Pros and cons of natural circulation

Advantages of a heating system with natural circulation of fluid:



Main disadvantage heating systems with natural circulation - restrictions on the area of ​​the house and radius of action. They install it in private houses, the area of ​​which does not exceed one hundred square meters. Due to the small circulation pressure, the radius of the heating system is limited to 30 meters in the horizontal direction. An indispensable requirement is the presence of an attic in the house in which the expansion tank will be located.

The most important disadvantage is also the slow heating of the entire house. In a system with natural movement, it is necessary to insulate pipes that run in unheated rooms, since there is a risk of liquid freezing.

Typically, such a system requires few materials, however, if the local resistance of the pipeline needs to be reduced, costs increase due to the need to use larger pipes.

Main requirements for laying pipes:

• a system with the least number of turns that will interfere with the flow of fluid;
• strict adherence to the recommended tilt angle;
• use of pipes with a designed diameter.

Installation of a heating system requires strict adherence to technical requirements. Failure to comply with the rules threatens to reduce fluid circulation. If there are gross errors in the organization of the system, it will not be possible to ensure the movement of coolant along the main line.

We calculate a single-pipe heating system ourselves

The main stages when calculating water heating:



Boiler power calculation

Boiler power indicators are calculated taking into account heat loss through the floors, walls and roof of the house. When determining power, you need to pay attention to the surface area, material of manufacture, as well as the difference in temperatures outside and inside the room when heating the house.

Calculation of battery power and pipe size

• Determine the circulation pressure, which depends on the height and length of the pipes, as well as the difference in liquid temperature at the boiler outlet;
• calculate pressure losses on straight sections, turns and in each heating device.

It is very difficult for a person without special knowledge to perform such calculations, as well as to calculate the entire heating scheme with natural circulation. A small mistake will lead to huge heat losses. Therefore, it is best to entrust the calculations and subsequent installation of the heating system to specialists.