Water circulation in the heating system

It is essential to comprehend the operation of the heating system if we are to maintain warm and comfortable living spaces. Water circulation is one of this system’s key components. It is the beating heart of your heating system, making sure that heat is distributed evenly and effectively throughout your home.

A network of pipes in a heating system circulates hot water from the boiler to different radiators or underfloor heating components located throughout the house. Heat is released by the water as it passes through these pipes, warming the surfaces and air around it.

Imagine it as a massive, unseen radiator that distributes heat throughout your house. Inefficient circulation can cause discomfort and wasteful energy use in certain areas, making others feel toasty while others feel chilly.

To solve problems and increase the efficiency of your heating system, you must comprehend how water flows through it. Every part of your home, from the boiler to the radiators and back, is essential to keeping it warm throughout the winter.

Topic	Water Circulation in Heating System
Key Components	Pump, Pipes, Radiators, Boiler
Function	Transport heated water from boiler to radiators and back for efficient heating throughout the house
Process	Pump pushes hot water through pipes into radiators, where heat is released into rooms; cooled water returns to boiler for reheating

Heating schemes with natural circulation in a private house

How does the diagram work with natural circulation

Commonly used as a coolant, ordinary water follows the curves from the boiler to the batteries and back because of variations in their thermodynamic characteristics. In other words, heat causes the fluid’s density to drop and its volume to rise, forcing out the cold stream that rises through the pipes. The coolant’s temperature drops as it diverges on horizontal branches and returns to the boiler. So, the circle is now complete.

If a private home was to have heating with natural circulation, all horizontal pipes would be installed with a slope toward the coolant’s direction of flow. This prevents the radiators from "gettingold." Because it travels up the pipes, into the expansion capacity, and finally into the air, the air is lighter than the liquid.

As the temperature rises, a liquid that has a higher volume merges into the tank, producing constant pressure.

What depends on the pressure?

When designing a private home, you must unquestionably account for the entire heating system in order to generate the required circulation pressure. It is dependent upon the lowest battery and the boiler’s midpoint level. The better the liquid flows through the system, the greater the height drop. The difference in the densities of the cooled and heated fluids affects it.

The heating system is characterized by a natural circulation caused by temperature changes in the boiler and radiators that happen along the central axis of the devices. Warm water comes from below and is at the top. The chilled liquid travels down the pipes due to gravity.

Movement is directly correlated with radiator installation height. Its increase is facilitated by the slope of the return line going to the boiler and the angle of inclination of the feed line facing the batteries. This makes it possible for liquid to more easily overcome the pipes’ local resistance.

In a private home with natural ventilation, the boiler is positioned lowest to raise all of the batteries when installing a heating system.

Heating systems schemes

The heating system’s design is dependent upon multiple factors:

• Battery connection method with feeding risers. There are single -pipe and two -pipe systems;
• place of laying the line that supplies hot water. It is necessary to choose between the upper and lower wiring;
• Line laying schemes: a deadlock system or passing water in the tracks;
• risers can be located horizontally or vertically.

What distinguishes forced circulation from natural circulation?

The forced movement of the coolant indicates that liquid is flowing through the roadway as a result of the pump’s laborious effort. The coolant in this natural system moves because of the difference in weight between the heated and cooled liquid, requiring no additional equipment.

One -pipe scheme: how to adjust the temperature?

There is only one wiring option available for a single-pipe heating system with natural circulation, and that is the upper. Since the liquid cooled by radiators returns to the supply line, it does not have a reverse riser. The water in the upper and lower batteries has a temperature differential thanks to the coolant’s movement.

The heating devices on the lower floor should have a slightly larger surface area than those on the upper floors in order to maintain a consistent temperature in rooms situated at different levels. The lower radiators are filled with a heated and cooled fluid from the upper heating devices.

In a single-pipe system, the fluid can be in one of two versions: in the first, it goes to the battery, and in the second, it goes further along the riser to the lower radiators.

In the second scenario, the coolant flows through every component beginning with the upper. One unique feature of this wiring is that the batteries are only connected to the lower floors’ chilled coolant.

Additionally, if the first version allows you to use cranes to change the temperature in the rooms, the second version prohibits this use because it will lower the coolant supply to all batteries that come after. Furthermore, the system’s fluid circulation will stop when the crane fully overlaps.

It is preferable to install a single-pipe system with wiring that allows the water supply to each battery to be adjusted. This will allow the temperature to be adjusted in different rooms, increasing the heating system’s flexibility and efficacy.

A single-pipe system can only be installed in buildings with an attic since it can only be the upper. A supply pipeline ought to exist. The primary drawback is that heating can only be turned on right away for the entire house. The system’s primary benefits are its reduced cost and ease of installation.

Pros and cons of natural circulation

Benefits of the natural fluid circulation heating system:

• lack of difficulties in installing, starting and using;
• The resistance of the heat of the system. Based on the gravitational movement of the liquid, it gives the greatest thermal return and maintains a microclimate in the rooms at the right level;
• economy (with good insulation of a private house);
• Work without noise. There is no pump – there is no vibration and hum;
• Independence from power outages with electricity. Of course, if the installed boiler can function without electric current;
• A long period of use. With a timely technical service without overhaul, the heating system can operate for more than thirty -five years.

The primary disadvantage of natural circulation heating systems is their limited coverage area and action radius. Place it in private residences that don’t have more than 100 square meters. The heating system’s horizontal radius is restricted to 30 meters because of the low circulation pressure. One essential need for any home is an attic big enough to accommodate an expansion tank.

The house warms up slowly, which is the biggest drawback. Pipes passing through unheated rooms in a system with natural movement must be insulated to prevent fluid from freezing.

Generally speaking, some materials require such a system; however, if the pipeline’s local resistance needs to be decreased, using larger pipes will increase costs.

An essential prerequisite for pipe laying is:

• a system with the smallest number of turns that will interfere with the fluid flow;
• harsh adherence to the recommended angle of inclination;
• The use of pipes with a design diameter.

Installing a heating system necessitates closely adhering to technical specifications. A decrease in fluid circulation is threatened by noncompliance with the regulations. It will not be able to guarantee that the coolant moves along the line if there are rough mistakes in the system’s arrangement.

We calculate the one -pipe heating system ourselves

The primary steps in determining water heating are:

• calculation of the desired power of the boiler;
• the calculation of the power of all heating devices that will be connected to the system;
• Selection of pipes size.

The computation of the boiler’s power

Heat loss through the house’s walls, ceiling, and floors is taken into account when calculating the boiler’s capacity. When calculating power, the area of surfaces, the manufacturing material, and the temperature differential between the interior and exterior of the house during heating must all be considered.

Determination of the battery power and pipe diameter

The following formula can be used to determine the pipes’ required diameter:

• Determine the circulation pressure, which depends on the height and length of the pipes, as well as the difference in fluid temperature at the output of the boiler;
• Count pressure losses in direct areas, turns and in each heating device.

Such computations can be completed by anyone without specialized knowledge, but it is highly challenging to calculate the whole heating scheme using natural circulation. Huge heat losses will result from even a tiny mistake. It is therefore best to leave the calculations and the subsequent heating system installation to the experts.

• Author: Vadim Nikolaevich Lozinsky

Heating system with natural circulation: common circuits of water circuits

If installing a circulation pump or connecting to a centralized power supply is not feasible, the construction of an autonomous gravitational type heating network is chosen. It is essential to compute the parameters of the natural circulation heating system, install the components correctly, and choose the water circuit diagram sensibly if you want it to run continuously.

The principles of the natural circulation process

Natural physical laws cause the water to move in the heating circuit without the need for a circulation pump.

Comprehending the characteristics of these procedures will enable the accurate development of heating system projects for both standard and unique scenarios.

Maximum difference in hydrostatic pressure

The primary physical characteristic of any coolant (water or antifreeze) that helps it flow naturally along the contour is a decrease in density as temperature rises. The hydrostatic pressure of the warm and cold liquid columns differs because hot water has a lower density than cold water. As cold water enters the heat exchanger, hot water is transferred out of the pipe.

The hydrostatic pressure drop between the liquid’s hot and cold columns is what propels the water in a circuit with natural circulation.

The house’s heating contour can be broken up into multiple pieces. The water is directed up for "hot" fragments and down for "cold" fragments. The upper and lower limits of the heating system define the boundaries of the fragments. The primary goal of simulating the natural circulation of water is to maximize the pressure differential between the fluid column in "hot" and "cold" segments.

The acceleration collector, also known as the main riser, is a traditional component of the water circuit for natural circulation. It is a vertical pipe that rises from the heat exchanger. The acceleration collector is insulated all the way along because it should have a maximum temperature. However, since the water inside does not have time to cool, insulation cannot be conducted in collectors that are not very tall (such as those found in one-story homes).

Typically, the system is built so that the circuit’s top point and the acceleration collector’s upper point line up. There, if a membrane tank is being used, they set a valve for air removal or an exit to an open-type explosor. This results in a reduction of heat loss in this region since the length of the "hot" segment of the contour is at its shortest.

It is also preferable that the lengthy region that transports the cooled coolant not be joined with the "hot" section of the circuit. The lower point of the heat exchanger inside the heating device should ideally line up with the lower point of the water circuit.

The fluid column’s hydrostatic pressure in the heated section of the contour decreases with decreasing boiler location within the heating system.

There are additional regulations specific to the "cold" portion of the water circuit that raise the fluid’s pressure:

• The more heat loss on the “cold” section of the heating network, the lower the temperature of the water and its density, therefore, the functioning of systems with natural circulation is possible only with significant heat transfer;
• The larger the distance from the lower point of the circuit to the connection points of the radiators, the greater the water column with a minimum temperature and maximum density.

Installing a stove or boiler at the lowest point of the house—the basement, for example—ensures that the last rule is followed. The boiler is positioned to provide the greatest possible separation between the water entry point into the heat exchanger and the lower level of radiators.

The distance, in actuality no more than ten meters, between the lower and upper points of the water circuit with natural circulation should be kept reasonable. Heat only the heat exchanger and the bottom portion of the acceleration collector using an oven or boiler. The pressure drop in the "hot" contour fragment will be negligible and the circulation process won’t start if this fragment is insignificant in relation to the height of the water circuit as a whole.

For two-story buildings, natural circulation systems are perfectly reasonable, and a circulation pump will be required for buildings with more stories.

Minimization of water resistance

The coolant’s speed along the contour must be considered when designing a system with natural circulation. First of all, heat transfer through the "boiler-heat exchanger-water circuit-heating radiators-room" will happen more quickly the faster the speed. Second, and this is particularly crucial for furnace heating, the faster the fluid velocity through the heat exchanger, the less likely it is to boil.

The system’s water boiling can be highly costly; disassembling, fixing, and reassembling the heat exchanger will cost a lot of money and time.

The circulation pump’s parameters primarily determine the water movement speed in heating systems that require it. The following variables affect the speed of natural circulation water heating:

• the pressure difference between fragments of the circuit at its lower point;
• hydrodynamic resistance of the heating system.

The above discussion covered techniques to guarantee the maximum pressure differential. Due to a complicated mathematical model and a large amount of incoming data, the hydrodynamic resistance of the real system cannot be accurately calculated with certainty. Nonetheless, there are general guidelines that, when followed, will lower the heating circuit’s resistance.

The resistance of the pipe walls and the existence of narrowing due to fittings or shut-off valves are the primary causes of the decrease in the water movement’s velocity. With the exception of long, thin pipes that are typical of heating systems with warm floors, wall resistance is almost nonexistent at low flow rates. Individual contours with forced circulation are typically identifiable to him.

You must consider the existence of technical narrowing when selecting pipe types for the contour with natural circulation when installing the system. For this reason, using metal-plastic pipes to allow for natural water circulation is not recommended.

Fittings for metal-plastic pipes severely reduce the inner diameter and pose a major risk to water flowing under low pressure.

Rules for choosing and mounting pipes

The decision between polypropylene and steel pipes for any kind of circulation is made based on several factors, including cost, ease of installation, and service life, in addition to the possibility of using the pipes for hot water. Since water has the highest temperature when passing through it, the feed riser is mounted from a metal pipe. Steam is an option in the event of a heat exchanger malfunction or furnace heating.

It is required to use pipes with a slightly larger diameter when using natural circulation than when using a circulation pump. The diameter of the acceleration collector and the pipes at the return heat exchanger’s input should typically be two inches for heating spaces up to 200 square meters. When compared to the forced circulation option, this is due to a lower water rate, which causes the following issues:

• a smaller volume of heat transferred per unit of time from the source to the heated room;
• Small pressure will not be able to plug clicks or air traffic jams.

When using natural circulation with the lower feed supply scheme, the issue of air removal from the system needs special attention. It can’t be taken out of the coolant entirely using an expansion tank. Water leaks into the devices along the highway below them before it gets inside of them.

When forced circulation is used, the air is driven to the airborne system—a device with automatic, manual, or semi-automatic control—by the water pressure at the system’s highest point. The primary adjustment of heat transfer is made possible by Maevsky cranes.

Maevsky cranes are used directly to drag air in gravitational heating networks where the feed is below the devices. Additionally, each riser’s air vent or the air line running parallel to the system’s systems can be used to redirect the air. Gravitational schemes with less wiring are very uncommon because of the remarkable quantity of air removal devices.

There are air release mechanisms on every modern heating radiator, so you can create a slope to direct air to the radiator and avoid circuit congestion problems.

A tiny air cork can totally stop the heating system with very little pressure. Thus, heating system pipelines cannot be installed without a slope and at a water speed of less than 0.25 m/s, per SNiP 41-01-2003.

It is impossible to achieve such speeds with natural circulation. Thus, to remove air from the heating system, constant slopes must be observed in addition to pipe diameter increases. In apartment networks, the slope reaches 5 mm on the linear meter of the horizontal line. The slope is designed at a rate of 2-3 mm per 1 meter.

In order to direct airflow to the Baku-expired tank or a system situated at the highest point of the contour, the supply is sloping in the direction of water movement. Even though you can create a counter-coating, in this instance, installing the valve for air removal is also required.

Typically, the return slope is made in the direction that the chilled water is moving. The reverse pipe’s entry into the heat generator will then align with the circuit’s lowest point.

The most popular way to clear air traffic jams from the water circuit with natural circulation is to reverse the pipes and change the direction of the supply slope.

It’s important to keep air from getting into the heating system’s horizontally oriented, narrow pipes when installing a warm floor in a small space with natural circulation. The air removal device must be placed in front of the heated floor.

It’s important to comprehend the basic yet essential process of water circulation in a heating system in order to maintain the warmth of your home. Imagine this: hot water from your boiler heats the area around it as it travels through radiators, pipes, and underfloor heating systems. It goes back into the boiler to be reheated and recirculated after it cools. Your house will always have a consistent supply of heat thanks to this ongoing loop. By comprehending the functioning of this circulation, you can enhance the efficiency and comfort of your heating system and guarantee a comfortable and reasonably priced living area throughout the year.

One -pipe and two -pipe heating schemes

One or more independent circuits can be designed when creating a heating plan for a home with natural water circulation. They may vary greatly from one another. They are carried out in a single-pipe or two-pipe scheme, depending on the length, number of radiators, and other factors.

Contour using one pipe

Single-pipe heating systems use a single pipe to supply radiators with water consistently. Heating with metal pipes instead of radiators is the most basic pipe option. When opting for natural coolant circulation, this is the least expensive and least troublesome solution for the home. The appearance of large pipes is the only real drawback.

In the most cost-effective variant of a single-pipe circuit with heating radiators, hot water passes through each component in turn. Here, a minimum quantity of pipes and shut-off valves are required. The number of sections needs to account for the coolant cooling down as you pass, which causes the water to get colder for radiators after you.

A basic top-level single-pipe scheme necessitates a minimum amount of installation labor and financial investment. You can turn off the radiators without stopping the system altogether with a more involved and expensive option at the bottom.

Diagonally connecting heating devices to a one-pipe network is the most efficient method. This heating contour scheme with natural circulation states that hot water enters the radiator at the top and is removed through the pipe below after cooling. Hot water provides the most heat when it passes in this manner.

Heat transfer is greatly decreased when the input and output pipes have lower connections to the battery because the heated coolant must travel a greater distance. Large-section batteries are not used in such schemes because of the significant cooling involved.

Impressive heat losses are a characteristic of "Leningrad" that need to be considered when calculating the system. One benefit is that devices can be selectively disabled for repairs without interrupting the heating cycle when locking valves are used on the input and output pipes.

"Leningradka" are heating contours that have a radiator connection that is similar to this. Because the pipeline is laid in a more aesthetically pleasing manner, they are preferred in the layout of apartment heating systems despite their noticeable heat losses.

The inability to turn off one heating section without also turning off water circulation along the entire contour is a major drawback of single-pipe networks. As a result, they typically install "Bypas" to update the traditional scheme and get around the radiator by using a branch with two ball valves or a three-way tap. This enables you to modify the radiator’s water supply all the way up to total shutdown.

Options for a single-pipe scheme with vertical risers are used for buildings with two floors or more. Compared to horizontal risers, the hot water distribution in this instance is more even. Vertical risers also blend in better with the interior of the house because they are less extended.

Natural circulation is a successful method of heating two-story rooms using a single-pipe scheme with vertical wiring. Disconnecting the upper radiators is an option that is presented.

Option using a reverse pipe

The term "two-pipe" refers to the heating system in which one pipe is used to remove hot water from the boiler or stove and the other to supply hot water to the radiators. When heating radiators are present, a supply and withdrawal scheme like this is employed more frequently than a single pipe. It costs more since a second pipe needs to be installed, but it offers several important benefits:

• there is a more uniform distribution of the temperature of the coolant supplied to radiators;
• It is easier to calculate the dependence of the parameters of the radiators on the area of the heated room and the required temperature values;
• easier to adjust heat supply to each radiator.

Two-pipe systems are classified as passing or dead-end depending on which way the relatively hot chilled water is moving. The length of the cycle for the whole circuit coincides in associated schemes because the movement of chilled water moves in the same direction as hot water.

Because chilled water in dead end schemes tends to flow toward heat, radiators vary in terms of how long coolant turnover cycles last. The system’s small speed means that there can be a large variation in the heating time. Heat will be produced more quickly in radiators with shorter water cycle lengths.

The primary deciding factor between heating schemes that pass below and those that dead end above is the return pipe’s convenience.

When it comes to heating radiators, there are two kinds of eyeliner: upper and lower. The hot water supply pipe is situated above the heating radiators for the upper eyeliner and below for the lower eyeliner.

This lower eyeliner makes it possible to drain air from radiators without having to install pipes on top, which is advantageous given the room’s layout. The pressure difference won’t be as great without the acceleration collector as it would be with the upper eyeliner. As a result, when heating a space using the natural circulation principle, the lower eyeliner is essentially never used.

When moving water in the heating circuit, using natural circulation calls for precise calculations and professionally executed installation work. When these requirements are met, the heating system will heat a private home’s interior and spare its owners from having to rely on electricity and loud pumps.

Did I enjoy the article? Talk about her

For your home’s heating system to operate effectively and efficiently, you must understand how water circulates. Homeowners can better maintain their systems and troubleshoot any issues that may arise by understanding the fundamentals of this process.

The boiler’s function in heating the water is an important lesson to learn. Heat is released into the rooms through pipes that carry heated water from the boiler to radiators or underfloor heating systems. To maximize the boiler’s efficiency, make sure it is appropriately sized for the heating needs of your house and gets regular maintenance.

The circulation pump, which maintains the flow of water throughout the system, is another essential component. Stasis, which can result in cold spots and inefficiencies, is avoided by this pump, which guarantees uniform heat distribution. The circulation pump needs to be maintained on a regular basis to avoid malfunctions and guarantee smooth operation.

Recognizing possible problems entails understanding the fundamentals of water circulation. These can include system leaks, blockages, or airlocks, all of which can impair water flow and lower heating efficiency. It takes routine inspections and fast repairs to take care of these problems and maintain the system’s functionality.

In the end, homeowners who understand the nuances of water circulation in their heating systems are better equipped to maintain and optimize their systems. Homeowners can potentially save money on energy bills and guarantee their homes remain cozy and warm during the winter months by being informed and watchful.

Video on the topic

Movement (circulation) of water in the heating system.