Heating system: existing schemes and features of organizing the supply and removal (return) of coolant. Features of the functioning of heating systems: pressure difference between supply and return Setting up the heating system

System diagram with regulators

Each heating season brings its own surprises with difficulties in heating rooms, both for residents of multi-storey buildings and private cottages. The quality of uniform heating of all rooms of the house depends on how the temperature of the heating radiators is adjusted.

Why do you need to make adjustments?

Setting the optimal temperature of the heating radiators allows you to create the most comfortable living conditions indoors. In addition, adjustment allows:

1. Remove the effect of air in the batteries, allow the coolant to move freely through the pipeline of the heating system, effectively transferring its heat to the interior of the room.
2. Reduce heat consumption costs by up to 25%.
3. Do not keep windows constantly open if the air in the room is excessively overheated.

It is advisable to set up heating and adjust batteries before the start of the heating season. This is necessary so that later you do not experience discomfort in the apartment and do not adjust the heating temperature of the batteries in emergency mode. Before setting up and adjusting the radiators, initially in the summer you need to thermally insulate all windows. In addition, you need to take into account the specific location of the apartment:

• In the middle or corner of the house.
• Lower or upper floor.

After analyzing the situation, it is advisable to use energy-saving technologies to maximize heat conservation inside the apartment:

• Insulate walls, corners, floors.
• Carry out hydro and thermal insulation of the seams between the concrete joints of the panel house.

Without this work, it will be useless to regulate the temperature of the radiators, since the lion's share of the heat will heat the street.

Types of heating systems and the principle of adjusting radiators

To correctly adjust the temperature of radiators, you need to know the general structure of the heating system and the layout of the coolant pipes.

• In the case of individual heating, adjustment is easier when:

1. The system is powered by a powerful boiler.
2. Each battery is equipped with a three-way valve.
3. Forced pumping of coolant has been installed.

At the stage of installation of individual heating, it is necessary to take into account the minimum number of bends in the system. This is necessary in order to reduce heat loss and not reduce the pressure of the coolant supplied to the radiators.

For uniform heating and rational use of heat, a valve is mounted on each battery. With it, you can reduce the water supply or disconnect it from the general heating system in an unused room.

• In the central heating system of multi-storey buildings, equipped with a vertical supply of coolant through a pipeline from top to bottom, it is impossible to adjust the radiators. In this situation, the upper floors open the windows due to the heat, and the rooms on the lower floors are cold, since the radiators there are barely warm.
• A more advanced one-pipe network. Here, the coolant is supplied to each battery and then returned to the central riser. Therefore, there is no noticeable temperature difference in the apartments on the upper and lower floors of these buildings. In this case, the supply pipe of each radiator is equipped with a control valve.
• A two-pipe system, where two risers are mounted, ensures the supply of coolant to the heating radiator and back. To increase or decrease the coolant flow, each battery is equipped with a separate valve with a manual or automatic thermostat.

Types of control valves

Existing modern heat supply technologies make it possible to install a special tap on each radiator that controls the quality of heat. This control valve is a shut-off valve heat exchanger, which is connected via pipes to the heating radiator.

According to the principle of their operation, these cranes are:

• Ball ones, which primarily serve as 100% protection against emergency situations. These shut-off devices are a structure that can be rotated 90 degrees and can allow water to pass through or prevent the passage of coolant.

The ball valve must not be left in a half-open state, as in this case the sealing ring may be damaged and a leak may form.

• Standard, where there is no temperature scale. They are represented by traditional budget valves. They do not provide absolute accuracy of adjustment. By partially blocking the access of coolant to the radiator, they change the temperature in the apartment to an indefinite value.
• With a thermal head that allows you to adjust and control the parameters of the heating system. Such thermostats are automatic and mechanical.

Conventional direct-acting thermostat

A direct-acting thermostat is a simple device for controlling the temperature in a heating radiator, which is installed near it. By its design, it is a sealed cylinder into which a siphon is inserted with a special liquid or gas that clearly reacts to changes in the temperature of the coolant.

As it increases, the liquid or gas expands. This leads to increased pressure on the rod in the thermostat valve. It, in turn, moving, blocks the flow of coolant. When the radiator cools, the reverse process occurs.

Thermostat with electronic sensor

This device is no different in operating principle from the previous version, the only difference is in the settings. If in a conventional thermostat they are performed manually, then an electronic sensor does not need this.

Here the temperature is set in advance, and the sensor monitors its maintenance within the specified limits. The electronic thermostatic sensor regulates the control parameters of the air temperature within the range from 6 to 26 degrees.

Step-by-step instructions for adjusting temperature

To ensure comfortable living conditions in the room, you need to perform some basic steps.

1. Initially, it is necessary to bleed the air on each battery until water flows from the tap in a trickle.
2. Then you need to adjust the pressure in the batteries.
3. To do this, in the first battery from the boiler you need to open the valve by two turns, on the second - by three, and then according to the same scheme, increasing the number of turns of the valve being opened on each radiator. Thus, the coolant pressure will be evenly distributed over all radiators. This will ensure its normal passage through the pipes and better heating of the batteries.
4. In a forced heating system, control valves will help to pump the coolant and control rational heat consumption.
5. In a flow-through system, the temperature is well regulated by thermostats built into each battery.
6. In a two-pipe heating system, you can control not only the temperature of the coolant, but also its quantity in the batteries using both manual and automatic control systems.

Most of the heating systems of apartment and private buildings are built precisely according to this scheme. What are its advantages and are there any disadvantages?

Can a two-pipe heating system be installed with your own hands?

The difference between a two-pipe heating system and a single-pipe one

Let's first define what kind of beast this is - a two-pipe heating system. It’s easy to guess from the name that it uses exactly two pipes; but where do they lead and why are they needed?

The fact is that to heat a heating device with any coolant, it needs circulation. This can be achieved in one of two ways:

1. Single-pipe scheme (so-called barracks type)
2. Two-pipe heating.

In the first case, the entire heating system is one large ring. It can be opened by heating devices, or, which is much more reasonable, they can be placed parallel to the pipe; the main thing is that there is no separate supply and return pipeline passing through the heated room.

Or rather, in this case these functions are combined by the same pipe.

What do we gain and what do we lose in this case?

• Advantage: minimal material costs.
• Disadvantage: large variation in coolant temperature between the radiators at the beginning and end of the ring.

The second scheme - two-pipe heating - is a little more complicated and more expensive. There are two pipelines running through the entire room (in the case of a multi-storey building - at least on one floor or in the basement) - supply and return.

According to the first, the hot coolant (most often ordinary process water) is sent to the heating devices to give them heat; according to the second, it is returned.

Each heating device (or a riser with several heating devices) is placed in the gap between the supply and return.

There are two main consequences of this connection scheme:

• Disadvantage: the pipe consumption is much higher for two pipelines instead of one.
• Advantage: the ability to supply coolant to ALL heating devices at approximately the same temperature.

Advice: in case of a large room, it is necessary to install a control throttle on each heating device.

This will allow you to equalize the temperature more accurately, making sure that the flow of water from the supply to the return on nearby radiators will not “sag” those more distant from the boiler or elevator.

Features of two-pipe heating systems in apartment buildings

In the case of apartment buildings, of course, no one installs throttles on individual risers and constantly regulates the water flow; Equalizing the temperature of the coolant at different distances from the elevator is achieved in another way: the supply and return pipelines running through the basement (the so-called heating pipe) have a much larger diameter than the heating risers.

Alas, in new houses built after the collapse of the Soviet Union and the disappearance of strict state control over construction organizations, the practice began to use pipes of approximately the same diameter on risers and benches, as well as thin-walled pipes installed for welding valves and other nice signs of the new social system.

The consequence of such savings is cold radiators in apartments located at the maximum distance from the elevator unit; By a funny coincidence, these apartments are usually corner and have a common wall with the street. Quite a cold wall.

However, we have deviated from the topic. A two-pipe heating system in an apartment building has one more feature: for its normal functioning, water must circulate through the risers, rising and falling up and down. If something interferes with it, the riser with all the batteries remains cold.

What to do if the heating system at home is running, but the radiators are at room temperature?

1. Make sure the riser valves are open.
2. If all the flags and switches are in the “open” position, close one of the paired risers (we are, of course, talking about a house with, where both beds are in the basement) and open the vent located next to it.
   If the water flows with normal pressure, there are no obstacles to the normal circulation of the riser, except for the air at its upper points. Tip: drain more water until, after a long snorting of the air-water mixture, a powerful and stable stream of hot water flows. Perhaps in this case you will not need to go up to the top floor and bleed the air there - circulation will be restored after startup.
3. If the water does not flow, try to bypass the riser in the opposite direction: perhaps a piece of scale or slag is stuck somewhere. The countercurrent can carry it out.
4. If all attempts have no effect and the riser does not drain, most likely you will have to search for a room in which repairs were made and heating appliances were changed. Here you can expect any trick: a removed and plugged radiator without a jumper, a completely cut off riser with plugs at both ends, a throttle closed for general reasons - again in the absence of a jumper... Human stupidity truly gives an idea of ​​​​infinity.

Features of the top filling system

Another way to install a two-pipe heating system is the so-called top filling. What is the difference? The only problem is that the supply pipeline migrates to the attic or upper floor. A vertical pipe connects the filling feed to the elevator.

Circulation from top to bottom; the path of water from supply to return with the same building height is half as long; all the air ends up not in the jumpers of the risers in apartments, but in a special expansion tank at the top of the supply pipeline.

Starting up such a heating system is immeasurably simpler: after all, for full operation of all heating risers, you do not need to get into each room on the top floor and bleed the air there.

It is more problematic to turn off the risers when repairs are necessary: ​​after all, you need to both go down to the basement and go up to the attic. Shut-off valves are located both here and there.

However, the above two-pipe heating systems are still more typical for apartment buildings. What about private owners?

It’s worth starting with the fact that in private houses the 2-pipe heating system used can be radial and sequential according to the type of connection of heating devices.

1. Radial: from the collector to each heating device there is its own supply and its own return.
2. Sequential: radiators are powered by all heating devices from a common pair of pipelines.

The advantages of the first connection scheme boil down mainly to the fact that with such a connection there is no need to balance a two-pipe heating system - there is no need to adjust the flow of the throttles of the radiators located closer to the boiler. The temperature will be the same everywhere (of course, with at least approximately the same length of the rays).

Its main disadvantage is the highest pipe consumption among all possible schemes. In addition, it will simply be impossible to extend the lines to most radiators along the walls while maintaining any decent appearance: they will have to be hidden under a screed during construction.

You can, of course, drag it through the basement, but remember: in private houses there are often no basements of sufficient height with free access there. In addition, the beam scheme is in any way convenient to use only when building a one-story house.

What do we have in the second case?

Of course, we have gotten away from the main disadvantage of single-pipe heating. The coolant temperature in all heating devices can theoretically be the same. The key word is theoretically.

Setting up the heating system

In order for everything to work exactly the way we want, we will need to configure a two-pipe heating system.

The setup procedure itself is extremely simple: you need to turn the throttles on the radiators, starting with those closest to the boiler, reducing the flow of water through them. The goal is to make sure that a decrease in water flow through nearby heating devices increases water consumption at distant ones.

The algorithm is simple: slightly press the valve and measure the temperature on the distant heating device. With a thermometer or by touch - in this case it doesn’t matter: the human hand perfectly feels a difference of five degrees, and we don’t need greater accuracy.

Alas, it is impossible to give a more accurate recipe other than “tighten and measure”: calculating the exact permeability for each throttle at each coolant temperature, and then adjusting it to achieve the required numbers is an unrealistic task.

Two points to consider when adjusting a two-pipe heating system:

1. It takes a long time simply because after each change in the dynamics of the coolant, the temperature distribution takes a long time to stabilize.
2. The heating adjustment of a two-pipe system must be carried out BEFORE the onset of cold weather. This will prevent you from defrosting your home heating system if you miss the settings.

Tip: with a small volume of coolant, you can use non-freezing coolants - the same antifreeze or oil. It’s more expensive, but you can leave your house without heating in winter without worrying about the pipes and radiators.

Horizontal wiring system

With the horizontal arrangement of the supply and return pipelines, it has recently begun to penetrate from its patrimony - private and low-rise houses - into multi-storey new buildings.

Apparently, this is largely due to the fact that studio apartments have begun to gain popularity: with a large area of ​​​​the room without internal partitions, it is simply unprofitable to pull risers through the ceilings, as a 2-pipe vertical heating system implies; It is much easier to do the wiring horizontally.

A two-pipe horizontal heating system in a typical modern house looks like this: risers from the basement run along the entrance. On each floor, taps are made into the risers, which supply coolant to the apartment through valves and discharge waste water into the return pipeline.

Everything else is exactly like in a private house: two pipes, batteries and chokes on each of them. By the way, a horizontal heating system - two-pipe or one-pipe - is easier to repair: to dismantle and replace a section of pipe, there is no need to violate the integrity of the ceiling; This is undoubtedly worth recording as an advantage of such a scheme.

The horizontal two-pipe heating system has one feature that follows from its design and leaves its mark on the start of heating. In order for the heating device to transfer maximum heat from the coolant to the air in the room, it must be completely filled.

This means that each such heating device, typically located above the supply and return pipelines, must be equipped with a Mayevsky valve or any other vent in the upper part.

Advice: Mayevsky taps are very compact and aesthetically pleasing, but they are not the most convenient device for removing air from a radiator.

Where aesthetics are not important (for example, when heating devices are covered with decorative grilles), it would be more convenient to install a water tap with the spout up or a ball valve.

We will not add this feature to the list of disadvantages: going around the radiators in one apartment once a year is not a big deal.

As you might easily guess, a two-pipe horizontal heating system is not only a solution strictly for one-story buildings or for apartment buildings with studio apartments. For example, a two-story house with separate rooms can also be heated in the same way; you just have to make the wiring identical on both floors and connect pipelines from the boiler to both systems.

Of course, balancing such a heating system will have to take a little more time; but this is a one-time event, and it is not difficult to experience it once in a few years.

Finally, a few definitions and simply useful tips.

Depending on the direction of water flow in the pipelines, a 2-pipe heating system can be dead-end or direct-flow.

• A two-pipe dead-end heating system is a system in which the coolant moves through the supply and return pipelines in opposite directions.
• In a direct-flow two-pipe heating system, the direction of the current in both pipelines coincides.

In private houses, two-pipe heating systems with both forced and natural circulation can be used.

• Forced circulation of the coolant is provided by a circulation pump; This quiet and low-power device is supplied, in particular, in the same housing with many electric boilers.
• Natural circulation is used in small-volume heating systems; the principle of its operation is based on the fact that hot water has a lower density and rushes upward.

A two-pipe closed heating system, that is, a system with constant pressure and without both water supply and external coolant flow, is the most popular solution for private houses with electric boilers.

In order to transfer heat to distant rooms from a solid fuel boiler or stove, an open one-pipe or two-pipe system is also quite suitable.

The design of a two-pipe heating system can include radiators of any type, registers and convectors as heating devices; warm floor implies a different connection method.

In order to install the heating of a two-pipe system, it is certainly better to involve specialists in the work. However, the abundance of materials on this topic on the Internet and the ease of assembling modern plumbing and heating systems with the help of fittings and machines make it possible for an amateur to do this work - if only he wanted to.

If you are installing a two-pipe heating system for a two-story house, when balancing the system it is worth taking into account the peculiarity of communicating floors in terms of heat distribution: all other things being equal, it will always be warmer on the second floor.

Any heating circuit operates at certain pressure and coolant temperature values, which are calculated at the design stage. However, during operation, situations are possible when the pressure drop in the heating system deviates from the standard level up or down and, as a rule, requires adjustment to ensure efficiency, and in some cases, safety.

Operating pressure in the heating system

Working pressure is considered to be the pressure whose value ensures optimal operation of all heating equipment (including the heating source, pump, expansion tank). In this case, it is taken equal to the sum of pressures:

• static - created by a column of water in the system (in calculations the ratio is taken: 1 atmosphere (0.1 MPa) per 10 meters);
• dynamic - due to the operation of the circulation pump and the convective movement of the coolant when it is heated.

It is clear that in different heating schemes the operating pressure will differ. So, if natural circulation of the coolant is provided for heating the house (applicable for individual low-rise construction), its value will exceed the static value by only a small amount. In forced schemes, it is taken as maximum permissible to ensure higher efficiency.

It should be borne in mind that the operating pressure limits are determined by the characteristics of the heating system elements. For example, when using cast iron radiators, it should not exceed 0.6 MPa.

Numerically, the working pressure is:

• for one-story buildings with an open layout and natural circulation of water – 0.1 MPa (1 atmosphere) for every 10 m of liquid column;
• for low-rise buildings with a closed layout - 0.2-0.4 MPa;
• for multi-storey buildings - up to 1 MPa.

Control of operating pressure in heating circuits

For normal, trouble-free operation of the heating system, it is necessary to regularly monitor the temperature and pressure of the coolant.

To check the latter, deformation pressure gauges with a Bourdon tube are usually used. To measure small pressures, their varieties can be used - diaphragm devices.

It must be remembered that after water hammer such models need to be verified, because they will show inflated values ​​in subsequent control measurements.

Figure 1 – Strain gauge with Bourdon tube

In systems where automatic control and regulation of pressure are provided, various types of sensors are additionally used (for example, electric contact).

The placement of pressure gauges (insertion points) are determined by regulations: devices must be installed in the most important areas of the system:

• at the inlet and outlet of the heating source;
• before and after the pump, filters, mud traps, pressure regulators (if any);
• at the exit of the main line from the thermal power plant or boiler house and at its entry into the building (with a centralized scheme).

You should not neglect these recommendations even when designing a small heating circuit using a low-power boiler, because This not only ensures the safety of the system, but also its efficiency due to optimal water and fuel consumption.

Figure 2 – Section of the heating circuit with installed pressure gauges

To make it possible to zero, purge and replace devices without stopping the system, it is recommended to connect them through three-way valves.

Pressure drop and its importance for the functioning of the heating system

For optimal functioning of any heating circuit, a stable and certain pressure drop is required, i.e. the difference between its values ​​at the coolant supply and return. As a rule, it should be 0.1-0.2 MPa.

If this indicator is less, this indicates a disruption in the movement of the coolant through the pipelines, as a result of which water passes through the radiators without heating them to the required degree.

If the difference exceeds the above value, we can talk about “stagnation” of the system, one of the reasons for which is airing.

It should be noted that sudden changes in pressure negatively affect the performance of individual elements of the heating circuit, often disabling them.

Methods for regulating operating pressure and ensuring the stability of its differential on the supply and return

1. First of all, it is necessary to remember that optimal operation of the heating system, incl. the creation of the required pressure in it depends on the correctness of the design, in particular, hydraulic calculations, and installation of mains and pipelines, namely:
   — the supply line in most schemes should be located at the top, the return line, respectively, at the bottom;
   — for the production of bottlings, pipes with a diameter of 50-80 mm should be used, for risers - 20-25 mm;
   — connections to heating devices can be made from the same pipes from which the risers are made, or one step less.

   It is allowed to underestimate the cross-section of radiator piping only if there is a jumper in front of them.

   

   Figure 3 – Jumper in front of the heating radiator

2. As you know, as the temperature rises, the coolant increases in volume and increases the pressure in the heating system. For example, at 20 0C it can increase by 0.13 MPa, at 70 0C - by 0.19 MPa. Therefore, one of the options for regulating the pressure is to change the degree of water heating.
3. To increase the coolant pressure, which is usually required to provide heat to the upper floors of high-rise buildings, circulation pumps are used.
4. Automatic regulation of operating pressure and its differential in heating circuits of small houses is carried out using expansion tanks, usually of the membrane type. They begin to work when the pressure in the system reaches 0.2 MPa. At the same time, these devices remove excess hot coolant, as a result of which the pressure is maintained at the required level.

   

   Figure 4 – Diaphragm expansion tank

   The expansion tank, the volume of which is usually taken to be about 10% of the total volume of the system, can be installed in any part of the circuit. However, experts recommend installing it on a straight section of the return pipeline in front of the circulation pump (if available).

   To prevent a situation where the device’s capacity is insufficient with a continued increase in pressure, the circuits provide for the use of a safety valve that removes excess coolant from the system.

5. In large and complex heating systems, for example, in multi-storey buildings, to maintain the standard pressure, regulators are used, which additionally prevent airing even with sudden changes in pressure in the lines, as well as noise generation on the control valves. They are mounted either on a jumper between the supply and return pipelines, or on the bypass line of the pump.

   

   Figure 5 – Pressure regulator

6. Another way to regulate pressure in heat supply schemes of multi-level buildings is the use of shut-off valves. For example, if it is necessary to increase the pressure, the cross-section of the return pipeline is reduced using a valve.

Finding the reasons for the drop and increase in pressure drop

Deviation of pressure more or less from the norm requires establishing the cause of this phenomenon and its elimination.

Pressure drop in the heating circuit

If the pressure in the heating system drops, then with a greater degree of probability we can talk about a coolant leak. The most vulnerable are the existing seams, joints and connections.

To check this, turn off the pump and monitor changes in static pressure. If the pressure continues to decrease, it is necessary to find the damaged area. To do this, it is recommended to sequentially disconnect different sections of the circuit, and after determining the exact location, repair or replace worn elements.

If the static pressure remains stable, the reason for the decrease in pressure is due to a malfunction of either the pump or the heating equipment.

It should be borne in mind that a short-term drop in pressure may be due to the peculiarity of the operation of the regulator, which at certain intervals transfers part of the water from the supply to the return. In the case when the heating radiators warm up evenly and to the required temperature, we can say that the difference was associated with the above cycle.

Other possible reasons include:

• removing air through vents, resulting in a decrease in the volume of coolant in the system;
• decrease in water temperature.

Increasing system pressure

A similar situation occurs when the movement of coolant in the heating circuit slows down or stops. The most likely reasons for this are:

• the occurrence of an air lock;
• contamination of filters and mud traps;
• features of the functioning of the pressure regulator or incorrect settings of its operation;
• constant replenishment of coolant due to automatic failure or incorrectly adjusted supply and return valves.

It should be noted that pressure instability is most often observed in newly launched systems and is associated with the gradual removal of air. This can be considered the norm if, after bringing the coolant volume and pressure to operating values, which lasts from several days to several weeks, no deviations are recorded.
Otherwise, we should talk about an incorrect hydraulic calculation, in particular, the accepted volume of the expansion tank.

A common situation is that one radiator is hotter than the other, which should not be the case. Or it’s cool in one part of the house and hot in another. This means that the heating system needs to be somehow adjusted, as experts say – balanced. It is possible that for this you do not need to call a plumber at all, and you can adjust the heating yourself.

To do this, control taps and/or balancing valves must be installed on each radiator or between the arms of the system.

But in some cases the system needs to be redone. Read more about possible heating problems and balancing rules below.

If there is not enough radiator power

It also happens that it is difficult to balance the heating system, since the distribution of radiator power does not at all correspond to the heat loss of the rooms.

Recommendations for the selection of radiators are as follows: for 10 sq. m. area - 1 kW, but this value is multiplied by 1.2 if the room has one window, 1.3 if the window is large, 1.4 if there are two windows and the room is corner, 1.5 if there are already 3 windows or a large glazing area.

In addition, the radiator power is indicated for a temperature of 90 degrees, but we are going to heat it at a maximum of 70 degrees, aren’t we? This means we multiply the heat loss by another 1.3. And if low-temperature heating is used - no more than 50 degrees, then multiply by 1.3 again.
Why is low-temperature heating the most comfortable and economical?

The power of one section of an aluminum, bimetallic radiator (approximately 80 mm thick and wide), or cast iron radiator (old MS-140 type) is approximately 170 - 180 W. A set of 7 sections is considered to be no less than a kilowatt.

In addition, radiators must be installed in characteristic places to create a thermal curtain to the cold source. Typically - under the windows, near the door.

It is better to distribute the number of battery sections (sizes) in accordance with heat loss and the characteristics of the heating system than to balance and cover the flow of liquid.

Simple causes of heating system problems

It is possible that there is air in the heating system and for this reason the coolant does not flow well to one or more heating devices.

In the highest places in the pipeline, air valves (Mayevsky valves) are installed that can be opened manually. Or automatic air vents. Mayevsky taps are usually installed on each radiator. Walk through the system, open the taps, bleed the air.

Another reason for poor performance is clogging, first of all, of the filter element. Unscrew the filter and clean it.
Before any balancing of the heating system, clean the filter.

In improperly assembled systems, in addition, there may be clogging at the lower points at differences in the pipeline level, and airing at the upper points, for example, the pipeline is wrapped around a door without an air vent.

Balancing the system using valve regulators

It is possible that the very design of the system requires balancing. For example, one long arm is used and the other is short.

Or the arm length of the dead-end pattern is too long. Or a beam scheme is used, which requires initial setup. And it happens that they make archaic single-pipe systems with shortcomings. In either case, the result is significant uneven heating.

So, balancing valves are installed on the radiators; all that remains is to ensure that the temperature of all radiators is approximately the same.

The principle of balancing is the simplest - do not close (open as much as possible) the taps on the coldest ones and “tighten” the hottest ones a little. As a result, more coolant will flow to the cold ones, less to the hot ones, and their temperature will equalize.

An example of how to adjust heating in a one-story house

A typical example is that it was not possible to make two arms of a dead-end circuit, since the pipes were being laid in the way of a door, so they made one arm and put “as many” 7 radiators on it.

As a result, the temperature of the latter in the shoulder is 9 degrees less than that closest to the boiler. You can do the following: on the last 3 radiators, leave the taps completely open. On the first, open the balancing valve from the fully closed position by 1.5 turns, on the second - by 2 turns, on 3 and 4 by 2.5 turns.

It is assumed that the balancing valve is adjustable in total by 4.5 turns, and the length of the pipelines is within the limits of a small house. But regulators come in different designs, different lengths, so in each case there is a different number of revolutions.

After balancing, you need to wait 20 minutes, then measure the temperature of the incoming radiator pipe again, you may have to additionally adjust something by a quarter turn...

Adjustment principles

Significant closures cannot be created.
The basic principle of balancing is to open the path for coolant movement as much as possible. Closure is a forced measure.

Therefore, achieving the same temperature in this example is not worth it. It is correct to agree that the first one will be hotter by 3 - 4 degrees at a coolant temperature of 80 degrees and by a couple of degrees with low-temperature heating of 50 degrees.

How to measure it? Professionals would look at each radiator through a thermal imager and take a thermal photo. But you can also get by with contact thermometers - special devices for heater installers. But in everyday life, they often measure simply with their hands and judge by how they feel. The earlobe is sensitive in this regard - but is it worth rubbing your ear on the radiators...

Example for a two-story house

Another typical example is when the designers and installers managed to design the heating system in such a way that they installed approximately equal power radiators on both the first and second floors (the areas are approximately equal), and they forgot to solder the balancing of the floors relative to each other.

As a result, it is still cold on the first floor, but it is already hot on the second floor.

Again, balancers installed directly on the radiators will help out. On the second floor, we simply open the taps by 2 turns instead of the full 4.5, thus reducing the liquid flow by 30 percent. By reducing the energy output, we equalize the temperature regime, and if necessary, close more...

Additional Information -

The diagram in which there is no possibility of balancing between two arms is a typical mistake in homemade systems.

Commissioning according to the project

With the usual proper installation of a modern heating system, balancing is not needed at all; the circuit is designed so that all radiators heat optimally. In addition, they are often automated with thermal heads, with which you can set the temperature in a separate room.

Designers and design data introduce a little confusion into the issues of heating adjustment. The project includes the amount of coolant passing through and the balancing of each radiator - how many revolutions each balancing valve of a certain type should be turned.

This achieves a certain accuracy in the implementation of design decisions. But for the user this practically does not matter, since adherence to design accuracy has very little effect on the final result. But large balancing values ​​(as in the examples above) cannot be included in the project. Therefore, very precise regulation according to the design can be ignored.

Noisy radiator

Another point that needs to be addressed is too much coolant passing through the radiator. At the same time, the radiator makes noise and it is unpleasant. Reasons: incorrect heating scheme, unbalanced (closed) other radiators, too powerful pump in the system. All this needs to be eliminated.

An overly powerful pump is a problem with homemade heating systems, because home craftsmen “seem” that they can’t spoil the porridge with oil. But what happens here is something else - a lot of money wasted and noise in the radiators.
A noisy radiator requires balancing the system or reworking it.

What causes the pressure difference in heating and water supply systems? What is it for? How to regulate the difference? For what reasons does the pressure drop in the heating system? In this article we will try to answer these questions.

Functions

First, let's find out why the difference is created. Its main function is to ensure coolant circulation. Water will always move from a point with more pressure to a point with less pressure. The greater the difference, the greater the speed.

Useful: the limiting factor is the hydraulic resistance that increases with increasing flow velocity.

In addition, a difference is artificially created between the circulation connections of hot water supply into one thread (supply or return).

Circulation in this case performs two functions:

1. Provides consistently high temperatures for heated towel rails, which in all modern houses open one of the hot water supply risers connected in pairs.
2. Guarantees fast flow of hot water to the faucet regardless of the time of day and water supply through the riser. In old houses without circulation taps, the water has to be drained for a long time in the morning before it is heated.

Finally, the difference is created by modern water and heat consumption meters.

How and why? To answer this question, the reader must be referred to Bernoulli's law, according to which the static pressure of a flow is inversely proportional to the speed of its movement.

This gives us the opportunity to design a device that records water flow without the use of unreliable impellers:

• We pass the flow through the section transition.
• We record the pressure in the narrow part of the meter and in the main pipe.

Knowing the pressures and diameters, using electronics it is possible to calculate in real time the flow rate and water consumption; when using temperature sensors at the inlet and outlet of the heating circuit, it is easy to calculate the amount of heat remaining in the heating system. At the same time, the consumption of hot water is calculated based on the difference in flow rates in the supply and return pipelines.

Creating a drop

How is pressure difference created?

Elevator

The main element of the heating system of an apartment building is the elevator unit. Its heart is the elevator itself - a nondescript cast-iron tube with three flanges and a nozzle inside. Before explaining the principle of operation of the elevator, it is worth mentioning one of the problems of central heating.

There is such a thing as a temperature graph - a table of the dependence of the temperatures of the supply and return routes on weather conditions. Let's give a short excerpt from it.

Deviations from the schedule up and down are equally undesirable. In the first case, it will be cold in the apartments, in the second, energy costs at the thermal power plant or boiler house will increase sharply.

At the same time, as is easy to see, the spread between the supply and return pipelines is quite large. With circulation slow enough for such a temperature delta, the temperature of the heating devices will be unevenly distributed. Residents of apartments whose radiators are connected to the supply risers will suffer from the heat, and owners of return radiators will freeze.

The elevator provides partial recirculation of the coolant from the return pipeline. By injecting a fast stream of hot water through the nozzle, in full compliance with Bernoulli's law, it creates a fast flow with low static pressure, which draws additional mass of water through the suction.

The temperature of the mixture is noticeably lower than that of the supply and slightly higher than that of the return pipeline. The circulation speed is high, and the temperature difference between the batteries is minimal.

Support washer

This simple device is a steel disk at least a millimeter thick with a hole drilled in it. It is placed on the flange of the elevator unit between the circulation taps. Washers are placed on both the supply and return pipelines.

Important: for normal operation of the elevator unit, the diameter of the holes in the retaining washers must be larger than the diameter of the nozzle.
Usually the difference is 1-2 millimeters.

Circulation pump

In autonomous heating systems, the pressure is created by one or more (according to the number of independent circuits) circulation pumps. The most common devices - with a wet rotor - are a design with a common shaft for the impeller and the rotor of the electric motor. The coolant performs the functions of cooling and lubrication of bearings.

Values

What is the pressure difference between different sections of the heating system?

• Between the supply and return lines of the heating main it is approximately 20 - 30 meters, or 2 - 3 kgf/cm2.

Reference: excess pressure of one atmosphere raises the water column to a height of 10 meters.

• The difference between the mixture after the elevator and the return pipeline is only 2 meters, or 0.2 kgf/cm2.
• The difference on the retaining washer between the circulation taps of the elevator unit rarely exceeds 1 meter.
• The pressure created by a circulation pump with a wet rotor usually varies from 2 to 6 meters (0.2 - 0.6 kgf/cm2).

Adjustment

How to adjust the pressure in the elevator unit?

Support washer

To be precise, in the case of a retaining washer, it is not necessary to adjust the pressure, but to periodically replace the washer with a similar one due to abrasive wear of a thin steel sheet in process water. How to replace the washer with your own hands?

The instructions are generally quite simple:

1. All gates or valves in the elevator are closed.
2. One drain valve is opened on the return and supply to drain the unit.
3. The bolts on the flange are loosened.
4. Instead of the old washer, a new one is installed, equipped with a pair of gaskets - one on each side.

Tip: in the absence of paronite, washers are cut from an old car inner tube.
Don't forget to cut an eyelet that will allow the washer to fit into the flange groove.

1. The bolts are tightened in pairs, crosswise. After the gaskets are pressed, the nuts are tightened until they stop, no more than half a turn at a time. If you rush, uneven compression will sooner or later lead to the gasket being torn out by the pressure on one side of the flange.

Heating system

The difference between the mixture and the return flow is normally regulated only by replacing, welding or drilling out the nozzle. However, sometimes it becomes necessary to remove the difference without stopping the heating (usually in case of serious deviations from the temperature schedule during the peak of cold weather).

This is done by adjusting the inlet valve on the return pipeline; Thus, we remove the difference between the forward and reverse threads and, accordingly, between the mixture and the return.

1. We measure the supply pressure after the inlet valve.
2. Switch the hot water supply to the supply thread.
3. We screw the pressure gauge into the vent on the return line.
4. We completely close the input check valve and then gradually open it until the difference decreases from the original by 0.2 kgf/cm2. Manipulation with the closing and subsequent opening of the valve is necessary to ensure that its cheeks are lowered as much as possible on the stem. If you simply close the valve, the cheeks may sag in the future; the price of ridiculous time savings is at least defrosted access heating.
5. The return pipe temperature is monitored at daily intervals. If it is necessary to further reduce it, the difference is removed 0.2 atmospheres at a time.

Pressure in the autonomous circuit

The immediate meaning of the word “difference” is a change in level, a fall. In the article we will touch on it too. So, why does the pressure drop in the heating system if it is a closed loop?

First, let's remember: water is practically incompressible.

Excessive pressure in the circuit is created due to two factors:

• The presence in the system of a membrane expansion tank with its air cushion.

• Elasticity. Their elasticity tends to zero, but with a significant area of ​​the inner surface of the circuit, this factor also affects the internal pressure.

From a practical point of view, this means that the pressure drop in the heating system recorded by the pressure gauge is usually caused by an extremely slight change in the volume of the circuit or a decrease in the amount of coolant.

Here's a possible list of both:

• When heated, polypropylene expands more than water. When starting a heating system assembled from polypropylene, the pressure in it may drop slightly.
• Many materials (including aluminum) are sufficiently plastic to change shape under prolonged exposure to moderate pressure. Aluminum radiators can simply swell over time.
• Gases dissolved in water gradually leave the circuit through the air vent, affecting the actual volume of water in it.
• Significant heating of the coolant when set too low can trigger the safety valve.

  The photo shows an intersectional leak on a cast iron radiator. Often it can only be noticed by traces of rust.

  Conclusion

  We hope that we were able to answer the reader’s questions. The video attached to the article, as usual, will offer additional thematic materials to his attention. Good luck!