Pyrolysis boiler on pellets. Differences between pyrolysis and pellet boilers. Disadvantages of pyrolysis boilers

The main task of the heating system is to maintain a comfortable air temperature in the building. This temperature may be different, depending on the purpose of the room, but a prerequisite is its invariability throughout the day.

Heat energy enters the room from the heating system through radiators. The amount of thermal energy given off by heating devices is regulated by the amount of coolant.

The device that regulates the flow of fluid entering the radiator is a valve or valve, which can be automatic or manual.

There is always heat exchange in the room with the surrounding space. This leads to an outflow or inflow of heat from the room, and, consequently, to a decrease or increase in air temperature in it.

To restore the heat balance in the room, it is necessary to increase or decrease the amount of heat coming from the heating devices. The thermostat on the battery, installed on the supply pipelines, will perfectly cope with this task.

Mechanical thermostat

This device consists of a valve and a sensitive element (thermal head). They function harmoniously without extraneous external energy. The thermal head is completed with a drive, a regulator and a liquid element, which can be replaced by an elastic or gas one.

It is necessary to choose a thermostat for a battery, taking into account all the factors that can further affect its operation. It is important to make a special calculation - only in this case this device will function as efficiently as possible.

Elements

The battery consists of the following elements:

• compensation mechanism.
• Stock.
• Detachable connection.
• Spool.
• sensitive element.
• thermostatic element.
• Setting scale.
• Cap nut.
• A ring that fixes the set temperature.

Impact factors

The following factors can affect the temperature in the room, and hence the operation of the mechanical thermostat:

on battery

When the air temperature in the heated room changes, the amount of coolant changes. At the same time, the volume of the bellows changes, which actuates the control spool. The movement of the spool is directly related to the change in air temperature in the room. When the temperature changes, the sensing element reacts and actuates the regulator valve stem. As a result, the stroke change regulates the supply of coolant to the heating device.

Mounting

The thermostat for a mechanical type battery must be installed on the supply pipeline. In this case, the head of the thermostat must be located horizontally, must not be exposed to direct sunlight and heat. If the valve is covered with a curtain or covered with furniture, then a dead zone is formed, in other words, the thermostat does not contact the ambient temperature, and for this reason it does not perform its functions effectively.

If another placement of this device is not possible, special sensors with an attached sensitive element are used, designed for remote control.

Electronic thermostats

Electronic heating is an automatic control device that maintains a given temperature regime in various thermal equipment.

In the heating system, it automatically controls the boiler and other actuators (valves, pumps, mixers, etc.). The main purpose of the electronic temperature controller is to create a temperature regime in the room that was predetermined by the user.

Principle of operation

The electronic type heating temperature controller is equipped with a temperature sensor, which is installed in a place free from direct exposure to electrical heating appliances, it provides the device with information about the thermal state of the room. Based on the data received, the electronic device controls the elements of the heating system.

There are digital and analog thermostats with temperature control. The former are most widely used due to their functionality. Electronic type thermostats are:

• Closed logic.
• With open logic.

Closed logic is a constant algorithm of work in time and a rigid internal structure that does not depend on changes in environmental factors. Only certain programmable parameters can be changed.

The open logic thermostat is a freely programmable device, characterized by a wide range of functions and settings, it can be adjusted to any work and environmental conditions.

Unlike devices with closed logic, these devices are not so widespread. This is justified by the fact that their management requires a certain qualification degree. Therefore, not every ordinary citizen is able to understand the modes and settings of electronic thermostats. Open logic has been widely used in the industrial segment, but over time it can become an integral element of the life of any person.

Installing a thermostat on a battery

During the installation process, it is very important to follow the instructions and not to place devices of this type in niches, behind decorative grilles and curtains. If for some reason this is not possible, a remote sensor is installed.

It is inefficient to install a thermostat for cast iron batteries, as they heat up and cool down for a very long time.

Before proceeding to the installation of thermostats, it is necessary to turn off the riser and drain the coolant from the heating system.

Only after that you can proceed to the installation of this device, it is recommended to perform them in the following sequence:

Setting

Setting the thermostat with temperature control is as follows:

• All windows and doors are tightly closed in the room to minimize heat leakage.
• In a room where it is required to maintain a certain temperature value, it is necessary to install
• The valve opens completely, for which the head of the thermostat is turned all the way to the left, in which case the radiator will function with maximum heat transfer, the temperature in the room will begin to rise.
• As soon as the temperature becomes 5-6 ° C higher than the initial one, you need to close the valve, for this its head turns all the way to the right, after which the air in the room will gradually cool down.
• After the temperature has reached the desired value, the valve is slowly opened by turning the knob to the left. In this case, you need to listen carefully, as soon as you hear the sound of water and feel a sharp heating of the thermostat housing, stop rotating the head and remember its position.
• The setup is complete. The room temperature will be kept accurate to 1 °C.

Thermostats on electric radiators

In the conditions of modern work of public utilities, when in the cold season in apartments the temperature is far from always at the value necessary for a comfortable feeling, many people switch to electric heating devices. They can perform both the function of an additional and the main source of heat.

As a rule, today many manufacturers produce with a thermostat, which allows you to set an individual temperature in each room. Electric radiators are a convenient alternative and a great addition to central heating.

First of all, let's talk about when thermostats are needed for radiators. They are needed in those rooms where you need to reduce the temperature. Most often, these are the upper apartments of high-rise buildings with an upper coolant supply and vertical wiring. By installing the thermostat on the battery, setting the desired temperature, you will be guaranteed to have the set parameter with an error of one degree.

When thermostats won't help If you need to increase the heat transfer of the heater. They can only lower, but not raise. What radiators do thermostats work well with? With everything except cast iron: they have a very large thermal inertia and such a device is practically useless. Now more about the types and features of their installation and operation.

Structure and principle of operation

Structurally, devices for regulating the temperature of batteries consist of:

• valve (valve);
• thermostatic element.

A thermal valve (also called a thermal valve) is, in fact, an ordinary valve. The same metal body with a bore, seat and cone. The cone is a locking mechanism. Lowering and rising, it changes the amount of flowing coolant. Everything is as usual, only the way this locking mechanism is set in motion is unusual.

The locking cone drives the thermal head (thermostatic element, thermoelement). Its base is a small hermetic and elastic cylinder filled with a thermal agent. The cylinder used in thermostats is called a "bellows". A thermal agent is a gas or liquid, but not any, but special ones: their volume must depend strongly on temperature. There are also bellows with solid thermal agents, but their response time to temperature changes is at least half an hour. So they are rarely used.

Here's how this device works: when heated, the substance expands, stretching the cylinder. He presses on the piston, which moves the shut-off cone of the thermal valve. The cone blocks the coolant flow, the substance in the bellows cools down. As it cools, it shrinks, and the cylinder shrinks in size. The spring-loaded mechanism raises the shut-off cone, the coolant enters the radiator again and the device head heats up. In this way, the temperature in the room can be maintained with an accuracy of one degree.

But different devices give different accuracy. The thing is that the expansion and contraction of the bellows does not occur abruptly, but gradually. Therefore, the coolant is cut off and opens not abruptly, but smoothly. Because of this, the position completely closed or completely open is quite rare. What does it say? That the room will be more comfortable.

The magnitude of the error is characterized by such an indicator as the "gestesis" of the thermal head. The lower this indicator, the faster the device reacts to temperature changes. But high accuracy is not always needed, and prices differ decently.

But when installing the regulator on the radiator, be prepared for the fact that it will never be warmed up evenly and completely. Some part will always be cold. To make sure that everything is normal in it, it is not clogged and not airy, remove the thermal head. The entire surface will become evenly warm after a while.

Type of thermostatic elements

The thermal head for the radiator is the upper, replaceable part of the device. It can be of several types:

• manual;
• mechanical;
• electronic.

Almost all major manufacturers make the valve (housing) compatible with any type of thermocouple. The principle of operation described above is a thermostat equipped with a mechanical head. This equipment is considered basic and there are a lot of modifications in this category. They differ in features and price.

To be able to navigate the prices: European manufacturers sell mechanical thermal heads from 15 euros to 25 euros, there are anti-vandal models, they cost from 40 euros. There are devices with a remote sensor. They are set if the conditions do not allow to regulate the temperature on the radiator (for example, it is installed behind a cabinet, closed in a niche, etc.). Here, the length of the capillary tube, which connects the sensor to the thermostat, is of great importance. Prices in this segment are from 40-50 euros.

It looks like a manual device for adjusting the temperature of radiators in the context

A manual thermostat is the same control valve for a radiator. And the principle of operation is the same: turn the knob, change the amount of passing coolant. The only difference is that if you wish, you can simply remove this thermocouple and install a mechanical or electronic one. The case does not need to be unscrewed or changed. They are universal. Heads for manual adjustment have a low price - from 4 euros.

Electronic thermal heads are the most expensive options, they are also the most massive: there is room for two batteries in the case. They differ in that they have more options. In addition to maintaining a stable temperature throughout the time, you can program the temperature by day of the week or by time of day. For example, after 9 am, all household members disperse, and appear only after 6 pm. It turns out that there is no need to spend money on maintaining a high temperature during the daytime. Electronic thermoelements make it possible to set a lower temperature during this interval on all days except weekends. Set at least 6-8 ° C, and in the evening you can again heat the air to a comfortable 20 degrees. With these devices, it is possible to save on heating without compromising comfort levels.

Thermal heads are also divided according to the type of temperature agent (substance that is in the bellows). They are:

• liquid;
• gas.

The gas thermostat is considered less inertial, they say it responds faster to temperature changes. But the difference is not so big as to give preference to a specific species. The main thing is the quality, not the type of temperature agent. Liquid thermostats are no less high quality. Moreover, they are easier to manufacture, therefore they are produced in a wider range.

When choosing a thermocouple, you need to pay attention to the temperature range that the device can support. Usually it is from +6 o C to +26-28 o C. But there may be differences. The wider the range, the higher the price. Dimensions and design, connection method also change.

Thermal valve for a heating radiator: classification

Now let's talk about the bottom of the thermostat - the valve (valve). First of all, you need to know that the industry produces control devices for different systems. And you only need to use devices for your system.

Devices for have at least twice the hydraulic resistance than for single-pipe ones. This is done on purpose, since balancing in this case occurs due to a pressure drop across the valves. Therefore, devices with a small flow area are installed. By putting such a device in, you will surely freeze. Therefore, be careful.

Sometimes modifications for single-pipe systems are positioned as devices for systems with. They have reduced hydraulic resistance, and they can be used in single tubes.

In a one-pipe system, install thermostats with a flow capacity of at least 3 (Kvs=3 and above).

According to the method of pipe connection, radiator temperature controllers are angular or straight (through). There are also axial models. Select in this case depending on the type of connection of the heater. If the pipe fits from the side, it is more convenient to install a straight valve, if from below - one of the corner ones.

Thermal valves also differ in the material from which they are made. Use metals that have good resistance to corrosion. Some of them have an additional protective coating (usually nickel or chrome plating). So, thermostatic valves are made from:

• bronze, nickel-plated and chrome-plated;
• brass, nickel-plated;
• stainless steel.

It is clear that stainless steel is better, but such valves cost a lot, and are rarely found on sale.

Installing a thermostat on a radiator

Thermostats on the radiator are installed mainly on the supply before entering the heater. Each of the valves passes the coolant in one direction. Where the flow should go is shown by an arrow on the body. The coolant should flow exactly there. If connected incorrectly, the device will not work. Another question is that you can put a thermostat, both at the inlet and at the outlet, but observing the direction of flow. And in both cases they work the same way.

Options for connecting and installing control valves. But in order to be able to repair the radiator without stopping the system, you need to install a ball valve before the regulator (click on the picture to enlarge it)

It is worth paying attention to the manufacturer's recommendations regarding the installation height. Most models should be at a height of 40-60 cm from the floor. They are calibrated for temperatures at this level. But not everywhere the feed is top. Often radiators have a bottom connection. Then, in addition to the type of system (one-pipe or two-pipe), select the height of the installation. If such a model is not found, you can set a lower temperature on the thermal head. If you set the recommended one, it will be too hot, because below, in the floor area, the air is cooler, and the model is set to maintain the temperature measured at the height of the upper edge of the radiator. The second option is to configure the device yourself. The procedure is usually described in the passport, and we will describe the most common sequence of actions below. And the third option is to put a thermostat with a remote sensor on the battery. Then it doesn't matter at what height the thermal head stands. The main thing is the location of the sensor. But these models are much more expensive. If this is critical, it is better to adjust the regulator.

Please note that the thermostatic head must be turned horizontally(look into the room). If it is welded up, then it is constantly in the stream of hot air that comes from the pipe. Therefore, the substance in the bellows is almost always heated, and the radiator is turned off. The result - the room is cold.

For the device to work correctly, you need to install it "head" into the room

The situation is slightly better if the battery is installed in a niche, closed or curtained. The thermoelement is also "hot" but not so much. Here you can go in two ways: either set a high temperature on the regulator, or use a remote sensor. Models with remote thermal controllers are, of course, not cheap, but you can choose the point of control at your discretion.

Another thing to remember: when installing in a one-pipe system, a bypass is required. And unregulated. Then, when the supply to the radiator is closed, the riser will not be blocked, and you will not receive “hello” from your neighbors.

Thermal valves also differ in the type of connection: they are with union nuts, there are with compression ones. Accordingly, they are joined with certain types of pipes. Usually, the specification or product description indicates the type of connection, as well as with which pipes it can be used.

Regulator setting

In order for the device to work correctly and maintain the desired temperature, it is necessary to pre-configure. With the heating in the room, close the doors, install a thermometer where you think it is right to control the temperature. Now let's start setting up:

• Open the coolant flow completely. This is done by turning the thermal head all the way to the left.
• The temperature will start to rise. When it becomes 5-6 o C higher, we proceed to the next item.
• Shut off the coolant flow by turning the thermostat head to the right as far as it will go. The room will gradually become cooler.
• When the desired temperature is reached, start gradually opening the valve. As soon as you hear that the coolant is noisy, and the case has become warm to the touch, stop rotating. This will be the position of the thermal head, which will maintain a comfortable temperature for you. Usually there are marks on the cap - numbers - and you can navigate by them.

Adjusting the thermostat is a simple procedure, but it is she who allows you to calibrate it to your requirements. For the most part, the sequence is standard, but sometimes it may differ. Then the entire sequence of actions should be described in the passport for the product. Some firms have even made videos showing how to install and adjust their products.

Results

Temperature controllers for heating batteries can be with three types of heads: manual, mechanical and electronic. Any species can only lower the temperature, it cannot raise it.

The saying “Everything is good in moderation” takes on particular relevance when talking about heating in winter. If you can fry eggs on your batteries, then you have two ways: open the window ( and catch a cold 🙂) or install temperature controllers on the batteries. What are they and how to choose?

What is a thermostat for a heating battery

Heating temperature controllers have been actively used in the West since the middle of the last century. Initially, they were intended to save heating costs. European manufacturers still focus on this function, developing the direction of electronic temperature controllers and thermostats for heating with economical operating modes. However, in Russia, heat regulators are often purchased for another - secondary - purpose: to reduce the temperature of heating a room. Some apartments are heated so intensively that their owners have to open the windows even in minus 30 degrees. In such cases, the main task is to normalize the temperature regime and create a comfortable living environment for a person. However, in recent years, the issue of saving resources has gradually come to the fore, and helping devices are becoming more and more in demand.

Types of thermostats for a radiator

Ball valve for radiator. Strictly speaking, this is not a thermostat at all, but a locking mechanism. But it would be wrong not to mention it: in some cases, this is the only option to reduce the intensity of heating. For example, for cast-iron batteries that take a long time to cool down and heat up for a long time, automatic thermostats for a radiator are not suitable, and a ball valve allows you to shut off the flow of coolant (hot water in the heating battery) and thereby reduce the temperature in the room.

Cost: from 200 rubles.

Battery thermostats, unlike ball valves, do not need to be controlled manually, they work "by themselves" - of course, after setting. Any thermostat for heating radiators consists of two parts: a valve and a control element. A valve is, roughly speaking, a piece of pipe with a closing mechanism (working cone). It crashes directly into the heating battery. But the control element is attached to the valve. It acts on the blocking mechanism, causing it to lower or rise, thereby partially closing and opening the flow channel.

Types of control elements:

1. Thermal head. Has no power supply. It reacts to the ambient temperature. Below we will analyze its device in detail.

Cost: from 1,000 rubles.

Temperature controllers on the battery reduce the intensity of heating by reducing the amount of incoming coolant. They do not affect the heating pipes in any way!

2. Electronic regulator, or thermostat. The thermostats are equipped with a temperature sensor and a processor. The flow control of the heating medium is based on the readings of the sensor. And the processor allows you to program the thermostat for the radiator to the operating mode suitable for your home. For example, you can set the minimum heating power during the weekday, when all your family members are busy with activities outside the home, and increase the temperature in the evening to return to warm rooms.

Electronic thermostats require mains or battery power. The most modern models allow you to control the process via the Internet or a mobile application.

With the help of electronic thermostats, heating costs can be reduced by 20-30%. It is calculated that when using a thermostat in houses with an individual heating boiler, the cost of a thermostat pays off in 1 year.

Cost: from 2,000 rubles.

The design of the regulator with a thermal head

Thermal head regulators are the most common temperature regulators for a heating battery. Let's talk about how they work.

Inside the thermal head there is a bellows with a temperature-sensitive composition (liquid or gaseous). The bellows is a sealed chamber, the corrugated walls of which can stretch when heated and return to their original shape when cooled.

Passing through the pipe of the heating battery, the coolant heats the composition inside the bellows. Increasing in volume, the bellows presses on the rod, which, in turn, presses on the working cone. The flow of coolant to the radiator is partially or completely blocked. Gradually, the bellows cools down and contracts. The cone rises and opens the passage for the coolant.

The composition inside the bellows (working medium) can be liquid or gaseous. Fluid bellows tend to cost less because they respond more slowly to temperature changes. Gas is more sensitive and therefore allows you to adjust the intensity of heating more accurately. If you are dealing with large areas, want to equip several radiators with thermostats and strive to save resources, then give preference to gas bellows. If you purchase a regulator for one battery, then the speed of response of the working environment will not be of fundamental importance to you.

Installing thermostats for a radiator consists of two parts: installing a valve and installing a control element.

The thermostatic valve cuts directly into the battery supply pipe. First of all, it is required to shut off the flow of coolant and drain the water from the radiator. Next, you need to cut out a fragment of the supply pipeline and install a valve in this place. For single-pipe heating systems, you will also have to install a bypass - a bypass, a jumper between the supply and discharge pipelines. The bypass will allow the coolant to circulate without obstacles through the heating system at home, even if you turn off the heat supply in your apartment.

As you can see, installing a radiator valve requires certain skills or the involvement of a specialist. But with the control element, whether it is a thermal head or a thermostat, everything is much simpler: it is simply screwed to the valve on the thread or inserted into special grooves and snaps into place. The first way is much more common, so if you want to be able to choose from a larger range of control elements and not be limited to one manufacturer, choose a threaded valve.

Some manufacturers of heating batteries equip their products with factory valves, to which you can purchase any suitable thermal head for threading. If you recently moved into a new building, examine your batteries, it may well turn out that this is exactly your case.

Installing regulators on heating radiators has a few more subtleties. Here are the most important ones:

1. Choose thermostats with the ability to completely block the coolant flow: it may be needed to service the radiator. Another option is to install a mechanical regulator - a ball valve - in front of the valve.

Probably a picture familiar to many - it is a frosty winter outside, and in some apartments of multi-storey buildings the windows are wide open. This only says that the owners in this way escape from the too hot, suffocating atmosphere created in the premises by heating radiators operating at full capacity. But there is nothing good in such an approach: drafts begin to walk in the apartment that can cause colds, and the thermal energy generated by boiler houses is thrown, literally, into the wind.

All this can be avoided if you modernize your heating system a little - equip it with a special device that will be sensitive to the current temperature in the rooms and make its own adjustments. This device is called a thermostat for a heating radiator. It is affordable, easy to install, easy to use. And with all this, the thermostat creates an optimal microclimate in the room for residents, bringing also the effect of serious savings on energy consumption.

The need for a device to regulate heat transfer by heating radiators

Any heating system should be created on the basis of carefully carried out thermal calculations. This takes into account a lot of different criteria, ranging from the area, height and other features of each particular room, to the specifics of the climatic conditions of the region of residence. Naturally, when carrying out such calculations, designers start from the most unfavorable conditions. In other words, even in the coldest decade of the year, heating must fully cope with its tasks, that is, a certain operating margin must be laid.

But such severe frosts, the parameters of which are taken into account, most often stand on the street for no longer than two or three weeks during the entire long winter period. It turns out that the rest of the time, the calculated thermal power of heating systems remains unclaimed.

In addition, it is not a secret for anyone that in any region a series of severe frosts can be replaced by a fairly long thaw. It is clear that in such conditions the need for incoming thermal energy is sharply reduced.

You can also recall the daily fluctuations in temperature, especially in rooms with windows facing the sunny side. And such differences on fine days can be quite impressive - during the day it becomes untidy hot in the rooms. So you have to open the windows wide open, although such a measure solves the problem only partially and can do more harm than good.

Centralized heat supply systems are simply not able to respond very quickly and flexibly to such changes in air temperature. Not only that, many of the existing systems were designed according to old building standards, with monotonous heating radiators and with the installation of ordinary wooden windows everywhere. The mass installation of new high-quality windows with double-glazed windows by residents also made its own adjustments - heat loss through them is much less, plus, one of the ways of natural air ventilation in the premises has disappeared. When carrying out repairs, the owners often refuse old batteries, installing modern models with increased heat dissipation. But if the temperature is not corrected at the same time, then this is again the path to the consequences mentioned above.

It would seem that it is much easier for the owners of private houses with an autonomous heating system, since they are able to quickly change the thermal power of the boiler itself. This is true, especially if the boiler equipment is equipped with a modern weather-dependent automation system. However, this does not completely solve the problem. Different rooms of the house may require different thermal conditions. Plus, the already mentioned daily temperature fluctuations. In addition, in some rooms it is often necessary to temporarily create completely individual conditions, for example, for the storage of certain products or materials. In temporarily uninhabited rooms, a thermal regime is sometimes needed, which, for example, would only ensure the guaranteed safety of the heating system itself. In a word, for all this it is necessary to have some kind of means to quickly and accurately control the temperature directly on the heat exchange device itself - the radiator.

It was for such purposes that the thermostat for the heating radiator was developed.

Video - Thermostat for a heating radiator: installation and configuration

How does the thermostat work and what is the principle of its operation

The principle of quantitative heat regulation

The liquid circulating through the heating circuits is not in vain called a coolant - this wording fully describes its purpose. Taking, due to its pronouncedly high heat capacity, "thermal charge" from the boiler equipment, it transfers it to heating radiators, where it gives it to the premises.

It would be natural to assume that the less coolant passes through the radiator per unit time, the less its total heat transfer will be. It is on this principle - quantitative regulation of the flow of the coolant, that the work of most thermostats for heating radiators is built.

This principle is by no means new - it has always been used, including the installation of control valves in front of the entrance to the heating radiator. To this day, in the houses of the old building, one can already find practically “antique”, but still functioning cast-iron batteries, equipped with manual taps for adjusting and temperature.

They do this in domestic conditions and now - they install one or another locking element on the supply pipe, which regulates the intensity of the coolant passing through the radiator. By the way, many people make the mistake of mounting only a ball valve. By its design, it is already designed to work in only two positions - fully open or closed. The intermediate position leads to rapid wear of the spherical valve and its seat, leading to product failure. If the ball valve is on the radiator (and this happens most often in our time), then this is only for repair and maintenance work associated with a complete shutdown and even dismantling. And it is undesirable to use it for adjustment.

Another thing is the well-known valve-type products, which are designed to regulate the flow of fluid passing through them. The translational movement of the valve plug parallel to the flow, from the position of its tight fit to the seat to a gradual rise above it, changes the internal section of the fluid passage channel. The durability of such shut-off and control devices is much higher. Looking ahead, we can say that it is precisely such a valve circuit that, in fact, is also used in modern temperature controllers.

The manual adjustment scheme is virgin, but extremely inconvenient, since the owners have to constantly intervene in the operation of the radiator, making the necessary adjustments depending on the initial conditions - the current weather, the air temperature in the room and the coolant - in the supply pipe. Of course, it would be much more convenient if the device was able to independently track changes and regulate the flow of the coolant so that the set temperature is maintained in the room.

Such compact devices were invented and put into production in the middle of the last century by specialists from the Danish company DANFOSS. By the way, to this day it remains a leader in the field of industrial and household thermal automation, has production facilities around the world, and two plants successfully operate in Russia.

There are practically no fundamental differences in the structure of most thermostats from various well-known manufacturers. Moreover, most of them are even adapted to the same standards, and are easily interchangeable.

The device of modern thermostats for heating radiators

In fact, any thermostat for a radiator, which is presented in a modern assortment, can be divided into two main nodes. One of them is a valve that regulates the flow of coolant, and a thermal head that controls the operation of this valve.

The valve itself (pos. 1) is a prefabricated structure, made according to a scheme similar to a conventional valve

In the transport or non-working position, the control part of the valve with a protruding stem is closed by a protective cap (pos. 3). In some models, it can also be used to manually control the valve, acting as a flywheel, although many manufacturers do not welcome this approach. And the durability of this cap with regular use is very doubtful.

The main control element is the thermal head (pos. H), which is installed and fixed on the valve instead of the removed cap.

The scheme for pairing nodes may vary, but basically manufacturers adhere to a single standard, that is, thermal heads can be replaced with others. Accordingly, in the store you can purchase both a ready-made kit and just a valve, then pick up the most liked and suitable thermal head for it.

Thermal valve

Let's start with the valve device. The circuit diagram is shown in the figure:

The valve body (item 1) is made of corrosion-resistant alloy - it can be brass, bronze or stainless steel. Non-ferrous alloys are usually coated with chrome or nickel plating. It is not worth buying a cheap product made of silumin alloy - it will not last long.

A threaded part is provided on the inlet body (there are models equipped with a press fitting for the corresponding pipelines). At the outlet - a connection with a fitting (pos. 2), which is usually “packed” into a heating radiator, performed using an “American” union nut, making such a unit detachable. The fitting with the "American" must be included in the valve kit.

Broad arrows show the direction of movement of the coolant. There must be a corresponding icon on the body itself showing the direction of flow, and changing the correct location of the valve is unacceptable.

Inside the body there is a seat of the valve part (pos. 4). The fluid passage is closed or restricted by the poppet valve itself (pos. 5) with a high quality synthetic rubber spool.

The poppet is connected to the stem (pos. 6), which provides translational movement of the valve part. The body has a return spring (key 7) that always guides the valve to the open position when it is not actuated.

Above the axis of the rod is a pusher pin (pos. 8), which in the initial position comes out of the body. It is this pin that will take on the control action from any type of thermal head, transferring it to the stem with a poppet valve that closes or regulates the fluid flow. Of course, the seals are thought out - annular (pos. 9) and stuffing box (pos. 10), which prevent the leakage of the coolant along the axis of the rod. This assembly in non-working condition should be covered with a protective cap (pos. 11).

For those who do not perceive the drawings well - a similar valve, but already in a "living section".

By the principle of their device, almost all valves are the same. However, among them there are specific differences that you should definitely be aware of.

• First, the valves differ in their mounting dimensions. So, for example, depending on the diameter of the supply to the heating radiator, it is fashionable to purchase thermal valves with a connecting thread of ½, ¾ and 1 inch.
• Secondly, the shape of the valve body may also differ. There are direct models that provide a through flow of the coolant, and angular models that change the flow direction to perpendicular. It is clear that the choice will depend on the location and connection of the supply pipe.

The figure shows several basic versions of a valve model that is approximately the same in design:

a- ordinary straight line;

b- angular vertical;

in– angular horizontal;

G- angular with the placement of nozzles and the valve head in three perpendicular axes. Moreover, such a model can also be left and right execution.

• Thirdly, when choosing a valve, you should pay attention to what heating system it is designed to work in. There can be significant differences here.

So, for single-pipe systems, large indicators of hydraulic resistance on control valves are unacceptable. Therefore, the valves usually have a wider passage in cross section, and outwardly they differ in a slightly larger volume. In the accepted classification, they are usually marked with the letter index G, for example, RTR-G. In principle, they are also suitable for two-pipe autonomous systems with natural circulation of the coolant.

And for two-pipe systems with forced circulation, where the pressure of the passing coolant can reach considerable values, other valves are used - marked N or D (various additional combinations are possible).

This is a very important question, since with the wrong choice, you can come to extremely incorrect operation of the heating system as a whole.

• Finally, fourthly, thermal valves for two-pipe systems can also have a device for presetting its throughput. So, you can pre-set the required value in the allowable range - from 0.04 to 0.73 m³ / h for valves ½ inch, or from 0.10 to 1.04 - for diameters ¾ and 1 inch.

Such a measure allows you to already pre-set the approximate value of the required coolant flow through the radiator - a much smaller load will fall on the thermal head, and it will last longer and will regulate faster and more accurately. The adjustment itself is not difficult and does not require any tool - just unlock the adjusting ring and, turning it in the right direction, set the required value according to the existing risk. The manual supplied with the valve provides recommendations, tables and diagrams, all for the correct determination of the desired preset position. The initial values ​​​​in this matter will be the thermal power of the radiator to which the thermostatic unit is connected, as well as the temperature difference in the supply and return pipes

After such a preset, when the thermal head is put on, this setting scale will become invisible, difficult to access for unauthorized intervention.

Finally, in thermal valves with the letter D, dynamic pressure equalization is also provided. The special design of the internal channels and nozzles keeps the pressure drop in such a valve at a value of only 0.1 bar. This is very convenient both for thermal engineering calculations and for ensuring the stability of the coolant flow passing through the heating radiator, regardless of the position of the valve.

Thermal heads

So, as we have seen, all thermal valves have a pusher pin protruding from the body, which transmits translational motion to the poppet valve stem. It remains to figure out which specific device will transmit this force, and how it all relates to maintaining the required temperature.

• The simplest solution is to install a so-called locking handle. It has exactly the same system of interfacing with the valve body as any other thermal head. By turning the installed handle, you can change the position of the poppet valve, that is, in principle, it makes it possible to manually adjust the temperature.

Of course, it is impossible to call such a handle a thermal head - the device will not react on its own to a change in temperature in the room. This approach is a direct analogy with a conventional plumbing valve placed on a half-dach pipe, as already mentioned above.

However, manufacturers do not position the locking handle as a regulating element of the system. Its purpose is to reliably close the valve in case of need for certain repair and maintenance work. This makes it possible to do without an additional ball valve on the supply pipe - the thermal head is removed, the mentioned handle is installed, the valve is tightly screwed with it - and the radiator can be dismantled without completely shutting down the system and without draining the coolant from it. Having such a “spare part” at home is useful, but using it for effective thermoregulation does not make much sense.

• The most popular option is the use of bellows-type thermal heads, which are sensitive to temperature changes in the room and create the same mechanical force on the peeking pin, through it on the stem, and then on the poppet valve itself, completely blocking or narrowing the coolant passage channel.

Since ordinary consumers have to deal with such thermal heads most often, their device will be considered in more detail below.

• If the house heating system is fully automated, or in cases where it is necessary to place remote temperature sensors in the premises, a servo head can be used. A miniature electric motor receives a control signal from the control unit and progressively moves the valve stem up or down, providing opening or closing of the channel for the movement of the coolant.

However, such complex control systems are used - infrequently. Usually it is enough to install a thermal head with a bellows principle of operation.

How the bellows thermal head works

The main advantage of this type of thermal heads is that they are able to operate in a fully automatic mode, without requiring any power at all. The principle of their operation is based on one of the basic laws of thermodynamics - the expansion of substances with increasing temperature.

An example of an automatic mechanical thermal head device is shown in the illustration:

Probably, everyone understands that in the lower part of the figure there is a section of a thermal valve, the device of which we “already went through”. But the thermal head itself is attached to it with the help of a union nut M30 × 1.5 (pos. 1). Some manufacturers also practice other connecting nodes of their own design: a key is not required to install the head - it is fixed in the adapter with a simple hand pressure. But all the same, the majority of thermal valves have a threaded part, unified precisely for this nut size - M30 × 15.

The device itself consists of two parts - a fixed one, which is attached to the thermal valve, and a movable head rotating about its axis (pos. 2). Its body is usually made of durable plastic. The head is usually provided with holes (round or slotted) to allow ambient air to contact the temperature sensing element.

This sensitive thermocouple or bellows (pos. 3) is, in fact, the main part of the entire device. It is a hermetically sealed cylindrical container filled with a liquid or gaseous substance (agent). The body of the bellows is made in such a way that it has the ability to change in volume - most often this is achieved due to the corrugated walls of the cylinder (pos. 4).

The principle of operation is extremely simple. Depending on changes in temperature in the room, the liquid or gaseous agent either increases in volume or, conversely, contracts. This thermal expansion is transferred to the bellows body, which in turn acts on the piston and rod (pos. 5). The stem is installed strictly coaxially with the pusher pin of the thermal valve, that is, it transfers mechanical force to it to close or open the valve part. Accordingly, when the temperature rises, the channel for the circulation of the coolant narrows, up to complete closure, when it drops, it opens slightly, which achieves the regulation of heat transfer from the heating radiator.

The movable head is connected to the fixed part by a threaded connection (pos. 6). Thus, by rotating the head, it is possible to progressively change the position of the piston, rod and bellows relative to the body of the thermal valve. This makes it possible to pre-set the thermostat to maintain a certain temperature. To visualize the setting, a scale (pos. 8) is applied on the body of the rotating head, and a pointer (pos. 9) is placed on the fixed part. The numbers or pictograms printed on the scale allow you to set the required temperature with an accuracy of literally up to a degree.

There are other variations in the execution of the thermal head. So, for example, if it is required to take temperature readings not directly near the radiator, but to the side, then a thermal head with an external probe is used. This sensor-probe is connected to the bellows of the thermal head with a thin metal capillary tube about 2 meters long.

Another option is also possible. For example, in cases where access to the radiator is difficult for one reason or another, not only the removal of the sensor, but also the adjustment mechanism is required. For such situations, a kit is offered that includes a head that acts only as a drive to transfer force to the valve fitting. And the control panel with an adjusting handwheel is placed on the wall in a place convenient for access and adjustment. In such devices, there are two bellows - a working one, located in the control panel itself, and a drive bellows connected to it by a capillary tube, which ensures the operation of the valve device on the radiator.

There are also more complex combinations - for example, a drive head connected to a control unit, which, in turn, also has an external temperature sensor.

Video - An animated demonstration of the device and the principle of operation of a thermostat for a heating radiator

Electronic thermal heads

Somewhat apart are electronic thermal heads. They are also adapted for installation on standard thermal valves, however, they will differ in larger overall dimensions, since they require power supply to operate, and a battery compartment is provided in the case (usually these are two AA cells).

These thermostatic heads are equipped with a digital display that allows you to accurately set the temperature. Modern models very often provide owners with the ability to program operating modes. For example, it is possible to reduce the air temperature in the room for the period of absence of people in the house or apartment, so that comfortable conditions are provided only by the time they arrive home. You can also lower the temperature at night - in a cool atmosphere, many people sleep much better, but so that in the morning, by the time of rising, an optimal microclimate is provided. Such settings are also carried out on the days of the week, taking into account weekends or holidays. This can bring a very tangible effect of energy savings.

Many electronic thermostatic heads also have preset modes. For example, "holiday", "economical", "frost protection" and others - transfer to such modes is carried out by simply pressing the corresponding buttons.

Electronic thermal heads of some models can fit perfectly into the concept of "smart home", combined into a single system with a common control and management unit. The temperature level in the premises is controlled from one center, and the transmission of control signals is carried out via one or another wireless communication channel.

Of course, such electronic systems have a very big future. But so far, they have not reached the peak of popularity, partly because of the considerable cost. Most consumers prefer to purchase automatic mechanical thermal heads.

Prices for different types of thermostats for heating radiators

thermostat for heating radiators

How to approach the choice of a thermostat for a heating radiator?

If it is decided to install thermostatic regulators on heating radiators, then when choosing the optimal models, certain evaluation criteria should be followed.

1. It has already been mentioned that almost all thermal valves are adapted to most of the thermal heads produced. This makes it possible to purchase the required kit separately. If there is limited funds, it is even fashionable to split the purchase into two “runs” - first purchase and install valves, temporarily adjusting them manually, and then supplement them with thermostatic heads.
2. The valves must match the type of heating system. This has already been mentioned - there are models for two-pipe systems (they, by the way, are the majority in the assortment of stores), and for one-pipe. Ignoring this rule is unacceptable.
3. It is necessary to evaluate in advance the places of the proposed installation of thermostats, since the shape of the valve body will depend on this - straight, angular, etc.

Important - the thermostat must be installed only on the supply pipe! In this case, the correct position of the thermal head must be horizontal. This rule is introduced so that the heated air rising from the supply pipe does not wash the temperature-sensitive element - the bellows, and does not “disorient” it, otherwise the operation of the device will become extremely incorrect.

Depending on the diameter of the supply pipe, the mounting dimensions of the valve are selected.

1. When choosing a control head, of course, you should give preference to models with automatic temperature control. Manual valves will not bring the expected comfort in operation.
2. It makes little sense to install devices with automatic adjustment on cast-iron radiators - too high thermal inertia of such batteries interferes with the correct operation of the thermostatic unit. Here you can limit yourself to a device with manual control.
3. When choosing the installation location of the thermostat, it is necessary to take into account the fact that direct sunlight, the proximity of other heat sources, including large household appliances, drafts, etc. can affect the correct operation of the thermostat. If the entrance of the supply pipe to the radiator is located in the listed "problem" areas, then it would be wiser to purchase a model with an external temperature sensor. A similar approach is practiced in those places where it is impossible to install the thermal head in the correct horizontal position.

Problems can also be created by other specific conditions for placing a radiator or heating convector. For example, according to the interior design, batteries are covered with decorative casings, thick curtains, or a very wide window sill is located on top of them. In such cases, it will also be more rational to use a regulator with a remote sensor, and if it is difficult to access the thermal head itself to make adjustments, use a remote control panel.

Such measures are often resorted to when the lower principle of connecting a radiator or converter assumes the proximity of the supply pipe to the floor, where the temperature readings will differ significantly from room temperature. It should be remembered that the optimal height for the location of the temperature sensor is 500 ÷ 800 mm from the floor level.

In principle, the speed and accuracy of the reaction in practical operation is not so noticeable, so it is quite possible to get by with a more affordable thermostat with a liquid bellows. In terms of durability, they are about the same.

• If there are fears that unauthorized changes may be made to the thermostat settings, or attempts to violate the integrity of the device are possible (alas, children left without control are quite capable of such “outrages”), then you should consider purchasing a device that has special anti-vandal protection. Calling children "vandals" is, of course, an exaggeration, but still...

• The range of variable temperature settings should be evaluated. Usually it lies in the range from +5 to +30 degrees, in increments of 1 degree. Often, the passport indicates the value of hysteresis - the temperature difference at which the device responds with a reaction. It is clear that the smaller it is, the more sensitive the device.

Many models allow the owner-adjuster to narrow the range of temperature changes by installing special stops (usually purchased separately). These additional details limit the sector of rotation of the adjusting head, that is, none of the residents will be able, through negligence or ignorance, to allow a critically high or low temperature level in the room.

• Such devices belong to the category of certified products. Therefore, it is worth choosing only models of trusted manufacturers who accompany their products with a factory warranty. Of course, the purchase should be made only in specialized stores, whose staff, at the request of the client, will present documents confirming the originality and certification of the proposed thermostats, make a note in the technical passport about the date and place of sale.

Among the manufacturers of such equipment, in addition to the already mentioned Danish company Danfoss (a significant part of the products of this brand is also produced at Russian enterprises), it is quite possible to trust the brands Oventrop (Germany), Caleffi (Italy), Royal Thermo "(Italy), "Teplokontrol" (Russia), "SALUS Controls". The choice of models is quite wide, as well as the price range, so it is quite possible to choose a quality model from the available range. It makes no sense to purchase a product of an unknown company - you can make a lot of problems with it.

Video - Recommendations for choosing a thermostatic head

A brief overview of models of thermostats for heating batteries

Since valves are for the most part a unified part of a thermostat, the review will mainly concern thermal heads:

Model name	Illustration	Brief description of the model	Approximate price level
"Oventrop Vindo TH M 30x1.5"		Thermostatic head with liquid bellows. There is a zero position - full closing of the valve.	750 rub.
"Oventrop Uni LH M 30x1.5"		Thermostatic head with remote sensor, capillary tube length - 2 m. Connection with the valve - union nut М30×15. The adjustment range is from 7 to 28 degrees. There is a zero position. Possibility of custom limiting of the tuning range. Permissible coolant temperature - up to 120 degrees.	1550 rub.
Caleffi		Model with built-in temperature sensor-bellows. Connection - with a certain series of valves or using a special adapter (may be included in the kit). The adjustment range is from 7 to 28 degrees.	1050 rub.
Royal Thermo RTE 50.030		The liquid filling of the bellows is toluene. Hysteresis - 0.55 degrees. Permissible coolant temperature - up to 100 degrees. Connection with the valve - union nut М30×15. Manufacturer's warranty - 5 years.	830 rub.
Caleffi 472000		A set of a drive head and a control unit connected by a capillary tube 2 meters long. The temperature adjustment range is from +6 to +28 degrees. Hysteresis - 0.6 degrees. Bellows - liquid. Connection: with a separate group of valves - direct, with the rest - through an adapter.	8100 rub.
Danfoss RTS Everis		Liquid bellows. Connection with Danfoss thermal valves - direct fixation, with others - through an adapter. The temperature adjustment range is from +8 to +28 degrees. Hysteresis - 0.5 degrees. Devices for limiting the range and fixing fine tuning. Freeze protection of the system at temperatures less than +8 degrees. Ergonomic design. Warranty - 1 year	1100 rub.
Salus PH60		Thermal head with electronic control. Connection with the valve - union nut М30×15. Possibility of programming - for a week, including with various modes of operation. LCD screen with backlight. Indication of current and set parameters, battery level, device status. Four preset work programs. The temperature adjustment range is from +5 to +40 degrees. Hysteresis - 0.5 degrees. Power - two AA cells, the charge of which should be enough for a year of operation.	3700 rub.

Valves for temperature controllers are presented in a wide variety of sizes, shapes and purposes for a specific system. The price of high-quality valves, for example, from the range of Danfoss, depending on their mounting size and type, ranges from 1200 to 2700 rubles.

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Installing a thermostat on a heating radiator and setting it up

Installing the instrument

It is very difficult to give step-by-step instructions for installing a thermostatic regulator on a radiator, since there can be a great many options in this matter, depending on the type and material of the internal wiring of the circuit. It is better to limit ourselves to a list of important recommendations and illustrations of the strappings made. Anyone who has experience in plumbing installation work will understand everything. And if you don’t have such skills, then radiators and thermostats are not the best place for training, and it’s better to practice something simpler to start with.

If you look at the photos of the work performed, then in the vast majority you can see such a crane. Just do not mount it between the thermostat and the radiator - this will already be a gross mistake.

• In the event that the thermostat is installed on a radiator connected to a single-pipe separation system, some additional rules must be observed. Firstly, the thermal valve itself must correspond to a one-pipe system - this has already been mentioned. And secondly, and this is the main thing, that a bypass is mounted between the supply and return pipes - a jumper pipe. The bypass diameter, according to the rules, should be one size smaller than the diameter of the liner. Any locking elements in the interval from the riser to the bypass are unacceptable - the same ball valve or thermostat must fall on the area between the bypass and the radiator.

What is a bypass and what role does it play?

In a properly planned heating system, there are no unnecessary details - any, even seemingly insignificant element performs a particular role. A vivid example of this is, which is described in detail in a separate article on our portal.

• After the thermal valve is mounted, it is necessary to fill the system with coolant and turn it on for circulation. This step will make it possible to check the tightness of the connections made - there should be no signs of leakage in the connecting nodes or from under the valve stem.
• If the valve requires presetting, now is the time to do it. The value to be set on the scale is determined in accordance with the recommendations of the product instruction manual. The installation itself is carried out manually - the ring with the scale is removed from the stopper (it is pulled progressively towards itself) and rotated until the desired division is combined with the mark, after which it stops again.

• Now you can install the thermal head. Here, options are possible that will necessarily be specified in the instructions for the device. Some heads are fixed by simply pressing the hand until it clicks (this is more typical for Danfoss products), others are attached to the valve body with a M30 × 15 union nut. Before fixing, the most convenient position of the regulator is selected - so that the installation scale is visible. After that, the nut can be tightened. At the same time, they do not offer much effort - often the muscle strength of the fingers is enough.

One more note. If two radiators are installed in the room, then there is no point in putting a thermostat on each - they will only interfere with each other in correct operation. If the radiators are equivalent, then the installation location does not matter - the device is placed on any, for reasons of ease of installation or use. But in the case when the radiators differ in power, the thermostat is installed on the one that has a greater heat transfer.

The installation and debugging of thermostats in a private residential building usually begins with the premises of the upper floor (if any), since warm air rises there from below. In one-story houses or apartments, premises with a high dynamics of air temperature changes come to the fore. This, of course, is the kitchen, where the air is very hot from the stove, the rooms facing the south side, as well as those where the most people traditionally visit - this also greatly changes the overall thermal background.

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Setting the thermostat

Thermal heads at the stage of technical control are calibrated accordingly. As a rule, the temperature values ​​corresponding to one or another division of the instrument scale are indicated in its passport. However, it should be understood correctly that calibration is carried out under certain laboratory conditions, on a thermal valve of a specific type, at a strictly set height of the thermal head relative to the floor level, etc. Much, by the way, depends on the type and power of the heating radiator in this matter. Therefore, in real operating conditions, deviations from the temperature calibration indicators are quite possible.

It doesn’t matter - fine tuning for the existing heating system can be done independently. It is performed in several steps:

1. It is advisable to place an ordinary thermometer in the room - so you can rely on its readings, and not just on your own feelings. It is clear that everything in the room is brought to a “warm” position - windows and doors are closed, drafts are excluded.
2. The valve opens completely - for this, the head is turned counterclockwise to the leftmost position. With this position, the coolant practically does not encounter obstacles, and its maximum flow through the heating radiator ensures a rapid increase in temperature in the room.
3. When the air temperature reaches sufficiently high values, in the region of 27 ÷ 30 degrees (it will be hot and feels), the head turns clockwise to the extreme right position. The valve closes completely.
4. Naturally, the air temperature in the room begins to gradually decrease. Here it is important to catch the moment when it reaches the most comfortable value according to personal perception (or according to the thermometer). At this point, you need to start turning the head of the device counterclockwise very smoothly. At some point, both by ear and by touch, it will be clearly indicated that the valve has opened slightly, and the coolant current has begun through it. That's it, stop - this is the value that is now on the scale, can be considered optimal and be guided by it in further operation. It probably makes sense to compare the readings of the thermometer and the value on the scale with the tabular data given in the product passport - whether they differ, and how much.

In the course of further operation of the thermostat, it will already be possible to make appropriate adjustments, choosing the optimal operating mode for a particular period.

Adjustment and programming of electronic thermostatic heads is carried out in accordance with the operating instructions attached to them.

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Conclusion and useful supplement to the article for users

What are the benefits of using thermostats on radiators?

As a summary, a few words about the benefits and conveniences that the installation of thermostats will bring:

1. The installation itself, as we have seen, is simple, and can be carried out both on a newly created and on a heating system that has been in operation for a long time.
2. The premises maintain an optimal temperature level, the most favorable for residents. At the same time, neither daily fluctuations in temperature, nor its sudden changes in the street, nor the use of household appliances, which are characterized by a large release of heat, affect the microclimate.
3. Temperature controllers in an autonomous system contribute to the most uniform, rational distribution of the coolant in all rooms. This eliminates the characteristic disadvantage of single-pipe systems, when the temperature in the radiators drops as the distance from the boiler room increases.
4. Thermostatic regulators are easy to operate and do not require any additional energy consumption. On the contrary, in the autonomous systems of a private house, they lead to significant, up to 20÷25% savings in energy consumption for heating, and as a rule, they pay off in one season.

The only thing that can be “blamed” on the thermostat is that it can only work to lower the temperature. If the conditions are such that the heating power is clearly insufficient, then it is not necessary to expect miracles from the installation of such devices, it will not get better anyway. This means that it is necessary to carefully analyze whether the heating system is properly arranged in principle, whether its parameters correspond to real conditions. Perhaps - the boiler power is insufficient, the general scheme of the circuits is incorrectly selected and needs to be optimized. Sometimes the error lies in the incorrectly calculated parameters of heating radiators for specific rooms.

However, it also happens that the reason is completely different: the owners just need to pay close attention to the quality and effectiveness of thermal insulation of their homes.

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Application - how to calculate the optimal radiator for a room

The calculation of the entire heating system and radiators in particular is always carried out in such a way as to ensure a normal microclimate in the most severe (but not exceeding the extreme limits) conditions. In a word, in a similar way, the necessary operational reserve is laid down in the design parameters, since with full load the entire system during the season will work for a rather limited time.

As we have seen, the thermostat is able to maintain the optimum temperature, as if eliminating the imbalance between the current settings of the heating system and the actual conditions in the room. But at the same time, the radiators in the room must be able to cope with the peak, most unfavorable conditions.

The often recommended ratio that 10 square meters of area needs 1 kW of thermal power is quite approximate, not taking into account a number of specific parameters inherent in a particular room. Therefore, we recommend that readers use a more advanced calculation algorithm, which is taken as the basis for compiling the online calculator below.

If questions arise during the calculations, the necessary comments are given below.