To ensure comfortable living in a house in winter, the boiler must produce enough thermal energy to fully compensate for the heat loss of the building. In addition, it is necessary to provide a certain reserve of power in case of extreme cold or an increase in the area of ​​the building. To calculate the boiler power, you need to take into account quite a few factors. In heating engineering, this calculation is one of the most difficult.

There are many calculations of the heating system, namely the boiler power - one of the most complex

The need to calculate the heat transfer of the boiler

No matter what materials a building is built from, it constantly releases heat to the outside. Heat loss at home for each room may differ and depend on the materials of construction and the degree of insulation. If you take the calculations seriously, then it is better to entrust such work to specialists. Then, in accordance with the results obtained, a boiler is selected.

It is not very difficult to independently calculate the heat loss of a building, but there are many factors to take into account. The easiest way to solve this problem is with the help of a special device - a thermal imager. This device small sizes, the display of which indicates the actual heat loss of the building. At the same time, you can clearly see those places where the maximum leaks of thermal energy are observed, and take measures to correct the situation.

You can immediately install a powerful boiler without calculations

Of course, you can just take a powerful boiler and not carry out any calculations. However, in such a situation, gas costs can be very high. In addition, if the boiler is underloaded, its service life is reduced. However, the heat generator can be additionally loaded, for example, by using it to heat previously unheated rooms. However, no owner of a private home will want to overpay for wasted fuel.

If the power of the heat generator turns out to be insufficient, then it will not be possible to create comfortable living conditions in the building, and the boiler itself will operate in constant overload mode. As a result, expensive equipment will fail prematurely. Thus, only one conclusion can be drawn - you need to calculate the power of the boiler for your home, thereby making a competent selection of heating equipment.

The easiest way is to independently calculate the power of the heating boiler based on the area of ​​the house. After this, it will be possible to say exactly which heating unit is needed to heat all rooms of the building.

Basic formula

If we analyze the results of calculations carried out over several years, one pattern is observed - to heat every 10 m 2 of area it is necessary to expend 1 kW of thermal energy. This statement is true for buildings with average insulation, and the ceiling height in them is in the range from 2.5 to 2.7 m.

If the building meets these standards, then determining the power of heating boilers will be quite simple, just use a simple formula:

Latest indicator for various regions of the country has the following meanings:

1. Moscow region - from 1.2 to 1.5 kW.
2. Middle band - from 1 to 1.2 kW.
3. South of the country - from 0.7 to 0.9 kW.
4. Northern territories - from 1.5 to 2 kW.

As an example, we can calculate the power of a heat generator for a house measuring 12x14 m, built of brick in the Moscow region. The total area of ​​the building is 168 m2. The specific power value Wsp is assumed to be 1. As a result, W = (168 × 1) / 10 = 16.8 kW. The resulting calculated power of the heat generator should be rounded up. However, this is not yet a complete calculation of a gas boiler for a house by area, since the resulting indicator needs to be adjusted.

Additional calculations

Residential buildings with average characteristics are quite rare in practice. In order for the boiler room power calculation to be as accurate as possible, additional indicators have to be taken into account. One of them has already been considered in the basic formula - the specific power spent on heating 10 m 2.

As a standard, it is necessary to use the indicator for middle zone. Moreover, in each zone one can see a rather serious scatter in the specific capacitance values. The way out of this situation is simple - the further north the area is located in the climatic zone, the higher the coefficient should be, and vice versa. For example, for Siberia with frosts of about 35 degrees, it is customary to use Wsp = 1.8.

Another factor influencing the calculation of boiler power is the height of the ceilings. If this parameter differs significantly from the average (2.6 m), then it is necessary to calculate a correction factor. To do this, the real value must be divided by the average.

It is equally important to take into account when calculating heat losses buildings. The process of heat leakage is observed in every building. For example, if the walls are poorly insulated, then losses can reach up to 35%. Thus, during calculations a special coefficient should be used:

1. A structure made of wood, foam blocks or bricks, the age of which exceeds 15 years with high-quality insulation - K=1.
2. Buildings of other materials with poorly insulated walls - K=1.5.
3. If the building was not insulated also the roof, and not just the walls - K = 1.8.
4. Modern high-quality insulated houses - K=0.6.

Do not forget to take into account the coefficient of wooden blocks

This is how the required power of the heat generator is calculated to make right choice equipment. However, if the boiler is also planned to be used for heating water, the resulting value of its power will have to be increased by 25%. Thus, to determine the required power of the heat generator you need to use the following algorithm:

1. Calculated total area structure and is divided by 10. In this case, the Wsp indicator does not need to be taken into account.
2. The calculated value is adjusted depending on the climatic zone in which the structure is built. The indicator determined at the first stage is multiplied by the region coefficient.
3. If the actual ceiling height differs significantly from the average, this must be taken into account when calculating. First you need to divide the actual figure by the average. The resulting coefficient is multiplied by the power of the heat generator, determined taking into account the correction for the climatic features of the area.
4. The heat losses of the building are taken into account. The result obtained at the previous stage must be multiplied by the heat loss coefficient.
5. If the boiler is also used to heat water, its power increases by 25%.

The result obtained using this algorithm is highly accurate, and it is suitable for choosing a boiler operating on any type of fuel.

In accordance with SNiP standards

You can calculate the power of equipment for a home heating system based on building codes and regulations (SNiP). This document determines the required amount of thermal energy to heat 1 m 3 of air. Calculation by volume is quite simple. It is enough just to determine the volume of the internal premises of the building and multiply it by the rate of thermal energy consumption.

According to SNiP, in a panel building, 41 W of heat energy must be consumed to heat 1 m 3 of air.

For a brick house the norm is 34 W. After performing the calculation, the resulting power value must be converted to kilowatts. It should also be recalled that in heating engineering, calculated indicators are rounded up.

If you want to get the most accurate results, then you need to take into account the correction factor:

1. If there is a heated room above or below the apartment, the correction is 0.7.
2. If it is unheated, the coefficient will be 1.
3. If the apartment is located above the basement or under the attic, the amendment will be 0.9.

You also need to take into account the number of external walls in the room. When only one wall faces the street, the coefficient will be 1.1, with two - 1.2, three - 1.3. Thus, the calculation of a boiler for heating a house can be calculated based on the total volume of the building or its area. Whatever method is chosen, the process is not very complex. All necessary calculations can be carried out by any person who does not have special knowledge.

The article was prepared with the information support of Teplodar company engineers https://www.teplodar.ru/catalog/kotli/ – heating boilers at prices from the manufacturer.

The most important characteristic taken into account when purchasing heating boilers, both gas, electric or solid fuel, is their power. Therefore, many consumers who are planning to purchase a heat generator for a room heating system are concerned with the question of how to calculate the boiler power based on the area of ​​the premises and other data. This is discussed in the following lines.

Calculation parameters. What to consider

But first, let’s figure out what this such an important quantity actually is, and most importantly, why it is so important.

In essence, the described characteristic of a heat generator operating on any type of fuel shows its performance - that is, how much area of ​​the room it can heat along with the heating circuit.

For example, a heating device with a power value of 3 - 5 kW is capable, as a rule, of “enveloping” a one-room or even two-room apartment, as well as a house with an area of ​​up to 50 sq. m. An installation with a value of 7 - 10 kW will “pull” a three-room apartment with an area of ​​up to 100 square meters. m.

In other words, they usually take a power equal to approximately a tenth of the entire heated area (in kW). But this is only in the most general case. To obtain a specific value, a calculation is needed. Various factors must be taken into account in the calculations. Let's list them:

• Total heated area.
• Region where calculated heating operates.
• House walls and their thermal insulation.
• Roof heat loss.
• Type of boiler fuel.

Now let’s talk directly about calculating power in relation to different types of boilers: gas, electric and solid fuel.

Gas boilers

Based on the above, the power of boiler equipment for heating is calculated using one fairly simple formula:

N boiler = S x N beat. / 10.

Here the values ​​of the quantities are deciphered as follows:

• N of the boiler is the power of this particular unit;
• S is the total sum of the areas of all rooms heated by the system;
• N beats – specific value of the heat generator required to warm up 10 kW. m. area of ​​the room.

One of the main determining factors for the calculation is the climatic zone, the region where this equipment is used. That is, the calculation of the power of a solid fuel boiler is carried out with reference to specific climatic conditions.

What is typical is that once upon a time, during the existence of Soviet standards for assigning the power of a heating installation, they considered 1 kW. always equal to 10 square meters. meters, then today it is extremely necessary to make accurate calculations for real conditions.

In this case, you need to take the following values ​​N beats.

For example, let's calculate the power of a solid fuel heating boiler relative to the Siberian region, where winter frosts sometimes reach -35 degrees Celsius. Let's take N beats. = 1.8 kW. Then, to heat a house with a total area of ​​100 square meters. m. you will need an installation with the following design value:

Boiler N = 100 sq. m. x 1.8 / 10 = 18 kW.

As you can see, the approximate ratio of the number of kilowatts to area as one to ten does not apply here.

Important to know! If you know how many kilowatts a particular solid fuel installation has, you can calculate the volume of coolant, in other words, the volume of water that is necessary to fill the system. To do this, simply multiply the resulting N of the heat generator by 15.

In our case, the volume of water in the heating system is 18 x 15 = 270 liters.

However, taking into account the climatic component to calculate the power characteristics of a heat generator is in some cases not enough. It must be remembered that heat losses may occur due to the specific design of the premises. First of all, you need to consider what the walls of the living space are. How insulated the house is - this factor is of great importance. It is also important to consider the structure of the roof.

In general, you can use a special coefficient by which you need to multiply the power obtained from our formula.

This coefficient has the following approximate values:

• K = 1, if the house is more than 15 years old, and the walls are made of brick, foam blocks or wood, and the walls are insulated;
• K = 1.5 if the walls are not insulated;
• K = 1.8, if, in addition to uninsulated walls, the house has a poor roof that allows heat to pass through;
• K = 0.6 for a modern house with insulation.

Suppose, in our case, the house is 20 years old, it is built of brick and well insulated. Then the power calculated in our example remains the same:

Boiler N = 18x1 = 18 kW.

If the boiler is installed in an apartment, then a similar coefficient must be taken into account. But for an ordinary apartment, if it is not on the first or last floor, K will be equal to 0.7. If the apartment is on the first or last floor, then K = 1.1 should be taken.

How to calculate power for electric boilers

Electric boilers are rarely used for heating. The main reason is that electricity is too expensive today, and the maximum power of such installations is low. In addition, failures and long-term power outages in the network are possible.

The calculation here can be made using the same formula:

N boiler = S x N beat. / 10,

after which you should multiply the resulting indicator by the necessary coefficients, we have already written about them.

However, there is another, more accurate in this case, method. Let's indicate it.

This method is based on the fact that the value of 40 W is initially taken. This value means that so much power, without taking into account additional factors, is necessary to warm up 1 m3. Further calculation is carried out as follows. Since windows and doors are sources of heat loss, you need to add 100 W per window, and 200 W per door.

At the last stage, the same coefficients that were already mentioned above are taken into account.

For example, let us calculate in this way the power of an electric boiler installed in a house of 80 m2 with a ceiling height of 3 m, with five windows and one door.

Boiler N = 40x80x3+500+200=10300 W, or approximately 10 kW.

If the calculation is carried out for an apartment on the third floor, it is necessary to multiply the resulting value, as already mentioned, by a reduction factor. Then N boiler = 10x0.7=7 kW.

Now let's talk about solid fuel boilers.

For solid fuel

This type of equipment, as the name implies, is characterized by the use of solid fuel for heating. The advantages of such units are obvious mostly in remote villages and dacha communities where there are no gas pipelines. Firewood or pellets - pressed shavings - are usually used as solid fuel.

The method for calculating the power of solid fuel boilers is identical to the above method, characteristic of gas heating boilers. In other words, the calculation is carried out according to the formula:

N boiler = S x N beat. / 10.

After calculating the strength indicator using this formula, it is also multiplied by the above coefficients.

However, in this case, it is necessary to take into account the fact that a solid fuel boiler has low efficiency. Therefore, after calculating using the described method, a power reserve of approximately 20% should be added. However, if it is planned to use a heat accumulator in the heating system in the form of a container for storing coolant, then you can leave the calculated value.

Drawing of a solid fuel boiler with estimated power

Too much and too little

Finally, we note that installing a heating boiler without first calculating its power can lead to two undesirable situations:

1. The boiler power is below that required to heat the existing premises.
2. The boiler power is greater than necessary to heat the existing premises.

In the first case, in addition to the fact that the house will be constantly cold, the unit itself may fail due to constant overloads. And fuel consumption will be unreasonably high. Reinstalling a boiler with a new one is associated with large material costs and difficulties during dismantling; is it worth talking about moral costs? That is why it is so important to correctly calculate the power of the unit!

In the second case, not everything is so bad. Excessive boiler power is mostly just an inconvenience. Firstly, this is the feeling of wasting money on an expensive unit. Secondly, oddly enough, an overly powerful unit that constantly works at half capacity reduces its efficiency and quickly wears out. In addition, a lot of fuel will be wasted.

As you can see, in the second case there are also significant disadvantages. However, the situation here can be corrected if, say, we add the function of heating hot water supply to the boiler. In any case, the final decision is up to the consumer.

So, we looked at ways to calculate the power of a heating boiler. These recommendations should help consumers during the complex process of selecting and purchasing a heating unit.

Autonomous heating for a private home is affordable, comfortable and varied. You can install a gas boiler and not depend on the vagaries of nature or failures in the central heating system. The main thing is to choose the right equipment and calculate the heating output of the boiler. If the power exceeds the heating needs of the room, then the money for installing the unit will be wasted. In order for the heat supply system to be comfortable and financially profitable, at the design stage it is necessary to calculate the power of the gas heating boiler.

Basic values ​​for calculating heating power

The easiest way to obtain data on the heating performance of a boiler by area of ​​the house: take 1 kW of power for every 10 sq. m. However, this formula has serious errors, because modern construction technologies, type of terrain, climatic temperature changes, level of thermal insulation, use of double-glazed windows, and the like.

To make a more accurate calculation of the heating power of the boiler, you need to take into account a number of important factors that influence the final result:

• dimensions of the living space;
• degree of insulation of the house;
• presence of double-glazed windows;
• thermal insulation of walls;
• building type;
• air temperature outside the window during the coldest time of the year;
• type of heating circuit wiring;
• ratio of the area of ​​supporting structures and openings;
• heat loss of the building.

In houses with forced ventilation, the calculation of the boiler's heating output must take into account the amount of energy required to heat the air. Experts advise making a gap of 20% when using the resulting heat output of the boiler in case of unforeseen situations, severe cold weather or a decrease in gas pressure in the system.

An unreasonable increase in thermal power can reduce the efficiency of the heating unit, increase the cost of purchasing system elements, and lead to rapid wear of components. That is why it is so important to correctly calculate the power of the heating boiler and apply it to the specified home. Data can be obtained using the simple formula W=S*W beat, where S is the area of ​​the house, W is the factory power of the boiler, W beat is the specific power for calculations in a certain climatic zone, it can be adjusted according to the characteristics of the user’s region. The result must be rounded to of great importance in conditions of heat leakage in the house.

For those who do not want to waste time on mathematical calculations, you can use the online gas boiler power calculator. Simply enter individual data on the characteristics of the room and receive a ready-made answer.

Formula for obtaining heating system power

The online heating boiler power calculator makes it possible to get required result taking into account all the above characteristics that affect the final result of the data obtained. To use such a program correctly, you need to enter the prepared data into the table: the type of window glazing, the level of thermal insulation of the walls, the ratio of the floor area to the window opening, the average temperature outside the house, the number of side walls, the type and area of ​​the room. And then click the “Calculate” button and get the result of heat loss and boiler heat output.

Choice necessary equipment for a heating system is an extremely important task. Owners of private houses are sure to encounter this, and recently many apartment owners are striving to achieve complete independence in this matter by creating their own autonomous systems. And one of the key points, naturally, is the issue of choosing a boiler.

If your home is connected to the main natural gas supply, then there is nothing to think about - the optimal solution would be to install gas equipment. The operation of such a heating system is incomparably more economical than all others - the cost of gas is relatively low, especially in comparison with electricity. All sorts of problems with additional acquisition, transportation and storage of fuel, typical for solid or liquid fuel installations, disappear. If all installation requirements are met and the rules of use are followed, it is completely safe and has high performance indicators. The main thing is to decide correctly the right model, for which you need to know how to choose a gas boiler so that it fully complies with specific operating conditions and meets the wishes of the owners in terms of functionality and ease of use.

Basic parameters for choosing a gas boiler

There are a number of criteria by which you should evaluate the model of boiler you are purchasing. It should be immediately noted that almost all of them are interconnected and even interdependent with each other, so they must be considered immediately and in their entirety:

• The key parameter is the total thermal output of the gas boiler, which must correspond to the tasks of a specific heating system.
• The location of the future installation of the boiler - this criterion will very often depend on the power mentioned above.
• Boiler type according to layout - wall-mounted or floor-mounted. The choice also directly depends on both the power and the installation location.

• The type of boiler burner - open or closed - will depend on the same criteria. Accordingly, a system for removing combustion products is organized - through a conventional chimney with natural draft or through a forced smoke removal system.
• Number of circuits - will the boiler be used only for heating needs, or will it also take over the provision hot water. If a double-circuit boiler is selected, then its type based on the structure of the heat exchangers is taken into account.
• The degree of dependence of the boiler on the energy supply. This parameter is especially important to take into account in cases where power outages in a populated area occur with alarming regularity.
• Additional equipment of the boiler with elements necessary for efficient operation of the heating system, the presence of built-in control systems and ensuring operational safety can be of great importance.
• And finally, the boiler manufacturer, and, of course, the price, which will depend on many of the factors listed above.

The first step is to correctly determine the boiler power

It is simply impossible to move on to choosing any boiler if there is no clarity about what heating installation must be in place.

The technical documentation of the boiler must indicate the value of the rated power, and in addition, recommendations are often given as to how much space it is designed to heat. However, these recommendations can be considered rather conditional, since they do not take into account the “specifics”, that is, the actual operating conditions and features of the house or apartment.

The same caution should be applied to common“axiom” that to heat 10 m² of housing area, 1 kW of thermal energy is needed. This value is also very approximate, which can only be valid under certain conditions - average ceiling height, one external wall with one window, etc. In addition, the climate zone, the location of the premises relative to the cardinal points, and a number of other important parameters are not taken into account at all.

Thermal engineering calculations according to all the rules can only be carried out by specialists. However, we will take the liberty of offering the reader a method for independently calculating power, taking into account most of the factors influencing the efficiency of heating a house. With such a calculation, there will certainly be an error, but within completely acceptable limits.

The method is based on calculating the required thermal power for each room where heating radiators will be installed, followed by summing the values. Well, the following parameters serve as initial data:

• Room area.
• Ceiling height.
• The number of external walls, the degree of their insulation, their location relative to the cardinal points.
• Level of minimum winter temperatures for the region of residence.
• Number, size and type of windows.
• “Neighborhood” of the room vertically - for example, heated rooms, a cold attic, etc.
• The presence or absence of doors to the street or to a cold balcony.

Any owner of a house or apartment has a plan for his housing. Having placed it in front of you, it will not be difficult to create a table (in an office application or even just on a sheet of paper), which indicates all the heated rooms and their characteristic features. For example, as shown below:

Premises:	Area, ceiling height	External walls (number where facing)	Number, type and size of windows	The presence of a door to the street or balcony	Required thermal power
TOTAL:	92.8 m²				13.54 kW
1st floor, insulated floors
Hall	9.9 m², 3 m	alone, West	single, double-glazed window, 110×80	No	0.94 kW
Kitchen	10.6 m, 3 m	one, South	one, wooden frame, 130×100	No	1.74 kW
Living room	18.8 m², 3 m	three, North, East	four, double-glazed window, 110×80	No	2.88 kW
Tambour	4.2 m², 3 m	alone, West	No	one	0.69 kW
Bathroom premises	6 m², 3 m	one, North	No	No	0.70 kW
2nd floor, above – cold attic
Hall	5.1 m², 3 m	one, North	No	No	0.49 kW
Bedroom No. 1	16.5 m², 3 m	three, South, West	single, double-glazed window, 120×100	No	1.74 kW
Bedroom No. 2	13.2 m², 3 m	two, North, East		No	1.63 kW
Bedroom No. 3	17.5 m², 3 m	two, East, South	two, double-glazed window, 120×100	one	2.73 kW

After the table has been compiled, you can proceed to calculations. To do this, below is a convenient calculator that will help you quickly determine the required heating power for each room.

The level of negative street temperatures is taken from the average characteristic of the coldest ten-day period of winter in the region of residence.

The comfort of people staying indoors, especially in the winter, largely depends on the temperature of the air around them. Therefore among engineering communications, equipped in residential premises, the heating system takes first place. In urban environments, issues of heating apartments are most often resolved centrally, but in private buildings their owners have to install autonomous heating systems, the main element of which is a hot water boiler. The efficiency of the entire system depends on the technical and economic characteristics of the latter.

How to calculate boiler power

Calculation of boiler power is carried out taking into account the area of ​​the heated object

The power of a heating boiler is the main indicator characterizing its capabilities associated with optimal heating of rooms during peak loads. The main thing here is to correctly calculate how much heat will be needed to heat them. Only in this case will it be possible to choose the right boiler for heating a private house in terms of power.

To calculate the power of a boiler for a home, use various techniques, in which the area or volume of heated premises is taken as a basis. More recently, the required power of a heating boiler was determined using the so-called house coefficients established for different types houses within (W/sq.m.):

• 130…200 – houses without thermal insulation;
• 90…110 – houses with a partially insulated facade;
• 50...70 – houses built using 21st century technologies.

By multiplying the area of ​​the house by the corresponding house coefficient, the required power of the heating boiler was obtained.

Calculation of boiler power based on the geometric dimensions of the room

Dependence of gas boiler power on room area

Wcat = S*Wud/10, Where:

• Wcat– design power of the boiler, kW;
• S– total area of ​​the heated room, sq. m.;
• Wud– specific power of the boiler, which falls on every 10 sq. m. heated area.

In general, it is accepted that, depending on the region in which the room is located, the specific power of the boiler is (kW/sq. m.):

• for the southern regions - 0.7...0.9;
• for areas of the middle zone - 1.0...1.2;
• for Moscow and the Moscow region – 1.2...1.5;
• for northern regions - 1.5...2.0.

The above formula for calculating a boiler for heating a house by area is used in cases where the water heating unit will be used only for heating rooms with a height of no more than 2.5 m.

If it is assumed that a double-circuit boiler will be installed in the room, which, in addition to heating, should provide users with hot water, the resulting calculated power must be increased by 25%.

If the height of the heated premises exceeds 2.5 m, then the obtained result is corrected by multiplying it by the coefficient Kv. Kv = N/2.5, where H is the actual height of the room, m.

In this case, the final formula looks like this: P = (S*Wsp/10)*Kv

This method of calculating the required power that a heating boiler must have is suitable for small buildings with an insulated attic, insulated walls and windows (double glazing), etc. In other cases, the result obtained from an approximate calculation may lead to that the purchased boiler will not be able to operate normally. At the same time, excess or insufficient power contributes to a number of problems that are undesirable for the user:

• reduction of technical and economic indicators of boiler operation;
• failure of automation systems;
• rapid wear of parts and components;
• formation of condensation in the chimney;
• clogging of the chimney with products of incomplete combustion of fuel, etc.;

To obtain more accurate results, it is necessary to take into account the amount of actual heat loss through individual elements of buildings (windows, doors, walls, etc.).

Refined calculation of boiler power

The power of a double-circuit boiler must be greater due to DHW

The calculation of a heating system that includes a heating boiler must be carried out individually for each facility. In addition to its geometric dimensions, it is important to take into account a number of such parameters:

• presence of forced ventilation;
• climate zone;
• availability of hot water supply;
• degree of insulation of individual elements of the facility;
• the presence of an attic and basement, etc.

IN general view the formula for a more precise calculation of boiler power is as follows:

Wcat = Qt*Kzap, Where:

• Qt– heat loss of the object, kW.
• Kzap– safety factor, by the amount of which it is recommended to increase the design capacity of the facility. As a rule, its value is in the range of 1.15...1.20 (15-20%).

Predicted heat losses are determined by the formulas:

Qt = V*ΔT*Kp/860, V = S*H; Where:

• V– volume of the room, cubic meters;
• ΔT– difference between external and internal air temperatures, °C;
• Kr– dissipation coefficient, depending on the degree of thermal insulation of the object.

The dissipation coefficient is selected based on the type of building and the degree of its thermal insulation.

• Objects without thermal insulation: hangars, wooden barracks, structures made of corrugated iron, etc. – Kr = 3.0...4.0.
• Buildings with a low level of thermal insulation: single brick walls, wooden windows, slate or iron roof - Kp is taken equal within 2.0...2.9.
• Houses with an average degree of thermal insulation: two-brick walls, a small number of windows, a standard roof, etc. - Kr is 1.0...1.9.
• Modern, well-insulated buildings: heated floors, double-glazed windows, etc. – Kp is in the range of 0.6...0.9.

To make it easier for consumers to find a heating boiler, many manufacturers place special calculators on their websites and dealer websites. With their help, by entering the necessary information in the appropriate fields, you can with a high degree of probability determine for what area, for example, a 24 kW boiler is designed.

Typically, such a calculator performs calculations using the following data:

• average value of outside air temperature in the coldest week in the winter season;
• air temperature inside the object;
• presence or absence of hot water supply;
• data on the thickness of external walls and ceilings;
• materials from which floors and external walls are made;
• ceiling height;
• geometric dimensions of all external walls;
• number of windows, their sizes and detailed description;
• information about the presence or absence of forced ventilation.

Having processed the received data, the calculator will give the customer the required power of the heating boiler, and also indicate the type and brand of the unit that satisfies the request. An example of calculating a line of gas boilers intended for heating houses of different sizes is given in the table:

Note to column 11: Нс – wall-mounted atmospheric boiler, А – floor-standing boiler, Нд – wall-mounted turbocharged boiler.

Using the above methods, the power of a gas boiler is calculated. However, they can also be used to calculate the power characteristics of water heating units operating on other types of fuel.

Heat loss accounting

Without taking into account heat loss, it is difficult to correctly calculate the boiler power

When starting to develop an autonomous heating system, you must first find out how much heat is lost to the street during the most severe frosts through the so-called enclosing structures. These include walls, windows, floors and roofs. Only after determining the amount of heat loss will it be possible to worry about selecting a heat source of appropriate power. It should be taken into account that the loss of heat from a building in the winter season occurs not only through the enclosing structures. A significant part of the generated heat (up to 30%) is spent on heating cold air coming from the street due to natural ventilation.

The total amount of heat required to heat the room is determined by the formula:

Q = Qdesign + Qair, Where:

• Qconstruct– the amount of heat lost through a similar structure, W;
• Qair– the amount of heat consumed to heat the air coming from the street, W.

By summing up the values ​​obtained as a result of calculations, the total heat load on the heating system of the entire building is determined.

All measurements are carried out on the outside of the building, necessarily taking into account its corners. Otherwise, the calculation of heat loss will be inaccurate.

There are other ways of heat leakage in rooms, for example, through a kitchen hood, open doors and windows, cracks in structures, etc. However, the amount of heat lost for these reasons practically does not exceed 5% of the total heat loss and is therefore not taken into account in calculations .

Calculation of heat loss through building envelopes

The complexity of the calculation lies in the fact that it must be carried out for each room separately, carefully inspecting, measuring and assessing the condition of each element adjacent to it. environment. Only in this case can you take into account all the heat leaving the house.

Based on the results of the measurements, the area S of each element of the enclosing structure is determined, which is then inserted into the basic formula for calculating the amount of lost thermal energy:

Qconstruct = 1/R*(Tv-Tn)*S*(1+Σβ), R = δ/λ; Where:

• R– thermal resistance of the construction material, m sq.°C/W;
• δ – thermal conductivity of the construction material, W/m°C);
• λ – thickness of the construction material, m;
• S– area of ​​the external fence, sq. m.;
• TV– indoor air temperature, °C;
• Tn– the most low temperature air in winter, °C;
• β – heat loss, which depends on the orientation of the building.

If the structure consists of several materials, for example, a brick wall with insulation, the value of thermal resistance R is calculated separately for each of these materials and then summed up.

Heat losses, depending on the orientation of the building, are selected based on where the enclosing element is oriented:

• to the north side – β = 0.1;
• to the west or southeast – β = 0.05;
• to the south or southwest – β = 0.

The calculation of heat losses through the elements of the building envelope is carried out for each room in the building, and then summing them up, the predicted value of the total heat losses in it is obtained. After this, they proceed to the calculation in the next room. As a result of the work carried out, the home owner will be able to identify ways of maximum heat leakage and eliminate the causes of their occurrence.

Calculation of heat consumed to heat ventilation air

The amount of heat that is spent on heating ventilation air reaches, in some cases, 30% of the total thermal energy losses. This is a fairly large value that is inappropriate to ignore. To calculate the amount of heat that will be forced to be spent on heating the supply air, the formula is used:

Qair = c*m* (Tv-Tn), Where:

• c– heat capacity of the air mixture, the value of which is 0.28 W/kg°C;
• m– mass flow of air entering the room from the street, kg.

The mass flow of air entering the room from the outside is determined by assuming that the air is renewed throughout the entire house once every hour. In this case, by adding up the volumes of all rooms, the volumetric air flow rate is obtained. Then, using the air density value, its volume is converted to mass. Here you need to take into account the fact that the density of air depends on its temperature.

Substituting all known quantities into the above formula, the amount of heat required to heat the supply air is determined.

Common mistakes

Calculation autonomous system heating is a complex process consisting of several interrelated, step-by-step procedures:

1. Calculation of heat losses of an object.
2. Definition temperature regime individual rooms and the building as a whole.
3. Calculation of the power of heating radiator batteries.
4. Hydraulic calculation of the heating system.
5. Calculation of heating boiler power.
6. Determination of the total volume of the autonomous heating system.

Thermal calculation of a heating system is not theoretical research, but an accurate and well-founded result, the practical implementation of which will allow you to correctly select all the necessary components and set up an effective heating system that functions without problems for many years.

The main mistake that many owners of private houses make is ignoring some stages of the calculation. They believe that to solve the problem it is enough to choose a more powerful boiler, focusing only on the data of the approximate calculation of its power based on the area of ​​the room. This approach threatens with unnecessary operating costs and often leads to the fact that the boiler will work constantly, the radiator batteries will be hot, and the room will be cold. In this case, it is necessary to return to the original state and perform a full calculation of the heating system. Only after this can we begin to eliminate the shortcomings caused by critical errors in calculations.