Battery power per square meter. Calculation of heating radiators: options and methods

It is very important to buy modern high-quality and efficient batteries. But it is much more important to correctly calculate the number of radiator sections so that in the cold season it properly heats the room and does not have to think about installing additional portable heaters that will increase the cost of heating.

SNiP and basic regulations

Today you can name a huge number of SNiPs that describe the rules for the design and operation of heating systems in various rooms. But the most understandable and simple is the document "Heating, ventilation and air conditioning" under the number 2.04.05.

It details the following sections:

General provisions regarding the design of heating systems
Rules for the design of heating systems for buildings
Features of the heating system

It is also necessary to install heating radiators in accordance with SNiP number 3.05.01. He prescribes the following installation rules, without which the calculations of the number of sections will be ineffective:

The maximum width of the radiator should not exceed 70% of the similar characteristic of the window opening under which it is installed.
The radiator must be mounted in the center of the window opening (a slight error is allowed - no more than 2 cm)
The recommended space between the radiators and the wall is 2-5 cm
Above the floor height should not be more than 12 cm
Distance to the window sill from the top of the battery - at least 5 cm
In other cases, to improve heat transfer, the surface of the walls is covered with a reflective material.

It is necessary to follow such rules so that air masses can circulate freely and replace each other.

Read also, different types of heating radiators

Volume calculation

In order to accurately calculate the number of heating radiator sections required for efficient and comfortable heating of a dwelling, its volume should be taken into account. The principle is very simple:

Determining the need for heat
Find out the number of sections capable of giving it away

SNiP prescribes to take into account the need for heat for any room - 41 W per 1 cubic meter. However, this figure is very relative. If the walls and floor are poorly insulated, it is recommended to increase this value to 47-50 W, because part of the heat will be lost. In situations where a high-quality heat insulator has already been laid on the surfaces, high-quality PVC windows have been installed and drafts have been eliminated, this indicator can be taken equal to 30-34 W.

If heating is located in the room, the heat demand must be increased to 20%. Part of the thermally heated air masses will not pass through the screen, circulating inside and cooling down quickly.

Formulas for calculating the number of sections by room volume, with an example

Having decided on the need for one cube, you can begin to calculate (example on specific numbers):

At the first step, we calculate the volume of the room using a simple formula: [height length Width] (3x4x5=60 cubic meters)
The next step is to determine the heat demand for the particular room under consideration according to the formula: [volume]*[need per m3] (60х41=2460 W)
You can determine the desired number of ribs using the formula: (2460/170=14.5)
Rounding is recommended to be done up - we get 15 sections

Many manufacturers do not take into account that the coolant circulating through the pipes is far from the maximum temperature. Therefore, the power of the ribs will be lower than the specified limit value (it is what is prescribed in the passport). If there is no minimum power indicator, then the available one is underestimated by 15-25% to simplify calculations.

Calculation by area

The previous calculation method is an excellent solution for rooms with a height of more than 2.7 m. In rooms with lower ceilings (up to 2.6 m), you can use a different method, taking the area as a basis.

In this case, calculating the total amount of thermal energy, the need for one square. m. take equal to 100 watts. There is no need to make any adjustments to it.

Formulas for calculating the number of sections by area of the room, with an example

At the first stage, the total area of \u200b\u200bthe room is determined: [length Width] (5х4=20 sq.m.)
The next step is to determine the heat required to heat the entire room: [area]* [need per sq. m.] (100x20=2000W)
In the passport attached to the heating radiator, you need to find out the power of one section - the average of modern models is 170 W
To determine the required number of sections, use the formula: [total heat demand]/[capacity of one section] (2000/170=11.7)
We introduce correction factors ( discussed further)
Rounding is recommended to be done up - we get 12 sections

The above methods for calculating the number of radiator sections are perfect for rooms whose height reaches 3 meters. If this indicator is greater, it is necessary to increase the thermal power in direct proportion to the increase in height.

If the whole house is equipped with modern plastic windows, in which the heat loss coefficient is as low as possible, it becomes possible to save money and reduce the result obtained by up to 20%.

It is believed that the standard temperature of the coolant circulating through the heating system is 70 degrees. If it is below this value, it is necessary to increase the result by 15% for every 10 degrees. If it is higher, on the contrary, decrease it.

Premises with an area of more than 25 square meters. m. to heat with one radiator, even consisting of two dozen sections, will be extremely problematic. To solve this problem, it is necessary to divide the calculated number of sections into two equal parts and install two batteries. Heat in this case will be distributed throughout the room more evenly.

If there are two window openings in the room, heating radiators should be placed under each of them. They should be 1.7 times more than the nominal power determined in the calculations.

Having bought stamped radiators, in which sections cannot be divided, it is necessary to take into account the total power of the product. If it is not enough, you should consider buying a second battery of the same or slightly less heat capacity.

Correction factors

Many factors can influence the final result. Consider in what situations it is necessary to make correction factors:

Windows with conventional glazing - magnification factor 1.27
Insufficient thermal insulation of the walls - increasing factor 1.27
More than two window openings per room - increasing factor 1.75
Bottom-wired manifolds - multiplying factor 1.2
Reserve in case of unforeseen situations - increasing factor 1.2
Use of improved thermal insulation materials - reduction factor 0.85
Installation of high-quality heat-insulating double-glazed windows - reducing factor 0.85

The number of adjustments to be made to the calculation can be huge and depends on each specific situation. However, it should be remembered that it is much easier to reduce the heat transfer of a heating radiator than to increase it. Therefore, all rounding is done up.

Summing up

If you need to make the most accurate calculation of the number of radiator sections in a complex room, do not be afraid to contact specialists. The most accurate methods, which are described in specialized literature, take into account not only the volume or area of the room, but also the temperature outside and inside, the thermal conductivity of the various materials from which the house box is built, and many other factors.

Of course, you can not be afraid and throw a few edges to the result. But an excessive increase in all indicators can lead to unjustified expenses, which are not immediately, sometimes and not always, possible to recoup.

Calculation of the number of sections of heating radiators

Heating radiators are the most common heating device that is installed in residential, public and industrial premises. It is hollow inside elements filled with coolant. Through them, thermal energy enters the room to heat it. When choosing radiators, it is necessary first of all to pay attention to two technical indicators. This is the power of the device and the coolant pressure it can withstand. But in order to finally determine the temperature regime of the room, it is necessary to carry out an accurate calculation of heating radiators.

This includes not only the number of devices themselves and their sections, but also the material from which they are made. The modern market for heating equipment offers a huge range of batteries with different technical characteristics. The main thing you need to know is the capabilities of one section of the battery, namely, its ability to release the maximum amount of thermal energy. This indicator will form the basis of the calculation for the entire heating system.

Let's carry out the calculation

Knowing that 100 watts of heat is needed per 1 square meter of a room, it is easy to calculate the number of required radiators. Therefore, first you need to accurately determine the area of \u200b\u200bthe room where the batteries will be installed.

Be sure to take into account the height of the ceilings, as well as the number of doors and windows - after all, these are openings through which heat escapes the fastest. Therefore, the material from which doors and windows are made is also taken into account.

Now the lowest temperature in your region and the coolant temperature at the same time are determined. All the nuances are calculated using the coefficients that are listed in the SNiP. Given these coefficients, the heating power can also be calculated.

A quick calculation is made by simply multiplying the floor area by 100 watts. But it won't be accurate. Coefficients are used for correction.

Power correction factors

There are two of them: decrease and increase.

Power reduction factors are applied as follows:

If plastic multi-chamber double-glazed windows are installed on the windows, then the indicator is multiplied by 0.2.
If the ceiling height is less than the standard (3 m), then a reduction factor is applied. It is defined as the ratio of the actual height to the standard. Example - the ceiling height is 2.7 m. This means that the coefficient is calculated by the formula: 2.7 / 3 \u003d 0.9.
If the heating boiler operates with increased power, then every 10 degrees of heat energy generated by it reduces the power of heating radiators by 15%.

Power increase factors are taken into account in the following situations:

If the ceiling height is higher than the standard size, then the coefficient is calculated using the same formula.
If the apartment is a corner apartment, then a factor of 1.8 is applied to increase the power of the heating devices.
If the radiators have a bottom connection, then 8% is added to the calculated value.
If the heating boiler lowers the temperature of the coolant on the coldest days, then for every 10 degrees of decrease, an increase in battery power by 17% is necessary.
If sometimes the temperature outside reaches critical levels, then you will have to increase the heating power by 2 times.

Determine the number of sections of one radiator

Equipment sections

Experts offer several options for calculating the number of heating radiators and their sections.

The first is the so-called ordinary method. He is the simplest. Usually, the technical parameters are set in the passport or quality certificate, which is issued as an accompanying document for each product. Here you can find information about how much power one section of heating radiators has.

For example, it is equal to 200 watts. The power required to heat the room is calculated, taking into account the step-down and step-up factors. Let's assume that it is equal to 2400 watts.

Now purely mathematical calculations are made: 2400/200 = 12. This is the number of sections that need to be installed in this room. One 12 cell battery or two 6 cell batteries can be used.

The second option - the calculation is made taking into account the heating capacity of one section for a certain amount of space. To do this, the total volume of the room is calculated and divided by the volume heating index of the section.

Coloring of heating equipment

The third is an approximate calculation used by the masters, based on their personal experience. All heating batteries have almost the same dimensions. There are differences, but minor ones. So it was noticed that with a ceiling height of 2.7 meters, one section can heat an area equal to 1.8 square meters.

There are no problems with the choice of heating radiators today. Here you have cast iron, and aluminum, and bimetallic - choose whichever you want. However, the very fact of buying expensive radiators of a special design is not a guarantee that your house will be warm. In this case, both quality and quantity play a role. Let's figure out how to properly calculate heating radiators.

Calculation of everything is the head - we start from the area

Incorrect calculation of the number of radiators can lead not only to a lack of heat in the room, but also to too high heating bills and too high temperatures in the rooms. The calculation should be made both during the very first installation of radiators, and when replacing the old system, where, it would seem, everything has been clear for a long time, since the heat transfer of radiators can differ significantly.

Different rooms - different calculations. For example, for an apartment in a multi-storey building, you can get by with the simplest formulas or ask your neighbors about their heating experience. In a large private house, simple formulas will not help - you will need to take into account many factors that are simply absent in city apartments, for example, the degree of insulation of the house.

Most importantly, do not trust the numbers randomly announced by all kinds of “consultants” who tell you the number of sections for heating by eye (even without seeing the room!) As a rule, it is significantly overestimated, because of which you will constantly overpay for excess heat, which will literally go out the open window. We recommend using several methods for calculating the number of radiators.

Simple formulas - for an apartment

Residents of multi-storey buildings can use fairly simple calculation methods that are completely unsuitable for a private house. The simplest calculation does not shine with high accuracy, but it is suitable for apartments with standard ceilings no higher than 2.6 m. Please note that a separate calculation of the number of sections is carried out for each room.

The statement is taken as a basis that 100 W of radiator heat power is needed to heat a square meter of a room. Accordingly, in order to calculate the amount of heat needed for a room, we multiply its area by 100 watts. So, for a room with an area of 25 m 2, it is necessary to purchase sections with a total power of 2500 W or 2.5 kW. Manufacturers always indicate the heat dissipation of the sections on the packaging, for example, 150 watts. Surely you already understood what to do next: 2500/150 = 16.6 sections

We round the result up, however, for the kitchen it can be rounded down as well - in addition to batteries, there will also be tiles and a kettle to heat the air.

You should also take into account possible heat losses depending on the location of the room. For example, if this is a room located on the corner of a building, then the thermal power of the batteries can be safely increased by 20% (17 * 1.2 = 20.4 sections), the same number of sections will be needed for a room with a balcony. Please note that if you intend to hide the radiators in a niche or hide them behind a beautiful screen, then you automatically lose up to 20% of the thermal power, which will have to be compensated by the number of sections.

Volume calculations - what does SNiP say?

A more accurate number of sections can be calculated taking into account the height of the ceilings - this method is especially relevant for apartments with non-standard room heights, as well as for a private house as a preliminary calculation. In this case, we will determine the heat output based on the volume of the room. According to the norms of SNiP, 41 W of thermal energy is needed to heat one cubic meter of living space in a standard multi-storey building. This standard value must be multiplied by the total volume that can be obtained by multiplying the height of the room by its area.

For example, the volume of a room with an area of 25 m 2 with ceilings of 2.8 m is 70 m 3. We multiply this figure by the standard 41 watts and get 2870 watts. Then we proceed as in the previous example - we divide the total number of W by the heat transfer of one section. So, if the heat transfer is 150 W, then the number of sections is approximately 19 (2870/150 = 19.1). By the way, be guided by the minimum heat transfer indicators of radiators, because the temperature of the carrier in the pipes rarely meets the requirements of SNiP in our realities. That is, if the data sheet of the radiator indicates frames from 150 to 250 W, then by default we take a lower figure. If you yourself are responsible for heating a private house, then take the average value.

Exact figures for private houses - we take into account all the nuances

Private houses and large modern apartments do not fall under standard calculations in any way - there are too many nuances to take into account. In these cases, you can apply the most accurate method of calculation, in which these nuances are taken into account. Actually, the formula itself is very simple - even a schoolboy will cope with this, the main thing is to correctly select all the coefficients that take into account the features of a house or apartment that affect the ability to save or lose thermal energy. So here is our exact formula:

KT = N*S*K 1 *K 2 *K 3 *K 4 *K 5 *K 6 *K 7
CT is the amount of heat output in W that we need to heat a particular room;
N - 100 W / sq.m, the standard amount of heat per square meter, to which we will apply decreasing or increasing coefficients;
S is the area of the room for which we will calculate the number of sections.

The following coefficients have both the property of increasing the amount of thermal energy and decreasing it, depending on the conditions of the room.

K 1 - we take into account the nature of the glazing of windows. If these are windows with ordinary double glazing, the coefficient is 1.27. Windows with double glazing - 1.0, with triple glazing - 0.85.
K 2 - we take into account the quality of the thermal insulation of the walls. For cold non-insulated walls, this coefficient is 1.27 by default, for normal thermal insulation (two-brick laying) - 1.0, for well-insulated walls - 0.85.
K 3 - we take into account the average air temperature at the peak of winter cold. So, for -10 ° C, the coefficient is 0.7. For every -5 ° C, add 0.2 to the coefficient. So, for -25 ° C, the coefficient will be equal to 1.3.
K 4 - take into account the ratio of floor and window area. Starting from 10% (the coefficient is 0.8), for every next 10% we add 0.1 to the coefficient. So, for a ratio of 40%, the coefficient will be equal to 1.1 (0.8 (10%) + 0.1 (20%) + 0.1 (30%) + 0.1 (40%)).
K 5 is a reduction factor that corrects the amount of heat energy, taking into account the type of room located above. We take a cold attic as a unit, if the attic is heated - 0.9, if there is a heated living space above the room - 0.8.
K 6 - we correct the result upwards, taking into account the number of walls in contact with the surrounding atmosphere. If 1 wall - the coefficient is 1.1, if two - 1.2 and so on up to 1.4.
K 7 - and the last coefficient that corrects the calculations regarding the height of the ceilings. A height of 2.5 is taken as a unit, and for every half a meter of height, 0.05 is added to the coefficient. Thus, for 3 meters the coefficient is 1.05, for 4 - 1.15.

Thanks to this calculation, you will receive the amount of thermal energy that is necessary to maintain a comfortable living environment in a private house or non-standard apartment. It remains only to divide the finished result by the heat transfer value of the radiators you have chosen to determine the number of sections.

At first glance, it is easy to calculate how many radiator sections to install in a particular room. The larger the room, the more sections the radiator should consist of. But in practice, how warm it will be in a particular room depends on more than a dozen factors. Given them, it is possible to calculate the required amount of heat from radiators much more accurately.

General information

The heat transfer of one section of the radiator is indicated in the technical characteristics of products from any manufacturer. The number of radiators in a room usually corresponds to the number of windows. Radiators are most often located under the windows. Their dimensions depend on the area of the free wall between the window and the floor. It should be borne in mind that the radiator must be lowered from the window sill by at least 10 cm. And between the floor and the bottom line of the radiator, the distance must be at least 6 cm. These parameters determine the height of the device.

The heat output of one section of a cast-iron radiator is 140 watts, more modern metal ones - from 170 and above.

You can calculate the number of sections of heating radiators , leaving the area of \u200b\u200bthe room or its volume.

According to the norms, it is considered that 100 watts of thermal energy is needed to heat one square meter of a room. If we proceed from the volume, then the amount of heat per 1 cubic meter will be at least 41 watts.

But none of these methods will be accurate if you do not take into account the characteristics of a particular room, the number and size of windows, the material of the walls, and much more. Therefore, when calculating the radiator sections according to the standard formula, we will add the coefficients created by one or another condition.

Room area - calculation of the number of sections of heating radiators

Such a calculation is usually applied to premises located in standard panel residential buildings with a ceiling height of up to 2.6 meters.

The area of the room is multiplied by 100 (the amount of heat for 1m2) and divided by the heat output of one section of the radiator indicated by the manufacturer. For example: the area of the room is 22 m2, the heat transfer of one section of the radiator is 170 watts.

22X100/170=12.9

This room needs 13 radiator sections.

If one section of the radiator has 190 watts of heat transfer, then we get 22X100 / 180 \u003d 11.57, that is, we can limit ourselves to 12 sections.

You need to add 20% to the calculations if the room has a balcony or is located at the end of the house. A battery installed in a niche will reduce heat transfer by another 15%. But in the kitchen it will be 10-15% warmer.

We make calculations according to the volume of the room

For a panel house with a standard ceiling height, as already mentioned above, the heat calculation is based on the need for 41 watts per 1m3. But if the house is new, brick, double-glazed windows are installed in it, and the outer walls are insulated, then 34 watts per 1 m3 are already needed.

The formula for calculating the number of radiator sections looks like this: the volume (area multiplied by the height of the ceiling) is multiplied by 41 or 34 (depending on the type of house) and divided by the heat transfer of one section of the radiator indicated in the manufacturer's passport.

For instance:

The area of the room is 18 m2, the ceiling height is 2.6 m. The house is a typical panel building. The heat output of one section of the radiator is 170 watts.

18X2.6X41 / 170 \u003d 11.2. So, we need 11 radiator sections. This is provided that the room is not corner and it does not have a balcony, otherwise it is better to install 12 sections.

Calculate as accurately as possible

And here is the formula by which you can calculate the number of radiator sections as accurately as possible :

The area of the room multiplied by 100 watts and by the coefficients q1, q2, q3, q4, q5, q6, q7 and divided by the heat transfer of one section of the radiator.

More about these ratios:

q1 - type of glazing : with triple glazing, the coefficient will be 0.85, with double glazing - 1 and with conventional glazing - 1.27.

Correctly calculating the required number of sections is, on the one hand, not a difficult, but nevertheless a very important task for any homeowner. It is on the correctness of the calculation that the comfort of staying in a home, even in the most severe frosts, will depend. At the same time, an excessive number of mounted sections will lead to the need to artificially limit the supply of coolant to the heater during the entire winter period or, much worse, open windows and heat the street, which is fraught with additional costs.

Standard calculation method for a heating radiator

The simplest calculation, often recommended by sellers of this equipment, is based on generally accepted standards, according to which about 100 W of heating device power should be used to heat one square meter of room space. This roughly corresponds, according to their own estimates, to one section of the battery per two square meters of the room.

This approach is oversimplified. A number of different factors influence the choice of the number of radiator sections or its area. First of all, it should be understood that heating batteries are selected not depending on the area in the premises, but depending on its heat losses, which are determined by the presence of one or more windows, doors, the location of the room, incl. angular, as well as a number of other factors.

Thermal power of the section is the most important parameter

In addition, different types of heaters have different heat output. For aluminum radiators, it can reach 185-200 W per section, and for cast iron radiators, it rarely exceeds 130 W. But in addition to the material of the sections, the thermal power is also strongly affected by the parameter (DT), which takes into account the temperature of the coolant entering and leaving the battery. So, the high thermal power of an aluminum battery, corresponding to 180 W according to the passport, is achieved at DT = 90/70, that is, the temperature of the incoming water should be 90 degrees, the outgoing - 70 degrees.

However, you need to understand that the operation of almost any boiler under such conditions is a rarity. For wall-mounted boilers, the maximum temperature is 85 degrees, and until the coolant reaches the battery, the temperature value will decrease even more. Therefore, even when buying aluminum batteries, one must proceed from the fact that the thermal power of the section will not exceed the value corresponding to DT \u003d 70/55, i.e. approximately 120 watts.

What determines the heat loss of the room

So, the selection of the thermal power of heating devices is made on the basis of the magnitude of heat losses in order to be able to fully compensate for them.

Factors affecting heat loss:

The location where the room is located. This is either the south, or the north, or the central part of the country, for which the values of the minimum annual temperature vary quite a lot.
How the room is located relative to the cardinal points. The presence of windows located both on the north and south sides greatly affects the heat loss of the room.
Ceiling height. In the case when the height in the building differs from the standard 2.5 meters, it is also necessary to make certain amendments to the calculation.
Required temperature. Not all rooms need the same temperature. In the hall, for example, the temperatures may be slightly lower than in the bedroom, which is also reflected in the calculation of the required power of heating devices.
The thickness of walls, ceilings, as well as their composition, the presence of thermal insulation, since the coefficient of thermal conductivity of different materials can vary greatly. Concrete, for example, has a maximum coefficient, while thermal insulation foam has a minimum coefficient.
The presence of window openings, doors and their number. It is clear that the larger the area in the room, the stronger the heat loss will be in it, since it is through these openings that the main heat loss occurs.
Availability of ventilation. This parameter cannot be ignored, even if there is no room. The so-called infiltration is always present - windows open from time to time, visitors enter through the doors, etc.

Determine the required heat output

However, it is possible to fully take into account all possible factors that increase or decrease heat losses using only fairly complex calculation methods and professional software. In general, such calculations confirm that for a room in which no special work has been carried out to improve energy efficiency, the indicator of 100 W of heating battery power per square meter is correct. This is true for the middle lane. For the northern regions, the parameter should be increased to 150 or even 200 watts.

However, if during the construction or repair floors were also carried out, energy-saving double-glazed windows are in the window openings, then even in a harsh winter, the power of heating devices even at 70 W will be quite enough. This issue, of course, is not so significant for owners of apartments with central heating, but for owners of private houses, reducing the required heat output will help save money throughout the year.

Calculate the number of battery sections

So, let's carry out a simple calculation of the number of sections of an aluminum battery needed to heat a small room with an area of 15 square meters and a normal ceiling height. Let's take a value of 100 W per 1 sq. m as the required power of heating devices, and the rated power of one section of the battery is 120 watts. Then the required number of sections can be determined by the formula:

N \u003d S * Qp / Qn, where

N is the number of sections,
S is the area of the room,
Qp - the required heat output depending on the type of room,
Qn - rated thermal power of one section of the battery.

In our case N = 15*100/120 = 12.5

Table: an example of the number of radiator sections depending on the area of the room

However, it should be borne in mind that the thermal power of modern batteries, whether it be not only aluminum, but also bimetallic, depending on the design and manufacturer, can vary greatly, ranging from 120 to 200 watts. Accordingly, the number of sections will also vary quite a lot.