Calculation of the power of a heating radiator by the volume of the room. How to calculate the number of heating radiators

To calculate the number of radiators, there are several methods, but their essence is the same: find out the maximum heat loss of the room, and then calculate the number of heaters needed to compensate for them.

There are different calculation methods. The simplest ones give approximate results. However, they can be used if the rooms are standard or apply coefficients that allow you to take into account the existing "non-standard" conditions of each particular room (corner room, balcony, full-wall window, etc.). There is a more complex calculation by formulas. But in fact, these are the same coefficients, only collected in one formula.

There is one more method. It determines the actual losses. A special device - a thermal imager - determines the actual heat loss. And on the basis of these data, they calculate how many radiators are needed to compensate them. Another advantage of this method is that the image of the thermal imager shows exactly where the heat is leaving the most actively. This may be a marriage in work or in building materials, a crack, etc. So at the same time you can rectify the situation.

Calculation of heating radiators by area

The easiest way. Calculate the amount of heat required for heating, based on the area of ​​\u200b\u200bthe room in which the radiators will be installed. You know the area of ​​\u200b\u200beach room, and the need for heat can be determined according to the building codes of SNiP:

  • for an average climatic zone, 60-100W is required for heating 1m 2 of a dwelling;
  • for areas above 60 o, 150-200W is required.

Based on these norms, you can calculate how much heat your room will require. If the apartment / house is located in the middle climatic zone, for heating an area of ​​​​16m 2, 1600W of heat will be required (16 * 100 = 1600). Since the norms are average, and the weather does not indulge in constancy, we believe that 100W is required. Although, if you live in the south of the middle climatic zone and your winters are mild, consider 60W.

A power reserve in heating is needed, but not very large: with an increase in the amount of power required, the number of radiators increases. And the more radiators, the more coolant in the system. If for those who are connected to central heating this is not critical, then for those who have or plan individual heating, a large volume of the system means large (extra) costs for heating the coolant and a large inertia of the system (the set temperature is maintained less accurately). And the logical question arises: “Why pay more?”

Having calculated the need for heat in the room, we can find out how many sections are required. Each of the heaters can emit a certain amount of heat, which is indicated in the passport. The found heat demand is taken and divided by the radiator power. The result is the required number of sections to make up for losses.

Let's count the number of radiators for the same room. We have determined that we need to allocate 1600W. Let the power of one section be 170W. It turns out 1600/170 \u003d 9.411 pieces. You can round up or down as you wish. You can round it into a smaller one, for example, in the kitchen - there are enough additional heat sources, and into a larger one - it is better in a room with a balcony, a large window or in a corner room.

The system is simple, but the disadvantages are obvious: the height of the ceilings can be different, the material of the walls, windows, insulation and a number of other factors are not taken into account. So the calculation of the number of sections of heating radiators according to SNiP is indicative. You need to make adjustments for accurate results.

How to calculate radiator sections by room volume

This calculation takes into account not only the area, but also the height of the ceilings, because you need to heat all the air in the room. So this approach is justified. And in this case, the procedure is similar. We determine the volume of the room, and then, according to the norms, we find out how much heat is needed to heat it:

Let's calculate everything for the same room with an area of ​​16m 2 and compare the results. Let the ceiling height be 2.7m. Volume: 16 * 2.7 \u003d 43.2m 3.

  • In a panel house. The heat required for heating is 43.2m 3 * 41V = 1771.2W. If we take all the same sections with a power of 170W, we get: 1771W / 170W = 10.418pcs (11pcs).
  • In a brick house. Heat is needed 43.2m 3 * 34W = 1468.8W. We consider radiators: 1468.8W / 170W = 8.64pcs (9pcs).

As you can see, the difference is quite large: 11pcs and 9pcs. Moreover, when calculating by area, we got the average value (if rounded in the same direction) - 10pcs.

Adjustment of results

In order to get a more accurate calculation, you need to take into account as many factors as possible that reduce or increase heat loss. This is what the walls are made of and how well they are insulated, how big the windows are, and what kind of glazing they have, how many walls in the room face the street, etc. To do this, there are coefficients by which you need to multiply the found values ​​\u200b\u200bof the heat loss of the room.

Window

Windows account for 15% to 35% of heat loss. The specific figure depends on the size of the window and how well it is insulated. Therefore, there are two corresponding coefficients:

  • ratio of window area to floor area:
    • 10% — 0,8
    • 20% — 0,9
    • 30% — 1,0
    • 40% — 1,1
    • 50% — 1,2
  • glazing:
    • three-chamber double-glazed window or argon in a two-chamber double-glazed window - 0.85
    • ordinary two-chamber double-glazed window - 1.0
    • conventional double frames - 1.27.

Walls and roof

To account for losses, the material of the walls, the degree of thermal insulation, the number of walls facing the street are important. Here are the coefficients for these factors.

Degree of thermal insulation:

  • brick walls with a thickness of two bricks are considered the norm - 1.0
  • insufficient (absent) - 1.27
  • good - 0.8

The presence of external walls:

  • indoors - no loss, factor 1.0
  • one - 1.1
  • two - 1.2
  • three - 1.3

The amount of heat loss is influenced by whether the room is heated or not located on top. If a habitable heated room is above (the second floor of a house, another apartment, etc.), the reducing factor is 0.7, if the heated attic is 0.9. It is generally accepted that an unheated attic does not affect the temperature in and (factor 1.0).

If the calculation was carried out by area, and the height of the ceilings is non-standard (a height of 2.7 m is taken as the standard), then a proportional increase / decrease using a coefficient is used. It is considered easy. To do this, divide the actual height of the ceilings in the room by the standard 2.7 m. Get the required coefficient.

Let's calculate for example: let the height of the ceilings be 3.0 m. We get: 3.0m / 2.7m = 1.1. This means that the number of radiator sections, which was calculated by the area for a given room, must be multiplied by 1.1.

All these norms and coefficients were determined for apartments. To take into account the heat loss of the house through the roof and basement / foundation, you need to increase the result by 50%, that is, the coefficient for a private house is 1.5.

climatic factors

You can make adjustments depending on the average temperatures in winter:

  • -10 o C and above - 0.7
  • -15 o C - 0.9
  • -20 o C - 1.1
  • -25 o C - 1.3
  • -30 o C - 1.5

Having made all the required adjustments, you will get a more accurate number of radiators required for heating the room, taking into account the parameters of the premises. But these are not all the criteria that affect the power of thermal radiation. There are other technical details, which we will discuss below.

Calculation of different types of radiators

If you are going to install sectional radiators of a standard size (with an axial distance of 50 cm in height) and have already chosen the material, model and desired size, there should be no difficulty in calculating their number. Most of the reputable companies that supply good heating equipment have the technical data of all modifications on their website, among which there is also thermal power. If not power is indicated, but the flow rate of the coolant, then it is easy to convert to power: the coolant flow rate of 1 l / min is approximately equal to the power of 1 kW (1000 W).

The axial distance of the radiator is determined by the height between the centers of the holes for supplying/removing the coolant.

To make life easier for buyers, many sites install a specially designed calculator program. Then the calculation of sections of heating radiators comes down to entering data on your room in the appropriate fields. And at the output you have the finished result: the number of sections of this model in pieces.

But if you are just considering possible options for now, then it is worth considering that radiators of the same size made of different materials have different thermal output. The method for calculating the number of sections of bimetallic radiators is no different from the calculation of aluminum, steel or cast iron. Only the thermal power of one section can be different.

  • aluminum - 190W
  • bimetallic - 185W
  • cast iron - 145W.

If you are still only figuring out which material to choose, you can use these data. For clarity, we present the simplest calculation of sections of bimetallic heating radiators, which takes into account only the area of ​​\u200b\u200bthe room.

When determining the number of bimetal heaters of a standard size (center distance 50 cm), it is assumed that one section can heat 1.8 m 2 of area. Then for a room of 16m 2 you need: 16m 2 / 1.8m 2 \u003d 8.88 pieces. Rounding up - 9 sections are needed.

Similarly, we consider for cast-iron or steel bars. All you need is the rules:

  • bimetallic radiator - 1.8m 2
  • aluminum - 1.9-2.0m 2
  • cast iron - 1.4-1.5m 2.

This data is for sections with a center distance of 50 cm. Today, there are models on sale with very different heights: from 60cm to 20cm and even lower. Models 20cm and below are called curb. Naturally, their power differs from the specified standard, and if you plan to use "non-standard", you will have to make adjustments. Or look for passport data, or count yourself. We proceed from the fact that the heat transfer of a thermal device directly depends on its area. With a decrease in height, the area of ​​\u200b\u200bthe device decreases, and, therefore, the power decreases proportionally. That is, you need to find the ratio of the heights of the selected radiator to the standard, and then use this coefficient to correct the result.

For clarity, we will calculate aluminum radiators by area. The room is the same: 16m 2. We consider the number of sections of a standard size: 16m 2 / 2m 2 \u003d 8pcs. But we want to use small sections with a height of 40 cm. We find the ratio of radiators of the selected size to the standard ones: 50cm/40cm=1.25. And now we adjust the quantity: 8pcs * 1.25 = 10pcs.

Correction depending on the mode of the heating system

Manufacturers in the passport data indicate the maximum power of radiators: in high-temperature mode of use - the temperature of the coolant in the supply is 90 ° C, in the return - 70 ° C (indicated by 90/70) in the room should be 20 ° C. But in this mode, modern systems heating rarely works. Usually, medium power mode is used 75/65/20 or even low temperature with parameters 55/45/20. It is clear that the calculation needs to be corrected.

To take into account the mode of operation of the system, it is necessary to determine the temperature difference of the system. The temperature difference is the difference between the temperature of the air and the heaters. In this case, the temperature of the heating devices is considered as the arithmetic mean between the supply and return values.

To make it clearer, we will calculate cast-iron heating radiators for two modes: high-temperature and low-temperature, sections of a standard size (50cm). The room is the same: 16m 2. One cast-iron section in the high-temperature mode 90/70/20 heats 1.5 m 2. Therefore, we need 16m 2 / 1.5m 2 \u003d 10.6 pieces. Rounding - 11 pcs. The system is planned to use low-temperature mode 55/45/20. Now we find the temperature difference for each of the systems:

  • high temperature 90/70/20- (90+70)/2-20=60 o C;
  • low-temperature 55/45/20 - (55 + 45) / 2-20 \u003d 30 ° C.

That is, if a low-temperature mode of operation is used, twice as many sections will be needed to provide the room with heat. For our example, a room of 16m 2 requires 22 sections of cast iron radiators. The battery is big. This, by the way, is one of the reasons why this type of heating device is not recommended for use in networks with low temperatures.

In this calculation, the desired air temperature can also be taken into account. If you want the room to be not 20 ° C but, for example, 25 ° C, simply calculate the heat head for this case and find the desired coefficient. Let's do the calculation for the same cast-iron radiators: the parameters will be 90/70/25. We consider the temperature difference for this case (90 + 70) / 2-25 \u003d 55 ° C. Now we find the ratio 60 ° C / 55 ° C \u003d 1.1. To ensure a temperature of 25 ° C, you need 11pcs * 1.1 \u003d 12.1pcs.

The dependence of the power of radiators on the connection and location

In addition to all the parameters described above, the heat transfer of the radiator varies depending on the type of connection. A diagonal connection with a supply from above is considered optimal, in which case there is no loss of thermal power. The biggest losses are observed with lateral connection - 22%. All the rest are average in efficiency. Approximate loss percentages are shown in the figure.

The actual power of the radiator also decreases in the presence of barrier elements. For example, if a window sill hangs from above, heat transfer drops by 7-8%, if it does not completely cover the radiator, then the loss is 3-5%. When installing a mesh screen that does not reach the floor, the losses are about the same as in the case of an overhanging window sill: 7-8%. But if the screen completely covers the entire heater, its heat transfer decreases by 20-25%.

Determination of the number of radiators for one-pipe systems

There is one more very important point: all of the above is true for when a coolant with the same temperature enters the inlet of each of the radiators. it is considered much more complicated: there, more and more cold water enters each subsequent heater. And if you want to calculate the number of radiators for a one-pipe system, you need to recalculate the temperature every time, and this is difficult and time consuming. Which exit? One of the possibilities is to determine the power of the radiators as for a two-pipe system, and then add sections in proportion to the drop in thermal power to increase the heat transfer of the battery as a whole.

Let's explain with an example. The diagram shows a single-pipe heating system with six radiators. The number of batteries was determined for two-pipe wiring. Now you need to make an adjustment. For the first heater, everything remains the same. The second one receives a coolant with a lower temperature. We determine the % power drop and increase the number of sections by the corresponding value. In the picture it turns out like this: 15kW-3kW = 12kW. We find the percentage: the temperature drop is 20%. Accordingly, to compensate, we increase the number of radiators: if you needed 8 pieces, it will be 20% more - 9 or 10 pieces. This is where knowledge of the room comes in handy: if it is a bedroom or a nursery, round it up, if it is a living room or other similar room, round it down. You also take into account the location relative to the cardinal points: in the north you round up to a large one, in the south - to a smaller one.

This method is clearly not ideal: after all, it turns out that the last battery in the branch will have to be simply huge: judging by the scheme, a coolant with a specific heat capacity equal to its power is supplied to its input, and it is unrealistic to remove all 100% in practice. Therefore, when determining the power of a boiler for single-pipe systems, they usually take some margin, put shutoff valves and connect radiators through a bypass so that heat transfer can be adjusted, and thus compensate for the drop in coolant temperature. One thing follows from all this: the number and / or dimensions of radiators in a single-pipe system must be increased, and as you move away from the beginning of the branch, more and more sections should be installed.

Results

An approximate calculation of the number of sections of heating radiators is a simple and quick matter. But clarification, depending on all the features of the premises, size, type of connection and location requires attention and time. But you can definitely decide on the number of heaters to create a comfortable atmosphere in winter.

There are different methods for calculating the number of heating radiators. This is influenced by the material from which the building is built, and the climatic zone where the house is located, and the temperature of the carrier, and the characteristics of the heat transfer of the radiator itself, as well as many other factors. Let us consider in more detail the technology for correctly calculating the number of heating radiators for private houses, because the efficiency of work, as well as the efficiency of the heating system at home, depend on this.

The most democratic way is to calculate the radiator based on power per square meter. In central Russia, the winter figure is 50-100 watts, in the regions of Siberia and the Urals 100-200 watts. Standard 8-section cast iron batteries with a center distance of 50 cm have heat dissipation 120-150 watts per section. Bimetallic radiations have a power of about 200 watts, which is slightly higher. If we mean a standard water coolant, then for a room of 18-20 m 2 with a standard ceiling height of 2.5-2.7 m, you will need two cast-iron radiators of 8 sections.

What determines the number of radiators

There are a number of other factors that should be taken into account when calculating the number of radiators:

  • the steam coolant has a large heat transfer than water;
  • corner room colder, since it has two walls facing the street;
  • the more windows indoors, the colder it is;
  • if the ceiling height above 3 meters, then the power of the coolant must be calculated based on the volume of the room, and not its area;
  • the material from which the radiator is made has its own thermal conductivity;
  • thermally insulated walls increase the thermal insulation of the room;
  • the lower the winter temperatures outside, the more batteries you need to install;
  • modern double-glazed windows increase the thermal insulation of the room;
  • with one-sided connection of pipes to the radiator, it does not make sense to install more than 10 sections;
  • if the coolant moves from top to bottom, its power increases by 20%;
  • ventilation means more power.

Formula and calculation example

Given the above factors, you can make a calculation. 100 W will be needed for 1 m 2, respectively, 1800 W should be spent on heating a room of 18 m 2. One battery of 8 cast iron sections emits 120 watts. Divide 1800 by 120 and get 15 sections. This is a very average figure.

In a private house with its own water heater, the coolant power is calculated to the maximum. Then we divide 1800 by 150 and get 12 sections. So much we need to heat a room of 18m 2. There is a very complex formula by which you can calculate the exact number of sections in the radiator.

Formula looks like that:

  • q 1 - this type of glazing: triple glazing 0.85; double glazing 1; ordinary glass 1.27;
  • q2- thermal insulation of walls: modern thermal insulation 0.85; wall in 2 bricks 1; poor insulation 1.27;
  • q 3 - ratio of window area to floor area: 10% 0.8; 20% 0.9; 30% 1.1; 40% 1.2;
  • q 4- minimum outside temperature: -10 0 C 0.7; -15 0 С 0.9; -20 0 C 1.1; -25 0 С 1.3; -35 0 С 1.5;
  • q 5 - number of external walls: one 1.1; two (angular) 1.2; three 1.3; four 1.4;
  • q 6 - type of room above the calculated room: heated room 0.8; heated attic 0.9; cold loft 1;
  • q 7 - ceiling height: 2.5 m - 1; 3 m - 1.05; 3.5m - 1.1; 4m - 1.15; 4.5m - 1.2;

Let's carry out a calculation for a corner room of 20 m 2 with a ceiling height of 3 m, two 2-fold windows with triple glazing, 2-brick walls, located under a cold attic in a house in a village near Moscow, where in winter the temperature drops to 20 0 C.

It turns out 1844.9 watts. Divide by 150 watts and get 12.3 or 12 sections.

The calculation of the power of cast iron batteries is studied in detail in this article:

Radiators are made of three types of metal: cast iron, aluminum and bimetallic. Cast iron and aluminum radiators have the same heat output, but heated cast iron cools more slowly than aluminum. Bimetallic batteries have a greater heat transfer than cast iron, but they cool faster. Steel radiators have a high heat dissipation, but they are prone to corrosion.

indoors is considered 21 0 C. However, for a good sound sleep, a temperature not higher than 18 0 C is more suitable, therefore the purpose of the heated room also plays a significant role. And if in the hall area 20 m 2 need to install 12 battery sections, then in a similar sleeping room it is preferable to install 10 batteries, and a person in such a room will sleep comfortably. In a corner room of the same area, feel free to place 16 batteries and you won't get hot. That is, the calculation of radiators in a room is very individual, and only rough recommendations can be given on how many sections should be installed in a particular room. The main thing is to make the installation correctly, and it will always be warm in your house.

Calculation of radiators in a two-pipe system (video)

The correct calculation of sections of heating radiators is a rather important task for every homeowner. If an insufficient number of sections is used, the room will not warm up during the winter cold, and the purchase and operation of too large radiators will entail unreasonably high heating costs.

For standard rooms, you can use the simplest calculations, but sometimes it becomes necessary to take into account various nuances in order to get the most accurate result.

To perform calculations, you need to know certain parameters

  • Dimensions of the room to be heated;
  • Type of battery, material of its manufacture;
  • The power of each section or whole battery, depending on its type;
  • The maximum allowable number of sections ;

According to the material of manufacture, radiators are divided as follows:

  • Steel. These radiators have thin walls and a very elegant design, but they are not popular due to numerous shortcomings. These include low heat capacity, rapid heating and cooling. During hydraulic shocks, leaks often occur at the joints, and cheap models quickly rust and do not last long. Usually they are solid, not divided into sections, the power of steel batteries is indicated in the passport.
  • Cast iron radiators are familiar to every person since childhood, this is a traditional material from which durable batteries with excellent technical characteristics are made. Each section of a Soviet-era cast-iron accordion produced a heat output of 160 watts. This is a prefabricated structure, the number of sections in it is not limited by anything. Available in both modern and vintage designs. Cast iron perfectly retains heat, is not subject to corrosion, abrasive wear, and is compatible with any heat carriers.
  • Aluminum batteries are light, modern, have a high heat dissipation, due to their advantages, they are becoming increasingly popular with buyers. The heat transfer of one section reaches 200 W, they are also produced in one-piece structures. Of the minuses, oxygen corrosion can be noted, but this problem is solved with the help of anodic oxidation of the metal.
  • Bimetal radiators consist of internal collectors and an external heat exchanger. The inside is made of steel and the outside is made of aluminium. High heat transfer rates, up to 200 W, are combined with excellent wear resistance. The relative minus of these batteries is the high price compared to other types.

Radiator materials differ in their characteristics, which affects the calculations

How to calculate the number of sections of heating radiators for a room

There are several ways to make calculations, each of which uses certain parameters.

By room area

A preliminary calculation can be made, focusing on the area of ​​\u200b\u200bthe room for which radiators are purchased. This is a very simple calculation and is suitable for rooms with low ceilings (2.40-2.60m). According to building codes, heating will require 100 watts of heat output per square meter of space.

We calculate the amount of heat that will be needed for the entire room. To do this, we multiply the area by 100 W, i.e. for a room of 20 square meters. m, the estimated thermal power will be 2,000 W (20 sq. M * 100 W) or 2 kW.

The correct calculation of heating radiators is necessary to guarantee sufficient heat in the house.

This result must be divided by the heat output of one section, specified by the manufacturer. For example, if it is equal to 170 W, then in our case the required number of radiator sections will be: 2,000 W / 170 W = 11.76, i.e. 12, since the result should be rounded up to a whole number. Rounding is usually done up, but for rooms where heat loss is below average, such as a kitchen, it can be rounded down.

Be sure to take into account possible heat losses depending on the specific situation. Of course, a room with a balcony or located in the corner of a building loses heat faster. In this case, you should increase the value of the calculated heat output for the room by 20%. It is worth increasing the calculations by about 15-20% if you plan to hide the radiators behind the screen or mount them in a niche.

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By volume

More accurate data can be obtained if the sections of heating radiators are calculated taking into account the height of the ceiling, i.e., by the volume of the room. The principle here is about the same as in the previous case. First, the total heat demand is calculated, then the number of radiator sections is calculated.

If the radiator is hidden by a screen, it is necessary to increase the need for thermal energy in the room by 15-20%.

According to the recommendations of SNIP, 41 W of thermal power is required to heat each cubic meter of a dwelling in a panel house. Multiplying the area of ​​​​the room by the height of the ceiling, we get the total volume, which we multiply by this standard value. For apartments with modern double-glazed windows and external insulation, less heat will be needed, only 34 W per cubic meter.

For example, let's calculate the required amount of heat for a room of 20 square meters. m with a ceiling height of 3 meters. The volume of the room will be 60 cubic meters. m (20 sq. m * 3 m). The calculated thermal power in this case will be equal to 2,460 W (60 cubic meters * 41 W).

And how to calculate the number of heating radiators? To do this, you need to divide the data obtained by the heat transfer of one section specified by the manufacturer. If we take, as in the previous example, 170 W, then the room will need: 2,460 W / 170 W = 14.47, i.e. 15 radiator sections.

Manufacturers tend to indicate overestimated heat transfer rates of their products, assuming that the temperature of the coolant in the system will be maximum. In real conditions, this requirement is rarely met, so you should focus on the minimum heat transfer rates of one section, which are reflected in the product passport. This will make the calculations more realistic and accurate.

If the room is not standard

Unfortunately, not every apartment can be considered standard. This is even more true for private residences. How to make calculations taking into account the individual conditions of their operation? To do this, you need to take into account many different factors.

When calculating the number of heating sections, it is necessary to take into account the height of the ceiling, the number and size of windows, the presence of wall insulation, etc.

The peculiarity of this method is that when calculating the required amount of heat, a number of coefficients are used that take into account the characteristics of a particular room that can affect its ability to store or release heat energy.

The calculation formula looks like this:

CT=100 W/sq. m* P*K1*K2*K3*K4*K5*K6*K7, where

KT - the amount of heat required for a particular room;
P is the area of ​​the room, sq. m;
K1 - coefficient taking into account the glazing of window openings:

  • for windows with ordinary double glazing - 1.27;
  • for windows with double glazing - 1.0;
  • for windows with triple glazing - 0.85.

K2 - coefficient of thermal insulation of walls:

  • low degree of thermal insulation - 1.27;
  • good thermal insulation (laying in two bricks or a layer of insulation) - 1.0;
  • high degree of thermal insulation - 0.85.

K3 - the ratio of the area of ​​\u200b\u200bwindows and the floor in the room:

  • 50% - 1,2;
  • 40% - 1,1;
  • 30% - 1,0;
  • 20% - 0,9;
  • 10% - 0,8.

K4 is a coefficient that takes into account the average air temperature in the coldest week of the year:

  • for -35 degrees - 1.5;
  • for -25 degrees - 1.3;
  • for -20 degrees - 1.1;
  • for -15 degrees - 0.9;
  • for -10 degrees - 0.7.

K5 - adjusts the need for heat, taking into account the number of external walls:

  • one wall - 1.1;
  • two walls - 1.2;
  • three walls - 1.3;
  • four walls - 1.4.

K6 - accounting for the type of room that is located above:

  • cold attic - 1.0;
  • heated attic - 0.9;
  • heated dwelling - 0.8

K7 - coefficient taking into account the height of the ceilings:

  • at 2.5 m - 1.0;
  • at 3.0 m - 1.05;
  • at 3.5 m - 1.1;
  • at 4.0 m - 1.15;
  • at 4.5 m - 1.2.

It remains to divide the result obtained by the heat transfer value of one section of the radiator and round the result to an integer.

Expert opinion

Viktor Kaploukhiy

Thanks to my versatile hobbies, I write on various topics, but my favorite ones are engineering, technology and construction.

When installing new heating radiators, you can focus on how efficient the old heating system was. If her work suited you, then the heat transfer was optimal - these data should be based on calculations. First of all, you need to find on the Web the value of the thermal efficiency of one section of the radiator that needs to be replaced. By multiplying the found value by the number of cells that the used battery consisted of, they obtain data on the amount of thermal energy that was enough for a comfortable stay. It is enough to divide the result obtained by the heat transfer of the new section (this information is indicated in the technical data sheet for the product), and you will receive accurate information on how many cells will be needed to install a radiator with the same thermal efficiency. If earlier the heating could not cope with heating the room, or vice versa, it was necessary to open the windows due to constant heat, then the heat transfer of the new radiator is corrected by adding or reducing the number of sections.

For example, earlier you had a common MS-140 cast-iron battery of 8 sections, which pleased with its warmth, but did not suit the aesthetic side. Paying tribute to fashion, you decided to replace it with a branded bimetallic radiator, assembled from separate sections with a heat output of 200 W each. The nameplate power of a used thermal device is 160 W, however, over time, deposits appeared on its walls, which reduce heat transfer by 10-15%. Therefore, the real heat transfer of one section of the old radiator is about 140 W, and its total thermal power is 140 * 8 = 1120 W. We divide this number by the heat transfer of one bimetallic cell and get the number of sections of the new radiator: 1120 / 200 = 5.6 pcs. As you can see for yourself, in order to keep the heat dissipation of the system at the same level, a bimetallic radiator of 6 sections will be enough.

How to take into account the effective power

When determining the parameters of the heating system or its individual circuit, one of the most important parameters, namely the heat head, should not be discounted. It often happens that the calculations are done correctly, and the boiler heats up well, but somehow it doesn’t add up with the heat in the house. One of the reasons for the decrease in thermal efficiency may be the temperature regime of the coolant. The thing is that most manufacturers indicate the power value for a pressure of 60 ° C, which takes place in high-temperature systems with a coolant temperature of 80-90 ° C. In practice, it often turns out that the temperature in the heating circuits is in the range of 40-70 ° C, which means that the value of the temperature difference does not rise above 30-50 ° C. For this reason, the heat transfer values ​​obtained in the previous sections should be multiplied by the actual head, and then the resulting number should be divided by the value indicated by the manufacturer in the data sheet. Of course, the figure obtained as a result of these calculations will be lower than that which was obtained when calculating according to the above formulas.

It remains to calculate the actual temperature difference. It can be found in tables on the Web, or you can calculate it yourself using the formula ΔT = ½ x (Tn + Tk) - Tvn). In it, Tn is the initial temperature of the water at the inlet to the battery, Tk is the final temperature of the water at the outlet of the radiator, Tvn is the ambient temperature. If we substitute the values ​​​​Tn = 90 ° С (the high-temperature heating system mentioned above), Тk = 70 ° С and Тvn = 20 ° С (room temperature) into this formula, then it is easy to understand why the manufacturer focuses on this value of thermal pressure. . Substituting these numbers into the formula for ΔT, we just get the “standard” value of 60 ° C.

Taking into account not the passport, but the real power of the thermal equipment, it is possible to calculate the system parameters with an allowable error. All that remains to be done is to make a correction of 10-15% in case of abnormally low temperatures and provide for the possibility of manual or automatic adjustment in the design of the heating system. In the first case, experts recommend putting ball valves on the bypass and the coolant supply branch to the radiator, and in the second case, installing thermostatic heads on the radiators. They will allow you to set the most comfortable temperature in each room, without releasing heat into the street.

How to correct calculation results

When calculating the number of sections, heat loss must also be taken into account. In a house, heat can escape in a fairly significant amount through walls and junctions, floors and basements, windows, roofs, and a natural ventilation system.

Moreover, you can save money if you insulate the slopes of windows and doors or a loggia by removing 1-2 sections, heated towel rails and a stove in the kitchen also allow you to remove one section of the radiator. Using a fireplace and underfloor heating system, proper wall and floor insulation will keep heat loss to a minimum and will also reduce the size of the battery.

Heat loss must be taken into account when calculating

The number of sections may vary depending on the mode of operation of the heating system, as well as on the location of the batteries and the connection of the system to the heating circuit.

In private houses, autonomous heating is used, this system is more efficient than the centralized one, which is used in apartment buildings.

The method of connecting radiators also affects the heat transfer performance. The diagonal method, when water is supplied from above, is considered the most economical, and the side connection creates a loss of 22%.

The number of sections may depend on the mode of the heating system and the method of connecting radiators

For single pipe systems, the final result is also subject to correction. If two-pipe radiators receive a coolant of the same temperature, then a single-pipe system works differently, and each subsequent section receives cooled water. In this case, first a calculation is made for a two-pipe system, and then the number of sections is increased, taking into account heat losses.

The calculation scheme for a single-pipe heating system is presented below.

In the case of a single-pipe system, successive sections receive cooled water

If we have 15 kW at the input, then 12 kW remains at the output, which means 3 kW is lost.

For a room with six batteries, the loss will average about 20%, making it necessary to add two sections per battery. The last battery in this calculation should be huge, to solve the problem, they use the installation of shut-off valves and connection through a bypass to regulate heat transfer.

Some manufacturers offer an easier way to get an answer. On their sites you can find a handy calculator specifically designed to do these calculations. To use the program, you need to enter the required values ​​in the appropriate fields, after which the exact result will be displayed. Or you can use a special program.

Such a calculation of the number of heating radiators includes almost all the nuances and is based on a fairly accurate determination of the room's need for thermal energy.

Adjustments allow you to save on the purchase of extra sections and payment of heating bills, ensure economical and efficient operation of the heating system for many years, and also allow you to create a comfortable and cozy warm atmosphere in your house or apartment.

The calculation of the number of radiators or a specific calculation for heat sources is associated with the maximum heat loss of the room. Based on this value, the calculation of a steel heating radiator by area is focused on the heaters themselves and their location in order to correctly compensate for the heat level.

Several methods. And the simplest of them will give relative results. In most cases, this is sufficient.

steel radiator for home

This is one of the easiest ways to calculate a specific value for heating, more precisely for compensation. Calculate the value, starting from the area of ​​\u200b\u200bthe apartment or house where they plan to install radiators. Nothing complicated: the area of ​​\u200b\u200beach of the rooms is known in advance, and the specific value for heat consumption is determined by SNiPs:

  1. The average climatic zone for a dwelling implies heating 1 square meter at 70-100 watts.
  2. Where the temperature falls below 60 degrees Celsius, it is necessary to spend from 150 to 220 watts per meter.

For your information! It is easy to calculate heating radiators according to these standards or using a calculator.

But they also take into account power reserves, which cannot be dispensed with. A large overrun is not welcome, because with a large amount of final power, the number of radiators in the room increases. When the apartment is connected to the central heating lines, then any overrun is not critical, because each user pays a fixed cost.

However, with individual heating, everything is serious, because any overspending is a payment for the heat carriers themselves and their work. Paying more is stupid, especially since the set temperature is usually not maintained accurately.

Having calculated the exact need for square meters on the calculator, it is easy to find out how many sections to buy. Because any heating device emits a specific amount of heat. These data are registered in the passport. They do this: they calculate a specific figure for heat and divide by the power of the radiators. The result of this calculation gives a figure for the number of purchased sections to restore heat loss in winter.

Let's look at a simple example: let's say that only 1600 watts are needed, with an area of ​​\u200b\u200beach section of 170 watts. We do this: we divide the total values ​​\u200b\u200bin 1600 by 170. It turns out that you need to buy 9.5 radiators. Rounding can be done in any direction, this is at the discretion of the owner. Usually rounded down in those rooms where there are additional heat sources, for example, in kitchens. And in the big direction they count on rooms with balconies or large windows. They also practice some margin of power next to bare walls or in corner rooms.

Nothing complicated, but remember about the height of the ceilings - this value is not always standard. The building material of the same windows or walls also affects. Therefore, the calculation of heating radiators by area for any room is usually approximate. It is more convenient to use a calculator that takes into account adjustments for specific building materials and area features.

Do I need to adjust the preliminary calculations?

Approximate calculations necessarily require adjustments. This is necessary to obtain concrete results, taking into account all factors. The latter have an effect on heat loss in a smaller or larger direction:

  • wall material;
  • the quality of the insulation;
  • window areas and their glazing;
  • the number of walls facing the street.

To take into account all these factors, coefficients have been invented that are clearly written in good calculators. They are simply multiplied among themselves, more precisely, they align the initial value according to the heat loss of the building.


Heat loss in %

Let's start with windows. As a rule, it is these components that consume from 14 to 30% of heat loss. The exact figures are related to the size and actual insulation. And if so, then the calculation is based on two coefficients:

  1. Window area to floor area:
  • 10% odds 0.8
  • 20% odds 0.9
  • 30% odds 1.0
  • 40% odds 1.1
  • 50% odds 1.2
  1. For glazing:
  • Three-chamber double-glazed windows multiplied by 0.85
  • Double glazing multiplied by 1.0
  • Wooden double frames are best multiplied by 1.27 or 1.3

For walls and roofing consider the degree of material and insulation. It turns out that there are also two quantities for calculation:

Thermal insulation.

  • A brick wall of standard thickness is the norm. The coefficient is equal to one.
  • Walls of insufficient thickness are multiplied by 1.27.
  • Good walls with a layer of insulation of 10 centimeters or more are multiplied by 0.8.

Outer wall:

  • Indoor spaces without heat loss are multiplied by one.
  • One for the entire area is multiplied by 1.1.
  • Two for the entire area multiplied by 1.2.
  • Etc.

More about calculations of steel radiators

The steel panel radiator is a relatively new appliance for space heating. A distinctive feature is that it is steel structures that are smaller in size, and the heat transfer coefficient is much higher. Moreover, the system may consist of several panels made of corrugated metal (fins). It turns out that the panels (and there can be 1, 2 or 3 of them) are plates that pass the coolant inside the system.

To calculate the power precisely by area, you need to know the types of steel radiators. There are 5 in total. Let's start with the most powerful:

  1. Three-panel. Significant dimensions due to three panels to which the fins are attached (designation 33).
  2. Two-panel. They already have two plates (designation 22).
  3. Double-panel with one plate (designation 21).
  4. Single panel radiator also with single fins. Weak power, low weight and the same dimensions (designation 11).
  5. Panel and coolant (designation 10).

Types of steel radiators

It is easier to determine the power for such types of devices by area, but not a square meter, but a cubic meter is taken into account. According to SNiP, the data is as follows:

  1. A brickwork room per 1 cubic meter requires 34 watts.
  2. A panel house for 1 cubic meter already requires 41 watts.

Panel house with dimensions of 3.2 by 3.5 meters, where the ceilings are exactly 3 meters. We calculate according to the formula 3.2, multiply by 3.5, we get 33.6 cubic meters. And we already multiply this value by the norms for a panel house (41). We get 1378 watts.

For a more accurate calculation, they already use a calculator, into which they enter into the above (approximate) value and data on the characteristics of the climate and the building itself.

About other factors affecting the calculation

Any manufacturer of steel radiators always indicates their maximum power. Here's what it looks like:

  1. High temperature mode. The coolant itself is heated to 90 degrees Celsius.
  2. processing mode. The maximum is 70 degrees Celsius (value 90/70).

In practice, any heating systems are not heated to the maximum, and the actual temperature regime or power has the following parameters:

  1. 75.65.20
  2. 55.45.20

For a competent calculation, it is desirable to know the temperature differences of the system itself. More specifically, they calculate the difference between the heater and the air temperature. Where the degrees of the heaters themselves are taken as the arithmetic average from supply to processing.

Even when planning or calculating for radiators, the connection of the liquid supply is taken into account. In practice, there are only 2 types:

  • Unilateral. Works at maximum with the top feed (97%).
  • Bilateral. Also, maximum heat transfer at the top connection (100%).

Results

Finding or choosing a specific radiator is not so difficult. It is much more difficult to make the correct calculation, focusing on the type of connection, the correct arrangement of devices. Plus, they always use a calculator where you need to enter the features of your building or a new apartment.

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:

  1. General provisions regarding the design of heating systems
  2. Rules for the design of heating systems for buildings
  3. 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:

  1. The maximum width of the radiator should not exceed 70% of the similar characteristic of the window opening under which it is installed.
  2. The radiator must be mounted in the center of the window opening (a slight error is allowed - no more than 2 cm)
  3. The recommended space between the radiators and the wall is 2-5 cm
  4. Above the floor height should not be more than 12 cm
  5. Distance to the window sill from the top of the battery - at least 5 cm
  6. 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 sections of the heating radiator required for efficient and comfortable heating of a dwelling, its volume should be taken into account. The principle is very simple:

  1. Determining the need for heat
  2. 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 thermal heated air masses will not be passed by 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):

  1. At the first step, we calculate the volume of the room using a simple formula: [height length Width] (3x4x5=60 cubic meters)
  2. 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)
  3. You can determine the desired number of ribs using the formula: (2460/170=14.5)
  4. 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

  1. At the first stage, the total area of ​​\u200b\u200bthe room is determined: [length Width] (5х4=20 sq.m.)
  2. The next step is to determine the heat required to heat the entire room: [area]* [need per sq. m.] (100x20=2000W)
  3. 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
  4. To determine the required number of sections, use the formula: [total heat demand]/[capacity of one section] (2000/170=11.7)
  5. We introduce correction factors ( discussed further)
  6. 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.