Comfortable living conditions in the winter are entirely dependent on an adequate supply of heat to living quarters. If this is a new building, for example, in a summer cottage or a personal plot, then you need to know how to calculate heating radiators for a private house.
All operations are reduced to calculating the number of radiator sections and are subject to a clear algorithm, so there is no need to be a qualified specialist - each person will be able to do a fairly accurate thermal calculation of his home.
Why accurate calculation is necessary
The heat transfer of heat supply devices depends on the material of manufacture and the area of \u200b\u200bindividual sections. Not only the heat in the house depends on correct calculations, but also the balance and efficiency of the system as a whole: an insufficient number of installed radiator sections will not provide adequate heat in the room, and an excessive number of sections will hit your pocket.
For calculations, it is necessary to determine the type of batteries and heat supply system. For example, the calculation of aluminum heat supply radiators for a private house differs from other elements of the system. Radiators are cast iron, steel, aluminum, anodized aluminum and bimetallic:
- The best known are cast iron batteries, the so-called "accordions". They are durable, resistant to corrosion, have a power of 160 W sections at a height of 50 cm and a water temperature of 70 degrees. A significant drawback of these devices is an unsightly appearance, but modern manufacturers produce smooth and quite aesthetic cast iron batteries, retaining all the advantages of the material and making them competitive.
- Aluminum radiators are superior to cast iron products in terms of thermal power, they are durable, have a light dead weight, which gives an advantage during installation. The only drawback is susceptibility to oxygen corrosion. To eliminate it, the production of anodized aluminum radiators has been adopted.
- Steel appliances do not have sufficient thermal power, cannot be disassembled and sections enlarged if necessary, are subject to corrosion, and therefore are not popular.
- Bimetallic radiators are a combination of steel and aluminum parts. Heat transfer media and fasteners in them are steel pipes and threaded joints, covered with an aluminum casing. The disadvantage is the rather high cost.
According to the type of heat supply system, one-pipe and two-pipe connection of heating elements are distinguished. In multi-storey residential buildings, a single-pipe heat supply system is mainly used. The disadvantage here is a rather significant difference in the temperature of the incoming and outgoing water at different ends of the system, which indicates the uneven distribution of thermal energy among battery devices.
For even distribution of heat energy in private houses, a two-pipe heat supply system can be used, when hot water is supplied through one pipe, and cooled water is removed through another.
In addition, the exact calculation of the number of heating batteries in a private house depends on the connection diagram of the devices, the height of the ceiling, the area of \u200b\u200bwindow openings, the number of external walls, the type of room, the enclosure of the devices with decorative panels and other factors.
Remember! It is necessary to correctly calculate the required number of heating radiators in a private house in order to guarantee sufficient heat in the room and ensure financial savings.
Types of heating calculations for a private house
The type of calculation of heating radiators for a private house depends on the goal, that is, how accurately you want to calculate heating radiators for a private house. Distinguish between simplified and accurate methods, as well as by area and volume of the calculated space.
According to a simplified or preliminary method, the calculations are reduced to multiplying the area of \u200b\u200bthe room by 100 W: the standard value of sufficient thermal energy per meter squared, while the calculation formula will take the following form:
Q \u003d S * 100, where
Q is the required heat power;
S is the estimated area of \u200b\u200bthe room;
The calculation of the required number of sections of collapsible radiators is carried out according to the formula:
N \u003d Q / Qx, where
N is the required number of sections;
Qx is the specific power of the section according to the product passport.
Since these formulas for the room height are 2.7 m, correction factors must be entered for other quantities. Calculations are reduced to determining the amount of heat per 1 m3 of room volume. The simplified formula looks like this:
Q \u003d S * h * Qy, where
H is the height of the room from floor to ceiling;
Qy is the average heat output depending on the type of fence, for brick walls it is 34 W / m3, for panel walls - 41 W / m3.
These formulas cannot guarantee a comfortable environment. Therefore, precise calculations are required, taking into account all the accompanying features of the building.
Accurate calculation of heating devices
The most accurate formula for the required thermal power is as follows:
Q \u003d S * 100 * (K1 * K2 * ... * Kn-1 * Kn), where
K1, K2… Kn - coefficients depending on various conditions.
What conditions affect the indoor climate? For an accurate calculation, up to 10 indicators are taken into account.
K1 is an indicator that depends on the number of external walls, the more the surface is in contact with the external environment, the greater the loss of thermal energy:
- with one outer wall, the indicator is equal to one;
- if there are two outer walls - 1.2;
- if three external walls - 1.3;
- if all four walls are external (i.e. one-room building) - 1.4.
K2 - takes into account the orientation of the building: it is believed that rooms warm up well if they are located in the south and west directions, here K2 \u003d 1.0, and vice versa, it is not enough - when the windows face north or east - K2 \u003d 1.1. One can argue with this: in the eastern direction, the room still warms up in the morning, so it is more expedient to apply a coefficient of 1.05.
K3 is an indicator of external wall insulation, depending on the material and the degree of thermal insulation:
- for outer walls in two bricks, as well as when using insulation for non-insulated walls, the indicator is equal to one;
- for non-insulated walls - K3 \u003d 1.27;
- when insulating a dwelling on the basis of heat engineering calculations according to SNiP - K3 \u003d 0.85.
K4 is a coefficient that takes into account the lowest temperatures of the cold season for a particular region:
- up to 35 ° C K4 \u003d 1.5;
- from 25 ° C to 35 ° C K4 \u003d 1.3;
- up to 20 ° C K4 \u003d 1.1;
- up to 15 ° C K4 \u003d 0.9;
- up to 10 ° C K4 \u003d 0.7.
K5 - depends on the height of the room from floor to ceiling. The standard height is h \u003d 2.7 m with an indicator equal to one. If the height of the room differs from the standard one, a correction factor is introduced:
- 2.8-3.0 m - K5 \u003d 1.05;
- 3.1-3.5 m - K5 \u003d 1.1;
- 3.6-4.0 m - K5 \u003d 1.15;
- more than 4 m - K5 \u003d 1.2.
K6 is an indicator that takes into account the nature of the room located above. The floors of residential buildings are always insulated, the rooms above can be heated or cold, and this will inevitably affect the microclimate of the calculated space:
- for a cold attic, and also if the room is not heated from above, the indicator will be equal to one;
- with an insulated attic or roof - K6 \u003d 0.9;
- if a heated room is located on top - K6 \u003d 0.8.
K7 is an indicator that takes into account the type of window blocks. The design of the window has a significant effect on heat loss. In this case, the value of the coefficient K7 is determined as follows:
- since wooden windows with double glazing do not sufficiently protect the room, the highest indicator is K7 \u003d 1.27;
- double-glazed windows have excellent properties of protection against heat loss, with a single-chamber double-glazed window made of two glasses K7 is equal to one;
- improved single-chamber glass unit with argon filling or double glass unit, consisting of three glasses K7 \u003d 0.85.
K8 is a coefficient that depends on the area of \u200b\u200bglazing of window openings. Heat loss depends on the number and area of \u200b\u200bthe installed windows. The ratio of the area of \u200b\u200bthe windows to the area of \u200b\u200bthe room should be adjusted so that the coefficient has the lowest values. Depending on the ratio of the area of \u200b\u200bthe windows to the area of \u200b\u200bthe room, the desired indicator is determined:
- less than 0.1 - K8 \u003d 0.8;
- from 0.11 to 0.2 - K8 \u003d 0.9;
- from 0.21 to 0.3 - K8 \u003d 1.0;
- from 0.31 to 0.4 - K8 \u003d 1.1;
- from 0.41 to 0.5 - K8 \u003d 1.2.
K9 - takes into account the device connection diagram. Heat dissipation depends on the method of connecting hot and cold water. This factor must be taken into account when installing and determining the required area of \u200b\u200bheating devices. Taking into account the connection diagram:
- with a diagonal arrangement of pipes, hot water is supplied from above, the return flow is from the bottom on the other side of the battery, and the indicator is equal to one;
- when connecting the supply and return from one side and from above and below one section K9 \u003d 1.03;
- the abutment of pipes on both sides implies both supply and return from below, while the coefficient K9 \u003d 1.13;
- variant of diagonal connection, when the flow is from the bottom, return from the top K9 \u003d 1.25;
- variant of one-sided connection with bottom feed, top return and one-sided bottom connection K9 \u003d 1.28.
K10 is a coefficient that depends on the degree of coverage of the devices with decorative panels. The openness of devices for the free exchange of heat with the space of the room is of no small importance, since the creation of artificial barriers reduces the heat transfer of the batteries.
Existing or artificially created barriers can significantly reduce the efficiency of the battery due to the deterioration in the exchange of heat with the room. Depending on these conditions, the coefficient is:
- when the radiator is open on the wall from all sides 0.9;
- if the device is covered from above by the unit;
- when the radiators are covered from above the wall niche 1.07;
- if the device is covered with a window sill and a decorative element 1.12;
- when the radiators are completely covered with a decorative casing 1.2.
In addition, there are special norms for the location of heating devices that must be observed. That is, the battery should be placed at least on:
- 10 cm from the bottom of the windowsill;
- 12 cm from the floor;
- 2 cm from the outside wall surface.
Substituting all the necessary indicators, you can get a fairly accurate value of the required heat output of the room. By dividing the results obtained into the passport data of the heat transfer of one section of the selected device and, rounded up to an integer, we obtain the number of required sections. Now you can, without fear of the consequences, select and install the necessary equipment with the required heat output.
Ways to simplify calculations
Despite the seeming simplicity of the formula, in fact, the practical calculation is not so simple, especially if the number of rooms to be calculated is large. To simplify the calculations will help the use of special calculators posted on the websites of some manufacturers. It is enough to enter all the necessary data in the appropriate fields, after which you can get an accurate result. You can also use the tabular method, since the calculation algorithm is quite simple and monotonous.
It is very important for every home owner to carry out the correct calculation of heating radiators. An insufficient number of sections will prevent radiators from heating the room in the most efficient and optimal way. If you buy radiators with too many sections, then the heating system will be very uneconomical, using the extra power of the heating radiators.
If you need to change the heating system or install a new one, then calculating the number of heating radiator sections will play a very important role. If the premises in your house or apartment are of a standard type, then simpler calculations will do. However, sometimes in order to obtain the best result, it is necessary to observe some features and nuances concerning such parameters as the power of the heating radiator per room and the pressure in the heating batteries.
Calculation based on the area of \u200b\u200bthe room
Let's figure out how to calculate heating batteries. Focusing on parameters such as the total area of \u200b\u200bthe room, it is possible to carry out a preliminary calculation of heating batteries for the area. This calculation is pretty straightforward. However, if you have high ceilings in the room, then you cannot take it as a basis. For each square meter of area, about 100 watts of power per hour is required. Thus, the calculation of sections of heating batteries will allow you to calculate how much heat will be needed to heat the entire room.
How to calculate the number of heating radiators? For example, the area of \u200b\u200bour premises is 25 sq. meters. We multiply the total area of \u200b\u200bthe room by 100 watts and we get the power of the heating battery at 2500 watts. That is, 2.5 kW per hour is needed to heat a room with an area of \u200b\u200b25 sq. meters. We divide the result obtained by the heat value that one section of the heating radiator is capable of emitting. For example, the documentation of the heater states that one section emits 180 watts of heat per hour.
Thus, the calculation of the power of heating radiators will look like this: 2500 W / 180 W \u003d 13.88. We round the result and get the figure 14. So, for heating a room of 25 sq. meters, a radiator with 14 sections is required.
You will also need to take into account various heat losses. A room in the corner of a house or a room with a balcony will heat up more slowly and also give off heat faster. In this case, the calculation of the heat transfer of the radiator of the heating batteries should be made with a certain margin. It is desirable that such a reserve be about 20%.
The calculation of heating batteries can be made taking into account the volume of the room. In this case, not only the total area of \u200b\u200bthe room plays a role, but also the height of the ceilings. How to calculate heating radiators? The calculation is made in approximately the same way as in the previous situation. First, you need to identify how much heat is needed, as well as how to calculate the number of heating batteries and their sections.
For example, you need to calculate the amount of heat needed for a room that has an area of \u200b\u200b20 sq. meters, and the ceiling height in it is 3 meters. We multiply 20 sq. meters by 3 meters in height and we get 60 cubic meters of the total volume of the room. For each cubic meter, about 41 W of heat is needed - this is what the data and recommendations of SNIP say.
We calculate the power of the heating batteries further. We multiply 60 sq. meters by 41 W and we get 2460 W. We also divide this figure by the heat output that one section of the heating radiator emits. For example, the documentation of the heater indicates that one section emits about 170 watts of heat per hour.
Divide 2460 W by 170 W and get the figure 14.47. We also round it off, thus, to heat a room with a volume of 60 cubic meters, we need a 15-section heating radiator.
You can make the most accurate calculation of the number of heating radiators. This may be needed for private houses with non-standard premises and rooms.
CT \u003d 100W / sq.m. x P x K1 x K2 x K3 x K4 x K5 x K6 x K7
CT is the amount of heat that is needed for a particular room;
P is the total area of \u200b\u200bthe room;
K1 is a coefficient that takes into account how glazed the openings for windows.
If the window is with double glazing, then kf. is 1.27.
For a double-glazed window - 1.00.
For triple glazing kf. is 0.87.
K2 is kf. wall insulation.
If the thermal insulation is rather low, then kf is taken. at 1.27.
For good thermal insulation - kf. \u003d 1.0.
For excellent thermal insulation kf. equals 0.85.
K3 is the ratio of the floor area and the area of \u200b\u200bthe windows in the room.
For 50%, it will be 1.2.
For 40% - 1.1.
For 30% - 1.0.
For 20% - 0.9.
For 10% - 0.8.
K4 is kph., Taking into account the average indoor temperature during the coldest week of the year.
For a temperature of -35 degrees, it will be equal to a value of 1.5.
For -25 - cf. \u003d 1.3.
For -20 - 1.1.
For -15 - 0.9.
For -10 - 0.7.
K5 is a coefficient that will help to identify the need for heat, taking into account how many external walls the room has.
For rooms with one wall kf. is 1.1.
Two walls - 1.2.
Three walls 1.3.
K6 - takes into account the type of premises that are located above our premises.
If the attic is not heated, then it is 1.0.
If the attic is heated, then kf. is 0.9.
If a dwelling is located above, which is heated, then the base is taken as a basis. at 0.7.
K7 is a consideration of the height of the ceilings in the room.
For a ceiling height of 2.5 m, kf. will be 1.0.
With a ceiling height of 3 meters, KF. is 1.05.
If the height of the ceilings is 3.5 meters, then the cf is taken as the basis. at 1.1.
At 4 meters - 1.15.
The result calculated according to this formula must be divided by the heat, which is produced by one section of the heating radiator, and the result that we have received must be rounded.
In the matter of maintaining the optimal temperature in the house, the main place is occupied by the radiator.
The choice is simply amazing: bimetallic, aluminum, steel of various sizes.
There is nothing worse than an incorrectly calculated required heat output in a room. In winter, such a mistake can be very expensive.
Thermal calculation of heating radiators is suitable for bimetallic, aluminum, steel and cast iron radiators. Experts identify three methods, each of which is based on certain indicators.
There are three methods here, which are based on general principles:
- the standard value of the power of one section can vary from 120 to 220 W, therefore the average value is taken
- to correct errors in calculations when buying a radiator, you should lay a 20% reserve
Now let's turn directly to the methods themselves.
Method one - standard
Based on building rules, for high-quality heating of one square meter, 100 watts of radiator power is required. Let's do the calculations.
Let's say the area of \u200b\u200bthe room is 30 m², the power of one section is taken equal to 180 watts, then 30 * 100/180 \u003d 16.6. Let's round the value up and get that 17 sections of the heating radiator are needed for a room of 30 square meters.
However, if the room is angular, then the resulting value should be multiplied by a factor of 1.2. In this case, the number of required radiator sections will be 20
Method two - approximate
This method differs from the previous one in that it is based not only on the area of \u200b\u200bthe room, but also on its height. Please note that this method only works for medium to high power appliances.
At low power (50 watts or less), such calculations will be ineffective due to too large an error.
So, if we take into account that the average height of the room is 2.5 meters (the standard height of the ceilings of most apartments), then one section of a standard radiator is capable of heating an area of \u200b\u200b1.8 m².
The calculation of sections for a room of 30 "squares" will be as follows: 30 / 1.8 \u003d 16. Rounding up again, we find that 17 radiator sections are needed to heat this room.
Method three - volumetric
As the name implies, the calculations in this method are based on the volume of the room.
It is conventionally assumed that to heat 5 cubic meters of a room, 1 section with a capacity of 200 watts is needed. With a length of 6 m, a width of 5 and a height of 2.5 m, the formula for the calculation will be as follows: (6 * 5 * 2.5) / 5 \u003d 15. Therefore, for a room with such parameters, you need 15 sections of a heating radiator with a capacity of 200 watts each.
If the radiator is planned to be located in a deep open niche, then the number of sections must be increased by 5%.
If the radiator is planned to be completely covered with a panel, then the increase should be made by 15%. Otherwise, it will be impossible to achieve optimal heat dissipation.
An alternative method for calculating the power of heating radiators
Calculating the number of heating radiator sections is far from the only way to properly organize the heating of a room.
Let's calculate the volume of the proposed room with an area of \u200b\u200b30 sq. m and a height of 2.5 m:
30 x 2.5 \u003d 75 cubic meters.
Now you need to decide on the climate.
For the territory of the European part of Russia, as well as Belarus and Ukraine, the standard is 41 watts of thermal power per cubic meter of room.
To determine the required power, we multiply the volume of the room by the standard:
75 x 41 \u003d 3075 W
Let's round the resulting value up - 3100 watts. For those people who live in very cold winters, this figure can be increased by 20%:
3100 x 1.2 \u003d 3720 W.
Having come to the store and having specified the power of the heating radiator, you can calculate how many radiator sections are required to maintain a comfortable temperature even in the most severe winter.
Calculation of the number of radiators
The calculation method is an excerpt from the previous paragraphs of the article.
After you calculate the required power for heating the room and the number of radiator sections, you come to the store.
If the number of sections is impressive (this happens in rooms with a large area), then it would be reasonable to purchase not one, but several radiators.
This scheme is also applicable to those conditions when the power of one radiator is lower than required.
But there is another quick way to calculate the number of radiators. If in your room there were old ones with a height of about 60 cm, and in winter you felt comfortable in this room, then count the number of sections.
Multiply the resulting figure by 150 W - this will be the required power of the new radiators.
If you choose or, you can buy them at the rate of 1 to 1 - for one rib of a cast-iron radiator, 1 rib of a bimetallic one.
The division into "warm" and "cold" apartments has long come into our lives.
Many people deliberately do not want to engage in the selection and installation of new radiators, explaining this by the fact that "it will always be cold in this apartment." But this is not the case.
The correct choice of radiators, coupled with a competent calculation of the required power, can make you feel warm and cozy outside your windows even in the coldest winter.
There are several methods for calculating the number of radiators, but their essence is the same: find out the maximum heat loss in a room, and then calculate the number of heating devices required to compensate them.
There are different calculation methods. The simplest ones give approximate results. Nevertheless, they can be used if the premises are standard or apply coefficients that allow taking into account the existing "non-standard" conditions of each particular room (corner room, exit to the balcony, full-wall window, etc.) There is a more complex calculation using the 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 real heat loss. And based on these data, they calculate how many radiators are needed to compensate them. What's more good about this method is that the thermal imager clearly shows where the heat is most actively removed. This can be a defect in work or building materials, a crack, etc. So at the same time you can straighten things out.
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 heat demand can be determined according to the building codes SNiP:
- for the middle climatic zone, 60-100W is required for heating 1m 2 of living space;
- 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 \u200b\u200b16m 2, 1600W of heat will be required (16 * 100 \u003d 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, count 60W.
A power reserve in heating is needed, but not very large: with an increase in the amount of required power, 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 are planning individual heating, a large volume of the system means large (extra) costs for heating the coolant and a greater inertia of the system (the set temperature is less accurately maintained). And a natural question arises: "Why pay more?"
Having calculated the heat demand of the room, we can find out how many sections are required. Each of the heating devices can emit a certain amount of heat, which is indicated in the passport. They take the found heat demand and divide it by the radiator power. The result is the required number of sections to make up for losses.
Let's calculate the number of radiators for the same room. We have determined that 1600W is required. Let the power of one section be 170W. It turns out 1600/170 \u003d 9.411 pcs. You can round up or down at your discretion. The smaller one can be rounded, for example, in the kitchen - there are enough additional heat sources, and the larger one 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 heating radiator sections according to SNiP is approximate. For an accurate result, you need to make adjustments.
How to calculate radiator sections by room volume
With this calculation, not only the area is taken into account, but also the height of the ceilings, because all the air in the room needs to be heated. So this approach is justified. And in this case, the technique 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 \u200b\u200b16m 2 and compare the results. Let the ceiling height be 2.7m. Volume: 16 * 2.7 \u003d 43.2m 3.
- In a panel house. Heat required for heating 43.2m 3 * 41V \u003d 1771.2W. If we take all the same sections with a power of 170W, we get: 1771W / 170W \u003d 10.418 pieces (11 pieces).
- In a brick house. Heat is needed 43.2m 3 * 34W \u003d 1468.8W. We count radiators: 1468.8W / 170W \u003d 8.64pcs (9pcs).
As you can see, the difference turns out to be quite large: 11 pieces and 9 pieces. Moreover, when calculating by area, an average value was obtained (if rounded in the same direction) - 10 pcs.
Correction 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 large the windows are, and what kind of glazing is on them, how many walls in the room face the street, etc. For 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 glass unit or argon in a two-chamber glass unit - 0.85
- ordinary 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.
Thermal insulation degree:
- brick walls two bricks thick are considered the norm - 1.0
- insufficient (absent) - 1.27
- good - 0.8
Exterior walls:
- indoor space - no losses, coefficient 1.0
- one - 1.1
- two - 1.2
- three - 1.3
The amount of heat loss is influenced by whether or not the room is heated above. If there is a living heated room on top (second floor of a house, another apartment, etc.), the decreasing coefficient is 0.7, if the heated attic is 0.9. It is generally accepted that an unheated attic does not affect the temperature in u (coefficient 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 real height of the ceilings in the room by the standard 2.7 m. You get the desired coefficient.
Let's calculate for example: let the ceiling height be 3.0 m. We get: 3.0m / 2.7m \u003d 1.1. This means 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 factors 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
Adjustments can be made based on average winter temperatures:
- -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 a 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 also technical subtleties, 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 the required size, there should be no difficulty in calculating their number. Most reputable companies that supply good heating equipment have technical data for all modifications on their website, including heat output. If not the power is indicated, but the flow rate of the coolant, then it is simple to translate into power: the flow rate of the coolant in 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 the supply / return of the coolant.
To make life easier for buyers, a specially designed calculator program is installed on many sites. 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 a finished result: the number of sections of this model in pieces.
But if you are just trying to figure out the possible options, then it is worth considering that radiators of the same size from different materials have different thermal power. The method of calculating the number of sections of bimetallic radiators does not differ from the calculation of aluminum, steel or cast iron. Only the heat output of one section can be different.
- aluminum - 190W
- bimetallic - 185W
- cast iron - 145W.
If you are just wondering which of the materials to choose, you can use this 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 heating devices made of bimetal of standard size (center distance 50cm), it is assumed that one section can heat 1.8m 2 of area. Then for a room of 16m 2 you need: 16m 2 / 1.8m 2 \u003d 8.88 pcs. Rounding up - we need 9 sections.
We consider the same for cast iron or steel barriers. We only need norms:
- 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 50cm. Today, there are models on sale with very different heights: from 60cm to 20cm and even lower. Models 20cm and below are called curbs. Naturally, their capacity differs from the specified standard, and if you plan to use a "non-standard", you will have to make adjustments. Either look for passport data, or count yourself. We proceed from the fact that the heat transfer of a heating 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, let's calculate the area of \u200b\u200baluminum radiators. The room is the same: 16m 2. We count 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 40cm. We find the ratio of the radiators of the selected size to the standard ones: 50cm / 40cm \u003d 1.25. And now we adjust the quantity: 8pcs * 1.25 \u003d 10pcs.
Correction depending on the mode of the heating system
Manufacturers in the passport data indicate the maximum power of the radiators: in the high-temperature mode of use - the temperature of the coolant in the supply is 90 ° C, in the return line - 70 ° C (denoted 90/70) in the room, while there should be 20 ° C. But in this mode, modern systems heating systems work very rarely. Typically, the medium power mode is 75/65/20 or even low-temperature mode with parameters 55/45/20. It is clear that the calculation needs to be corrected.
To take into account the operating mode of the system, it is necessary to determine the temperature head of the system. Temperature head is the difference between the temperature of the air and the heaters. In this case, the temperature of the heaters is considered as the arithmetic mean between the flow 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 high-temperature mode 90/70/20 heats 1.5m 2. Therefore, we need 16m 2 / 1.5m 2 \u003d 10.6 pcs. Round off - 11pcs. The system is planned to use the low temperature mode 55/45/20. Now let's find the temperature head for each of the systems:
- high-temperature 90/70 / 20- (90 + 70) / 2-20 \u003d 60 о С;
- low-temperature 55/45/20 - (55 + 45) / 2-20 \u003d 30 о С.
That is, if a low-temperature operating mode is used, twice as many sections will be needed to provide the room with heat. For our example, 22 sections of cast iron radiators are required for a room of 16m 2. 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.
With 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, just calculate the thermal 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 head for this case (90 + 70) / 2-25 \u003d 55 о С. Now we find the ratio 60 о С / 55 о С \u003d 1.1. To provide a temperature of 25 ° C, 11pcs * 1.1 \u003d 12.1pcs are needed.
Dependence of the power of radiators on 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 the top is considered optimal, in which case there is no heat loss. The largest losses are observed with lateral connection - 22%. All others are average in efficiency. The approximate percentage loss values \u200b\u200bare shown in the figure.
The actual power of the radiator also decreases in the presence of barriers. For example, if a window sill hangs from above, the heat transfer drops by 7-8%, if it does not completely cover the radiator, then the losses are 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 heating device, 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 is supplied to the input of each of the radiators. it is considered much more complicated: there, for each subsequent heating device, water is supplied increasingly colder. 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 us explain with an example. The diagram shows a one-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 is supplied with a coolant with a lower temperature. Determine the% power drop and increase the number of sections by the corresponding value. The picture looks like this: 15kW-3kW \u003d 12kW. Find the percentage: the temperature drop is 20%. Accordingly, to compensate, we increase the number of radiators: if 8 pieces were needed, there 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 a living room or other similar room, round it down. Take into account the location relative to the cardinal points: in the north you round it up, in the south - down it.
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 equal to its power is supplied to its input, and it is impossible to remove 100% in practice. Therefore, usually, when determining the boiler power for one-pipe systems, they take a certain margin, put shut-off valves and connect the radiators through the bypass so that heat transfer can be adjusted, and thus compensate for the drop in the coolant temperature. One thing follows from all this: the number and / or the size of radiators in a one-pipe system must be increased, and more and more sections must be installed as the distance from the beginning of the branch increases.
Outcome
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 heating devices to create a comfortable atmosphere in winter.
To increase the efficiency of the heating system, you need to correctly calculate the area and purchase high-quality heating elements.
Area based formula
The formula for calculating the power of a steel heating device, taking into account the area:
P \u003d V x 40 + heat loss due to windows + heat loss due to external door
- Р - power;
- V is the volume of the room;
- 40 W - thermal power for heating 1m 3;
- heat losses due to windows - to be calculated from the value of 100 W (0.1 kW) per 1 window;
- heat loss due to external door - calculate from 150-200 W.
Example:
A room 3x5 meters, 2.7 meters high, with one window and one door.
P \u003d (3 x 5 x 2.7) x40 +100 +150 \u003d 1870 W
So you can find out what the heat transfer of the heating device will be to ensure sufficient heating of a given area.
If the room is located in a corner or end of a building, an additional 20% of the headroom must be added to the battery power calculations. The same amount must be added in case of frequent drops in the temperature of the coolant.
Steel heating radiators, on average, produce 0.1-0.14 kW / section of heat energy.
T 11 (1 rib)
Tank depth: 63 mm. P \u003d 1.1 kW
T 22 (2 sections)
Depth: 100 mm. P \u003d 1.9 kW
T 33 (3 ribs)
Depth: 155 mm. P \u003d 2.7 kW
Power P is given for batteries 500 mm high, 1 m long at dT \u003d 60 deg (90/70/20) - a typical design of radiators, suitable for models from different manufacturers.
Table: heat transfer from heating radiators
Design for 1 (11 type), 2 (22 type), 3 (33 type) ribs
The heat transfer of the heating device must be at least 10% of the area of \u200b\u200bthe room if the ceiling height is less than 3 m. If the ceiling is higher, then another 30% is added.
Read also: Manufacturing a heating battery from a profile pipe
In the room, the batteries are installed under the windows against the outer wall, as a result of which the heat is distributed in the most optimal way. Cold air from the windows is blocked by the upward heat flow from the radiators, thereby eliminating the formation of drafts. 
If the dwelling is located in an area with severe frosts and cold winters, you need to multiply the obtained figures by 1.2 - the heat loss coefficient.
Another calculation example
As an example, a room with an area of \u200b\u200b15 m 2 and a ceiling height of 3 m is taken. The volume of the room is calculated: 15 x 3 \u003d 45 m 3. It is known that 41 W / 1 m 3 is needed to heat a room in an area with an average climate.
45 x 41 \u003d 1845 W.
The principle is the same as in the previous example, but the loss of heat transfer due to windows and doors is not taken into account, which creates a certain percentage of error. For a correct calculation, you need to know how much heat each of the sections gives out. The ribs can be in different numbers in steel panel batteries: from 1 to 3. How many ribs a battery has, that is how much heat transfer will increase.
The more heat transfer from the heating system, the better.