The basis of any heating is a boiler. Whether the house will be warm depends on how correctly its parameters are selected. In order for the parameters to be correct, it is necessary to calculate the boiler power. These are not the most complex calculations - at the third grade level, you will only need a calculator and some data on your possessions. You can handle everything yourself, with your own hands.
General points
In order for the house to be warm, the heating system must replenish all existing heat losses in full. Heat escapes through walls, windows, floors, and roofs. That is, when calculating the boiler power, it is necessary to take into account the degree of insulation of all these parts of the apartment or house. With a serious approach, they order a calculation of the building’s heat loss from specialists, and based on the results, they select the boiler and all other parameters of the heating system. This task is not to say that it is very difficult, but it is necessary to take into account what the walls, floor, ceiling are made of, their thickness and the degree of insulation. They also take into account the cost of windows and doors, whether there is a supply ventilation system and what its performance is. In general, a long process.
There is a second way to determine heat loss. You can actually determine the amount of heat that a house/room loses using a thermal imager. This is a small device that displays the actual picture of heat loss on the screen. At the same time, you can see where the outflow of heat is greater and take measures to eliminate leaks.
Determining actual heat loss - an easier way
Now let’s talk about whether it’s worth taking a boiler with a power reserve. In general, constant operation of equipment at the limit of its capabilities negatively affects its service life. Therefore, it is advisable to have a performance reserve. Small, about 15-20% of the calculated value. It is quite enough to ensure that the equipment does not work at the limit of its capabilities.
Too much stock is not economically profitable: the more powerful the equipment, the more expensive it is. Moreover, the price difference is significant. So, if you are not considering the possibility of increasing the heated area, you should not take a boiler with a large power reserve.
Calculation of boiler power by area
This is the easiest way to select a heating boiler by power. When analyzing many ready-made calculations, an average figure was derived: heating 10 square meters of area requires 1 kW of heat. This pattern is valid for rooms with a ceiling height of 2.5-2.7 m and average insulation. If your house or apartment fits these parameters, knowing the area of your house, you can easily determine the approximate performance of the boiler.
To make it clearer, we present An example of calculating the power of a heating boiler by area. There is a one-story house 12*14 m. Find its area. To do this, multiply its length and width: 12 m * 14 m = 168 sq.m. According to the method, we divide the area by 10 and get the required number of kilowatts: 168 / 10 = 16.8 kW. For ease of use, the figure can be rounded: the required heating boiler power is 17 kW.
Taking ceiling heights into account
But in private homes, ceilings may be higher. If the difference is only 10-15 cm, it can be ignored, but if the ceiling height is more than 2.9 m, you will have to recalculate. To do this, find a correction factor (dividing the actual height by the standard 2.6 m) and multiply the found figure by it.
Example of correction for ceiling heights. The building's ceiling height is 3.2 meters. It is necessary to recalculate the power of the heating boiler for these conditions (the parameters of the house are the same as in the first example):
As you can see, the difference is quite significant. If you do not take it into account, there is no guarantee that the house will be warm even at average winter temperatures, let alone severe frosts.
Accounting for region of residence
Something else worth considering is the location. After all, it is clear that in the south much less heat is required than in the Middle Zone, and for those who live in the north, the “Moscow region” power will clearly be insufficient. There are also coefficients to take into account the region of residence. They are given with a certain range, since within one zone the climate still varies greatly. If the house is located closer to the southern border, a smaller coefficient is used, closer to the northern - a larger one. It is also worth considering the presence/absence of strong winds and choosing a coefficient taking them into account.
Example of adjustment by zones. Let the house for which we calculate the boiler power be located in the north of the Moscow region. Then the found figure of 21 kW is multiplied by 1.5. Total we get: 21 kW * 1.5 = 31.5 kW.
As you can see, when compared with the original figure obtained when calculating by area (17 kW), obtained as a result of using only two coefficients, it is significantly different. Almost twice. So these parameters need to be taken into account.
Double-circuit boiler power
Above we discussed calculating the power of a boiler that only works for heating. If you also plan to heat water, you need to increase the productivity even more. When calculating the power of a boiler with the ability to heat water for domestic needs, 20-25% of the reserve is included (must be multiplied by 1.2-1.25).
To avoid having to buy a very powerful boiler, you need the house to
Example: we adjust for the possibility of DHW. We multiply the found figure of 31.5 kW by 1.2 and get 37.8 kW. The difference is significant. Please note that the reserve for water heating is taken after the location is taken into account in the calculations - the water temperature also depends on the location.
Features of calculating boiler performance for apartments
Calculation of boiler power for heating apartments is calculated according to the same norm: 1 kW of heat per 10 square meters. But the correction is taking place according to other parameters. The first thing that needs to be taken into account is the presence or absence of an unheated room above and below.
- if there is another heated apartment below/above, a coefficient of 0.7 is applied;
- if the room below/at the top is unheated, we do not make any changes;
- heated basement/attic - coefficient 0.9.
When making calculations, it is also worth taking into account the number of walls facing the street. Corner apartments require more heat:
- if there is one external wall - 1.1;
- two walls face the street - 1.2;
- three external ones - 1.3.
These are the main areas through which heat escapes. It is imperative to take them into account. You can also take into account the quality of the windows. If these are double-glazed windows, adjustments need not be made. If there are old wooden windows, the found figure must be multiplied by 1.2.
You can also take into account factors such as the location of the apartment. In the same way, you need to increase the power if you want to buy a double-circuit boiler (for heating hot water).
Calculation by volume
In the case of determining the power of a heating boiler for an apartment, you can use another method, which is based on SNiP standards. They stipulate standards for heating buildings:
- heating one cubic meter in a panel house requires 41 W of heat;
- to compensate for heat loss in a brick building - 34 W.
To use this method, you need to know the total volume of the premises. In principle, this approach is more correct, since it immediately takes into account the height of the ceilings. A slight difficulty may arise here: usually we know the area of our apartment. The volume will have to be calculated. To do this, we multiply the total heated area by the height of the ceilings. We get the required volume.
An example of calculating the power of a boiler for heating an apartment. Let the apartment be on the third floor of a five-story brick building. Its total area is 87 sq. m, ceiling height 2.8 m.
- Finding the volume. 87 * 2.7 = 234.9 cu. m.
- Round up - 235 cubic meters. m.
- We calculate the required power: 235 cubic meters. m * 34 W = 7990 W or 7.99 kW.
- Round up, we get 8 kW.
- Since there are heated apartments at the top and bottom, we apply a coefficient of 0.7. 8 kW * 0.7 = 5.6 kW.
- Round up: 6 kW.
- The boiler will also heat water for domestic needs. We will give a reserve of 25% for this. 6 kW * 1.25 = 7.5 kW.
- The windows in the apartment have not been replaced; they are old, wooden. Therefore, we use a multiplying factor of 1.2: 7.5 kW * 1.2 = 9 kW.
- Two walls in the apartment are external, so once again we multiply the found figure by 1.2: 9 kW * 1.2 = 10.8 kW.
- Round up: 11 kW.
In general, here is this technique for you. In principle, it can also be used to calculate the power of a boiler for a brick house. For other types of building materials, standards are not prescribed, and a panel private house is a rarity.
The heating boiler is the basis of the heating system; it is the main device, the performance of which will determine the ability of the communication network to provide the house with the amount of heat that is needed. And if you calculate the power of the heating boiler correctly and correctly, this will eliminate the occurrence of unnecessary costs associated with the purchase of devices and their operation. A boiler selected based on preliminary calculations will operate with the heat output that is included in it by the manufacturer - this will help maintain its technical parameters.
What is the calculation based on?
Calculating the power of a heating boiler is an important point. Power, as a rule, can be compared with the entire heat transfer of the heating system, which will provide a house with a certain size, with a given number of floors, and thermal properties.
To equip a one-story country or private house, you don’t need a very powerful heating boiler.
Thus, in calculating the performance of a boiler for an autonomous house, area is the main parameter if we consider the heating technology of the building in accordance with the climate of the region. So, the area of the house is the most important parameter to calculate the boiler for heating.
Characteristics that will influence the calculation
Those who want to calculate a boiler for heating a house with maximum accuracy can use the methodology provided by SNiP II-3-79. In this case, professional calculations will take into account the following factors:
- The average temperature of the region during the coldest time.
- Insulating properties of materials that were used to build enclosing structures.
- Type of heating circuit wiring.
- The ratio of the area of supporting structures and openings.
- Separate information about each room.
How to calculate the power of a heating boiler? To perform the most accurate calculations, even information such as data on household appliances and digital appliances is used - after all, all of this also somehow releases heat into the premises.
However, we note that not every owner of a heating system requires professional calculations - it is usually customary to purchase autonomous heating circuits with devices with a power reserve.
Thus, the efficiency of heating boilers may be higher than the calculated values, especially since they are usually rounded.
What must be taken into account?
How to calculate the power of a heating boiler, what data must be present? One rule should be remembered: every 10 sq.m of a cottage with insulating characteristics, a standard ceiling height limit (up to 3 m) will require approximately 1 kW for heating. You will need to add at least 20% to the power of the boiler, which is designed to work together in heating and hot water supply.
An autonomous heating circuit that has unstable pressure in the heating boiler will need to be equipped with a device so that its power reserve is higher than the calculated value by at least 15 percent. To the power of the boiler, which provides heating and hot water supply, you need to add 15%.
We take into account heat loss
Let us note that regardless of whether the power of an electric boiler, a gas boiler, a diesel boiler or a wood boiler is calculated, in any case, the operation of the heating system will be accompanied by heat losses:
- Ventilation of the premises is necessary, but if the windows are constantly open, the house will lose about 15% of energy.
- If the walls are poorly insulated, then 35% of the heat will be lost.
- 10% of the heat will escape through the window openings, and even more if the frames are old.
- If the floor is not insulated, then 15% of the heat will be transferred to the basement or ground.
- 25% of the heat will escape through the roof.
The simplest formula
Thermal calculations in any case will have to be rounded and also increased in order to provide a power reserve. That is why, in order to determine the power of a heating boiler, you can use a very simple formula:
W = S*Wsp.
Here S is the total area of the heated building, which takes into account residential and household rooms in sq.m.
W is the power of the heating boiler, kW.
Wud. – this is the average specific power, this parameter is used for calculations taking into account a certain climatic zone, kW/sq.m. And it is worth noting that this characteristic is based on many years of experience in the operation of different heating systems in the regions. And when we multiply the area by this indicator, we get the average power value. It will need to be adjusted based on the features listed above.
Calculation example
Let's look at an example using a heating boiler power calculator. Natural gas is the most affordable fuel used in Russia. For this reason, it is so widespread and in demand. Therefore, we will calculate the power of a gas boiler. As an example, let’s take a private house with an area of 140 sq.m. Territory - Krasnodar region. In the example, we also take into account that our boiler will provide not only heating for the house, but also water for plumbing fixtures. We will do the calculations for a system with natural circulation; the pressure here will not be maintained by a circulation pump.
Specific power – 0.85 kW/sq.m.
So, 140 sq.m/10 sq.m = 14 is an intermediate calculation coefficient. It will provide for the condition that for every 10 square meters of heated premises, 1 kW of heat will be required, which will be provided by the boiler.
14 * 0.85 = 11.9 kW.
We receive thermal energy that the house will need, which has standard thermal properties. To ensure hot water supply for showers and sinks, we will add another 20%.
11.9 + 11.9 * 0.2 = 14.28 kW.
We are not using a circulation pump, so we have to remember that the pressure here may be unstable. Therefore, we must add another 15% to provide thermal energy reserves.
14.28 + 11.9 * 0.15 = 16.07 kW.
You should also remember that there will be some heat leakage. This is why we must round our result up. Thus, we will need a heating boiler with a power of at least 17 kW.
As a rule, the calculation of the heating boiler power is carried out at the building design stage. After all, in order for the heating system to work efficiently, specific conditions are required - arrangement of the combustion chamber, provision of the premises with a chimney and ventilation.
The main question that arises when it is necessary to install autonomous heating at home is how to calculate the power of a gas boiler so that living quarters are comfortable in winter, and at the same time avoid unnecessary costs. It would be a mistake to think that you can select a boiler without calculations, simply by installing a unit with a large power reserve, since all modern heat generators are equipped with automatic systems that allow you to regulate fuel consumption. However, the installation of a boiler unit, the power of which will exceed the actual heat requirements, will lead, firstly, to additional costs for the purchase of the boiler itself and the corresponding components, and secondly, to its inefficient operation, which can cause automation failures and increased wear and tear of the equipment.
For large facilities, boiler units are selected by designers based on complex calculations, but for low-rise private houses this can be done independently, using simplified methods.
Boiler power calculation
Wall-mounted boiler with piping
Calculating the power of a gas boiler using simplified methods can be done both for an apartment or house built according to a standard design, and for a private house built according to an individual project.
Calculation for a typical house
To simplify the calculation of boiler power for a typical house, we proceed from the standard required specific thermal power of the boiler Um = 1 kW/10 m2, which means that to maintain a comfortable temperature in a room of 10 m2, 1 kW of thermal energy is required. The calculation does not take into account the volume of premises, since in all houses built according to standard designs, the height of the premises does not exceed 3 meters.
The formula for calculating the power of a boiler unit is as follows:
Rm = Mind x P x Kr
- P – the sum of all areas of heated premises;
- Kr is a coefficient that takes into account the climatic characteristics of the regions.
Since in Russia the climate in the regions is significantly different, a correction factor Kp is introduced, the value of which is accepted:
- for regions of southern Russia – 0.9;
- for middle zone regions – 1.2;
- for the Moscow region – 1.5;
- for northern regions – 2.0.
For example, for an apartment or house with a total area of 120 m2 located in the Moscow region, the required boiler power will be equal to:
Рм = 120 x 1.5/ 10 = 18 kW
The example shows a calculation for a boiler used only for heating purposes. In the case when it is necessary to calculate the power of a double-circuit unit intended, in addition to heating, for hot water supply, the power obtained from the formula should be increased by approximately 30%. In this case, the optimal boiler power will be equal to: 18 x 1.3 = 23.4 kW. Since the boiler capacities offered by manufacturers are given in whole numbers, you should choose a unit with the power closest to the design indicator - 25 kW.
Calculation of boiler power for an individual house
Heating system of a private house
Calculating the power of a gas boiler for a house built according to an individual project is more accurate, since it takes into account the height of the premises and some other parameters. The calculation is made using the formula:
Рм = Тп x Кз
- Рм – required design power of the boiler unit;
- Тп – possible heat losses of the building;
- Kz – safety factor, accepted within the range of 1.15-1.2.
In turn, the amount of possible heat loss from the building is calculated using the following formula:
Tp = Oz x RT x Kr
- Oz - the total volume of heated premises of the house;
- RT – temperature difference between outdoor air and indoor air;
- Kr is a coefficient that takes into account the dissipation of thermal energy and depends on the type of building envelope, the type of filling of window openings, and the degree of insulation of the building.
The dispersion coefficient value is taken for:
- buildings with a low degree of thermal protection, the walls of which, for example, are made of brick without a layer of insulation with standard wooden windows equal to 2.0-2.9;
- for buildings with an average degree of thermal protection, double walls with insulation, a small number of windows equal to 1.0-1.9;
- for houses with a high degree of thermal protection - insulated floors, double-glazed windows, wooden frames, timber or rounded logs, etc., equal to 0.6-0.9.
For example, for a house with an average degree of thermal protection, a total volume of heated premises of 630 m3 (two-story, with an area of one floor of 100 m2, but the height of the premises on the 1st floor is 3.3 m, on the 2nd floor - 3.0 m), the temperature difference between the outside air and indoor air 45 (calculated as the difference between the standard temperature in residential premises, taken to be 20 degrees, and the temperature of the coldest period of the year according to SNiP data for a given region, for example, 25 degrees below zero), the amount of heat loss will be equal to:
Tp = 630 x 45 x 1.0 = 28350 W.
The design power of the boiler will then be:
Рм = 28.35 x 1.2 = 34 kW
Calculation of boiler power using a calculator on the manufacturer’s website
Online calculator
Many manufacturers or companies selling heating equipment offer online calculators on their websites. Typically, for such a calculation you simply need to enter the following parameters into the calculator program:
- the temperature that needs to be maintained in the house;
- outside air temperature during the coldest period of the year;
- need for hot water supply;
- presence of a forced ventilation system;
- number of storeys of the house;
- height of premises;
- the nature of the floor structure;
- parameters of external walls - what material they are made of, whether there is insulation or not;
- information about the length of each external wall;
- information about the number and size of window openings and the nature of their filling;
It’s not difficult to determine all this data yourself, and then all you have to do is insert it into the appropriate sections of the program and get a ready-made calculation of the boiler power.
Detailed video lesson on calculation:
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To ensure comfortable living in a house in winter, the boiler must produce enough thermal energy to fully compensate for the heat loss of the building. In addition, it is necessary to provide a certain reserve of power in case of extreme cold or an increase in the area of the building. To calculate the boiler power, you need to take into account quite a few factors. In heating engineering, this calculation is one of the most difficult.
There are many calculations of the heating system, namely boiler power - one of the most complex
The need to calculate the heat transfer of the boiler
No matter what materials a building is built from, it constantly releases heat to the outside. Heat loss at home for each room may differ and depend on the materials of construction and the degree of insulation. If you take the calculations seriously, then it is better to entrust such work to specialists. Then, in accordance with the results obtained, a boiler is selected.
It is not very difficult to independently calculate the heat loss of a building, but there are many factors to take into account. The easiest way to solve this problem is with the help of a special device - a thermal imager. This is a small device, the display of which indicates the actual heat loss of the building. At the same time, you can clearly see those places where the maximum leaks of thermal energy are observed, and take measures to correct the situation.
You can immediately install a powerful boiler without calculations
Of course, you can just take a powerful boiler and not carry out any calculations. However, in such a situation, gas costs can be very high. In addition, if the boiler is underloaded, its service life is reduced. However, the heat generator can be additionally loaded, for example, by using it to heat previously unheated rooms. However, no owner of a private home will want to overpay for wasted fuel.
If the power of the heat generator turns out to be insufficient, then it will not be possible to create comfortable living conditions in the building, and the boiler itself will operate in constant overload mode. As a result, expensive equipment will fail prematurely. Thus, only one conclusion can be drawn - you need to calculate the power of the boiler for your home, thereby making a competent selection of heating equipment.
The easiest way is to independently calculate the power of the heating boiler based on the area of the house. After this, it will be possible to say exactly which heating unit is needed to heat all rooms of the building.
Basic formula
If we analyze the results of calculations carried out over several years, one pattern is observed - to heat every 10 m 2 of area it is necessary to expend 1 kW of thermal energy. This statement is true for buildings with average insulation, and the ceiling height in them is in the range from 2.5 to 2.7 m.
If the building meets these standards, then determining the power of heating boilers will be quite simple, just use a simple formula:
Latest indicator for various regions of the country has the following meanings:
- Moscow region - from 1.2 to 1.5 kW.
- Middle band - from 1 to 1.2 kW.
- South of the country - from 0.7 to 0.9 kW.
- Northern territories - from 1.5 to 2 kW.
As an example, we can calculate the power of a heat generator for a house measuring 12x14 m, built of brick in the Moscow region. The total area of the building is 168 m2. The specific power value Wsp is assumed to be 1. As a result, W = (168 × 1) / 10 = 16.8 kW. The resulting calculated power of the heat generator should be rounded up. However, this is not yet a complete calculation of a gas boiler for a house by area, since the resulting indicator needs to be adjusted.
Additional calculations
Residential buildings with average characteristics are quite rare in practice. In order for the boiler room power calculation to be as accurate as possible, additional indicators have to be taken into account. One of them has already been considered in the basic formula - the specific power spent on heating 10 m 2.
It is necessary to use the indicator for the middle band as a standard. Moreover, in each zone one can see a rather serious scatter in the specific capacitance values. The way out of this situation is simple - the further north the area is located in the climatic zone, the higher the coefficient should be, and vice versa. For example, for Siberia with frosts of about 35 degrees, it is customary to use Wsp = 1.8.
Another factor influencing the calculation of boiler power is the height of the ceilings. If this parameter differs significantly from the average (2.6 m), then it is necessary to calculate a correction factor. To do this, the real value must be divided by the average.
It is equally important to take into account the heat losses of the structure when making calculations. The process of heat leakage is observed in every building. For example, if the walls are poorly insulated, then losses can reach up to 35%. Thus, during calculations a special coefficient should be used:
- A structure made of wood, foam blocks or bricks, the age of which exceeds 15 years with high-quality insulation - K=1.
- Buildings of other materials with poorly insulated walls - K=1.5.
- If the building was not insulated also the roof, and not just the walls - K = 1.8.
- Modern high-quality insulated houses - K=0.6.
This is how the required power of the heat generator is calculated in order to make the right choice of equipment. However, if the boiler is also planned to be used for heating water, the resulting value of its power will have to be increased by 25%. Thus, to determine the required power of the heat generator you need to use the following algorithm:
- The total area of the building is calculated and divided by 10. In this case, the Wsp indicator does not need to be taken into account.
- The calculated value is adjusted depending on the climatic zone in which the structure is built. The indicator determined at the first stage is multiplied by the region coefficient.
- If the actual ceiling height differs significantly from the average, this must be taken into account when calculating. First you need to divide the actual figure by the average. The resulting coefficient is multiplied by the power of the heat generator, determined taking into account the correction for the climatic features of the area.
- The heat losses of the building are taken into account. The result obtained at the previous stage must be multiplied by the heat loss coefficient.
- If the boiler is also used to heat water, its power increases by 25%.
The result obtained using this algorithm is highly accurate, and it is suitable for selecting a boiler operating on any type of fuel.
In accordance with SNiP standards
You can calculate the power of equipment for a home heating system based on building codes and regulations (SNiP). This document determines the required amount of thermal energy to heat 1 m 3 of air. Calculation by volume is quite simple. It is enough just to determine the volume of the internal premises of the building and multiply it by the rate of thermal energy consumption.
According to SNiP, in a panel building, 41 W of heat energy must be consumed to heat 1 m 3 of air.
For a brick house the norm is 34 W. After performing the calculation, the resulting power value must be converted to kilowatts. It should also be recalled that in heating engineering, calculated indicators are rounded up.
If you want to get the most accurate results, then you need to take into account the correction factor:
- If there is a heated room above or below the apartment, the correction is 0.7.
- If it is unheated, the coefficient will be 1.
- If the apartment is located above the basement or under the attic, the amendment will be 0.9.
You also need to take into account the number of external walls in the room. When only one wall faces the street, the coefficient will be 1.1, with two - 1.2, three - 1.3. Thus, the calculation of a boiler for heating a house can be calculated based on the total volume of the building or its area. Whatever method is chosen, the process is not very complex. All necessary calculations can be carried out by any person who does not have special knowledge.
