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How to calculate a gas heating boiler by area. Rules for calculating the power of a boiler for heating a private house

One of the first parameters that people pay attention to when choosing heating equipment is performance. The calculation of the power of a gas heating boiler is performed in several ways. Comfort during operation depends on accurate calculations.

How to choose the power of a gas boiler

The calculation of the power of a gas heating boiler from the area is carried out in three different ways:

European manufacturers often calculate the performance of boiler equipment from the volume of the room. Therefore, in the technical documentation, the possibility of heating in m³ is indicated. This factor is taken into account when choosing a unit manufactured in the EU countries.

Most consultants who sell heating equipment independently calculate the required performance using the formula 1 kW = 10 m². Additional calculations are carried out according to the amount of coolant in the heating system.

Calculation of a single-circuit heating boiler

As noted above, independent calculations of the operating parameters of heating equipment are performed according to the formula 1 kW \u003d 10 m². To the result obtained, 15-20% of the reserve is added, due to which the heat generator, even in severe frosts, does not work at full load, which prolongs its service life.

For 60 m² - the unit will be able to satisfy the need for heat on 6 kW + 20% = 7.5 kilowatts. If there is no model with a suitable performance size, preference is given to heating equipment with a large power value.
In a similar way, calculations are made for 100 m² - the required power of boiler equipment, 12 kW.
For heating 150 m², a gas boiler is needed, with a capacity of 15 kW + 20% (3 kilowatts) = 18 kW. Accordingly, for 200 m², a 22 kW boiler is required.

These calculations are only suitable for single-circuit models that are not connected to an indirect heating boiler.

How to calculate the power of a double-circuit boiler

The formula for calculating the required power of a double-circuit gas boiler in terms of the heating area and hot water draw-off points is as follows, 10 m² = 1 kW + 20% (power reserve) + 20% (for water heating). It turns out that 40% is added immediately to the calculated performance.

The power of a double-circuit gas boiler for heating and hot water heating for 250 m² will be 25 kW + 40% (10 kilowatts) = 35 kW. Calculations are suitable for two-circuit equipment. To calculate the performance of a single-circuit unit connected to an indirect heating boiler, a different formula is used.

Calculation of the power of an indirect heating boiler and a single-circuit boiler

To calculate the required power of a single-circuit gas boiler with an indirect heating boiler, you must perform the following steps:

Determine what volume of the boiler will be sufficient to meet the needs of the residents of the house.
In the technical documentation for the storage tank, the required performance of the boiler equipment is indicated in order to maintain the heating of hot water, without taking into account the necessary heat for heating. A 200 liter boiler will require an average of about 30 kW.
The performance of the boiler equipment required for heating the house is calculated.

The resulting numbers are added up. The amount equal to 20% is subtracted from the result. This must be done for the reason that the heating will not simultaneously work for heating and DHW. The calculation of the thermal power of a single-circuit heating boiler, taking into account an external water heater for hot water supply, is done taking into account this feature.

What power reserve should a gas boiler have

The performance margin is calculated depending on the configuration of the heating equipment:

For single-circuit models, the margin is about 20%.
For two-circuit units, 20% + 20%.
Boilers with connection to an indirect heating boiler - in the storage tank configuration, the required additional performance margin is indicated.

The specified power reserve is valid for rooms up to 300 m². Houses with a larger area require competent heat engineering calculations.

Calculation of gas demand based on boiler power

The formula for calculating gas consumption, depending on the power of the boiler used, takes into account the efficiency of the heating equipment. For standard models of classical heating heat generators, the efficiency will be 92%, for condensing ones up to 108%.

In practice, this means that 1 m³ of gas is equal to 10 kW of thermal energy, assuming 100% heat transfer. Accordingly, with an efficiency of 92%, fuel costs will be 1.12 m³, and at 108% no more than 0.92 m³.

The method for calculating the volume of consumed gas takes into account the performance of the unit. So, a 10 kW heating device, within an hour, will burn 1.12 m³ of fuel, a 40 kW unit, 4.48 m³. This dependence of gas consumption on the power of boiler equipment is taken into account in complex heat engineering calculations.

The ratio is also built into the online heating costs. Manufacturers often indicate the average gas consumption for each model produced.

In order to fully calculate the approximate material costs of heating, it will be necessary to calculate the electricity consumption in volatile heating boilers. At the moment, boiler equipment operating on main gas is the most economical way of heating.

For heated buildings of a large area, calculations are carried out only after an audit of the heat loss of the building. In other cases, when calculating, they use special formulas or online services.

The basis of any heating system is the boiler. Whether it will be warm in the house depends on how correctly its parameters are selected. And in order for the parameters to be correct, it is necessary to calculate the power of the boiler. These are not the most complex calculations - at the level of the third grade, you will only need a calculator and some data on your possessions. Handle everything yourself, with your own hands.

General points

In order for the house to be warm, the heating system must make up for all the existing heat losses in full. Heat escapes through walls, windows, floor, roof. That is, when calculating the power of the boiler, it is necessary to take into account the degree of insulation of all these parts of an apartment or house. With a serious approach, specialists are ordered to calculate the heat loss of the building, and according to the results, the boiler and all other parameters of the heating system are already selected. This task is not to say that it is very difficult, but it is required to take into account what the walls, floor, ceiling are made of, their thickness and degree of insulation. They also take into account what windows and doors cost, whether there is a supply ventilation system and what is its performance. 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 with the help of 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.

Determination of actual heat losses - an easier way

Now about whether it is worth taking a boiler with a power reserve. In general, the constant operation of the equipment on the verge of capabilities negatively affects its service life. Therefore, it is desirable to have a margin of performance. 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 unprofitable economically: the more powerful the equipment, the more expensive it is. And 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 choose 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 medium insulation. If your house or apartment fits these parameters, knowing the area of \u200b\u200byour 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. We find its area. To do this, we 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 off: the required power of the heating boiler is 17 kW.

Accounting for ceiling heights

But in private homes, ceilings can 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, it finds a correction factor (by dividing the actual height by the standard 2.6 m) and multiplies the figure found by it.

Ceiling Height Adjustment Example. The building has a ceiling height of 3.2 meters. It is required 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 it is not taken into account, there is no guarantee that the house will be warm even at average winter temperatures, and there is no need to talk about severe frosts.

Accounting for the region of residence

Another thing to consider is the location. After all, it is clear that much less heat is required in the south than in the Middle Strip, and for those who live in the north, the “Moscow Region” power will obviously be insufficient. To account for the region of residence, there are also coefficients. They are given with a certain range, since within the same zone the climate still changes a lot. If the house is located closer to the southern border, a smaller coefficient is applied, closer to the north - a larger one. It is also worth considering the presence / absence of strong winds and choose a coefficient taking them into account.

An example of adjustment by zones. Let the house for which we are calculating the power of the boiler 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 the area (17 kW), obtained as a result of using only two coefficients, it differs significantly. Almost twice. So these parameters must be taken into account.

Power of a double-circuit boiler

Above we talked about calculating the power of the boiler, which works only for heating. If you plan to also heat the water, you need to increase the productivity even more. In calculating the power of the boiler with the possibility of heating water for domestic needs, 20-25% of the reserve is included (multiply by 1.2-1.25).

In order not to have to buy a very powerful boiler, you need a house as much as possible

Example: we adjust for the possibility of hot water supply. The found figure of 31.5 kW is multiplied by 1.2 and we get 37.8 kW. The difference is solid. 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 the performance of the boiler for apartments

The calculation of the boiler power for heating apartments is calculated according to the same norm: 1 kW of heat per 10 square meters. But the correction is going on in other ways. The first thing that needs to be taken into account is the presence or absence of an unheated room above and below.

if another heated apartment is located below / above, a coefficient of 0.7 is applied;
if there is an unheated room below / above, we do not make any changes;
heated basement / attic - coefficient 0.9.

It is also worth considering the number of walls facing the street when calculating. Corner apartments require more heat:

in the presence of one external wall - 1.1;
two walls face the street - 1.2;
three outer - 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 can not be made. If there are old wooden windows, the figure found must be multiplied by 1.2.

You can also take into account such factors 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).

Volume calculation

In the case of determining the power of a heating boiler for an apartment, you can use a different method, which is based on the norms of SNiP. They prescribe the norms for heating buildings:

heating one cubic meter in a panel house requires 41 W of heat;
to compensate for heat loss in brick - 34 watts.

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 little difficulty may arise here: usually we know the area of \u200b\u200byour apartment. The volume will have to be calculated. To do this, multiply the total heated area by the height of the ceilings. We get the desired 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 volume. 87 * 2.7 = 234.9 cu. m.
Rounding up - 235 cu. m.
We consider the required power: 235 cubic meters. m * 34 W = 7990 W or 7.99 kW.
We round up, we get 8 kW.
Since there are heated apartments above and below, we apply a coefficient of 0.7. 8 kW * 0.7 = 5.6 kW.
Rounding up: 6 kW.
The boiler will also heat domestic water. We will give a margin of 25% for this. 6 kW * 1.25 = 7.5 kW.
The windows in the apartment have not been changed, 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 figure found by 1.2: 9 kW * 1.2 = 10.8 kW.
Rounding up: 11 kW.

In general, here is the method 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, the norms are not prescribed, and a panel private house is a rarity.

When choosing a boiler, it is sometimes difficult to determine its compliance with the heating requirements of a particular house. It seems that there is data on the size, internal volume. But this is not enough. The modern definition requires knowledge of the heat loss characteristic of this house. It is with heat losses that the possibility of choosing the power of the future boiler is associated, which should compensate for them in the course of its work.

Incorrectly selected boiler power leads to additional fuel costs(gas, solid and liquid). Each option will be discussed below, but for now it must be taken into account that, as a first approximation, insufficient boiler power leads to a low temperature in the heating system, due to its slow and insufficient heating. Power that exceeds the required leads to the operation of the system in a pulsed mode. It causes a sharp increase in gas consumption, wear of the gas valve. The right choice of boiler power and calculation of the heating system can help reduce heating costs.

Method for calculating heat losses

Calculation of heat losses is carried out according to certain methods, different from the climatic zone of the country. Having such calculations on hand, it is much easier to navigate in the choice of all the devices of the future heating system. The abundance of incoming data, basic and auxiliary, as well as the formalization of calculations, made it possible to introduce automation and carry them out using computer programs. Thanks to this, such calculations have become available for individual execution on the websites of construction companies.

Of course, only a specialist can determine the exact results. But an independent determination of the magnitude of heat loss will give quite visible results with the determination of the required power. By entering the data requested by the program, according to the parameters of the house(cubic capacity, materials, insulation, windows and doors, etc.), after performing the proposed actions, the value of heat losses is obtained. The resulting accuracy is sufficient to determine the required power of the boiler.

Using house ratios

The old way of determining the amount of heat loss was use of house coefficients of 3 types for an individual calculation of the power of a gas boiler using a simplified method:

from 130 to 200 W / m2 - houses without thermal insulation;
from 90 to 110 W / m2 - houses with thermal insulation, 20-30 years;
from 50 to 70 W/m2 - heat-insulated house with new windows, 21st century.

Knowing the value of your coefficient and the area of \u200b\u200bthe house, by multiplying, the desired value is obtained. The required power was even easier to determine during the Soviet era. Then it was believed that 10 kW per 100 meters of area is just right.

However, today such accuracy is no longer enough.

What affects the power of the boiler

If it is too small, then a powerful solid fuel boiler will not “burn out” the remaining fuel due to lack of air supply, the chimney will quickly become clogged, and fuel consumption will be excessive. Gas or oil fired (LF) boilers will quickly heat a small amount of water and turn off the burners. This burning time will be the shorter, the more powerful the boilers. In such a short time, the removed combustion products will not have time to warm up the chimney, and condensate will accumulate there. Acids formed quickly will render unusable like a chimney, and the boiler itself.

Long burner operation allows the chimney to warm up and the condensate to disappear. Frequent switching on of the boiler leads to wear of it and the chimney, as well as increased fuel consumption due to the need to warm up the chimney channel and the boiler itself. To calculate the power of a liquid fuel (diesel) boiler, you can use calculator program, taking into account many of the features described above (designs, materials, windows, insulation), but express analysis can be performed using the above method.

It is believed that 1-1.5 kW of boiler power is needed to heat 10 square meters of a house. DHW is not taken into account in a house with high-quality insulation, without heat loss, with an area of 100 sq. m. Coefficients for the level of insulation used to calculate the required power of the boiler ZhT:

0,11 - apartment, 1st and last floors of an apartment building;
0,065 - an apartment in an apartment building;
0,15 (0,16) - a private house, a wall of 1.5 bricks, without insulation;
0,07 (0,08) - private house, wall 2 bricks, 1 layer of insulation.

For calculation, an area of 100 sq. m. is multiplied by a factor of 0.07 (0.08). The received power is 70-80 W per 1 sq. m. area. The boiler power is reserved by 10–20%, for hot water supply the reserve increases to 50%. This calculation is very approximate.

Knowing the heat losses, we can say about the required amount of heat generated. Usually, for comfort in the house, the value is taken +20 degrees Celsius. Since there is a period of minimum temperatures in the year, the demand for heat increases sharply on these days. Taking into account the periods when temperatures fluctuate around the average for the winter, the boiler power can be taken equal to half of the previously obtained value. In this case, compensation for heat losses due to other heat sources is taken into account.

Solving the problem of excess power

In the case of low heat demand, the boiler output becomes obviously high. There are several solutions. Firstly, during this period, the use of 4-way mixing valves in hydraulic systems is proposed. Can be applied thermohydraulic distributor. That allows you to regulate the heating of water without changing the boiler power, due to valves and circulation pumps. This ensures optimal operation of the boiler.

Due to the high cost of the method, a budget option is being considered. multi-stage burners in inexpensive gas and LT boilers. With the onset of the specified period, a stepwise transition to reduced combustion reduces the boiler power. A variant of smooth transition is modulation or smooth adjustment, commonly used in wall-mounted gas appliances. This possibility is almost not used in the designs of LT boilers, although a modulating burner is a more advanced option than a mixing valve. Modern pellet boilers are already equipped power control system and automatic fuel supply.

For the inexperienced consumer the presence of a modulating burner system may seem like a sufficient reason to abandon the calculation of heat losses at home, or at least limit themselves to an approximate definition. By no means, the presence of such a function cannot solve all the problems that arise: if, when the boiler is turned on, it starts working at maximum power, then after a while the machine reduces it to the optimum.

At the same time, a powerful boiler in a small system has time heat water and turn off even before the transition of the modulating burner, I needed the desired level of combustion. The water cools down quickly enough, the situation will repeat itself “to a blot”. As a result, the operation of the boiler takes place in impulses as with a single-stage powerful burner. The change in power can reach no more than 30%, which will eventually lead to failures with a further increase in the external temperature. It is worth remembering that it is about relatively cheap devices.

In more expensive condensing boilers, the modulation limits are wider. ZhT boilers can cause tangible difficulties when trying to use in small and well-insulated houses. In such a house, about 150 sq. m, 10 kW of power is enough to cover heat losses. In the line of ZhT boilers offered by manufacturers, the minimum power is twice as much. And here an attempt to use such a boiler can lead to a situation even worse than that described above.

ZhT (diesel fuel) is burning in the furnace, everyone saw a black plume behind an unheated and unregulated diesel engine. And here in the products of incomplete combustion, soot falls abundantly, it and unburned products are thoroughly clog the combustion chamber. And now the brand new boiler needs to be urgently cleaned so as not to reduce the efficiency and restore heat transfer. And after all, if you first select the correct power of the boiler, there would not be all the problems described.

In practice, you should choose the boiler power slightly lower than the heat losses of the house. Popularity and practical use have gained boilers with TsOGVS, i.e. double-circuit, heating water for heating and hot water supply. And among these two functions, the required capacity for CH is less than for DHW. Of course, this approach made the choice of boiler power more difficult.

The method of obtaining hot water in a 2-circuit boiler - flow heating. Since the time of contact (heating) of running water is insignificant, the power of the boiler heater must be high. Even for low-power double-circuit boilers, the DHW system has 18 kW of power and this is only the minimum, which makes it possible to take a normal shower. The presence of a modulating burner in such a device will make it possible to work with a minimum power of 6 kW, almost equal to the heat loss in a 100-meter house with high-quality thermal insulation.

In real life, average, for the heating season, the needs will be no more than 3 kW. That is, although the situation is not ideal, it is acceptable. A way to reduce the required capacity of the DHW system is to use a DHW storage tank. And it is very similar to a single-circuit boiler equipped with a boiler. The boiler connected through the heat exchanger to the boiler has a capacity at least 100 liters. This is a minimum, designed for several points of water intake and their simultaneous use.

This scheme allows reduce boiler output combined with a water heater. As a result, the task is completed and the boiler power is sufficient to compensate for heat losses (CH) and hot water (boiler). At first glance, as a result, during the operation of the boiler to the boiler, hot water will not go into the heating system and the temperature in the house will drop. In fact, for this to happen, the boiler must turn off for 3 - 4 hours. The process of replacing heated water from the boiler with cold water occurs gradually. The practice of using heated water says that even draining half the volume, which is 50 liters at a temperature of about 85 degrees Celsius and the same amount of cold to use, leads to the remainder in the tank of half the volume of hot and the same amount of cold. The heating time will be no more than 25 minutes. Since such a volume is not consumed at a time in the family, the heating time of the boiler will be much less.

An example of determining the boiler power

An approximate method for determining the power of a gas boiler based on its specific power (Rud) per 10 sq. m and taking into account the conditions of climatic zones, heated area - P.

0.7−0.9 - south;
1.2−1.5 kW - middle band;
1.5−2.0 kW - north

Boiler power is determined Pk \u003d (P * Rud) / 10; where Rud = 1;

The volume of water in the system Osist \u003d Pk * 15; where 1 kW is accepted for 15 liters of water

So for the house from the example with a LT boiler, in the north, the calculation will look like this:
Pk \u003d 100 * 2/10 \u003d 20 (kW);

How to calculate the power of a gas boiler for the given parameters of a heated room? I know at least three different ways that give different levels of reliability of results, and today we will get acquainted with each of them.

general information

Why do we calculate the parameters specifically for gas heating?
The fact is that gas is the most economical (and, accordingly, the most popular) source of heat. A kilowatt-hour of thermal energy obtained by its combustion costs the consumer 50-70 kopecks.
For comparison, the price of a kilowatt-hour of heat for other energy carriers:

solid fuel- 1.1-1.6 rubles per kilowatt-hour;

Diesel fuel- 3.5 rubles / kWh;

Electricity- 5 rubles / kWh.

In addition to efficiency, gas equipment attracts with ease of use. The boiler requires maintenance no more than once a year, does not need kindling, cleaning the ash pan and replenishing the fuel supply. Devices with electronic ignition work with remote thermostats and are able to automatically maintain a constant temperature in the house, regardless of the weather.

Does the calculation of a gas boiler for a home differ from the calculation of a solid fuel, liquid fuel or electric boiler?

In general, no. Any heat source must compensate for heat loss through the floor, walls, windows and ceiling of the building. Its thermal power has nothing to do with the energy carrier used.

In the case of a double-circuit boiler supplying the house with domestic hot water, we need a reserve of power to heat it. Excess power will ensure the simultaneous flow of water in the DHW system and the heating of the coolant for heating.

Calculation methods

Scheme 1: by area

We will be helped in this by the normative documentation of half a century ago. According to Soviet SNiP, heating should be designed at the rate of 100 watts of heat per square meter of heated space.

Let's, for example, calculate the power for a house measuring 6x8 meters:

The area of the house is equal to the product of its overall dimensions. 6x8x48 m2;

With a specific power of 100 W / m2, the total power of the boiler should be 48x100 \u003d 4800 watts, or 4.8 kW.

The choice of boiler power according to the area of the heated room is simple, understandable and ... in most cases gives the wrong result.

Because he neglects a number of important factors that affect real heat loss:

Number of windows and doors. More heat is lost through glazing and doorways than through a main wall;

ceiling height. In Soviet-built apartment buildings, it was standard - 2.5 meters with a minimum error. But in modern cottages you can find ceilings 3, 4 or more meters high. The higher the ceiling, the larger the heated volume;

climate zone. With the same quality of thermal insulation, heat loss is directly proportional to the difference between indoor and outdoor temperatures.

In an apartment building, heat loss is affected by the location of the living space relative to the outer walls: end and corner rooms lose more heat. However, in a typical cottage, all rooms have common walls with the street, so the appropriate correction factor is included in the base value of the heat output.

Scheme 2: by volume, taking into account additional factors

How to do the calculation of a gas boiler for heating a private house with your own hands, taking into account all the factors I mentioned?

First and foremost: in the calculation, we take into account not the area of \u200b\u200bthe house, but its volume, that is, the product of the area by the height of the ceilings.

base value boiler power per cubic meter of heated volume - 60 watts;

Window increases heat loss by 100 watts;

Door adds 200 watts;

Heat losses are multiplied by the regional coefficient. It is determined by the average temperature of the coldest month:

Image Coefficient and climate zone

0,6-0,9 - for regions with an average January temperature of about 0 °C (Krasnodar Territory, Crimea).

1,2-1,3 - for the average temperature of the coldest month at -15-20 °C (Moscow and Leningrad regions).

1,5-1,6 - for areas with an average January temperature of -25-30 ° C (Novosibirsk region, Khabarovsk Territory).

2 - for -40 and below (Chukotka, Yakutia).
Let's again calculate the boiler power for our house measuring 6x8 meters, specifying a few additional parameters:

House location- the city of Sevastopol (the average January temperature is +3 degrees Celsius);

Number of windows- 5. One door leads to the street;

Ceiling height- 3.2 meters.

House volume(with external walls) is equal to the product of its three dimensions: 6x8x3.2 = 153.6 cubic meters;

Base power for this volume - 153.6x60 \u003d 9216 W;

Including windows and doors it will increase by 5x100+200=700 watts. 9216+700=9916;

Regional coefficient for the warm climate of the Crimea, we will take equal to 0.6.

9916*0.6=6000 (with rounding) watts.

As you can see, the complicated calculation scheme gave a result that is noticeably different from the previous one. How accurate is it?

The calculation will give a reliable result for a house, the quality of insulation of which approximately corresponds to the quality of insulation of Soviet-built houses. The scheme is based on the same 100 watts per square area, recalculated taking into account the standard ceiling height of 2.5 meters at 40 W / m3 and multiplied by a factor of 1.5 to compensate for the heat loss of a private house through the roof and floor.

How to determine the need for heat in a house with non-standard insulation?

Scheme 3: by volume, taking into account the quality of insulation

The most universal formula for calculating the heat output of a boiler is Q=V*Dt*k/860.

In this formula:

Q - heat loss of the house in kilowatts;

V is the volume to be heated by the boiler, in cubic meters;

Dt is the calculated temperature delta between the heated room and the air behind the outer walls;

k - dispersion coefficient, determined by the quality of insulation of the house.

How to choose the coefficient k?

Select its value for your conditions, guided by the following table:

Image Coefficient value and description of the building

3-4 - building without insulation (a warehouse made of profiled sheets, a panel house with walls made of planks in one layer)

2.0-2.9 - walls made of timber 10 cm thick or bricks 25 cm thick, wooden frames, single glazing

1.0-1.9 - brick walls 50 cm thick, double glazing in the windows

0.6-0.9 - facade insulated with foam plastic or mineral wool, plastic windows with triple or energy-saving double-glazed windows
How to choose the value of the calculated outdoor temperature? In calculations, it is customary to use the temperature of the coldest five-day winter for a given region. Rare extreme frosts are not taken into account: when the thermometer falls below the usual levels, auxiliary heat sources (heaters, fan heaters, etc.) can be used.

Where can I get relevant information? The instruction is quite predictable: the necessary data can be found in SNiP 23-01-99, a regulatory document on building climatology.

For the convenience of readers, I will give here a short excerpt from the text of SNiP.

City Temperature of the coldest 5 days of winter, °С
Maykop -22
Barnaul -42
Blagoveshchensk -37
Tynda -46
Shimanovsk -41
Arkhangelsk -37
Astrakhan -26
Ufa -39
Belgorod -28
Bryansk -30
Ulan-Ude -40
Vladimir -34
Vologda -37
Voronezh -31
Makhachkala -19
Irkutsk -38
Kaliningrad -24
Petropavlovsk-Kamchatsky -22
Pechora -48
Kostroma -35
Agatha -55
Turukhansk -56
St. Petersburg -30
Susuman -57
Moscow -32
Novosibirsk -42
Vladivostok -26
Komsomolsk-on-Amur -37
Yalta -8
Sevastopol -11

Let's return to our example with a house in Sevastopol, once again clarifying a few details:

Window glazing- single, in wooden large-slotted frames;

wall material- but, about half a meter thick.

Let's start with the calculations.

For the calculated internal temperature, we will take the corresponding sanitary standards + 20 ° С. Given the data from the table above, the Dt parameter will be equal to 20 - -11 = 31 degrees;

We take the dispersion coefficient equal to 2.0: the thermal conductivity of rubble walls is much higher than that of brick walls;

We calculated the volume of the house earlier. It is equal to 153.6 cubes;

Substitute the values of the variables in our formula. Q \u003d 153.6x31 * 2 / 860 \u003d 11 kW.

As you can see, the correction for significant heat losses almost doubled the calculated capacity of the gas boiler.

Two circuits

It's very simple: a 20% reserve is included in the project for the operation of the second flow. In our case, the required power will be 11x1.2 = 13.2 kW.

How not to make a mistake and correctly choose a device so as not to freeze and not to thin the budget - read on. From the article you will find out which technique will be correct and necessary for you.

Calculation of heat losses at home

We say right away - there is no single method for calculating the coefficient. The setting varies depending on your climate. It is all the more important to pay more attention to this stage of preparation. Even a specialist will not determine by eye, without calculations, information on the required boiler power. Even low-power ones, such as, can heat an average apartment up to 65m². But what it exactly should be - it will become known after filling out a special questionnaire - the document is freely available, anyone can fill it out on the Internet.

Experts approached the compilation of the questionnaire responsibly. By filling in the fields, you will not be able to make a mistake. The only exception is the incorrect filling of the online form. All other calculations of the boiler for the house will be performed by the program.

So, here are the questions you need to be prepared for - specify:

1. Heat loss through walls

This parameter is affected by the area of the facade and the ventilated layer (walls are with it, and sometimes without it). The first wall covering is the paramount criterion, without which it will be too risky to choose a heating boiler. Reinforced concrete or foam concrete, mineral wool, drywall, plywood or wood - the material affects the decision of what power to buy solid fuel equipment. The thickness of the first layer of the house is also important. For thin-walled houses, buy a medium power boiler - for example,.

2. Heat loss through windows

Important condition. It is logical that more heat will "leave" with a single-chamber double-glazed window than with two-chamber ones. The area of windows is also important when calculating the power of the boiler. Before filling out the questionnaire, measure it again.

3. Heat loss through ceiling and floor

As you understand, in a room with an attic and an unheated basement, you need to install powerful equipment - like. Incorrectly selected power of the device will spoil several winter months spent in a country house - heating is clearly not enough for a comfortable life.

Useful to know:

If you do everything right, your efforts will be rewarded with a profitable investment in the purchase. Consider that you have coped with the task - most likely, you will get the best result in terms of price and quality.

Why is it important to accurately determine the power of the boiler

The first thing that comes to mind is saving money on a purchase. For this alone, it is worth spending a couple of hours on calculations. Given the good work and efficient operation of the boiler, the calculation of the power of the equipment becomes even more necessary.

Here are some unhappy scenarios that will inevitably unfold if you do not take into account the above.

Remember: The correction for the region for our climate is a factor of 1.2.

An incorrect calculation of the power of a not so popular, but still occurring pellet device (for example) and a wood-fired boiler is the first choice parameter. To calculate the parameter, do not be too lazy to spend time, otherwise you cannot avoid the above problems in the lack of heat (if we are talking about weak appliances) or inefficient waste of fuel (when you pick up an expensive and too powerful boiler, like).

Determining the power of the boiler is the most important stage of work

So you got acquainted with the theoretical part of the question, having received information about the importance of calculating the power of boilers. Now it's time to move on to the practical part - the most important. As an option, a specialist responsible for the calculation of parameters and installation. But you yourself can find out what technique is really needed.

When calculating power, we start from the area of \u200b\u200bthe heated object - it is she who will help to evaluate performance. Keep in mind that with a room height of 2.7 m (and such ceilings are in almost all houses), it takes 1 kW to heat 10 m².

This ratio is approximate. It is influenced by the climate of the region and, again, the height of the ceilings, the presence of basements, etc.

Advice: in order to calculate the power of an ideal boiler for high ceilings, it is necessary to determine the correction factor by dividing the parameter by the standard 2.7m.

Example:

The ceilings are 3.1m.

We divide the parameter by 2.7 - we get 1.14.

So, for high-quality heating of a house of 200 m² with ceilings of 3.1 m, a boiler with a capacity of 200 kW * 1.14 = 22.8 kW is useful.

In order not to freeze for sure, we recommend rounding the parameter up. Then get 23kW. We are suitable for 24 kW.

Please note that this calculation is suitable for a single-circuit boiler. In the case of c, you need to calculate what water temperature you want to get in the cold, and choose a technique in accordance with the parameter (+ 25%, power, if you like hot water).

Step-by-step calculation of boiler power (double-circuit) for apartments

With apartments, the situation is somewhat different. Here the coefficient is less than in the house - in apartments there is no heat loss through the roof (if we are not talking about the last floor) and losses through the floor (except for the first floor).

if another room "warms up" the apartment from above, the coefficient will be 0.7

if there is an attic above you - 1

To calculate the parameter, we use the technique indicated above, taking into account the coefficient.

Example: The area of the apartment is 163m². Its ceilings are 2.9 m, the apartment is located in our lane.

We determine the power in five steps:

We divide the area by the coefficient: 163m² / 10m² = 16.3 kW.

Do not forget about the correction for the region: 16.3 kW * 1.2 = 19.56 kW.

Since the double-circuit boiler is designed for hot water, we add 25% 7.56 kW * 1.25 = 9.45 kW.

And now do not forget about the cold (experts advise adding another 10%): 9.45 kW * 1.1 \u003d 24.45 kW.

We round up, and it turns out 25 kW. It turns out that it will suit us - a device that runs on natural gas and interacts with solar collectors.

Please note that in this way the power of the boilers is calculated, no matter what fuel they operate on - even gas, even electricity, even solid fuel. .

Step-by-step calculation of the power of the boiler (single-circuit) for an apartment

But what if you do not need a double-circuit boiler, and with tasks? We will make calculations, taking into account one more factor - the material of manufacture of the house. The norm of heating established at the legislative level looks like this:

Heating 1m³ in a panel house will require 41 watts.

Heating 1m³ in a brick house will require 34 watts.

We invite you to familiarize yourself with:

We remember the area of the apartment, multiply it by the height of the ceilings, we get the volume. This indicator must be multiplied by the norm - we get the power of the boiler.

Example:

You live in a 120m² apartment with 2.6m ceilings.

The volume will be as follows: 120m² * 2.6m = 192.4m³

We multiply by the coefficient, we calculate the need for heat 192.4m³ * 34W = 106081W.

We translate into kilowatts and rounding up, we get 11kW. This is the power that a thermal single-circuit unit should have. A good option is the model. A little "with a margin", the power of this technique is more than enough for a comfortable microclimate in your home.

As you can see, the task of selecting a boiler will not take more than an hour. By choosing the right heating device, you will insure yourself against uncomfortable cold weather for the whole winter, saving money on the purchase of a boiler and utilities. Correctly calculate the parameter - it is equally important for all types of heaters: coal, TT,