How to independently calculate the power of a heating boiler. Rules for calculating the power of a boiler for heating a private house 30 kW boiler for how many squares is enough

24.10.2023

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What does boiler power affect?

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 liquid fuel boilers will quickly heat a small amount of water and turn off the burners. This burning time will be 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 condensation will accumulate there. Acids formed quickly will fall into disrepair like a chimney, and the boiler itself.

Long burner operating time allows the chimney to warm up and the condensation will disappear. Frequent switching on of the boiler leads to wear and tear on the boiler and the chimney, as well as increased fuel consumption due to the need to heat up the chimney duct 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 (structures, materials, windows, insulation), but express analysis can be carried out using the given methodology.

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

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

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

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

Power calculation practical examples

The power indicator depends primarily on 3 factors:

House area.
Features of the climate of the region.
Thermal insulation, wall material.

House area per 100 m2, 150 m2, 200 m2

Assuming that we are talking about a private house of standard quality, in which thermal insulation is carried out in accordance with building codes, The ratio works well - 1 kilowatt of power per 10 m2 of house. The formula is suitable for cases when several conditions are met simultaneously:

the house has normal thermal insulation of walls, floors, and ceilings;
ceiling height is standard (up to 330-350 cm);
The windows have double glazed windows (Euro windows);
the number of windows is standard, their sizes are typical;
at least 2 doors at the entrance with an unheated or partially heated hallway (canopy);
a region with normal climatic characteristics, moderately frosty winters (average January temperature is about -13°C).

Regional climate and correction factor

Despite the fact that on average 10 m2 requires 1 kW, it is required to enter climate correction factor:

0.8 for the southern regions;
1.2 for the Middle Band;
1.5 for the Moscow region and the North-West;
1.8 for Western Siberia and the Far East;
2.0 for Eastern Siberia;
more than 2.0 – for some regions with a particularly harsh climate (Yamalo-Nenets Autonomous Okrug, Republic of Sakha, Chukotka Autonomous Okrug, etc.).

Then the general formula for the power M of a gas boiler is as follows:

where S is the area of the house in m2, k is the climate coefficient for the regions.

For example:

for the regions of Western Siberia the approximate figure per 100 sq. m. house: 100*1.8/10 = 18 kW,
for the Middle Band the indicator is per 100 sq. m. house: 100*1.2/10 = 12 kW.

This formula represents the basic ratio (for a standard home). With its help, you can calculate the power of the device for any area - 150 m2, 200 m2, etc. The table shows an example of calculation for buildings of different sizes (provided that it is located in the climatic zone of the Moscow region).

The degree of thermal insulation of the house

If the thermal insulation of a house does not meet construction standards, and the wear and tear of the building is quite large, experts recommend increasing the calculated value by another 15-20%. Then for Western Siberia a power of 20 kW is sufficient, and for the Middle Zone - about 14 kW.

The exact ratios of power and thermal insulation of the building are presented in the table.

The resulting value should be multiplied by this coefficient to obtain the final answer.

EXAMPLE

A private house of 150 m2 is located in the North-West (Vologda region), the level of insulation is average. The calculation of the power of a gas boiler for heating a house is as follows: 150 * 1.5 * 2/10 = 45 kW.

Typical mistakes when choosing a boiler

Correct calculation of the power of a gas boiler will not only save on consumables, but will also increase the efficiency of the device. Equipment whose heat output exceeds the actual heat requirements will work ineffectively when, as an insufficiently powerful device, it cannot heat the room properly.

There is modern automated equipment that independently regulates the gas supply, which eliminates unnecessary costs. But if such a boiler performs its work to the limit of its capabilities, then its service life decreases, efficiency decreases, parts wear out faster, and condensation forms. Therefore, there is a need to calculate optimal power.

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The main condition for installing a gas boiler is the installation of an internal gas network connected to a centralized gas supply, a group of cylinders or a gas holder

When choosing a gas boiler, it is necessary to take into account the diameter of the gas and heating supply pipes. To install a double-circuit boiler, the house must be equipped with a water supply system, the minimum pressure in which also requires consideration before purchase

To select a gas boiler correctly, it is necessary to take into account the pressure in the gas supply line. If connected to a centralized network, it is indicated by the fuel supplier

The power of gas equipment is directly related to the size of the unit, type of installation and design

The wall-mounted version is more compact, but it should be noted that in 1 minute a wall-mounted boiler heats only 0.57 liters of water at 25º. This is acceptable for a dacha or apartment; to heat a large building, a more powerful unit is needed

Floor-standing gas boilers are purchased if the volume of coolant circulating through the system is more than 150 liters. Power varies from 10 to 55 or more kW

Floor-standing gas boilers can be used both as a heating boiler and as a water heater, capable of simultaneously providing water to up to 4 water points

Conditions for installing a gas boiler

Supply of pipelines to equipment

Internal gas pipeline in the room

Dimensions and design type

Power limitations of wall-mounted options

Floor-standing boiler for a large house

Boiler as a water heater

Volume of floor-standing gas boilers

There is an opinion that the power of the boiler depends solely on the surface area of the room, and for any home the optimal calculation would be 100 W per 1 sq.m. Therefore, in order to select the boiler power, for example, for a house of 100 sq. m, you will need equipment generating 100*10=10000 W or 10 kW.

Such calculations are fundamentally incorrect due to the advent of new finishing materials and improved insulation materials, which reduce the need to purchase high-power equipment.

The power of the gas boiler is selected taking into account the individual characteristics of the home. Correctly selected equipment will work as efficiently as possible with minimal fuel consumption

There are two ways to calculate the power of a gas heating boiler - manually or using a special Valtec program, which is designed for professional high-precision calculations.

The required power of the equipment directly depends on the heat loss of the room. Once you know the heat loss rate, you can calculate the power of a gas boiler or any other heating device.

It is very simple, because it provides that for heating each 1 sq. m need to create 100 W of heat. True, the formula has a more complex form:

Where S is the area of the house ,

k is a coefficient that determines heat loss depending on the air temperature outside the window. For regions where the winter air temperature does not drop below -10 °C, it is 0.7. It is clear that it increases as the degrees outside the window decrease. For every 5 °C it increases by 0.2. For regions where thermometers show -35 °C in winter, k is 1.2.

If you need to heat a house that has an area of 115 square meters. m and is located in an area where the minimum winter temperature is -20 ° C, then you need to install an economical electric boiler with a power of 115 * 1.1 * 100 = 12,650 W = 12.65 kW.

This calculation is very simple, but is not always correct. It's because Many factors influence heat loss. In this case, it is valid for a house that has:

windows with double glazing and an area of no more than 30% of the area of all rooms;
average thermal insulation (wall thickness equal to the length of 2 bricks, insulation 15 cm thick);
cold attic;
rooms whose height is 2.5 m.

External walls are not taken into account here. This is because even with 1 such wall the correction factor should be 1.1. For 2 walls it is equal to 1.2, 3 - 1.3, etc.

That is, to heat the above-mentioned house you need to use an economical heating boiler with the power 12.65*1.4 = 17.71 kW/h. It is clear that it is better to take a device that is capable of delivering 20 kW/hour.

Basic calculation rules

At the beginning of our story about how to calculate the power of a heating boiler, we will consider the quantities used in the calculations:

room area (S);
specific heater power per 10 m² of heated area – (W spec.). This value is determined adjusted for the climatic conditions of a particular region.

This value (W beat) is:

for the Moscow region - from 1.2 kW to 1.5 kW;
for the southern regions of the country - from 0.7 kW to 0.9 kW;
for the northern regions of the country - from 1.5 kW to 2.0 kW.

Let's do the calculations

Power calculation is carried out as follows:

W cat.=(S*Wsp.):10

Advice! For simplicity, you can use a simplified version of this calculation. In it Wsp.=1. Therefore, the heat output of the boiler is determined as 10 kW per 100 m² of heated area. But with such calculations, you must add at least 15% to the resulting value in order to get a more objective figure.

Calculation example

As you can see, the instructions for calculating the heat transfer intensity are simple. But, nevertheless, we will accompany it with a specific example.

The conditions will be as follows. The area of heated premises in the house is 100 m². The specific power for the Moscow region is 1.2 kW. Substituting the available values into the formula, we get the following:

W boiler = (100x1.2)/10 = 12 kilowatts.

What is room heat loss

Any room has certain heat losses. Heat comes out of walls, windows, floors, doors, ceilings, so the task of a gas boiler is to compensate for the amount of heat coming out and provide a certain temperature in the room. This requires a certain thermal power.

It has been experimentally established that the largest amount of heat escapes through the walls (up to 70%). Up to 30% of thermal energy can escape through the roof and windows, and up to 40% through the ventilation system. Lowest heat loss at doors (up to 6%) and floors (up to 15%)

The following factors influence heat loss at home.

Location of the house. Each city has its own climatic characteristics. When calculating heat loss, it is necessary to take into account the critical negative temperature characteristic of the region, as well as the average temperature and duration of the heating season (for accurate calculations using the program).
The location of the walls relative to the cardinal directions. It is known that the wind rose is located in the north side, so the heat loss of a wall located in this area will be the greatest. In winter, cold wind blows with great force from the western, northern and eastern sides, so the heat loss of these walls will be higher.
The area of the heated room. The amount of heat lost depends on the size of the room, the area of walls, ceilings, windows, doors.
Thermal engineering of building structures. Any material has its own coefficient of thermal resistance and heat transfer coefficient - the ability to pass a certain amount of heat through itself. To find them out, you need to use tabular data, as well as apply certain formulas. Information about the composition of walls, ceilings, floors, and their thickness can be found in the technical plan of housing.
Window and door openings. Size, modification of door and double-glazed windows. The larger the area of window and door openings, the higher the heat loss. It is important to take into account the characteristics of installed doors and double-glazed windows when making calculations.
Ventilation accounting. Ventilation always exists in the house, regardless of the presence of artificial hood. The room is ventilated through open windows; air movement is created when the entrance doors are closed and opened, people move from room to room, which helps warm air leave the room and circulate it.

Knowing the above parameters, you can not only calculate the heat losses of the house and determine the power of the boiler, but also identify places that need additional insulation.

How to choose the power of a gas boiler

Accurate thermal calculations are performed only after an audit of the building for possible heat losses. For research, a thermal imager is used. The location of the heated building is taken into account. Calculations are performed using complex thermotechnical formulas.
1. The disadvantage of the solution is the cost of paying for the services of a specialist.
2. The advantage is the most accurate calculation results.
Online calculator - calculations are performed using a special program. To obtain the results, you will need to enter data on thermal insulation, the total number of window and door openings, wall thickness, etc. Using an online calculator is the optimal solution when calculating boiler equipment for domestic needs. With its help, a heat generator with the smallest error in performance is selected, without material costs.
Independent calculations per square meters of heated premises. To calculate operating parameters, it is not necessary to use complex calculations and online calculators. You can calculate the ratio of the required power of a gas boiler relative to the area of the room yourself, without resorting to the services of specialists, without software. Calculations are performed using the formula 1 kW = 10 m². Selecting a gas boiler using these calculations is suitable for rooms with an average degree of thermal insulation and a ceiling height of 2.7 m.

Most consultants selling heating equipment independently calculate the required performance using the formula 1 kW = 10 m². Additional calculations are made based on the amount of coolant in the heating system.

Calculation of a single-circuit heating boiler

For 60 m², a unit of 6 kW + 20% = 7.5 kilowatts can satisfy the heat demand. If there is no model with a suitable performance size, preference is given to heating equipment with a higher power value.
Calculations are carried out in a similar way for 100 m² - the required power of the boiler equipment is 12 kW.
To heat 150 m² you need a gas boiler with a capacity of 15 kW + 20% (3 kilowatts) = 18 kW. Accordingly, for 200 m², a 22 kW boiler is required.

How to calculate the power of a double-circuit boiler

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

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

What power reserve should a gas boiler have?

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

Calculation of gas demand based on boiler power

Power determination methods

The magnitude of these losses can be calculated using various methods. Some of them involve the use of very complex formulas, which, of course, many buyers do not like. After all, you need to spend a lot of time to calculate the desired figure. Therefore, two simple methods will be considered below:

Allows determine the amount of heat loss at home, knowing only the area .
Allows set the thermal power of an economical electric boiler with high efficiency using the volume .

Before considering each method, it is worth noting that all electric boilers are distinguished by the fact that they are capable of converting 100% of electrical energy into almost 100% of thermal energy. In this case, it does not matter whether it heats the water with heating elements, electrodes or inductance coils. Thanks to this feature, after determining the heat loss of the house, there is no need to adjust this figure, taking into account the efficiency of the heating boiler.

For comparison, you can take a solid fuel boiler with an efficiency of 90%. If 1 kg of firewood produces 3 kW/h, then this means that only 3x0.9 = 2.7 kW/h will enter the heating network. In the case of electrical devices, 3 kW/h of electricity will be converted into 3 kW/h of thermal energy. As you can see, this feature partially simplifies the calculation.

Dependence of the power of electric boilers on heat loss

We have already found out that calculating an electric boiler for heating a house based only on the square footage of the room, at least, does not reflect the real picture. The frequently asked question of how many meters a heater of a certain power will heat does not have a correct answer. It's all about heat loss. If you have panoramic windows in all directions, uninsulated walls and ceilings, cracks in windows and doors, then you will mainly heat the street, not the house. It's big, no matter how much you drown it, it won't get warmer.

The boiler must give off no less heat than the room loses it. In other words, if the heat loss of a house is 15 kilowatts, then the heater must be no less than this value in order to maintain a comfortable temperature. At the same time, heat loss occurs continuously, and it turns out that the boiler must operate constantly, and this is unacceptable. The heater must take breaks, so you need to calculate the power of an electric heating boiler with a good margin. Otherwise, the unit, working in emergency mode, may soon fail, and during the heating season this is fraught with serious consequences.

material of walls and ceilings;
thickness and area of walls and ceilings;
number of cameras and window area.

All this is needed to determine the thermal resistance of the house. Each material has its own thermal conductivity. It can be found out from the table.

The table shows the thermal conductivity values of the most common materials.

To calculate the thermal resistance of walls and ceilings, you need to divide their thickness by the thermal conductivity coefficient of the materials from which they are made. The calculation is done for each material separately. Then all values are summed up.

Once we know the thermal resistance of the house, we can move on to calculating the total heat loss. To do this, we multiply the square footage of the house by the temperature delta in the room and outside the window, and divide the result by the thermal resistance. The temperature delta should be taken for the coldest period. Calculating the power of an electric boiler for heating a house, taking into account, first of all, heat loss, will be the most accurate. Therefore, do not be lazy and use this method. Yes, it is more troublesome, and you need to take a lot of things into account, but the result will be adequate, you will do the calculation correctly.

Today, heating a garage with electricity is as important as heating a private home with electrical appliances.

Attention! Conservative-minded citizens, a brick stove for heating a garage is your option.

Power calculation for DHW

It is carried out in the following sequence:

The volume of warm water used by all family members is determined.
The volume of hot water (90-95 °C) is determined, which will be diluted with running water to form a liquid that has a comfortable temperature for the body.
The additional boiler power is calculated.

So, let a family live in a house that uses 150 liters of warm water per day, that is, liquid with a temperature of 37 °C. This water will be supplied after mixing hot and running water. The volume of hot water is determined by the formula:

Vв is the volume of demanded warm water,
Tzh - the desired temperature of warm water at the outlet of the tap,
Tp is the temperature of running water,
Tg is the temperature of the heated liquid in the indirect boiler.

For the above example, Vv = 150 l, Tp = 8 °C, Tzh = 37 °C, Tg = 95 °C. Vg = 150*(37-8)/(95-8) = 50 l. This means that a 50 liter boiler is enough for a home.

The formula for determining additional power is:

Where c is the specific heat capacity of water(always equals 4.218 kJ/kg*K),

ΔT represents the difference between temperatures heated and running water.

Рд = 4.218*50*(95-8) = 18,348.3 kJ. In terms of kW/h, this figure is 5.1 kW/h.

As you can see, to heat a house you need to purchase an electric heating boiler with a power of 20+5.1 = 25.1 kW/hour. This is the case if the water in the boiler must be heated in 1 hour. If it needs to be heated in 2, then you can install a boiler whose power is 20+2.55 = 22.55 kW/hour.

Power and number of sections of aluminum radiators Connecting an electric boiler to the heating system Manufacturing the Scorpion electric boiler Power of heating radiators

What factors need to be taken into account when calculating boiler power

The first thing you need to start calculating is the premises of the house. You need to take into account all their characteristics, including volume and area, the materials from which the structure is built and the degree of its insulation.
In addition, you need to calculate the sources of cold, which are the elements of the house, and without which it cannot do - doors and windows, floors, walls and roof, ventilation system.

Possible points of heat loss in a private home

All these structural elements or technical equipment contain heat in rooms in different ways, but each of them gives a certain percentage of heat loss, depending on the material of its manufacture.
The difference in air temperature in the rooms of the home and outside also plays an important role in the calculations - the lower it is outside the building, the faster the house cools down.
The average winter temperature in the region where the building is located is also taken into account.
If the boiler is intended not only for heating, but also for heating water, this factor must also be taken into account when calculating.

The calculations take into account all loads placed on the boiler

Armed with such indicators, you can make calculations and determine the power of the heating boiler in different ways.

Heating boiler power theory and real facts

A heating device operating on coal, wood or other organic fuel performs a certain job related to heating the coolant. The amount of work of boiler equipment is determined by the volume of heat load that a solid fuel boiler can withstand when burning a certain amount of fuel. The ratio of the amount of fuel consumed, the amount of thermal energy released at optimal operating modes of the equipment is the boiler power.

A heating unit that is incorrectly selected for power will not be able to provide the required boiler water temperature in the heating circuit. Low-power solid fuel devices will not allow the autonomous system to fully meet your needs in terms of heating your home and ensuring the operation of the hot water supply. There will be a need to increase the power of the autonomous device. A powerful device, on the contrary, will create problems during operation. It will be necessary to make design changes to the existing heating complex to reduce the thermal load of the solid fuel heating device. Why waste precious fuel if there is no need for so much heat.

For reference: Exceeding the boiler power of the technological parameters of the heating system leads to the fact that the coolant in the circuit will disperse impulsively. Frequent switching on and off of the heating unit leads to excessive fuel consumption and a decrease in the operational capabilities of heating equipment in general.

From a theoretical point of view, calculating the optimal operating mode of boiler equipment is not difficult. It is generally accepted that 10 kW is enough to heat a living space of 10 m2. This indicator is taken taking into account the high thermal efficiency of the building and standard design features of the building (ceiling height, glazing area).

In theory, the calculation is made based on the following parameters:

area of the heated room;
specific power of heating equipment for heating is 10 kW. m, taking into account the climatic conditions of your region.

The table shows the average parameters of boiler equipment used by consumers in the Moscow region:

The thermal load parameters look optimal on paper, in theory, which is clearly not enough in relation to local conditions. The selected unit in reality should have redundant capabilities. In reality, you need to focus on equipment that can operate with a small power reserve.

On a note: The excess power of a solid fuel boiler will allow the entire heating system in the house to quickly reach optimal operating conditions. The additional resource should exceed the calculated data by 20-30%.

The actual load indicators of solid fuel units depend on a combination of various factors. The climatic conditions of the region in which you live may make adjustments when choosing a heating boiler. For the middle zone, the following power parameters of boiler equipment are considered optimal:

one-room city apartment - boiler with an output load of 4.16-5 kW;
for a two-room apartment - equipment rated at 5.85-6 kW;
for a three-room apartment it will be enough to have a unit of 8.71-10 kW;
a four-room apartment or a private residential house will require a boiler with parameters of 12-24 kW for heating.

Important! When it comes to installing solid fuel boiler equipment in private homes and suburban residential buildings, it is necessary to focus on devices with greater technological capabilities. To heat and provide hot water supply to a residential building with an area of 150 m2 or more, you will need to install a solid fuel boiler of 24 kW or more

It all depends on the intensity of the heating system and the volume of domestic needs for hot water.

It is always necessary to choose heating equipment individually, based on calculated data and your own needs.

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.

Heat flows out of the house in different directions

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):

We calculate the coefficient. 3.2 m / 2.6 m = 1.23.
Let's correct the result: 17 kW * 1.23 = 20.91 kW.
Rounding up, we get 21 kW required for heating.

When choosing a boiler based on power, do not forget that with increasing power, the size of the unit also increases

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.

Central Russia is taken as a standard. Here the coefficient is 1-1.1 (closer to the northern border of the region it is still worth increasing the boiler power).
For Moscow and the Moscow region, the result obtained must be multiplied by 1.2 - 1.5.
For northern regions, when calculating the boiler power by area, the found figure is multiplied by 1.5-2.0.
For the southern part of the region, the reduction coefficients are: 0.7-0.9.

It is also necessary to take into account your region of residence

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 to insulate the house as much as possible

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.

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

Electrical energy consumption. How to determine it

We will need some calculations to achieve the desired result.

In addition, the calculation requires taking into account a number of parameters:

Average daily duration of work at maximum load;
Residence mode;
Efficiency and productivity;
Calculation of operating hours during the heating season;
The volume of coolant in the heating circuit;
Tank size of the heating device;
Calculation of heating area;
Heating device voltage;
Calculation of power cable cross-section;
Calculation of the volume of heated premises;
Number of circuits in the equipment.

The calculation assumes the use of average values. Several adjustments are required for factors such as the type of thermal insulation used, the thermal conductivity of the walls, temperature readings, and so on. Power should also take this into account.

An electric heating boiler requires the use of a special cable. The main factor when choosing it is power. There is a simple empirical relationship here, which is not difficult to understand: the cross-sectional area of the cable in mm2 for a single-phase electric boiler must be no less than the heating power, expressed in kW. This makes the calculation simpler. It is necessary to coordinate your actions with the authorities that monitor the use of resources if the indicator for the boiler is at the level of 10 kW or more.

Rice. 2 Device from the inside

Installation of floor and wall boilers

Design of a three-phase electric boiler.

It is advisable to install electric boilers in rooms with an area of up to 500 m2. You can install the heating system and connect the boiler to it yourself. In the wall version they are secured with anchor bolts, and in the floor version they are usually installed on a special stand. If you do not have experience installing and connecting circuit breakers against short circuits and leakage currents, then it is better to contact a specialist electrician. In this matter, liberties are unacceptable.

The cross-section of the cable cores must comply with the requirements specified in the accompanying documentation; it depends on the power. There may be problems with protective grounding. Keep in mind that grounding is not just a pin driven into the ground, but a device on which life depends. All metal parts of the heating system must be connected to the ground loop.

And most importantly. The resistance of the grounding loop must meet the standards for the corresponding soil. The maximum value of grounding resistance depends on the physical properties of the soil and must be indicated in the issued permits. The lower the ground resistance, the better. The maximum value should not exceed 10 ohms. To reduce the resistance of the grounding circuit, copper plates must be used, and the grounding site must be impregnated with a saline solution. The grounding resistance value must be checked before the start of the heating season.

Types of boilers

Classification and selection features

The type of boiler is of particular importance when organizing autonomous heating in a house. Now in most modern buildings the following types of boilers are installed:

electrical,
gas,
solid fuel,
liquid fuel.

Each of these species has unique characteristics. Therefore, during installation the following parameters are taken into account:

frequency of use of a country house,
number of inhabitants,
region,
footage, etc.

Also, the type of boiler largely affects its cost.

Because of this, you need to be doubly careful when purchasing.

Kinds

A solid fuel heating boiler has the following characteristic qualities:

affordability,
complete autonomy,
efficiency.

An important disadvantage of the device is its relatively low efficiency. Moreover, storing solid fuel requires a lot of space. But the most important disadvantage of a solid fuel boiler, which must be taken into account when calculating, is the variability of temperature. During the day it can fall or rise by 2-3 degrees.

An electric heating boiler has the following advantages:

compactness,
environmental friendliness,
ease of use.

The main disadvantage of an electric heating boiler is the high cost of energy, and this must be taken into account when calculating. Liquid fuel boilers are highly convenient to use. However, their fire hazard is at a high level.

Gas heating boilers are quite economical. Especially considering that gas prices are at an affordable level. They are very often installed in various organizations. Their advantages include:

ease of use,
efficiency,
compactness.

Unfortunately, their benefits largely depend on the price of gas. If it grows, then using equipment of this type will simply be unprofitable.

Basic calculation of the power of an electric heat generator

Definition! The power of the electric heating unit must completely replenish the heat loss of all rooms. If necessary, the power that will be spent on heating water is taken into account.

Professional calculation of the power of electric heating equipment takes into account the following factors:

The average temperature during the coldest period of the year.
Insulating characteristics of materials used in the construction of building envelopes.
Type of heating circuit wiring.
The ratio of the total area of door and window openings and the area of supporting structures.
Specific information about each heated room - the number of corner walls, the estimated number of radiators, etc.

Attention! To perform particularly accurate calculations, household appliances, the number of computers and video equipment, which also generate thermal energy, are taken into account. . Typically, professional calculations are rarely carried out, and when purchasing, they choose a unit whose power exceeds the approximately calculated value

Typically, professional calculations are rarely carried out, and when purchasing, they choose a unit whose power exceeds the approximately calculated value.

To approximately calculate power (W), use the following formula:

W=S*Wud/10m2, where S is the area of the heated building in m2.

Wsp is the specific power of the unit, the value of which is individual for each region:

for cold climates – 1.2-2.0;
for the middle zone – 1.0-1.2;
for the southern regions - 0.7-0.9.

Calculation of heating boiler power by area

For a rough estimate of the required performance of a heating unit, the area of the premises is sufficient. In the simplest version for central Russia, it is believed that 1 kW of power can heat 10 m2 of area. If you have a house with an area of 160 m2, the boiler power for heating it is 16 kW.

These calculations are approximate, because neither ceiling height nor climate are taken into account. For this purpose, there are coefficients derived experimentally, with the help of which appropriate adjustments are made.

The specified norm is 1 kW per 10 m2, suitable for ceilings of 2.5-2.7 m. If you have higher ceilings in the room, you need to calculate the coefficients and recalculate. To do this, divide the height of your premises by the standard 2.7 m and obtain a correction factor.

Calculating the power of a heating boiler by area is the easiest way

For example, the ceiling height is 3.2 m. We calculate the coefficient: 3.2m/2.7m=1.18, round it up, we get 1.2. It turns out that to heat a room of 160 m2 with a ceiling height of 3.2 m, a heating boiler with a capacity of 16 kW * 1.2 = 19.2 kW is required. They usually round up, so 20 kW.

To take into account climatic features, there are ready-made coefficients. For Russia they are:

1.5-2.0 for northern regions;
1.2-1.5 for Moscow region regions;
1.0-1.2 for the middle band;
0.7-0.9 for the southern regions.

If the house is located in the middle zone, just south of Moscow, a coefficient of 1.2 is used (20 kW * 1.2 = 24 kW), if in the south of Russia in the Krasnodar Territory, for example, the coefficient is 0.8, that is, less power is required (20 kW * 0 ,8=16kW).

Heating calculations and boiler selection are an important step. Find the power incorrectly and you can get the following result...

These are the main factors that need to be taken into account. But the values found are valid if the boiler operates only for heating. If you also need to heat water, you need to add 20-25% of the calculated figure. Then you need to add a “reserve” for peak winter temperatures. That's another 10%. In total we get:

For heating a house and hot water in the middle zone 24 kW + 20% = 28.8 kW. Then the reserve for cold weather is 28.8 kW + 10% = 31.68 kW. We round up and get 32 kW. If we compare it with the original figure of 16 kW, the difference is twofold.
House in Krasnodar region. We add power to heat hot water: 16 kW + 20% = 19.2 kW. Now the “reserve” for cold weather is 19.2+10%=21.12 kW. Round up: 22 kW. The difference is not so striking, but still quite significant.

From the examples it is clear that at least these values must be taken into account. But it is obvious that when calculating the boiler power for a house and an apartment, there should be a difference. You can go the same way and use coefficients for each factor. But there is an easier way that allows you to make corrections in one go.

When calculating a heating boiler for a home, a coefficient of 1.5 is used. It takes into account the presence of heat loss through the roof, floor, and foundation. Valid for an average (normal) degree of wall insulation - masonry with two bricks or building materials with similar characteristics.

For apartments, different coefficients apply. If there is a heated room on top (another apartment) the coefficient is 0.7, if there is a heated attic - 0.9, if there is an unheated attic - 1.0. You need to multiply the boiler power found using the method described above by one of these coefficients and get a fairly reliable value.

To demonstrate the progress of the calculations, we will calculate the power of a gas heating boiler for an apartment of 65 m2 with 3 m ceilings, which is located in central Russia.

We determine the required power by area: 65m2/10m2=6.5kW.
We make an adjustment for the region: 6.5 kW * 1.2 = 7.8 kW.
The boiler will heat the water, so we add 25% (we like it hot) 7.8 kW * 1.25 = 9.75 kW.
Add 10% for cold weather: 7.95 kW * 1.1 = 10.725 kW.

Now we round the result and get: 11KW.

This algorithm is valid for selecting heating boilers using any type of fuel. Calculating the power of an electric heating boiler will be no different from calculating a solid fuel, gas or liquid fuel boiler. The main thing is the productivity and efficiency of the boiler, and heat loss does not change depending on the type of boiler. The whole question is how to spend less energy. And this is the area of insulation.

general information

Why do we calculate 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 during its combustion costs the consumer 50-70 kopecks.

For comparison, the price of a kilowatt-hour of heat for other energy sources:

Solid fuel- 1.1-1.6 rubles per kilowatt-hour;
Diesel fuel- 3.5 rubles/kWh;
Electricity- 5 rubles/kWh.

In addition to being economical, gas equipment is attractive due to its ease of use. The boiler requires maintenance no more than once a year, does not require 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.

A main gas boiler equipped with electronic ignition combines maximum efficiency with ease of use.

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 is in no way related to the energy carrier used.

In the case of a double-circuit boiler that supplies the house with hot water for household needs, we need a power reserve to heat it. Excess power will ensure simultaneous water consumption in the hot water system and heating of the heating medium.

Factors affecting thermal output

Number of external walls.
Window type.
Level of thermal insulation of walls.
Window area.
Height of rooms.
The presence of an insulated attic.

Conventional windows with standard glazing allow 27% of the heat to escape. That is, with such windows, the result obtained using the formula described above must be multiplied by 1.27. For windows with a triple package, the correction factor is 0.85.

The same coefficients are applied for poorly and very well insulated walls, respectively. As for the window area, in the case when it is 40% of the room area, an additional 10% of heat can be lost through windows. That is, the coefficient is 1.1. With a further increase in the ratio of window area to floor area by 10%, it rises by 0.1.

The height of the room should be taken into account when it exceeds 2.5 m. For this figure, the correction factor is 1. With a further increase in height by 0.5 m, it becomes larger by 0.5. That is, for 4-meter walls it is equal to 1.15. If there is a cold attic, the resulting figure does not need to be adjusted. If it is insulated or there is a heated room on top, then the result is multiplied by 0.9 or 0.8.

What types of gas boilers are there for heating?

Modern boilers for heating systems can be placed both on the floor and on the wall, having their inherent features:

Floor-standing appliances are the most common gas boilers for heating large rooms. This design is installed in special boiler rooms with an area of about 6-10 square meters and with good ventilation. When installing a floor-standing device, you need to retreat about 1 meter from the walls.
Wall-mounted units are used to heat small rooms. This design takes up very little space. They are manufactured in two versions: with a flow heating system or with a combustion chamber. The room should also have a small ventilation hole.

It is also necessary to mention the design types of gas boilers, since this parameter is also taken into account when choosing heating equipment:

A boiler with a closed firebox is equipped with a special fan that transports air into the firebox, ensuring high-quality combustion of gas. The advantage of such a device is that the combustion chamber is purged both before fuel is supplied and after it is turned off, which significantly reduces the risk of gas ignition in the firebox itself. The efficiency of this design is very high at low economic costs.
A boiler with an open combustion chamber is a classic design in which the draft for fuel combustion is created by a chimney. Moreover, the cost of such a unit is much lower than that of designs with a closed combustion chamber. However, the absence of a fan in the design itself significantly reduces the efficiency of the device, increasing the requirements for the chimney duct.

The material from which the gas boiler is made is an equally important parameter when choosing equipment. There are three types of heating units, based on the material of manufacture:

Steel units are “economy” class structures that are cheaper in price, but inferior to other systems in terms of technical characteristics.
Stainless steel systems are mainly used for wall structures. These are modern high-tech devices with good power.
Cast iron products are the most reliable floor-mounted heat exchangers; their power is slightly higher than that of stainless steel models. Such a boiler is durable and has a high heat capacity, due to the thickness of the walls and large mass.

Thus, for a gas heating system in a house, it is better to choose cast iron boilers, since such units are very practical, reliable and durable.

Determining the ideal ratio of power and economy

Several boilers included in one system

To follow the principles of economy, you need to take into account some more points when operating the boiler.

In cold weather, it is necessary to maintain a temperature in the house of 20-22 degrees; it is optimally comfortable for the human body. But given that the temperature changes during the winter, and the coldest days occur only a few times during the heating season, you can warm the house using a boiler with a power half lower than that obtained in the calculations.

For the normal functioning of the boiler for many years, it is better if it operates at rated rather than peak power. But during the heating season, the need to maintain a high temperature in the house sometimes disappears. To get out of this situation, mixing valves are used.

Mixing valve

They are needed so that you can regulate the temperature of the coolant in the batteries. For this purpose, hydraulic systems with thermohydraulic distributors or four-way valves are used. If they are installed in a heating system, the temperature can be changed with a regulator, leaving the boiler power constant.

After such upgrades, even a small boiler will operate in optimal mode, sufficient for high-quality heating of all rooms. This solution is quite expensive, but it will help save on fuel consumption.

Another case is when the boiler has a power that is exceeded for a given room, and you don’t want to overpay for excess fuel, which should ensure its operation. To avoid these unpleasant expenses, you can install a buffer tank (battery tank), which is completely filled with water.

This addition will come in handy if solid fuel boilers are used for heating - the device will operate at full power, even if only short-term heat is required.

When the temperature outside rises and it is too early to turn off the boiler, the automatic valve begins to limit the flow of heated water into the radiators. He directs it to the heat exchanger of the buffer tank, and there it will heat the water that is already in the tank. The volume of the tank should be 10:1 in relation to the area of the house, for example, for 50 square meters of area you will need a tank with a volume of 500 liters.

Installing a storage tank provides significant energy savings

This water, having heated up, begins to function after the water in the circuit cools - it begins to flow into the radiators, and the system will continue to heat the rooms for some time.

Each manufacturer is now trying to provide the buyer with a full set of equipment that he may need, power is also taken into account. The electric boiler was no exception. It comes complete with a programmer, a pump for coolant circulation, and an expansion tank. Thanks to this, it is easy to understand what the power indicator of an electric boiler should be. Even a novice user can handle this.

In addition, devices to protect equipment and special cables are required. Thus, the installation can be completely done by yourself. The power of the boiler does not matter.

But sometimes independent additional equipment is required. For those who understand electric models, this solution is often the most relevant. Including power. The power supply system can be used of the usual type if an electric boiler is installed, the power of which reaches 6 kW.

Recently, the electricity consumption of an electric boiler has become no less important an indicator than the installation of a special pump in the system. This solution also helps to understand how much electricity is being wasted and why. In this case, consumption is noticeably reduced. The system will be able to use pipes with a smaller diameter than in a normal situation. A wet rotor pump is the main type of equipment that can most often be seen in private homes. Its power fully meets the requirements.

The rotor is washed with liquid, which is never pumped by electrical equipment. Resource consumption becomes more profitable.
No additional fan is required because the device never overheats. The boiler's power is sufficient for normal loads.
Due to the fact that there is no fan, the operation of the entire system becomes almost silent. In residential premises this becomes especially relevant; power does not suffer from this.

Such pumps themselves can support automatic or manual adjustment. Power in this case does not play a big role. The first option is the most preferable because it saves energy. Then heating with an electric boiler itself becomes more profitable.

How much does his work cost? To make a calculation, it is enough to know about some operating features. For example, what temperature is most often maintained in the room. As for the general scheme for heating a house, it is better to choose forced circulation. This is also the best option, allowing you to achieve maximum results with minimal investment.

Concept of dispersion coefficient

The dissipation coefficient is one of the important indicators of heat exchange between a living space and the environment. Depending on how well the house is insulated. There are indicators that are used in the most accurate calculation formula:

3.0 – 4.0 is the dissipation coefficient for structures that do not have any thermal insulation at all. Most often in such cases we are talking about temporary structures made of corrugated iron or wood.
A coefficient of 2.9 to 2.0 is typical for buildings with a low level of thermal insulation. This refers to houses with thin walls (for example, one brick) without insulation, with ordinary wooden frames and a simple roof.
An average level of thermal insulation and a coefficient of 1.9 to 1.0 are assigned to houses with double plastic windows, insulation of external walls or double masonry, as well as with an insulated roof or attic.
The lowest dispersion coefficient from 0.6 to 0.9 is typical for houses built using modern materials and technologies. In such houses, the walls, roof and floor are insulated, good windows are installed and the ventilation system is well thought out.

Table for calculating the cost of heating in a private house

The formula that uses the value of the dissipation coefficient is one of the most accurate and allows you to calculate the heat loss of a particular structure. She looks like this:

In the formula Qt – this is the level of heat loss, V – is the volume of the room (the product of length, width and height), Pt – this is the temperature difference (to calculate it is necessary to subtract from the desired temperature in the room the minimum air temperature that can be at this latitude), k – this is the dissipation coefficient.

Let's substitute the numbers into our formula and try to find out the heat loss of a house with a volume of 300 m³ (10 m*10 m*3 m) with an average level of thermal insulation at a desired air temperature of +20C° and a minimum winter temperature of -20C°.

Having this figure, we can find out what power boiler is needed for such a house. To do this, the resulting heat loss value should be multiplied by the safety factor, which is usually from 1.15 to 1.2 (the same 15-20%). We get that:

By rounding the resulting number down, we find out the required number. To heat a house under the conditions we have specified, you will need a 38 kW boiler.

This formula will allow you to very accurately determine the power of the gas boiler required for a particular home. Also today, many different calculators and programs have been developed that allow you to take into account the data of each individual building.

One of the main components of comfortable housing is the presence of a well-thought-out heating system. At the same time, the choice of the type of heating and the required equipment is one of the main questions that must be answered at the stage of designing a house. An objective calculation of the heating boiler power by area will ultimately result in a completely efficient heating system.

We will now tell you about how to carry out this work correctly. At the same time, we will consider the features inherent in different types of heating. After all, they must be taken into account when carrying out calculations and subsequent decision-making on the installation of this or that type of heating.

Basic calculation rules

At the beginning of our story about how to calculate the power of a heating boiler, we will consider the quantities used in the calculations:

room area (S);
specific heater power per 10 m² of heated area – (W spec.). This value is determined adjusted for the climatic conditions of a particular region.

This value (W beat) is:

for the Moscow region - from 1.2 kW to 1.5 kW;
for the southern regions of the country - from 0.7 kW to 0.9 kW;
for the northern regions of the country - from 1.5 kW to 2.0 kW.

Power calculation is carried out as follows:

W cat.=(S*Wsp.):10

Advice! For simplicity, you can use a simplified version of this calculation. In it Wsp.=1. Therefore, the heat output of the boiler is determined as 10 kW per 100 m² of heated area. But with such calculations, you must add at least 15% to the resulting value in order to get a more objective figure.

Calculation example

As you can see, the instructions for calculating the heat transfer intensity are simple. But, nevertheless, we will accompany it with a specific example.

W boiler = (100x1.2)/10 = 12 kilowatts.

Calculation for different types of heating boilers

The degree of efficiency of a heating system depends primarily on the correct choice of its type. And of course, it depends on the accuracy of the calculation of the required performance of the heating boiler. If the calculation of the thermal power of the heating system was not carried out accurately enough, then negative consequences will inevitably arise.

If the boiler heat transfer is less than required, the rooms will be cold in winter. In case of excess productivity, there will be an overconsumption of energy and, accordingly, money spent on heating the building.

To avoid these and other problems, just knowing how to calculate the power of a heating boiler is not enough.

It is also necessary to take into account the features inherent in systems using different types of heaters (you can see photos of each of them below in the text):

solid fuel;
electric;
liquid fuel;
gas.

The choice of one type or another largely depends on the region of residence and the level of infrastructure development. It is important to have the opportunity to purchase a certain type of fuel. And, of course, its cost.

Solid fuel boilers

Calculation of the power of a solid fuel boiler must be made taking into account the features characterized by the following features of such heaters:

low popularity;
relative accessibility;
the possibility of autonomous operation - it is provided in a number of modern models of these devices;
efficiency during operation;
the need for additional space for fuel storage.

Another characteristic feature that should be taken into account when calculating the heating power of a solid fuel boiler is the cyclicity of the resulting temperature. That is, in rooms heated with its help, the daily temperature will fluctuate within 5ºC.

Therefore, such a system is far from the best. And if possible, you should refuse it. But, if this is not possible, there are two ways to smooth out the existing shortcomings:

Using a thermal balloon, which is needed to regulate the air supply. This will increase the burning time and reduce the number of fireboxes;
Application of water heat accumulators, having a capacity from 2 to 10 m². They are included in the heating system, allowing you to reduce energy costs and, thereby, save fuel.

All this will reduce the required productivity. Therefore, the effect of these measures must be taken into account when calculating the power of the heating system.

Electric boilers

Characterized by the following features:

high cost of fuel - electricity;
possible problems due to network outages;
environmental friendliness;
ease of control;
compactness.

All these parameters should be taken into account when calculating the power of an electric heating boiler. After all, it is not purchased for one year.

Liquid fuel boilers

They have the following characteristic features:

not environmentally friendly;
easy to use;
require additional space for fuel storage;
have an increased fire hazard;
They use fuel, the price of which is quite high.

Gas boilers

In most cases, they are the most optimal option for organizing a heating system. have the following characteristic features that must be taken into account when calculating the power of a heating boiler:

ease of operation;
do not require space for fuel storage;
safe to use;
low cost of fuel;
efficiency.

Calculation for heating radiators

Let's say you decide to install a heating radiator yourself. But first you need to purchase it. And choose exactly the one that is suitable in terms of power.

First we determine the volume of the room. To do this, multiply the area of the room by its height. As a result, we get 42m³.
Next, you should know that heating 1 m³ of room area in central Russia requires spending 41 watts. Therefore, to find out the required radiator performance, we multiply this figure (41 W) by the volume of the room. As a result, we get 1722W.
Now let's calculate how many sections our radiator should have. It's easy to do. Each element of a bimetallic or aluminum radiator has a heat output of 150 W.
Therefore, we divide the performance we received (1722W) by 150. We get 11.48. Round up to 11.
Now you need to add another 15% to the resulting figure. This will help smooth out the increase in required heat transfer during the most severe winters. 15% of 11 is 1.68. Round up to 2.
As a result, we add 2 more to the existing number (11). We get 13. So, to heat a room with an area of 14 m², we need a radiator with a power of 1722 W, having 13 sections.

Now you know how to calculate the required performance of the boiler, as well as the heating radiator. Use our tips and ensure yourself an efficient and at the same time not wasteful heating system. If you need more detailed information, you can easily find it in the corresponding video on our website.

Reading time: 5 min

Many homeowners are happy to install gas boilers indoors for heating and hot water supply, so as not to depend on the whims of bad weather and pitfalls associated with the operation of municipal heating systems.

In this situation, the correct choice of boiler equipment is of great importance, for which you will need to know how to calculate the power of a gas boiler.

If it exceeds the actual heat loss of the facility, then part of the cost of generating thermal energy will be lost. And units with low heating capacity will not be able to provide households with the required amount of heat.

What is the power of a gas boiler

The performance of a boiler unit or its power is the most important indicator of the thermal process, on which the comfort of people in heated buildings directly depends.

The power of the boiler unit is the amount of thermal energy transferred to the heated water when the energy carrier is burned in the combustion device.

The indicator is measured in Gcal or MW. For household devices, the passport usually indicates the size in kW. In order to understand the physical meaning of this indicator, we can imagine the following relationships:

1 Gcal/hour is 40.0 m3 of coolant circulating for an hour and heated in the boiler at 25 C. Conversion ratio between the values:

1.0 Gcal = 1.16 MW.

Calculation of the power of a gas boiler can be obtained using the formula:

Mo = (t1 - t2) * Rv/ 1000,

Рв - flow rate of circulating water, m3/hour;
t1 - t2 - difference T of water at the inlet/outlet of the boiler unit, C.

Heat loss can be very high

A sample calculation of the power indicator, which is carried out before choosing a boiler unit:

The temperature of the coolant on the supply line from the boiler is 60 C.
The coolant temperature on the return line from the network to the boiler is 40 C.
Network consumption is 1.0 m3/hour.

Mo= (60-40)*1/1000=0.02 Gcal. * 1.16 = 0.0232 MW = 23.2 kW,

with rounding Mo = 24 kW.

Many users, in order to save money, are wondering how to reduce the power of a gas boiler. From this example it is obvious that in order to do this it will be necessary to either reduce the temperature difference or the heating area.

The second value is constant, so you can work towards reducing the temperature difference. This can be done by installing a reliable thermal protection system for your home.

Calculation of gas boiler power depending on area

In most cases, an approximate calculation of the thermal power of the boiler unit by heating area is used, for example, for a private house:

10 kW per 100 sq.m;
15 kW per 150 sq.m;
20 kW per 200 sq.m.

It must be taken into account that these standards were adopted back in Soviet times and do not provide for the level of thermal insulation characteristics of modern construction and installation materials. They are also not used in areas whose climate differs significantly from the conditions of the central regions of Russia and the Moscow region.

Such calculations may be suitable for a not very large building with an insulated attic floor, low ceilings, good thermal insulation, double-glazed windows, but nothing more.

According to old calculations, it is better not to do this. Photo source: porjati.ru

Unfortunately, only a few buildings meet these conditions. In order to carry out the most thorough calculation of the boiler power indicator, it is necessary to take into account the full package of interrelated quantities, including:

atmospheric conditions in the area;
size of residential building;
wall thermal conductivity coefficient;
actual thermal insulation of the building;
gas boiler power control system;
the amount of heat required for DHW.

Calculation of a single-circuit heating boiler

Calculating the power of a single-circuit boiler unit for a wall-mounted or floor-mounted boiler modification using the ratio: 10 kW per 100 m2 must be increased by 15-20%.

For example, you need to heat a building with an area of 80 m2.

Calculation of the power of a gas heating boiler:

10*80/100*1.2 = 9.60 kW.

In the case where the required type of device does not exist in the retail network, a modification with a larger kW size is purchased. A similar method is suitable for single-circuit heating sources, without a load on the hot water supply, and can be used as the basis for calculating gas consumption for the season. Sometimes, instead of living space, calculations are made taking into account the volume of the residential building of the apartment and the degree of insulation.

For individual premises built according to a standard design, with a ceiling height of 3 m, the calculation formula is quite simple.

Another way to calculate boiler OK

In this option, the built-up area (P) and the specific power coefficient of the boiler unit (SPC), depending on the climatic location of the facility, are taken into account.

It varies in kW:

0.7 to 0.9 southern territories of the Russian Federation;
1.0 to 1.2 central regions of the Russian Federation;
1.2 to 1.5 Moscow region;
1.5 to 2.0 northern regions of the Russian Federation.

Therefore, the formula for calculation looks like this:
Mo=P*UMK/10

For example, the required power of a heating source for a building of 80 m2, located in the northern region:

Mo = 80*2/10 = 16 kW

If the owner installs a double-circuit boiler unit for heating and hot water supply, professionals advise adding another 20% of the power for water heating to the result obtained.

How to calculate the power of a double-circuit boiler

Calculation of the heating capacity of a double-circuit boiler unit is carried out based on the following proportion:

10 m2 = 1,000 W + 20% (heat loss) + 20% (DHW heating).

If the building has an area of 200 m2, then the required size will be: 20.0 kW + 40.0% = 28.0 kW

This is an approximate calculation, it is better to clarify it based on the rate of water use for hot water supply per person. The following data is provided in SNIP:

bathroom - 8.0-9.0 l/min;
shower installation - 9 l/min;
toilet - 4.0 l/min;
mixer in the sink - 4 l/min.

The technical documentation for the water heater indicates what heating output of the boiler is required to ensure high-quality water heating.

For a 200 l heat exchanger, a heater with a load of approximately 30.0 kW will be sufficient. Afterwards, the productivity sufficient for heating is calculated, and at the end the results are summed up.

Calculation of indirect heating boiler power

In order to balance the required power of a single-circuit unit running on gas fuel with an indirect heating boiler, you need to determine how much heat exchanger volume is required to provide hot water to the residents of the house. Using data on hot water consumption standards, you can easily establish that the consumption per day for a family of 4 people will be 500 liters.

The performance of an indirect heating water heater directly depends on the area of the internal heat exchanger; the larger the coil, the more thermal energy it transfers to the water per hour. You can detail such information by studying the characteristics according to the equipment passport.

There are optimal ratios of these values for the average power range of indirect heating boilers and the time to obtain a given temperature:

100 l, Mo - 24 kW, 14 min;
120 l, Mo - 24 kW, 17 min;
200 l, Mo - 24 kW, 28 min.

What power reserve should be

The power for selecting a heating source with an indirect heating boiler with simultaneous operation of heating and hot water supply is determined by the formula:

M k= (Mo+Mgvs)*Kz,

Mk-combined power, kW;
Mo - source power sufficient to provide the heating load of the house, kW;
Mgvs - source power required to compensate for the load on hot water supply, kW;
Кз - safety factor.

In the case of alternating operation of heating and hot water systems:

Mk = Mgvs * Kz

Very important! When calculating the performance of heating and hot water equipment, it is necessary to take into account that the power of the BKN does not in any way exceed the same indicator in the boiler. For this reason, it must be selected with a heating capacity in kW so that it can cover the load of both heating and domestic hot water with a margin.

The performance reserve is calculated depending on the design of the heating equipment.

For single-circuit modifications, the margin is 20.0%;
for dual-circuit - 20.0%+20.0%.

For the above examples, the heating output of the boiler will be equal.

When heating and hot water systems operate simultaneously:

Mo = 24 kW.
Mgvs = 24 kW.
Kz= 1.4.

Mk= (24+24)* 1.4= 67.2 kW.

When operating heating and hot water systems alternately:

Mk=24*1.4= 33.6 kW.

Thus, performing an initial calculation of the power of a gas thermal energy source is not a difficult process. It may be used for preliminary selection of boiler equipment.

If the subscriber lacks an approximate calculation of the efficiency of gas boilers, and it is necessary that the heat loss of the building, the DHW load and the boiler performance be determined more accurately, he will need to contact qualified specialists to carry out a comprehensive home heating project with the development of a diagram and selection of equipment .

When choosing a solid fuel boiler, you need to consider power. It determines whether the device can create the required amount of heat for the entire house or not. It is undesirable to choose a boiler that is too powerful, because it will operate in economy mode, and this will affect the reduction in efficiency.

To make the right one, you need to know two indicators:

The amount of heat required to heat the room and heat the water.
The real power of the device.

Calculation of power depending on the volume of the room

The calculation formula is:

Q = VxΔTxK/850,

where Q – The amount of heat, defined in kW/h4;
V – room volume(unit of measurement cubic m);
ΔT is the difference between the outside temperature and the indoor temperature;
TO - correction factor, taking into account heat loss;
the number 850 is used to convert the product of the above three indicators to kW/hour.

K can have the following meanings:

3-4 – for premises that are a simplified wooden structure or a building made of corrugated sheets.
2-2,9 – for buildings with little thermal insulation. The design of such houses is simplified, the wall thickness is equal to the length of 1 brick, the windows and roof have a simple structure.
1-1,9 – for houses whose design is standard. The brickwork is double, the number of simple windows is small. The roof has a conventional roof.
0,6-0,9 – for houses with improved construction, double thermal insulation of brick walls, double glazed windows, thick floor base, roof made of good thermal insulation material.

As an example, let's take a modern house with an area of 200 square meters. m, wall height 3 m and first-class thermal insulation. The house is located in an area where in winter the temperature does not drop below -25 °C. In this case, ΔT = 20 – (-25) = 45 °C. Therefore, to heat a house you need to create Q = 200*3*45*0.9/850 = 28.58 kW/h. The figure should not be rounded, because it is not final and you need to increase it with your own hands by the amount of heat for the hot water supply. If the water is planned to be heated in a different way, then the result obtained is not adjusted, and part of the calculation is completed.

Calculation of heat for hot water supply

where c is specific heat capacity of water(the indicator is always 4200 J/kg*K);
m – mass of water in kg;
Δt temperature difference between heated water from the water supply.

Read also: Cleaning a solid fuel boiler from tar and soot

Example. The average family's need for warm water can reach 150 liters. If the boiler heats the coolant to a temperature of 80 °C, and the water from the pipeline has a temperature of 10 °C, then Δt = 80 – 10 = 70 °C.

Qв = 4200*150*70 = 44,100,000 J or 12.25 kW/h.

If 150 liters need to be heated at a time, the capacity of the indirect boiler is 150 liters, then 12.25 kW/h is added to 28.58 kW/h. This must be done because if Qzag is less than 40.83, the room will be colder than the calculated 20 °C.
If the water must be heated in portions, the volume of the indirect boiler is 50 liters, then 12.25 is divided by 3 and added with your own hands to 28.58. Qzag will be equal to 32.67 kW/h. This is the power of the device for the heating system.

Calculation by area

It is more accurate because it takes into account more factors. The calculation is made using the formula:

Q = 0.1*S*k1*k2*k3*k4*k5*k6*k7, Where:

0.1 kW is the heat norm per 1 sq. m;

S – area of the heated house;

k1 demonstrates heat loss caused by window design. Has the meaning:

1.27 – if the windows have one glass;
1.0 – if there are double-glazed windows;
0.85 – if there are windows with triple glass.

k2 demonstrates heat loss caused by window area (Sw). Is the ratio of Sw to the floor area Sf. Its meanings are:

0.8 at Sw/Sf = 0.1;
0.9 at Sw/Sf = 0.2;
1 at Sw/Sf = 0.3;
1.1 at Sw/Sf = 0.4;
1.2 at Sw/Sf = 0.5.

k3 is coefficient of heat loss through walls. It happens like this:

1.27 with very poor thermal insulation;
1 in houses with a wall of 2 bricks or insulation, the thickness of which is 15 cm;
0.854 with good thermal insulation.

k4 shows heat loss depending on the air temperature outside the house (tz). Has the following meanings:

0.7, if tз = -10 °С;
0.9 for tз = -15 °С;
1.1 for tз = -20 °С;
1.3 for tз = -25 °С;
1.5 for tз = -30 °С.

Read also: Advantages of the Popov boiler

k5 demonstrates heat loss through external walls. Is like this:

1.1 for rooms with one external wall;
1.2 for 2 external walls;
1.3 for 3 external walls;
1.4 for a building with 4 external walls.

K6 shows how much Additional heat required depending on ceiling height (H). Its meanings are:

1 for H = 2.5 m;
1.05 for H = 3.0 m;
1.1 for H = 3.5 m;
1.15 for H = 4.0 m;
1.2 for H = 4.5 m.

k7 determines heat loss depending on the type of room located above the heated room. It happens like this:

0.8 for heated rooms;
0.9 for a warm attic;
1 for a cold attic.

Example. The conditions of the problem are the same. The windows are triple glazed and make up 30% of the floor area. The number of external walls is 4. There is a cold attic upstairs.

Q = 0.1*200*0.85*1*0.854*1.3*1.4*1.05*1 = 27.74 kW/h. This figure must be increased by adding with your own hands the amount of heat required for hot water supply.

Real power of a long-burning boiler

Many devices are designed for a specific type of fuel. If other types of fuel are burned in them, their efficiency will be lower.

The power calculation will be carried out on the basis of the Viessmann Vitoligno 100-S 60 pyrolysis boiler. Its features are as follows:

Powered by wood.
In 1 hour, from 6 to 15 kg of firewood burns in the loading chamber.
Its rated power is 60 kW.
The loading chamber volume is 294 liters.
Efficiency is 87%

Let the owner plan to burn aspen wood in it. 1 kg of such firewood produces 2.82 kW/h. If a boiler burns 15 kg in 1 hour, then it emits 2.82*15*0.87 = 36.801 kW/h of heat (0.87 is efficiency). Such a device is not enough for heating a house with a 150 liter boiler, but it is quite enough for hot water supply with a 50 liter boiler. To get the figure 32.67 kW/h, you need to burn 13.31 kg of aspen firewood in 1 hour (32.67/(2.82*0.87) = 13.31). This is the case if you calculate the heat demand by volume.

A competent choice of boiler will allow you to maintain a comfortable indoor temperature during the winter season. A large selection of devices allows you to most accurately select the desired model depending on the required parameters. But in order to provide warmth in the house and at the same time avoid unnecessary expenditure of resources, you need to know how to calculate the power of a gas boiler for heating a private house.

A floor-standing gas boiler has greater power Source termoresurs.ru

The main characteristics affecting the boiler power

The boiler power indicator is the main characteristic, however, the calculation can be carried out using different formulas, depending on the configuration of the device and other parameters. For example, a detailed calculation may take into account the height of the building and its energy efficiency.

Varieties of boiler models

Boilers can be divided into two types depending on the purpose of application:

Single-circuit– used only for heating;

Dual-circuit– used for heating, as well as in hot water supply systems.

Units with one circuit have a simple structure, consisting of a burner and a single heat exchanger.

Source ideahome.pp.ua

In dual-circuit systems, the water heating function is primarily provided. When using hot water, the heating is automatically turned off while hot water is being used so that the system is not overloaded. The advantage of a dual-circuit system is its compactness. Such a heating complex takes up much less space than if the hot water supply and heating systems were used separately.

Boiler models are often divided by placement method.

Depending on their type, boilers can be installed in different ways. You can choose a wall-mounted or floor-mounted model. It all depends on the preferences of the owner of the house, the capacity and functionality of the room in which the boiler will be located. The installation method of the boiler is also affected by its power. For example, floor-standing boilers have more power compared to wall-mounted models.

In addition to fundamental differences in purpose of use and placement methods, gas boilers also differ in control methods. There are models with electronic and mechanical control. Electronic systems can only operate in homes with constant access to the power grid.

Source norogum.am

On our website you can find contacts of construction companies that offer house insulation services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

Typical power calculations for devices

There is no single algorithm for calculating both single- and double-circuit boilers - each system must be selected separately.

Formula for a typical project

When calculating the required power for heating a house built according to a standard design, that is, with a room height of no more than 3 meters, the volume of the premises is not taken into account, and the power indicator is calculated as follows:

Determine the specific thermal power: Um = 1 kW/10 m 2 ;

Rm = Mind * P * Kr, where

P – a value equal to the sum of the areas of heated premises,

Kr is a correction factor that is taken in accordance with the climatic zone in which the building is located.

Some coefficient values for different regions of Russia:

Southern – 0.9;

Located in the middle zone – 1.2;

Northern – 2.0.

For the Moscow region, a coefficient value of 1.5 is taken.

This technique does not reflect the main factors influencing the microclimate in the house, and only approximately shows how to calculate the power of a gas boiler for a private home.

Some manufacturers issue recommendations, but for accurate calculations they still recommend contacting specialists Source parki48.ru

Example calculation for a single-circuit device installed in a room with an area of 100 m2, located in the Moscow region:

Рм = 1/10 * 100 * 1.5 = 15 (kW)

Calculations for dual-circuit devices

Double-circuit devices have the following operating principle. For heating, water is heated and supplied through the heating system to radiators, which release heat to the environment, thereby heating the rooms and cooling them. When cooling, the water flows back to be heated. Thus, water circulates along the heating system circuit, and goes through heating cycles and transfer to the radiators. At the moment when the ambient temperature becomes equal to the set one, the boiler goes into standby mode for some time, i.e. Temporarily stops heating the water, then starts heating again.

For domestic needs, the boiler heats water and supplies it to the taps, and not to the heating system.

Source idn37.ru

When calculating the power of a device with two circuits, another 20% of the calculated value is usually added to the resulting power.

An example of calculation for a two-circuit device that is installed in a room with an area of 100 m2; the coefficient is taken for the Moscow region:

R m = 1/10 * 100 * 1.5 = 15 (kW)

P total = 15 + 15*20% = 18 (kW)

Additional factors taken into account when installing the boiler

In construction, there is also the concept of energy efficiency of a building, that is, how much heat a building releases to the environment.

One of the indicators of heat transfer is the dissipation coefficient (Kp). This value is a constant, i.e. constant and does not change when calculating the level of heat transfer of structures made of the same materials.

It is necessary to take into account not only the power of the boiler, but also the possible heat loss of the building itself Source pechiudachi.ru

For calculations, a coefficient is taken, which, depending on the building, can be equal to different values and the use of which will help you understand how to calculate the power of a gas boiler for a home more accurately:

The lowest level of heat transfer, corresponding to a K p value of 0.6 to 0.9, is assigned to buildings made of modern materials, with insulated floors, walls and roofs;

K p is equal to from 1.0 to 1.9, if the external walls of the building are insulated, the roof is insulated;

K p is equal to from 2.0 to 2.9 in houses without insulation, for example, brick houses with single masonry;

K p is equal to from 3.0 to 4.0 in non-insulated rooms, in which the level of thermal insulation is low.

Heat loss level QT calculated according to the formula:

Q T = V * P t *k/860 where

V – is the volume of the room

Pt- R temperature difference calculated by subtracting the minimum possible air temperature in the region from the desired room temperature,

k – safety factor.

Source tr.decorexpro.com

The boiler power, when taking into account the dissipation coefficient, is calculated by multiplying the calculated level of heat loss by the safety factor (usually from 15% to 20%, then multiply by 1.15 and 1.20, respectively)

This technique allows you to more accurately determine productivity and, therefore, approach the issue of choosing a boiler as efficiently as possible.

What happens if you incorrectly calculate the required power

It is still worth choosing a boiler so that it matches the power required to heat the building. This will be the best option, since first of all, purchasing a boiler that does not match the power level can lead to two types of problems:

A low-power boiler will always work at the limit, trying to heat the room to the set temperature, and can quickly fail;

A device with an excessively high power level costs more and, even in economy mode, consumes more gas than a less powerful device.

Calculator for calculating boiler power

For those who do not like to do calculations, even if they are not very complicated, a special calculator will help you calculate a boiler for heating your home - a free online application.

Interface of an online calculator for calculating boiler power Source idn37.ru

As a rule, the calculation service requires you to fill out all the fields, which will help you make the most accurate calculations, including the power of the device and the thermal insulation of the house.

To obtain the final result, you will also need to enter the total area that will require heating.

Next, you should fill out information about the type of glazing, the level of thermal insulation of walls, floors and ceilings. As additional parameters, the height at which the ceiling is located in the room is also taken into account, and information about the number of walls interacting with the street is entered. The number of floors of the building and the presence of structures on top of the house are taken into account.

After entering the required fields, the calculation button becomes “active” and you can get the calculation by clicking on the corresponding button. To check the information received, you can use calculation formulas.

Video description

To see how to calculate the power of a gas boiler, watch the video:

Advantages of using gas boilers

Gas equipment has a number of advantages and disadvantages. The advantages include:

possibility of partial automation of the boiler operation process;

unlike other energy sources, natural gas has a low cost;

The devices do not require frequent maintenance.

The disadvantages of gas systems include the high risk of gas explosion, however, with proper storage of gas cylinders and timely maintenance, this risk is minimal.

On our website you can familiarize yourself with construction companies that offer services for connecting electrical and gas equipment. You can communicate directly with representatives at the Low-Rise Country exhibition of houses.

Conclusion

Despite the apparent simplicity of the calculations, we must remember that gas equipment must be selected and installed by professionals. In this case, you will receive a trouble-free device that will work properly for many years.