The heating system is the most important, complex and expensive of all residential communications. Heating installations require careful design to avoid unpleasant consequences, which are often difficult to correct.
Present on the heating equipment market big choice boilers Many models differ from each other in design, energy source, and power. Boilers are produced with a power range from 4 kW to several thousand kW. Thus, it is possible to select the optimally suitable boiler for a building of any size, both for country house, so country cottage. The choice of a boiler of one type or another: solid fuel, electric, liquid fuel or gas largely depends on the region of residence and the level of infrastructure development. Equally important is the availability of a certain type of fuel and its cost.
One of the key points in planning residential heating is calculating the boiler power, while it is necessary to take into account the features inherent in systems operating with different types heaters. Errors in selecting boiler power are unacceptable, both exceeding and decreasing it. If the boiler power is insufficient, the house will be cold. Excessive power will lead to excessive consumption of electricity or fuel.
Calculation of heating boiler power by room area
One of the main conditions for comfortable housing is the presence of a well-thought-out heating system. The type of heating and the required equipment are chosen at the design stage of the house. Determining the power of a heating boiler by area allows us to obtain completely objective data.
Basic calculation rules and parameters used in calculations:
- Area of the heated room (S).
- Specific power per 10 m² of heated area – (Wsp). This value is determined with adjustments to the climatic conditions of a particular region.
- Wud. For the Moscow region it ranges from 1.2 kW to 1.5 kW.
- For the southern regions - from 0.7 kW to 0.9 kW.
- For the northern zone - from 1.5 kW to 2.0 kW.
- The boiler power is calculated using the formula: Wbot = (SxWsp.):10.
It is possible to use a simplified version of the formula, in which Wsp = 1, and the heat transfer of the boiler is measured as 10 kW per 100 m² of heated area. With this calculation, at least 15% is added to the obtained value to get a more realistic figure.
Example: calculating the power of a heating boiler for a house with an area of 100 m².
The specific power for the Moscow region is 1.2 kW.
Thus, W boiler = (100x1.2)/10 = 12 kilowatts.
To more accurately calculate the required power of heating devices, it is necessary to collect an extended list of data:
- Actual heat loss of the room. Heat leakage from any building occurs through doors, windows, roof, floor, walls, and ventilation system.
- The difference in temperature inside the building and outside. When calculating the power of a heating boiler, the difference in temperature inside and outside the room is taken into account. The greater the temperature difference, the greater the heat loss.
- Thermal insulation characteristics of building structures. The thermal conductivity properties of doors, windows, walls and floors depend on the material from which they are made, therefore, heat loss through their surfaces will also differ.
To obtain the necessary indicators and coefficients when determining the boiler power, use a construction reference book.
How to calculate the real heat loss of a building
Heat is lost from the room through walls, windows, floors, roofs, ventilation system. The size of heat loss is influenced by many factors: the difference between the temperature inside the building and outside, thermal conductivity properties building materials. Thermal conductivity of walls, doors, windows, floors and ceiling different from each other. The unit of measurement for heat transfer resistance is W/m2, this characteristic means the amount of heat lost from 1 m² of the building envelope at a certain temperature range.
Formula No. 1 for determining heat transfer resistance: R = ΔT/q
- R – heat transfer resistance (°Схм²/W or °С/W/m²);
- ΔT – temperature difference between the street and the building (°C);
- q is the amount of heat loss per square meter of the surface of the enclosing structures (W/m²).
When determining the heat transfer resistance R of multilayer structures, the heat transfer resistance indicators of each layer are summed up. This calculation takes into account the average outdoor temperature of the coldest week of the year; reference sources indicate the heat transfer resistance based on these conditions. For example, the heat transfer resistance of materials at ΔT = 50°C (Toutside = –30°C, Tinside = 20°C).
When determining the thermal conductivity properties of windows, the following are taken into account:
- Heat transfer resistance of materials window designs and their heat loss at ΔT = 50°C. glass thickness (mm).
- The thickness of the gap between the glasses in mm.
- Type of gas filling the gap: air or argon.
- Availability of a transparent heat-protective coating.
A common mistake is the belief that heat loss can be compensated by choosing a boiler of higher power. In fact, it makes more sense to prevent unwanted heat loss as much as possible by insulating windows, roofs, and doors than to overpay for gas or electricity every month. Double-glazed windows alone reduce heat loss by approximately 2 times, which saves 800 kW/h of electricity per month. More accurately, heat loss is calculated using the proportion method.
Formula No. 2 for determining the heat transfer resistance of structures made of combined materials: R2 = R1хΔT2/ΔT1
R1—heat loss at temperature difference ΔT1 = 50°C;
R2 - heat loss at temperature difference ΔT2 in accordance with specific data.
An example of calculating the heat loss of a wall:
- Wall thickness 20 cm,
- The wall material is a log frame. In the materials reference book, find the value of heat transfer resistance R. For timber R = 0.806 m²×°C/W.
The temperature difference ΔT is 50°C. Substituting the values into formula No. 1:
R = ΔT/q, the heat loss value for 1 m² is 50/0.806 = 62 W/m².
Heat loss is determined in the same way for all other materials. The greater the difference in temperature outside and inside the building ΔT, the higher the heat loss.
For ease of calculation, most construction reference books provide ready-made heat loss indicators for various types of building structures at individual air temperatures in winter.
For example, heat loss in corner rooms, where air turbulence affects, and non-corner rooms, as well as rooms on the upper and lower floors, which also differ in the degree of heating.
Example: calculation of heat loss in a corner room located on the first floor
1. Initial parameters of the room:
- dimensions and area - 10.0 m x 6.4 m, S = 64.0 m²;
- ceiling height - 2.7 m;
- number of external walls – 2;
- material and thickness of external walls - masonry of 3 bricks (76 cm);
- number of double glazed windows – 4;
- window dimensions: height - 1.8 m, width - 1.2 m;
- floor - wooden insulated;
- ceilings: below - basement, above - attic;
- estimated room temperature +20°C;
- The estimated temperature outside is -30°C.
Settlement actions:
2. First, calculate the area of surfaces that lose heat.
Area of external walls excluding windows (Swalls): (6.4+10)x2.7 – 4x1.2x1.8 = 35.64 m². Window area (Swindow): 4x1.2x1.8 = 8.64 m². Ceiling area (Sceiling): 10.0x6.4 = 64.0 m².
Floor area (Sfloor): 10.0x6.4 = 64.0 m².
Area indicators internal partitions and there are no doors in this calculation, so there is no heat loss through them.
3. Determine the heat transfer resistance for a brick wall:
R = ΔT/q, where ΔT=50, and q of the brick wall = 0.592
Thus, R=50/0.592, and is 84.46 m²×°C⁄W.
- Qwall = 35.64x84.46 = 2956.1 W,
- Qwindows = 8.64x135 = 1166.4 W,
- Qfloor = 64×26 = 1664.0 W,
- Qceiling = 64x35 = 2240.0 W.
Total: the amount of heat loss in a room with an area of 64 sq.m. Qsum=8026.5 W.
IN in this example The greatest heat loss occurs on the walls, to a lesser extent on the ceiling, floor, and windows. The calculation result reflects heat losses rooms in very coldy at a temperature of -30 C°. The higher the air temperature outside, the less heat leaks from the room.
Calculation of the power of a gas heating boiler
Gas boiler for autonomous heating private home is deservedly popular. This system is convenient, accessible and effective. And if the house is located remotely from central heating networks, then there is simply no other alternative. Household gas boilers in most cases, they are the most optimal option for a heating system due to such undeniable advantages as: simplicity and safety of operation; no need to allocate space for fuel storage, low price fuel, efficiency.
Very important when purchasing gas boiler choose the right power. If the power exceeds the actual heat needs of the building, heating costs will be excessive. On the other hand, equipment with low performance is not able to provide sufficient heating of the room. The most basic calculation of the power of a gas boiler by area: 1 kW for every 10 sq.m. But such results are very approximate. To perform a more accurate calculation of the power of a gas boiler, take into account whole line factors:
- climatic conditions of the region;
- dimensions of the heated room;
- degree of thermal insulation of the house;
- probable heat loss of the building;
- amount of heat to heat water;
- the amount of energy to heat the air in a forced ventilation system.
As a rule, special software is used in calculations: approximately 20% is added to the reserve power of a gas boiler in case of severe cold weather, a decrease in gas pressure in the system, or other unforeseen situations. Modern heating devices equipped with an automatic device that regulates gas consumption. This is convenient, as it eliminates excess fuel consumption and unnecessary costs.
Many people mistakenly believe that calculating the power of a heating boiler is an unnecessary formality, and that you can simply buy a gas boiler with high power. In fact, unreasonably exceeding the power of heating equipment may necessitate the purchase of components, which means increased costs for system repairs, reduction in the functional efficiency of the boiler, interruptions in operation automatic device, rapid wear of elements, the appearance of condensation in the chimney and other negative consequences.
Calculation of boiler power and correct selection heating equipment will help increase its service life. When choosing a gas or other boiler, you need to carefully study the accompanying documentation. The heating boiler instructions indicate the rated power that is generated at the rated pressure natural gas 13-20 mbar. A decrease in pressure in the main line will cause a boiler with a capacity of, for example, 30 kW to lose a third of its power. In this case, the boiler will be able to effectively heat a house with an area of only 200 square meters, instead of the estimated 300.
Formula for the required power of a gas boiler for buildings according to a standard design: M K = SxUM K /10
- S – total area of the heated room (sq.m);
- UM K is the specific power of the boiler per every 10 sq.m of surface. The specific power of the boiler depends on climatic conditions and is: 0.7-0.9 kW for the southern regions; 1.0-1.2 kW for areas middle zone; 1.5-2.0 for northern regions.
Example: according to the formula, the estimated power of a heating boiler for a house with an area of 200 sq.m, located in a temperate climate zone, will be: 200X1.1/10 = 22 kW.
It should be remembered that this formula is used to calculate the power of the boiler, provided that it is used only for heating the house. If you plan to install a double-circuit system to heat water for domestic needs, then additionally increase the power heating equipment by 25%.
To correctly calculate the power of a gas heating boiler for a house with non-standard layout for individual orders, use a different formula.
Formula for calculating the power of a gas boiler for buildings according to an individual project: M K = QthKzap,
- M K – design power of the boiler (kW);
- Qt – predicted heat losses (kW); Kzap – safety factor equal to 1.15-1.2 (15-20%).
The amount of predicted heat loss of a building is determined by the formula:
Qt = VхРtхk/860
- V is the volume of the heated room (cubic meters);
- Pt - difference between outdoor and indoor temperatures (C);
- k - dissipation coefficient.
The value of the dissipation coefficient depends on the type of building structure and the degree of its thermal insulation. For buildings in the form of simple structures made of wood or corrugated iron without thermal insulation, a dissipation factor of 3.0-4.0 is used.
If the walls of the building are with single brickwork, standard windows and roof, low thermal insulation, then the dissipation coefficient is 2.0-2.9.
For houses with an average level of thermal protection, with double walls brickwork, with a regular roof and a small number of windows, a dispersion coefficient of 1.0-1.9 is taken. For houses with a high degree of thermal protection, well-insulated floors, roofs, walls and plastic windows with double glazing, a dispersion coefficient of 0.6-0.9 is used.
The design power of a heating boiler for compact buildings with high-quality thermal insulation may turn out to be quite small. It is possible that a suitable gas boiler with the required characteristics is simply not available for sale. In this case, purchase equipment whose power slightly exceeds calculated value. Many modern modifications gas boilers are equipped with devices automatic regulation heating, which allows you to even out the difference.
Calculating the power of a gas boiler using a calculator program
For the convenience of customers, gas boiler manufacturers post special services on their web resources, which makes it easy and quick to calculate the estimated power of the boiler. To do this, just enter the following data into the calculator program:
- the temperature that is expected to be maintained in the room;
- average outdoor temperature for the coldest week of the year;
- need for hot water supply;
- the presence or absence of a forced ventilation system;
- number of floors in the house;
- ceiling height;
- description of floors;
- dimensions of external walls: thickness and length of each of them;
- description of the materials from which the walls are made;
- number and sizes of windows;
- description of the type of windows: number of chambers, glass thickness, heat-protective film, type of gas in the gaps.
After filling out all the fields, click the “Perform calculation” button, and the program will display the required design power of the boiler.
For even greater convenience, we offer options for ready-made boiler power calculations various types, clearly presented in tables. It should be borne in mind that these calculation methods may not be suitable for complex structures. For example, the presence of ceilings in a building different heights, underfloor heating systems, structures that require additional heating (swimming pool, greenhouse, sauna). All these conditions must be taken into account when designing. Any additional load on the heating system requires an increase in boiler power.
The most optimal power calculation heating system Only specialists and heating engineers can prepare it.
Calculation of solid fuel boiler power
Solid fuel boilers in Lately They are used much less frequently than electric and gas ones. They are characterized by accessibility, the possibility of autonomous operation, economical operation, and the need for space for fuel storage.
A distinctive feature that should be taken into account when determining the power of a solid fuel boiler is the cyclicity of the resulting temperature. The daily temperature in a heated room fluctuates within 5ºC. If it is not possible to refuse similar system, there are two ways to maintain a stable temperature in the room: using a thermal cylinder and using water heat accumulators.
The thermal cylinder serves to regulate the air supply, which allows you to increase the burning time and reduce the number of fireboxes. Water thermal accumulators with a volume of 2 to 10 m² are installed in the heating system, reducing energy costs and saving fuel. All these measures help reduce the required performance of a solid fuel boiler for heating a private home. The effect of these measures should be taken into account when determining the power of heating equipment.
Calculation of the power of an electric heating boiler
A heating system using an electric boiler is characterized by a number of positive and negative features: high cost of fuel - electricity, possible problems due to power outages in the network, environmental friendliness, simplicity and ease of management, compact equipment.
Calculating the power of an electric heating boiler using a calculator program
Often, heating equipment manufacturers post on their websites formulas for calculating boiler power or even calculators that allow you to take into account several determining factors at once and make the most accurate calculation.
To calculate using a calculator, the following information is usually required:
- Planned room temperature.
- Average outdoor temperature for the coldest week of the year.
- Demand for hot water supply.
- Availability of a ventilation system.
- Number of floors.
- Ceiling height.
- Top and bottom overlap.
- Material. external walls.
- Length and thickness of external walls.
- Number, type and sizes of windows.
- Glass thickness. The size of the gap between glass with air or argon. The presence of a heat-protective transparent coating on the glass.
It should be taken into account that in reality the specific power of the heating system increases to 127 W/m2 for a small house area (100-150 m2) and decreases to 85-80 W/m2 for houses with an area of 400-500 m2, which is not corresponds to accepted standard value 100 W/m2, which is usually recommended for equipment selection.
This is due to the fact that in houses with small area heat is wasted inefficiently. With an increase in the total area of the house, more rooms appear, adjacent to heated ones, as well as without external walls and located in the depths of the house. As a result, the specific heat loss of the house is slightly reduced.
How to calculate the power of an oil-fuel boiler
Heating liquid fuel boilers They have both advantages and disadvantages: they are easy to use, but not environmentally friendly, require additional space for storing fuel, are characterized by an increased fire hazard, and are quite expensive.
Calculation of the power of an oil-fuel boiler is carried out similarly to a gas and electric one. The more factors that influence the efficiency of the heating system are taken into account, the more accurate the calculation will be, which in turn will allow optimal choice equipment.
The quality of heating primarily depends on the right choice the type of heating system and the accuracy of calculating the required performance of the heating boiler. Design errors will inevitably lead to negative consequences. Therefore, it is very important before purchasing heating equipment and installing the system to assemble full information, perform careful calculations and planning.
The boiler is the heart of the heating system and produces required amount heat for comfortable conditions and provides hot water supply. If there is a gas supply line near the house, then the most best option- installation of a gas boiler. Gas boilers have their pros and cons.
Let's define the advantages:
- more economical than other types of fuel;
— high power (possibility of heating a large area);
— ease of operation (fully automated);
— the equipment can be installed in the kitchen (boiler with a capacity of up to 30 kW);
- small dimensions;
— environmental friendliness (a small amount of harmful substances is released into the atmosphere).
Let us now list the disadvantages:
— before installation, it is necessary to obtain permission from Gazgortekhnadzor;
— risk of gas leakage;
— there are established requirements for the premises for the boiler;
When choosing a boiler, the first thing you need to do is decide on its power. And for this it is necessary to calculate the power of the gas heating boiler. This is not difficult to do.
The first way to select the power of a gas boiler
A correct calculation of the power of a gas boiler will guarantee efficient and reliable operation heating systems. The basis of the calculation is the provision of premises optimal temperature. Most often, the boiler is the source of heat in houses and cottages.
The following parameters determine the power of a gas boiler:
— heated area (S);
- specific boiler power based on 10 m2, taking into account climatic conditions in a certain region (Wsp).
There are generally accepted power densities for individual climatic zones:
— for the Moscow region is from 1.2 to 1.5 kW;
— for server areas - from 1.5 to 2.0 kW;
— for southern regions it ranges from 0.7 to 0.9 kW.
The boiler power itself (Wbot) is determined by the formula:
Wcat = (S * Wsp)/10
Most often, for convenience of calculation, one is taken as the average value of Wsp. Accordingly, the boiler power is calculated at 10 kW per 100 square meters.
Vsyst = Wcat. 15
For example, let’s calculate the boiler power and the required volume of liquid for heating 100 square meters of a room located in the southern region.
Let's take the maximum power density for the southern regions, which is 0.9 kW, then:
Wcat = 100. 0.9 / 10 = 9 kW;
Vsyst = 9. 15 = 135 l.
- desired constant temperature in the room;
— the lowest average weekly temperature for the year;
— room parameters;
- type of floors;
- quantity, material and thickness of external walls;
- sizes, type and number of windows.
IMPORTANT! Before purchasing a boiler, you should carefully study its technical characteristics and read the passport, then you can be absolutely sure of its thermal power, since sometimes instead of the power that it can deliver to the system, the power of the burner is indicated, and this is of no interest to consumer.
The second way to select the power of a gas boiler
Also, when choosing a boiler, you can rely on information about the heat loss of the house, which it will need to compensate. They need to be calculated. This can be done by an architect who draws up a house project. And based on this data, you can choose a gas boiler of the required power. Determining the calculation of heat loss is greatly facilitated by special computer programs, which installation companies must have. This program has advanced additional functions, thanks to which calculations can be made by people who have never encountered design before.
They contain questions that relate to: the thickness of the walls and their material, the cubic capacity of the house; material, insulation used and its thickness; window sizes and their number, number of chambers in double-glazed windows and others. There are several answers to each question posed. The task is to choose it correctly, the one that best suits the description of your home. And for each answer there is a specific number. It is not difficult to carry out calculations with these numbers according to the attached instructions and you will get a value that describes the heat loss of your home. The accuracy of this value is quite suitable for correctly choosing the boiler power. It only takes a few minutes to fill out the form and make the calculations. The most in a simple way heat loss calculation specific house is to determine them using a conditional coefficient approximately equal to:
- from 130 to 200 W/m - houses without thermal insulation;
- from 90 to 110 W/m - houses with thermal insulation, built in the 80-90s of the 20th century;
- from 50 to 70 W/m2 - houses with modern windows, well insulated and built, first of the 21st century.
Heat loss is determined by multiplying the coefficient value by the entire area of the house. but these calculations are quite approximate, they do not take into account the size and number of windows, the location of the house and its shape, and these factors significantly affect the heat loss of the house. This calculation should not form the basis for choosing a boiler; it can be used as an assessment of the designer’s calculations. The difference in these results, unfortunately, can be significant, because this method can only detect a gross error.
Boiler power and heat loss
The calculated heat loss is equal to the maximum heat demand of the house, which is necessary to maintain a comfortable temperature (it is usually +20°C). The greatest need for heat occurs during the coldest periods, when the temperature drops to -22°C. It should be taken into account that frosts occur only a few days a year, and sometimes they may not occur for several years. Despite this, the gas boiler must function fully heating season when the temperature is near zero. Then, to heat the house, a boiler with a power half the design power is enough. Therefore, it is not worth purchasing a boiler of higher power, this is due not only to financial side, but also because the efficiency of the boiler will be significantly reduced. The lack of heat in cold weather can be compensated by other sources, for example, electric heater or fireplace.
Combining high power with low fuel consumption
Most the best option when the boiler operates at the same rated power all the time. But outside temperature is constantly changing, so the need for heat is also different. How can this be combined? Mixing valves must be used.
Can be used hydraulic systems with a four-way mixing valve or with a thermo-hydraulic distributor. Then the temperature of the water entering the radiators can be adjusted without changing the boiler power. Only the position of the control valve and the performance will change circulation pumps. Thus, gas boilers low power will work in optimal conditions. This solution is very good, but quite expensive.
Using excess boiler power
In the event that you nevertheless purchased a boiler whose power is higher than the calculated requirement, you can improve its operating conditions with the help of an accumulator tank (buffer tank).
This should be done, first of all, when using solid fuel boilers. Thanks to the buffer tank, the boiler will operate with the highest efficiency output, despite short-term heat demand. The battery tank is completely filled with water.
The optimal volume of a solid fuel boiler can be determined as follows: 10 liters per square meter of area. When it gets warm outside, automatic control valves limit the flow of hot water into the radiator, directing it to the heat exchanger of the storage tank and will heat the water located there. If the area of the house is 100 square meters, then the storage tank should have a volume of 1000 liters.
After the fuel burns in the boiler and the current cools, the flow will begin warm water into radiators from the buffer tank. Thus, the heating system will continue to function.
Heating systems with large volumes of water have significant thermal inertia, due to which the burners of oil and gas boilers operate at the most favorable conditions. The duration of the burner operation and breaks will be longer, since the greater the amount of water, the longer it takes to heat up, therefore, the longer it takes to cool down. But the system reacts much slower to changes outside temperature, so support comfortable temperature indoors is more difficult.
The most best boilers- these are Conord gas boilers, which are produced by LLC "Plant CONORD" in Russia, Ferroli gas heating boilers - made in Italy, and a Turbo gas boiler, which is installed at sites without installing a traditional chimney.
Before designing a heating system or installing heating equipment, it is important to select a gas boiler capable of generating the required amount of heat for the room. Therefore, it is important to choose a device of such power that its performance is as high as possible and its resource is long.
We will tell you how to calculate the power of a gas boiler with high accuracy and taking into account certain parameters. The article we presented describes in detail all types of heat loss through openings and building construction, formulas for their calculation are given. A specific example introduces the features of calculations.
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 is reduced.
As a result, the efficiency of the equipment decreases, parts wear out faster, and condensation forms. Therefore, there is a need to calculate optimal power.
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Technical consultants of the Termomir company, who have been working with gas boiler equipment for many years, often hear the question - How to choose a gas boiler based on the size of the house. Let's look at this topic in more detail.
A gas heating boiler is a device that uses fuel combustion (natural or liquefied gas) to heat the coolant.
Design (design) of a gas boiler: burner, heat exchanger, thermally insulated housing, hydraulic unit, as well as safety and control devices. Such gas boilers require a chimney connection to remove combustion products. The chimney can be either ordinary vertical or coaxial (“pipe in pipe”) for boilers with closed camera combustion. Many modern boilers equipped with built-in pumps for forced water circulation.
The principle of operation of a gas boiler- the coolant, passing through the heat exchanger, heats up and then circulates through the heating system, releasing the resulting thermal energy through radiators, heated floors, heated towel rails, and also by heating water in the boiler indirect heating(if it is connected to a gas boiler).
A heat exchanger is a metal container in which the coolant (water or antifreeze) is heated - can be made of steel, cast iron, copper, etc. The reliability and durability of a gas boiler depend primarily on the quality of the heat exchanger. Cast iron heat exchangers They are resistant to corrosion and have a long service life, but are sensitive to sudden temperature changes and have a significant weight. Steel containers can suffer from rust, so they internal surfaces protected with various anti-corrosion coatings, ensuring extended “life” of the device. Steel heat exchangers are the most common in boiler production. Copper heat exchangers are not susceptible to corrosion, and due to their high heat transfer coefficient, low weight and dimensions, such heat exchangers are often used in wall-mounted boilers, but one of the minuses should be noted that they are more expensive than steel ones.
In addition to the heat exchanger, an important part of gas boilers is the burner, which can be various types: atmospheric or fan, single-stage or two-stage, with smooth modulation, double.
To control a gas boiler, automation is used with various settings and functions (for example, a weather-dependent control system), as well as devices for programming operation and remote control of the boiler.
Main technical characteristics gas heating boilers are: power, number of heating circuits, type of fuel., type of combustion chamber, type of burner, installation method, presence of a pump and expansion tank, automatic boiler control.
To determine required power gas heating boiler for private country house or apartment used simple formula- 1 kW of boiler power for heating 10 m 2 of a well-insulated room with a ceiling height of up to 3 m. If heating a basement, glassed-in winter garden, rooms with non-standard ceilings, etc. is required. The power of the gas boiler must be increased. It is also necessary to increase the power (about 20-50%) when providing a gas boiler and hot water supply (especially if it is necessary to heat the water in the pool).
Feature of power calculation for gas boilers: the nominal gas pressure at which the boiler operates at 100% of the power declared by the manufacturer, for most boilers is from 13 to 20 mbar, and the actual pressure in gas networks in Russia can be 10 mbar, and sometimes lower . Accordingly, a gas boiler often operates at only 2/3 of its capacity and this must be taken into account when calculating. For more details, see the table for calculating the power of a heating boiler.
Most gas boilers can be convert from natural gas to liquefied gas (cylindered propane). Many models switch to liquefied gas at the factory (when purchasing, check these characteristics of the model), or the gas boiler is additionally supplied with nozzles (nozzles) for switching to bottled gas.
Pros and cons of gas boilers:
Boiler piping- These are devices for the full operation of the heating and water supply system. It includes: pumps, expansion tanks, filters (if necessary), collectors, return and safety valves, air valves, valves, etc. You will also need to purchase radiators, connecting pipes and valves, thermostats, a boiler, etc. The issue of choosing a boiler is quite serious, so it is better to entrust the selection of equipment and its complete set to professionals.
Which boiler is the best? On Russian market gas boiler equipment has its own leaders in quality and reliability. The best manufacturing companies and brands of gas boilers are presented in an assortment:
"Premium class" or "Lux"- the most reliable and durable, easy to use, the kit is assembled like a “construction set”, more expensive than others. Such manufacturers include German companies
How to calculate the power of a gas boiler for the given parameters of a heated room? I know of at least three different ways, giving different levels of reliability of the results, and today we will get acquainted with each of them.
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 attracts with 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.
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.
When double-circuit boiler supplying the house 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.
Calculation methods
Scheme 1: by area
It will help us with this normative documents half a century ago. According to Soviet SNiP, heating should be designed at the rate of 100 watts of heat per square meter of heated space.
Let's, as an example, calculate the power for a house measuring 6x8 meters:
- The area of a house is equal to its product overall dimensions. 6x8x48 m2;
- With a specific power of 100 W/m2, the total boiler power should be equal to 48x100=4800 watts, or 4.8 kW.
Choosing the boiler power according to the area of the heated room is simple, understandable and... in most cases gives the wrong result.
Because he neglects a number of important factors that influence real heat loss:
- Number of windows and doors. More heat is lost through glazing and doorways than through a solid wall;
- Ceiling height. In Soviet-built apartment buildings it was standard - 2.5 meters with a minimum error. But in modern cottages You can find ceilings 3, 4 or more meters high. The higher the ceiling, the larger the heated volume;
- Climatic zone. With the same quality of thermal insulation, heat loss is directly proportional to the difference between indoor and outdoor temperatures.
IN apartment building Heat loss is affected by the location of the living space relative to the external walls: end and corner rooms lose more heat. However, in a typical cottage, all rooms have common walls with the street, so the corresponding correction factor is included in the basic value of thermal power.
Scheme 2: by volume, taking into account additional factors
How to calculate a gas boiler for heating a private house with your own hands, taking into account all the factors I mentioned?
First and foremost: in the calculation we take into account not the area of the house, but its volume, that is, the product of the area and the height of the ceilings.
- Base value boiler power per cubic meter of heated volume - 60 watts;
- Window increases heat loss by 100 watts;
- Door adds 200 W;
- Heat loss is multiplied by a regional coefficient. It is determined by the average temperature of the coldest month:
| Image | Coefficient and climate zone |
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0,6-0,9 - for regions with an average January temperature of about 0 °C (Krasnodar Territory, Crimea). |
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1,2-1,3 - for the average temperature of the coldest month of -15-20 ° C (Moscow and Leningrad regions). |
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1,5-1,6 - for areas with an average January temperature of -25-30 °C (Novosibirsk region, Khabarovsk Territory). |
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2 - for -40 and below (Chukotka, Yakutia). |
Let's again calculate the boiler power for our house measuring 6x8 meters, specifying a few additional parameters:
- Location of the house- the city of Sevastopol (the average temperature in January is +3 degrees Celsius);
- Number of windows- 5. One door leads to the street;
- Ceiling height- 3.2 meters.
- House volume(With external walls) is equal to the product of its three dimensions: 6x8x3.2 = 153.6 cubic meters;
- Base power for this volume - 153.6x60=9216 W;
- Including windows and doors it will increase by 5x100+200=700 watts. 9216+700=9916;
- Regional coefficient for the warm climate of Crimea we will take it equal to 0.6.
9916*0.6=6000 (rounded) watts.
As you can see, the complicated calculation scheme gave a result noticeably different from the previous one. How accurate is it?
The calculation will give a reliable result for a house, the quality of insulation of which approximately corresponds to the quality of insulation of Soviet-built houses. The scheme is based on the same 100 watts per square area, recalculated taking into account standard height ceilings of 2.5 meters at 40 W/m3 and multiplied by a factor of 1.5 to compensate for the heat loss of a private house through the roof and floor.
How to determine the heat requirement of a house with non-standard insulation?
Scheme 3: by volume, taking into account the quality of insulation
The most universal formula calculating the thermal power of the boiler has the form Q=V*Dt*k/860.
In this formula:
- Q - heat loss of the house in kilowatts;
- V is the volume to be heated by the boiler, in cubic meters;
- Dt is the calculated temperature delta between the heated room and the air outside the external walls;
- k is the dissipation coefficient, determined by the quality of the house insulation.
How to choose the coefficient k?
Select its value for your conditions using the following table:
| Image | Coefficient value and description of the building |
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3-4 - building without insulation (warehouse made of corrugated sheets, panel house with walls made of boards in one layer) |
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2.0-2.9 - walls made of timber 10 cm thick or brick 25 cm thick, wooden frames, single glazing |
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1,0-1,9 - brick walls 50 cm thick, double glazed windows |
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0.6-0.9 - facade insulated with foam plastic or mineral wool, plastic windows with triple or energy-saving double-glazed windows |
How to choose the value of the estimated street temperature? In calculations, it is customary to use the temperature of the coldest five-day winter for a given region. Rare extreme frosts are not taken into account: when the thermometer drops below the usual levels, auxiliary heat sources (heaters, fan heaters, etc.) can be used.
Where can I get the relevant information? The instructions are quite predictable: the necessary data will be found in SNiP 01/23/99, regulatory document, dedicated to construction climatology.
For the convenience of readers, I will provide here a small excerpt from the text of SNiP.
| City | Temperature of the coldest 5 days of winter, °C |
| Maykop | -22 |
| Barnaul | -42 |
| Blagoveshchensk | -37 |
| Tynda | -46 |
| Shimanovsk | -41 |
| Arkhangelsk | -37 |
| Astrakhan | -26 |
| Ufa | -39 |
| Belgorod | -28 |
| Bryansk | -30 |
| Ulan-Ude | -40 |
| Vladimir | -34 |
| Vologda | -37 |
| Voronezh | -31 |
| Makhachkala | -19 |
| Irkutsk | -38 |
| Kaliningrad | -24 |
| Petropavlovsk-Kamchatsky | -22 |
| Pechora | -48 |
| Kostroma | -35 |
| Agatha | -55 |
| Turukhansk | -56 |
| Saint Petersburg | -30 |
| Susuman | -57 |
| Moscow | -32 |
| Novosibirsk | -42 |
| Vladivostok | -26 |
| Komsomolsk-on-Amur | -37 |
| Yalta | -8 |
| Sevastopol | -11 |
Let's return to our example with the house in Sevastopol, once again clarifying a few details:
- Window glazing- single, in wooden large-slot frames;
- Wall material- rubble, about half a meter thick.
Let's start with the calculations.
- For the calculated internal temperature we will take the corresponding sanitary standards+20°С. Taking into account the data from the table above, the Dt parameter will be equal to 20 - -11 = 31 degrees;
- Let us take the dissipation coefficient equal to 2.0: rubble walls have much higher thermal conductivity than brick walls;
- We calculated the volume of the house earlier. It is equal to 153.6 cubes;
- Let's substitute the values of the variables into our formula. Q=153.6x31*2/860=11 kW.
As you can see, the adjustment for significant heat losses almost doubled the calculated power of the gas boiler.
Two circuits
It’s very simple: a 20 percent reserve is included in the project for the operation of the second flow. In our case, the required power will be 11x1.2=13.2 kW.
