Currently, there is a fairly large selection of heating devices with which you can effectively organize an autonomous heating system. The desire of consumers to reduce dependence on centralized heat and power services is understandable. Saving money spent on gas heating is a significant factor that residents of private houses pay attention to.
In addition, it is not always technologically possible to connect to a centralized gas supply. In such a situation, solid fuel boiler equipment comes into play. A powerful solid fuel boiler is an excellent alternative to gas equipment. Manufacturers have managed not only to improve the manufacturability of heating equipment of this type, but also to achieve a significant increase in the efficiency of solid fuel units. The high power and high efficiency of a solid fuel boiler operating on various types of fossil and fossil fuels make such devices in demand and popular.
An important aspect in order to choose the right heating device for your own needs is the calculation of the boiler power. Let's take a closer look at how to do this and what you should pay attention to.
Why is it necessary to calculate the power of the heating device
The appearance of heating equipment, high technological characteristics, stated in the technical data sheet, give only a superficial idea of the technical capabilities of a solid fuel boiler. The main parameter influencing your choice is the power of the device. In pursuit of it, we sometimes draw hasty conclusions and overpay, acquiring powerful units that do not meet real requirements and tasks.
Price-quality + heat output, the ratio is of decisive importance for any heating equipment. Manufacturers offer the consumer heating boilers of various models, each of which corresponds to certain operating conditions. Despite this, in each hotel case it is important to have an understanding of how the heating device should work and what the resource of the heating unit will be spent on. The parameter of operation of a solid fuel heater, calculated taking into account the needs and design features of the room, and the correct installation of the equipment, will allow the home heating system to be brought to the optimal operating mode.
Many consumers are wondering. How to calculate the power of your own solid fuel boiler yourself, so that in the future there would be no problems with the operation of the heating system. There is nothing difficult. With a minimum of knowledge and effort, you can get preliminary data that give an idea of what a heating device should be and how it is better to heat it.
Heating boiler power - theory and real facts
A heating apparatus operating on coal, wood or other organic fuel performs certain work related to heating the coolant. The amount of work of boiler equipment is determined by the amount of heat load that a solid fuel boiler can withstand when a certain amount of fuel is burned. The ratio of the amount of fuel consumed, the amount of heat energy released at the optimal operating modes of the equipment is the boiler power.
An incorrectly selected heating unit in terms of power will not be able to provide the required temperature of the boiler water in the heating circuit. Low-power solid fuel devices will not allow an autonomous system to fully meet your needs in terms of heating your home and providing hot water. There will be a need to increase the power of an autonomous device. A powerful device, on the contrary, will create problems during operation. It will be necessary to make structural changes to the existing heating complex to reduce the thermal load of the solid fuel heating device. Why burn precious fuel in vain if there is no need for such an amount of heat.
For reference: exceeding the power of the boiler of the technological parameters of the heating system, leads to the fact that the coolant in the circuit will diverge impulsively. Frequent switching on and off of the heating unit leads to excessive fuel consumption, a decrease in the operational capabilities of the heating equipment as a whole.
From a theoretical point of view, it is not difficult to calculate the optimal operating mode of boiler equipment. It is tentatively considered that 10 kW is enough to heat a living area of 10 m 2. This indicator is taken taking into account the high thermal efficiency of the building and the standard design features of the building (ceiling height, glazing area).
In theory, the calculation is done based on the following parameters:
- the area of the heated room;
- specific power of heating equipment for heating 10 sq. 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 work with a small margin of power.
On a note: The excess power of a solid fuel boiler will allow you to quickly reach the optimal operating mode for the entire heating system in the house. 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 band, the following power parameters of boiler equipment are considered optimal:
- one-room city apartment - a boiler with an output load of 4.16-5 kW;
- for a two-room apartment - equipment with a nominal value of 5.85-6 kW;
- a three-room apartment will be enough to have a unit of 8.71-10 kW;
- a four-room apartment, a residential private house will require a boiler installation with parameters of 12-24 kW for heating.
Important! If we are talking about the installation of solid fuel boiler equipment in private houses and suburban residential buildings, it is necessary to focus on devices with great technological capabilities. To heat and provide hot water supply to a residential building with an area of 150 m 2 or more, it will be necessary 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 household needs for hot water.
It is always necessary to choose heating equipment individually, based on the calculated data and your own needs.
Options for calculating the power of solid fuel units
The accuracy of your calculations depends on taking into account all the factors and indicators that we paid attention to above. For greater clarity, you can perform a number of actions that will give an idea of \u200b\u200bhow this is done.
The specific power of the heating device is indicated by the letter W. For regions of our country with a harsh climate, this parameter is 1.2-2 kW. In the southern regions, the specific value of the heater varies between 0.7-0.9 kW. The average value in this case is 1.2-1.5 kW.
First, we determine the area of \u200b\u200bthe premises to be heated. Further, we divide the obtained area data by the specific power of the boiler installed in the house in a certain area. We divide the result by 10, based on the theoretical ratio of the power consumed by the heating equipment for heating 10 square meters. meters.
For example: we calculate the maximum load of a coal-fired heating boiler for an average residential building with an area of 150 m 2.
- The living area is 150 sq. meters.
- The specific power of the heater for heating 10 m 2 is 1.5 kW.
We use the following formula for work: W = (150 x 1.5) / 10. As a result, we get 22.5 kW. The value obtained is the starting point for choosing an autonomous solid fuel boiler, taking into account the technological capabilities of the heating system and its own domestic needs.
On a note: having found a similar model of heating equipment, throw in 20-30% of the power to increase the technological capabilities of all heating equipment. The load on the DHW system, the comfortable temperature in the house, provided that the boiler is operating at optimal conditions, depends on the number of residents in the house.
The optimal choice of heating equipment - the nuances and subtleties of the issue
Having learned for yourself the necessary power parameters of a solid fuel boiler that will be in your house, you can proceed to the design and installation of the heating system. You should be aware that the declared data on the resource of the thermal load of the equipment affect the cost of the unit. Heating devices of low power have limited technological capabilities and are mainly designed for heating small rooms. These can be country houses, saunas and guest buildings of a country type.
If necessary, the question arises of how to increase the functionality and efficiency of a solid fuel device. In this case, there are reasonable technical and engineering solutions, with the help of which an increase in the efficiency of the boiler will give a tangible effect.
On a note: It is possible to significantly increase the efficiency of the device by installing an additional heat exchanger in the chimney, which will receive heat from volatile combustion wastes escaping into the atmosphere. The economizer (additional heat exchanger) will give an increase of 20-30% to the rated power of the boiler equipment.
It is not advisable to use solid fuel boilers of high power for autonomous heating of residential buildings. Such equipment is bulky and requires a large area for the installation of a special room. Given the size and enormous power of industrial boiler equipment, one should be aware of the significant consumption of the fuel resource.
This technique is ideal for heating on an industrial scale. A lot of heat will be required when heating large industrial facilities and structures. Solid fuel units with a large thermal load are installed at enterprises.
conclusions
The selection of heating equipment is a complex and responsible task. Do not immediately chase after models of solid fuel units that have a lot of power. In some cases, for heating a residential building, it is enough to install a unit with output parameters of 24-36 kW. At a temperature outside the window of -30 0 C, such a boiler will make it possible to create an indoor temperature of + 20-22 0 C and heat water in the DHW system to 40-45 0 C.
In each individual case, you can make a choice in favor of one or another type of heating technology.
Large boiler power may be required in peak situations, when climatic conditions force the heating system to work in enhanced mode. However, such situations are not systematic, and most of the time your heater will operate at reduced modes. If you expect a large consumption of hot water for domestic purposes, then you should immediately focus on equipment of greater power. In modern private houses, more than 50% of the power of heating equipment is used to provide hot water to the inhabitants of the house. Connecting the "warm floor" heating system also forces you to pay attention to boiler equipment with more power.
It is necessary to select a boiler not only based on its actual power. The operational capabilities of heating equipment, the method and quality of maintenance of boiler equipment play a role here. Using the optimal type of fuel for your heating equipment, the presence of automation will allow you to achieve the normal operation of a solid fuel boiler.
To answer this question, only data on its cubic capacity is not enough. To choose the right heating equipment, you need information about the heat loss of the house.
To ensure proper comfort in using the DHW system, the power of a double-circuit boiler must be significantly greater than when the boiler only heats the house.
When building or reconstructing a house, it becomes necessary to select the power of the boiler to provide the home with heat and hot water.
Without mathematics - not a step.
The main information needed to select the power of the boiler is the heat loss of the house, which it must compensate for. They need to be calculated. Each country has adopted a specific methodology for calculating heat losses, which takes into account local climatic conditions.
In Ukraine, there is a methodology set forth in DBN B 2.6-31:2006 "Thermal insulation of structures", which contains requirements for thermal performance of enclosing structures of houses and structures and the procedure for their calculation.
When ordering a house project from an architect, you have the right to demand that the project contains the results of such calculations. Based on them, you can choose not only a boiler, but also heating equipment for all rooms. With the use of a computer program. Calculating heat loss is facilitated by computer programs, free versions of which are distributed by many installation companies. Thanks to advanced additional functions, the program allows you to perform calculations even for people who have never dealt with design before. But due to the lack of relevant experience, they will most likely need much more time to carry out the calculation. According to the results of such calculations, it is better to consult with a specialist.
With the help of a questionnaire. If you do not have a project with heat losses calculated by the architect (designer), you can try to determine them yourself using simplified calculation methods. Sufficiently accurate for small private houses are still not very common with us, but very practical questionnaires.
They raise questions regarding: the cubic capacity of the house, the material of the walls and their thickness; insulation material and its thickness; the number of windows and their sizes, the number of chambers in double-glazed windows and others. For each of the questions, there are several possible answers. You need to choose the one that best describes your home. Each answer corresponds to a certain number. Performing mathematical operations with these numbers according to the attached instructions, we will get a value that describes the heat loss of your home. Its accuracy is quite acceptable for selecting the power of the boiler. Filling out the questionnaire and calculations takes only a few minutes. Approximately. The simplest method for calculating the heat loss of a house is to determine them using a conditional coefficient, which is approximately:
130-200 W / m - for houses without thermal insulation;
90-110 W / m - for houses with thermal insulation built in the 80-90s of the XX century;
50-70 W/m2 - for houses with modern windows, well insulated and built since the late 90s of the XX century.
Heat loss is determined by multiplying the value of the coefficient by the area of the house. These calculations are very approximate, they do not take into account the number and size of windows, the shape of the house and its location - factors that significantly affect the heat loss of the house. Such calculations should not be the main criterion when choosing a boiler, they can be used to evaluate the designer's calculations. Unfortunately, the difference between these results can be significant, so only a gross error can be detected in this way.
« Approximately". More recently, when fuel was cheap, houses were practically not insulated, and the windows were leaky and no one thought about the concept of energy saving - the installers selected the boiler power very simply - 1 kW for every 10 m2 of the house area. But today you need to select a boiler, based on strict calculations.
More comfort means more power.
A double-circuit boiler with a power of 18 kW allows you to comfortably use hot water for only one person. Opening a second tap at this time will lead to a significant decrease in pressure and temperature of hot water. A large family will experience discomfort from the operation of the hot water supply that such a boiler provides. Purchasing a larger boiler, such as 28 kW, may eliminate the discomfort of using hot water, but you need to weigh whether the minimum power of such a boiler will be too large compared to the heat demand for heating the house.
In order for the boiler to work in the most suitable mode for it, that is, with a constant [approximately the same] power, hydraulic systems with a four-way mixing valve are used.
A similar effect, but for less money, can be achieved by installing the so-called thermo-hydraulic distributor
Heat loss and boiler power.
The calculated heat loss of the house is equal to its maximum heat demand, necessary to maintain a comfortable temperature in the house - usually + 20 ° C. The maximum heat demand occurs on the coldest days, when the outside temperature drops (depending on the temperature zone) to -22°C. It should be borne in mind that such frosts occur only a few days a year, and sometimes they are not observed for several years in a row. However, the boiler must function effectively throughout the heating season, when the temperature fluctuates most often near zero. In this case, a boiler of half the (than the calculated) power is enough to heat the house. Therefore, it often makes no sense to buy a boiler with a larger capacity - not only due to its higher price, but also taking into account the decrease in the efficiency of its operation when the heat demand is much lower than the calculated one. The lack of heat on cold days can be made up by other sources, such as a fireplace or electric heaters.
How to combine high power with low demand.
It is best if the boiler operates at a constant, rated power throughout the entire time. But the need for thermal energy (depending on the outside temperature) changes all the time. How to solve this problem? Mixing valves. One way to do this is to use hydraulic systems with a four-way mixing valve or with a thermo-hydraulic distributor. In such systems, the temperature of the water entering the radiators is not regulated by changing the power of the boiler, but by changing the position of the control valve and the performance of the circulation pumps. Thanks to this, the boiler constantly works in optimal conditions. This is a very good, but rather expensive solution.
Multistage burners.
In small and not very expensive systems with gas or oil boilers, the issue of adapting the boiler performance to the actual heat demand is solved using multi-stage burners. When full power is not needed, a boiler equipped with such a burner operates at a lower power (lower burner stage). A more perfect option are burners with smooth power control, the so-called modulation. They are widely used in hinged gas boilers. In liquid fuel boilers, they are much less common. A modulating burner boiler is a cheaper and less troublesome option than a mixing valve system. No additional elements are required - all the necessary fittings are mounted in the boiler body. Power adjustment is also possible in modern solid fuel boilers that work on pellets and are equipped with an automated fuel supply system (unfortunately, expensive).
Modulation is not an ideal solution.
A boiler with a modulating burner generates energy equal to the current heat demand. At first glance, one might assume that when choosing such a boiler, it is not necessary to accurately determine the heat loss of the house. After all, knowing them only approximately, you can buy a boiler of greater power, which in any case will work with the power required at a certain moment. Unfortunately, in practice, modulating the power of the boiler does not completely solve all issues. Immediately after switching on, the boiler starts to work with maximum power, after a certain time, its automation begins to reduce power to the optimum level. If a large boiler is to be operated in a small system, then in conditions where the heat demand is low (i.e. outside temperature near zero or above), the water in the system will heat up before the burner reaches the required level of modulation and the boiler switches off. The water in the system will quickly cool down and the situation will repeat itself. The boiler will operate in pulsed mode, as if it were equipped with a single-stage high power burner. Power modulation is possible only within a limited range, which is usually no less than 30% of the maximum power. Therefore, too high a maximum boiler output will lead to difficulties in adapting its performance at a higher outside temperature. There are boilers with a wider power modulation range, but these are more expensive condensing boilers.
The oil boiler is not for a small house.
Quite big difficulties arise when choosing a liquid fuel boiler for a small house. To compensate for the heat loss of a well-insulated house with an area of about 150 m: usually a boiler with a capacity of no more than 10 kW is enough, and the power of liquid fuel boilers on the market is at least twice as high. The operation of a liquid fuel boiler in a pulsed mode (that is, frequent switching on and off) is even more unfavorable for it than for a gas boiler. Immediately after turning on the oil burner, a lot of soot and products of incomplete combustion are released from the combustion products, which clog the combustion chamber of the boiler. Therefore, it will have to be cleaned frequently, otherwise the soot layer will impede heat transfer, and the efficiency of the boiler will decrease, that is, it will consume more fuel.
Central heating is just the beginning.
Most of the described problems that arise can theoretically be avoided by choosing a boiler with a capacity that does not exceed, and even slightly below, the calculated heat loss of the house. But in practice, the energy of the boiler is usually used not only for the central heating system, but also for heating the water of the DHW system. In small, well-insulated houses, the power needed to heat the house is much less than that needed to quickly heat the required amount of DHW water. This complicates the problem of optimal boiler selection.
Boiler power and hot water.
A double-circuit boiler heats water for the DHW system in a flow-through manner. The time for water to flow through the heat exchanger is short, so the boiler must have a high power so that it can heat enough water during this time. The smallest double-circuit boilers have a power of 18 kW, because this is the minimum that still allows you to cook enough amount of hot water. If such a boiler is equipped with a modulating burner, it will be able to operate with a minimum power of about 6 kW, that is, close to the maximum heat loss in a well-insulated house with an area of about 100 m2. In practice, during most of the heating season, the power requirement for heating such a house will most likely be about 3 kW. Therefore, this is not an ideal, but acceptable situation.
One of the ways to reduce the required power of a double-circuit boiler is to use a storage tank for domestic hot water. Then the boiler can heat water more slowly, because after opening the tap there is a supply of warm water in the storage tank. The larger its volume, the longer it can replenish the missing amount of hot water prepared by the boiler. Therefore, the boiler power may be lower.
Single-circuit boiler with a boiler.
The volume of an indirect heating boiler (storage water heater with a heat exchanger), which is connected to a single-circuit boiler, is usually more than 100 liters. Due to this, the simultaneous use of hot water by several consumers does not lead to the exhaustion of its supply for several minutes, therefore, the power of the boiler operating in conjunction with the water heater may be lower than the power of a two-circuit boiler. Therefore, we can assume that the power of the boiler, which is necessary to compensate for the heat loss of the house, is also sufficient to heat the water in the boiler. However, when choosing the power of a single-circuit boiler, it is better to calculate how long it will take to heat the water in the boiler. This can be done using the formula:
T \u003d mc B (t 2 - t 1) / P,
where: T - water heating time (s); m is the mass of water in the boiler (kg); c B - specific heat capacity of water - 4.2 kJ / (kg x K); t2 is the temperature to which the water must be heated (°C); t 1 - initial water temperature in the boiler (°С); P - boiler power (kW).
For example: the heating time of water having a temperature of 10 ° C (it is generally accepted that this is the temperature of cold water entering the water heater) to 50 ° C in a 200-liter boiler with a 12 kW boiler will be: 200 x 4.2 x (50 - 10J/12 = 2800 (s) = 46.7 (min).
It's long enough, especially considering that during the heating of water in the boiler, from the boiler operating at full capacity, warm water does not enter the central heating system. During this time, the rooms may become cool.
However, it should be noted that the situation in which the entire volume of water has a temperature of 10°C can only occur after the boiler has been switched off for at least a few hours. In practice, cold water enters the boiler as hot water is consumed. Even if it is used intensively, for example, when filling the bathtub to the brim very quickly, about half of the hot water will be used from such a large boiler. After that, the temperature of the water (hot, mixed with cold) in the boiler will be about 30°C. In this case, the water heating time will be 23 minutes and it can be considered satisfactory. One-time hot water consumption in a single-family home is usually much lower, so the water in the boiler will heat up even faster.
Solution to the problem. The problem of sharing the power of the boiler for the central heating system and for the preparation of DHW water can be solved in a radical way: by purchasing two independent devices - a boiler for the central heating system and a water heater for DHW. But this is definitely an expensive solution.
Why not more powerful?
What happens if the boiler has too much power?
Its performance can be adjusted only by changing the amount of air entering the furnace. When operating at a power lower than the nominal one (that is, with a lack of air), the fuel will not burn completely, so its consumption will be greater. In addition, unburned connections will go into the chimney, causing it to clog more quickly.
Gas or oil boiler, working with a modern central heating system (containing a small amount of water), after turning on the burner, it very quickly heats the water in the system to the desired temperature and turns off the burner. The burner operation time will be shorter, the higher the boiler power. It may happen that it will be too short and the combustion products will not be able to heat the chimney to normal temperature. Then condensate will fall in the chimney, which, combining with other products of combustion, forms acids that destroy the chimney, and sometimes the boiler itself.
If the burner has been operating for a long time, the exhaust gases heat the chimney to a high temperature, so that condensate will not form, and the condensate that occurs in the initial phase of the burner will evaporate.
With frequent switching on and off, the boiler consumes more fuel than during continuous operation, because with each switching on, part of the energy will be spent on heating the elements of the boiler and the chimney. In addition, frequent temperature changes adversely affect its strength.
An overly powerful solid fuel boiler uses more fuel, and the heat energy in any case will not be fully used for heating
An overly powerful gas boiler will often turn on, which reduces its energy efficiency and accelerates the wear of the elements.
How to use excess boiler power?
If you nevertheless bought a boiler, the power of which is much higher than the calculated heat demand for heating the house, its working conditions can be significantly improved by installing a storage tank (also called a buffer tank).
This solution, used in systems with solar collectors, is recommended to be used primarily in systems with solid fuel boilers. Thanks to the battery, regardless of the short-term heat demand, the boiler can be operated with the rated output at which it has the highest efficiency. The storage tank is completely filled with water.
In systems with a solid fuel boiler its optimal volume can be determined from the calculation: 10 liters per square meter of heated area. When it is relatively warm outside, automatic control valves limit the flow of hot water to the radiators, directing it to the heat exchanger of a well-insulated storage tank, heating the water there. Its large volume (for a house with an area of 100 m: it should be 1000 l) during the operation of the boiler accumulates a large amount of excess heat energy from the system.
When the fuel in the boiler burns out and its furnace cools down, warm water from the buffer tank will begin to flow into the radiators. As a result, the heating system will still function properly.
Heating systems with a large amount of water have a significant thermal inertia, due to which the burners of gas and oil boilers work in more favorable conditions. The periods of operation of the burner and the breaks between them are longer - it takes longer to heat more water, which then cools down longer. However, the response of the system to changes in outside temperature is slower, which makes it more difficult to maintain a comfortable temperature in the rooms.
When choosing a boiler, it is sometimes difficult to determine its compliance with the heating requirements of a particular house. It seems that there is data on the size, internal volume. But this is not enough. The modern definition requires knowledge of the heat loss characteristic of this house. It is with heat losses that the possibility of choosing the power of the future boiler is associated, which should compensate for them in the course of its work.
Incorrectly selected boiler power leads to additional fuel costs(gas, solid and liquid). Each option will be discussed below, but for now it must be taken into account that, as a first approximation, insufficient boiler power leads to a low temperature in the heating system, due to its slow and insufficient heating. Power that exceeds the required leads to the operation of the system in a pulsed mode. It causes a sharp increase in gas consumption, wear of the gas valve. The right choice of boiler power and calculation of the heating system can help reduce heating costs.
Method for calculating heat losses
Calculation of heat losses is carried out according to certain methods, different from the climatic zone of the country. Having such calculations on hand, it is much easier to navigate in the choice of all the devices of the future heating system. The abundance of incoming data, basic and auxiliary, as well as the formalization of calculations, made it possible to introduce automation and carry them out using computer programs. Thanks to this, such calculations have become available for individual execution on the websites of construction companies.
Of course, only a specialist can determine the exact results. But an independent determination of the magnitude of heat loss will give quite visible results with the determination of the required power. By entering the data requested by the program, according to the parameters of the house(cubic capacity, materials, insulation, windows and doors, etc.), after performing the proposed actions, the value of heat losses is obtained. The resulting accuracy is sufficient to determine the required power of the boiler.
Using house ratios
The old way of determining the amount of heat loss was use of house coefficients of 3 types for an individual calculation of the power of a gas boiler using a simplified method:
- from 130 to 200 W / m2 - houses without thermal insulation;
- from 90 to 110 W / m2 - houses with thermal insulation, 20-30 years;
- from 50 to 70 W/m2 - heat-insulated house with new windows, 21st century.
Knowing the value of your coefficient and the area of \u200b\u200bthe house, by multiplying, the desired value is obtained. The required power was even easier to determine during the Soviet era. Then it was believed that 10 kW per 100 meters of area is just right.
However, today such accuracy is no longer enough.
What affects the power of the boiler
If it is too small, then a powerful solid fuel boiler will not “burn out” the remaining fuel due to lack of air supply, the chimney will quickly become clogged, and fuel consumption will be excessive. Gas or oil fired (LF) boilers will quickly heat a small amount of water and turn off the burners. This burning time will be the shorter, the more powerful the boilers. In such a short time, the removed combustion products will not have time to warm up the chimney, and condensate will accumulate there. Acids formed quickly will render unusable like a chimney, and the boiler itself.
Long burner operation allows the chimney to warm up and the condensate to disappear. Frequent switching on of the boiler leads to wear of it and the chimney, as well as increased fuel consumption due to the need to warm up the chimney channel and the boiler itself. To calculate the power of a liquid fuel (diesel) boiler, you can use calculator program, taking into account many of the features described above (designs, materials, windows, insulation), but express analysis can be performed using the above method.
It is believed that 1-1.5 kW of boiler power is needed to heat 10 square meters of a house. DHW is not taken into account in a house with high-quality insulation, without heat loss, with an area of 100 sq. m. Coefficients for the level of insulation used to calculate the required power of the boiler ZhT:
- 0,11 - apartment, 1st and last floors of an apartment building;
- 0,065 - an apartment in an apartment building;
- 0,15 (0,16) - a private house, a wall of 1.5 bricks, without insulation;
- 0,07 (0,08) - private house, wall 2 bricks, 1 layer of insulation.
For calculation, an area of 100 sq. m. is multiplied by a factor of 0.07 (0.08). The received power is 70-80 W per 1 sq. m. area. The boiler power is reserved by 10–20%, for hot water supply the reserve increases to 50%. This calculation is very approximate.
Knowing the heat losses, we can say about the required amount of heat generated. Usually, for comfort in the house, the value is taken +20 degrees Celsius. Since there is a period of minimum temperatures in the year, the demand for heat increases sharply on these days. Taking into account the periods when temperatures fluctuate around the average for the winter, the boiler power can be taken equal to half of the previously obtained value. In this case, compensation for heat losses due to other heat sources is taken into account.
Solving the problem of excess power
In the case of low heat demand, the boiler output becomes obviously high. There are several solutions. Firstly, during this period, the use of 4-way mixing valves in hydraulic systems is proposed. Can be applied thermohydraulic distributor. That allows you to regulate the heating of water without changing the boiler power, due to valves and circulation pumps. This ensures optimal operation of the boiler.
Due to the high cost of the method, a budget option is being considered. multi-stage burners in inexpensive gas and LT boilers. With the onset of the specified period, a stepwise transition to reduced combustion reduces the boiler power. A variant of smooth transition is modulation or smooth adjustment, commonly used in wall-mounted gas appliances. This possibility is almost not used in the designs of LT boilers, although a modulating burner is a more advanced option than a mixing valve. Modern pellet boilers are already equipped power control system and automatic fuel supply.
For the inexperienced consumer the presence of a modulating burner system may seem like a sufficient reason to abandon the calculation of heat losses at home, or at least limit themselves to an approximate definition. By no means, the presence of such a function cannot solve all the problems that arise: if, when the boiler is turned on, it starts to work at maximum power, then after a while the machine reduces it to the optimum.
At the same time, a powerful boiler in a small system has time heat water and turn off even before the transition of the modulating burner, I needed the desired level of combustion. The water cools down quickly enough, the situation will repeat itself “to a blot”. As a result, the operation of the boiler takes place in impulses as with a single-stage powerful burner. The change in power can reach no more than 30%, which will eventually lead to failures with a further increase in the external temperature. It is worth remembering that it is about relatively cheap devices.
In more expensive condensing boilers, the modulation limits are wider. ZhT boilers can cause tangible difficulties when trying to use in small and well-insulated houses. In such a house, about 150 sq. m, 10 kW of power is enough to cover heat losses. In the line of ZhT boilers offered by manufacturers, the minimum power is twice as much. And here an attempt to use such a boiler can lead to a situation even worse than that described above.
ZhT (diesel fuel) is burning in the furnace, everyone saw a black plume behind an unheated and unregulated diesel engine. And here in the products of incomplete combustion, soot falls abundantly, it and unburned products are thoroughly clog the combustion chamber. And now the brand new boiler needs to be urgently cleaned so as not to reduce the efficiency and restore heat transfer. And after all, if you first select the correct power of the boiler, there would not be all the problems described.
In practice, you should choose the boiler power slightly lower than the heat losses of the house. Popularity and practical use have gained boilers with TsOGVS, i.e. double-circuit, heating water for heating and hot water supply. And among these two functions, the required capacity for CH is less than for DHW. Of course, this approach made the choice of boiler power more difficult.
The method of obtaining hot water in a 2-circuit boiler - flow heating. Since the time of contact (heating) of running water is insignificant, the power of the boiler heater must be high. Even for low-power double-circuit boilers, the DHW system has 18 kW of power and this is only the minimum, which makes it possible to take a normal shower. The presence of a modulating burner in such a device will make it possible to work with a minimum power of 6 kW, almost equal to the heat loss in a 100-meter house with high-quality thermal insulation.
In real life, average, for the heating season, the needs will be no more than 3 kW. That is, although the situation is not ideal, it is acceptable. A way to reduce the required capacity of the DHW system is to use a DHW storage tank. And it is very similar to a single-circuit boiler equipped with a boiler. The boiler connected through the heat exchanger to the boiler has a capacity at least 100 liters. This is a minimum, designed for several points of water intake and their simultaneous use.
This scheme allows reduce boiler output combined with a water heater. As a result, the task is completed and the boiler power is sufficient to compensate for heat losses (CH) and hot water (boiler). At first glance, as a result, during the operation of the boiler to the boiler, hot water will not go into the heating system and the temperature in the house will drop. In fact, for this to happen, the boiler must turn off for 3 - 4 hours. The process of replacing heated water from the boiler with cold water occurs gradually. The practice of using heated water says that even draining half the volume, which is 50 liters at a temperature of about 85 degrees Celsius and the same amount of cold to use, leads to the remainder in the tank of half the volume of hot and the same amount of cold. The heating time will be no more than 25 minutes. Since such a volume is not consumed at a time in the family, the heating time of the boiler will be much less.
An example of determining the boiler power
An approximate method for determining the power of a gas boiler based on its specific power (Rud) per 10 sq. m and taking into account the conditions of climatic zones, heated area - P.
- 0.7−0.9 - south;
- 1.2−1.5 kW - middle band;
- 1.5−2.0 kW - north
Boiler power is determined Pk \u003d (P * Rud) / 10; where Rud = 1;
The volume of water in the system Osist \u003d Pk * 15; where 1 kW is accepted for 15 liters of water
So for the house from the example with a LT boiler, in the north, the calculation will look like this:
Pk \u003d 100 * 2/10 \u003d 20 (kW);
Advantages and disadvantages of gas boilers
The boiler is the main part of the heating system. It generates the amount of heat necessary for comfortable conditions and provides hot water. If there is a gas pipeline near the house, the best option would be to install a gas boiler. It has its pros and cons. The advantages of gas equipment are efficiency, high power, ease of operation, medium-sized boilers can be installed even in the kitchen, compact size and environmental friendliness (the boiler emits the least amount of harmful substances into the atmosphere).
The disadvantages of such a boiler are the requirement for a special permit for its installation, the risk of gas leaks, the presence of certain requirements for the room in which the boiler will be located, and the presence of an automatic shutdown of gas in the event of a leak or insufficient ventilation. In any case, if you decide to install gas heating equipment, you will have a question about how to calculate the power of a gas boiler.
Calculation of a gas boiler: the first method
Correctly calculated boiler power is a guarantee of reliable and efficient operation of the heating system. The basis of the calculation is to provide the house with an optimal temperature. Most often, the main source of heat in a house or cottage is the boiler. In order to calculate the necessary parameters and record the data obtained, you will need the following materials and tools:
- roulette;
- paper, pen;
- calculator.
The efficiency of the heating system depends entirely on the power of the boiler. Excessive power leads to excessive fuel consumption, and insufficient power leads to the inability to maintain the desired temperature in the house, especially in the winter season. The power of the gas boiler is determined based on the following parameters: the specific power of the unit per 10 m2, taking into account the climatic conditions of a certain region (Wsp), the area of heated premises (S). Specific power, depending on the climatic zone, can take on different values: 1.2-1.5 kW - for central Russia, 0.7-0.9 - for the southern regions and 1.5-2.0 kW - for the northern areas.
The boiler power is calculated using the formula Wcat = (S * Wsp) / 10. For convenience of calculation, unit is most often taken as specific power. The power is accordingly calculated as 10 kW per 100 m2. Another important parameter is the volume of coolant circulating in the system (Vsyst). When calculating, use the proportion 1 kW: 15 l (unit power: liquid volume. The formula will look like this: Vsyst \u003d Wcat 15
As an example, the calculation of the power of a gas boiler and the required volume of coolant for heating a house of 100 m2 located in the northern region will be given. The maximum specific power for the northern regions is 2 kW, then:
- Wcat \u003d 100 2 / 10 \u003d 20 kW;
- Vsyst \u003d 20 15 \u003d 300 l.
In order to make the calculation more accurate, you can use a special calculator that also takes into account the desired constant temperature in the house, the lowest average annual temperature, room parameters, wall thickness and material, type of ceilings and number of windows.
Before purchasing a boiler, it is necessary to carefully study its technical characteristics and technical passport.
So you will be sure of its thermal power, because in some cases, instead of the power given to the system, the technical characteristics of the burner may be indicated, which are of no interest to consumers.
The second way to calculate the power of equipment
When choosing a boiler, it is necessary to take into account information about the heat losses of the room, which will need to be compensated. They need to be calculated. This is usually done by the architect who designs the house. Using this data, you can select the boiler of the required power. You can calculate heat losses using special programs with advanced features, with the help of which even those who have never dealt with design can make calculations.
If there is no house project and heat loss calculations, they can be determined independently using a simplified calculation method. Questionnaires are accurate enough for small private houses. They contain questions regarding the material and thickness of the walls, the number and size of windows and the type of double-glazed windows. For each question, there are several possible answers. Each answer has its own number.
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The boiler is calculated using these numbers, the result is a value that reflects the heat loss of the house. It is quite suitable for determining the power of the unit. It will take only a few minutes to fill out the questionnaire and make calculations. The simplest method for calculating heat losses is to calculate them using a conditional coefficient having the following values:
- from 130 to 200 W / m2 - houses without thermal insulation;
- from 90 to 110 W / m2 - houses with thermal insulation, built 20-30 years ago;
- from 50 to 70 W / m2 - modern thermally insulated houses with new windows, built in the 21st century.
To determine heat loss, the coefficient is multiplied by the area of the house, however, these calculations are approximate, they do not take into account the number and size of windows, the location and shape of the house, which affect heat loss. This calculation is not the main one when choosing a boiler.
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The calculated heat loss reflects the maximum heat demand of the house, necessary to maintain a normal temperature. The greatest need for heat occurs at temperatures below -22°C. Such frosts usually occur several days a year, and sometimes do not occur at all for several years. And the boiler must work throughout the heating season, when the average temperature is zero. In this case, heating the house will require half the estimated capacity of the equipment. It is not worth buying a boiler of greater power, this leads not only to unnecessary expenses, but also lowers its efficiency. The lack of heat in extreme cold can be compensated by other appliances, such as a fireplace or an electric heater.In any heating system using a liquid heat carrier, its “heart” is the boiler. It is here that the energy potential of the fuel (solid, gaseous, liquid) or electricity is converted into heat, which is transferred to the coolant, and is already distributed to all heated rooms of the house or apartment. Naturally, the possibilities of any boiler are not unlimited, that is, they are limited by its technical and operational characteristics indicated in the product passport.
One of the key characteristics is the thermal power of the unit. Simply put, it must be able to produce in a unit of time such an amount of heat that would be sufficient to fully heat all the premises of a house or apartment. The selection of a suitable model "by eye" or according to some overly generalized concepts can lead to an error in one direction or another. Therefore, in this publication we will try to offer the reader, although not professional, but still with a sufficiently high degree of accuracy, an algorithm on how to calculate the boiler power for heating a house.
A banal question - why know the required boiler power
Despite the fact that the question does seem rhetorical, it still seems necessary to give a couple of explanations. The fact is that some owners of houses or apartments still manage to make mistakes, falling into one or another extreme. That is, purchasing equipment of either obviously insufficient thermal performance, in the hope of saving money, or greatly overestimated, so that, in their opinion, it is guaranteed, with a large margin, to provide themselves with heat in any situation.
Both of these are completely wrong, and negatively affect both the provision of comfortable living conditions and the durability of the equipment itself.
- Well, with the lack of calorific value, everything is more or less clear. With the onset of winter cold weather, the boiler will operate at its full capacity, and it is not a fact that there will be a comfortable microclimate in the rooms. This means that you will have to “catch up with heat” with the help of electric heaters, which will entail considerable extra costs. And the boiler itself, functioning at the limit of its capabilities, is unlikely to last long. In any case, after a year or two, homeowners clearly realize the need to replace the unit with a more powerful one. One way or another, the cost of a mistake is quite impressive.
- Well, why not buy a boiler with a large margin, what can prevent it? Yes, of course, high-quality space heating will be provided. But now we list the "cons" of this approach:
Firstly, a boiler of greater power can cost much more in itself, and it is difficult to call such a purchase rational.
Secondly, with increasing power, the dimensions and weight of the unit almost always increase. These are unnecessary installation difficulties, "stolen" space, which is especially important if the boiler is planned to be placed, for example, in the kitchen or in another room in the living area of the house.
Thirdly, you may encounter uneconomical operation of the heating system - part of the energy spent will be spent, in fact, wasted.
Fourthly, excess power is regular long shutdowns of the boiler, which, in addition, are accompanied by cooling of the chimney and, accordingly, abundant formation of condensate.
Fifth, if powerful equipment is never properly loaded, it does not benefit him. Such a statement may seem paradoxical, but it is true - wear becomes higher, the duration of trouble-free operation is significantly reduced.
Prices for popular heating boilers
An excess of boiler power will be appropriate only if it is planned to connect a water heating system for household needs to it - an indirect heating boiler. Well, or when it is planned to expand the heating system in the future. For example, in the plans of the owners - the construction of a residential extension to the house.
Methods for calculating the required boiler power
In truth, it is always better to entrust the conduct of heat engineering calculations to specialists - there are too many nuances to take into account. But, it is clear that such services are not provided free of charge, so many owners prefer to take responsibility for choosing the parameters of boiler equipment.
Let's see what methods of calculating thermal power are most often offered on the Internet. But first, let's clarify the question of what exactly should affect this parameter. So it will be easier to understand the advantages and disadvantages of each of the proposed calculation methods.
What principles are key in making calculations
So, the heating system faces two main tasks. Let us immediately clarify that there is no clear division between them - on the contrary, there is a very close relationship.
- The first is the creation and maintenance of a comfortable temperature for living in the premises. Moreover, this level of heating should apply to the entire volume of the room. Of course, due to physical laws, temperature gradation in height is still inevitable, but it should not affect the feeling of comfort in the room. It turns out that it should be able to warm up a certain volume of air.
The degree of temperature comfort is, of course, a subjective value, that is, different people can evaluate it in their own way. But still, it is generally accepted that this indicator is in the region of +20 ÷ 22 ° С. Usually, it is precisely this temperature that is used during thermal engineering calculations.
This is also indicated by the standards established by the current GOST, SNiP and SanPiN. For example, the table below shows the requirements of GOST 30494-96:
Room type Air temperature level, °С optimal admissible Living spaces 20÷22 18:24 Residential premises for regions with minimum winter temperatures from -31 °С and below 21÷23 20÷24 Kitchen 19:21 18:26 Toilet 19:21 18:26 Bathroom, combined bathroom 24÷26 18:26 Office, recreation and study rooms 20÷22 18:24 The corridor 18:20 16:22 lobby, stairwell 16÷18 14:20 Storerooms 16÷18 12÷22 Residential premises (the rest are not standardized) 22÷25 20÷28
- The second task is the constant compensation of possible heat losses. To create an “ideal” house in which there would be no heat leakage is a problem of problems, practically unsolvable. You can only reduce them to the ultimate minimum. And almost all elements of the building structure become leakage paths to one degree or another.
Building element Approximate share of total heat loss Foundation, basement, floors of the first floor (on the ground or over an unheated basement) from 5 to 10% Joints of building structures from 5 to 10% Sections of the passage of engineering communications through building structures (sewerage, water supply, gas supply pipes, electrical or communication cables, etc.) up to 5% External walls, depending on the level of thermal insulation from 20 to 30% Windows and doors to the street about 20÷25%, of which about half - due to insufficient sealing of boxes, poor fit of frames or canvases Roof up to 20% Chimney and ventilation up to 25÷30% Why were all these rather lengthy explanations given? And only in order for the reader to have complete clarity that in the calculations, willy-nilly, it is necessary to take into account both directions. That is, the "geometry" of the heated premises of the house, and the approximate level of heat loss from them. And the amount of these heat leaks, in turn, depends on a number of factors. This is the temperature difference in the street and in the house, and the quality of thermal insulation, and the features of the whole house as a whole and the location of each of its premises, and other evaluation criteria.
You might be interested in information on which are suitable
Now, armed with this preliminary knowledge, we turn to the consideration of various methods for calculating the required thermal power.
Calculation of power by the area of heated premises
It is proposed to proceed from their conditional ratio, that for high-quality heating of one square meter of the area of the room it is necessary to spend 100 W of thermal energy. Thus, it will help to calculate which:
Q=Stotal / 10
Q- the required thermal power of the heating system, expressed in kilowatts.
Stot- the total area of the heated premises of the house, square meters.
However, there are caveats:
- The first - the ceiling height of the room should be on average 2.7 meters, a range of 2.5 to 3 meters is allowed.
- The second - you can make an adjustment for the region of residence, that is, take not a rigid norm of 100 W / m², but a “floating” one:
That is, the formula will take a slightly different form:
Q=Stot ×Qud / 1000
Qud - the value of the specific heat output per square meter taken from the table shown above.
- Third - the calculation is valid for houses or apartments with an average degree of insulation of enclosing structures.
However, despite the above reservations, such a calculation cannot be called accurate. Agree that it is largely based on the "geometry" of the house and its premises. But heat losses are practically not taken into account, except for the rather “blurred” ranges of specific thermal power by region (which are also with very vague boundaries), and remarks that the walls should have an average degree of insulation.
But be that as it may, this method is still popular, precisely for its simplicity.
It is clear that it is necessary to add the operating power reserve of the boiler to the calculated value obtained. It should not be excessively overestimated - experts advise stopping at a range of 10 to 20%. This, by the way, applies to all methods for calculating the power of heating equipment, which will be discussed below.
Calculation of the required heat output by the volume of the premises
By and large, this method of calculation largely repeats the previous one. True, the initial value here is no longer the area, but the volume - in fact, the same area, but multiplied by the height of the ceilings.
And the norms of specific thermal power here are accepted as follows:
- for brick houses - 34 W / m³;
- for panel houses - 41 W / m³.
Even based on the proposed values (from their wording), it becomes clear that these norms were established for apartment buildings, and are mainly used to calculate the heat demand for premises connected to a central separation system or to an autonomous boiler station.
It is quite obvious that "geometry" is again put at the forefront. And the whole system for accounting for heat losses comes down only to differences in the thermal conductivity of brick and panel walls.
In a word, this approach to calculating thermal power also does not differ in accuracy.
Calculation algorithm taking into account the characteristics of the house and its individual premises
Description of the calculation method
So, the methods proposed above give only a general idea of the required amount of thermal energy for heating a house or apartment. They have a common vulnerability - the almost complete disregard for possible heat losses, which are recommended to be considered "average".
But it is quite possible to carry out more precise calculations. This will help the proposed calculation algorithm, which is embodied, in addition, in the form of an online calculator, which will be proposed below. Just before starting the calculations, it makes sense to consider step by step the very principle of their implementation.
First of all, an important note. The proposed methodology involves the assessment not of the entire house or apartment in terms of total area or volume, but of each heated room separately. Agree that rooms of equal area, but differing, say, in the number of external walls, will require a different amount of heat. It is impossible to put an equal sign between rooms that have a significant difference in the number and area of windows. And there are many such criteria for evaluating each of the rooms.
So it would be more correct to calculate the required power for each of the premises separately. Well, then a simple summation of the obtained values \u200b\u200bwill lead us to the desired indicator of the total heat output for the entire heating system. That is, in fact, for its "heart" - the boiler.
One more note. The proposed algorithm does not claim to be "scientific", that is, it is not directly based on any specific formulas established by SNiP or other governing documents. However, it has been field tested and shows results with a high degree of accuracy. Differences with the results of professionally carried out heat engineering calculations are minimal, and do not affect the correct choice of equipment in terms of its rated thermal power.
The "architecture" of the calculation is as follows - the base value of the specific thermal power mentioned above is taken, equal to 100 W / m², and then a whole series of correction factors is introduced, to one degree or another reflecting the amount of heat loss in a particular room.
If this is expressed by a mathematical formula, then it will turn out something like this:
Qk= 0.1 × Sk× k1 × k2 × k3 × k4 × k5 × k6 × k7 × k8 × k9× k10 × k11
Qk- the desired thermal power required for the full heating of a particular room
0.1 - translation of 100 W into 0.1 kW, just for the convenience of obtaining the result in kilowatts.
Sk- area of the room.
k1 hk11- correction factors for adjusting the result, taking into account the characteristics of the room.
With the determination of the area of \u200b\u200bthe room, presumably, there should be no problems. So let's move on to a detailed discussion of the correction factors.
- k1 is a coefficient that takes into account the height of the ceilings in the room.
It is clear that the height of the ceilings directly affects the amount of air that the heating system must warm up. For the calculation, it is proposed to accept the following values of the correction factor:
- k2 is a coefficient that takes into account the number of walls in the room that are in contact with the street.
The larger the area of contact with the external environment, the higher the level of heat loss. Everyone knows that it is always much cooler in a corner room than in a room with only one outer wall. And some rooms of a house or apartment may even be internal, not having contact with the street.
According to the mind, of course, one should take not only the number of external walls, but also their area. But our calculation is still simplified, so we restrict ourselves only to the introduction of a correction factor.
The coefficients for various cases are shown in the table below:
The case when all four walls are external is not considered. This is no longer a residential building, but just some kind of barn.
- k3 is a coefficient that takes into account the position of the outer walls relative to the cardinal points.
Even in winter, you should not discount the possible impact of the energy of the sun's rays. On a clear day, they penetrate through the windows into the premises, thereby being included in the overall heat supply. In addition, the walls receive a charge of solar energy, which leads to a decrease in the total amount of heat loss through them. But all this is true only for those walls that "see" the Sun. There is no such influence on the north and northeast side of the house, which can also be corrected.
The values of the correction factor for the cardinal points are in the table below:
- k4 is a coefficient that takes into account the direction of winter winds.
Perhaps this amendment is not mandatory, but for houses located in open areas, it makes sense to take it into account.
You may be interested in information about what they are
In almost any area there is a predominance of winter winds - this is also called the "wind rose". Local meteorologists must have such a scheme - it is compiled based on the results of many years of weather observations. Quite often, the locals themselves are well aware of which winds most often disturb them in winter.
And if the wall of the room is located on the windward side, and is not protected by any natural or artificial barriers from the wind, then it will cool much more. That is, the heat loss of the room increases. To a lesser extent, this will be expressed near the wall located parallel to the direction of the wind, and to a minimum - located on the leeward side.
If there is no desire to "bother" with this factor, or there is no reliable information about the winter wind rose, then you can leave the coefficient equal to one. Or, on the contrary, take it to the maximum, just in case, that is, for the most unfavorable conditions.
The values of this correction factor are in the table:
- k5 is a coefficient that takes into account the level of winter temperatures in the region of residence.
If heat engineering calculations are carried out in accordance with all the rules, then the assessment of heat losses is carried out taking into account the temperature difference in the room and on the street. It is clear that the colder the climatic conditions of the region, the more heat is required to be supplied to the heating system.
In our algorithm, this will also be taken into account to a certain extent, but with an acceptable simplification. Depending on the level of minimum winter temperatures falling on the coldest decade, a correction factor k5 is selected .
Here it would be appropriate to make one remark. The calculation will be correct if temperatures are taken into account, which are considered normal for a given region. There is no need to recall the anomalous frosts that happened, say, a few years ago (and that's why, by the way, they are remembered). That is, the lowest, but normal temperature for the area should be selected.
- k6 is a coefficient that takes into account the quality of the thermal insulation of the walls.
It is quite clear that the more efficient the wall insulation system, the lower the level of heat loss. Ideally, to which one should strive, thermal insulation in general should be complete, carried out on the basis of heat engineering calculations performed, taking into account the climatic conditions of the region and the design features of the house.
When calculating the required heat output of the heating system, the existing thermal insulation of the walls should also be taken into account. The following gradation of correction factors is proposed:
An insufficient degree of thermal insulation or its complete absence, in theory, should not be observed at all in a residential building. Otherwise, the heating system will be very expensive, and even without a guarantee of creating really comfortable living conditions.
You might be interested in information about the heating system
If the reader wishes to independently assess the level of thermal insulation of his home, he can use the information and calculator that are located in the last section of this publication.
- k7 andk8 - coefficients that take into account heat loss through the floor and ceiling.
The next two coefficients are similar - their introduction into the calculation takes into account the approximate level of heat loss through the floors and ceilings of the premises. There is no need to describe in detail here - both the possible options and the corresponding values of these coefficients are shown in the tables:
To begin with, the k7 coefficient, which corrects the result depending on the characteristics of the floor:
Now - the coefficient k8, which corrects for the neighborhood from above:
- k9 is a coefficient that takes into account the quality of the windows in the room.
Here, too, everything is simple - the better the windows, the less heat loss through them. Old wooden frames usually do not have good thermal insulation properties. This is better with modern window systems equipped with double-glazed windows. But they can also have a certain gradation - according to the number of cameras in a double-glazed window and according to other design features.
For our simplified calculation, the following values of the coefficient k9 can be applied:
- k10 is a coefficient that corrects for the room's glazing area.
The quality of windows does not yet fully reveal all the volumes of possible heat loss through them. Glazing area is very important. Agree, it is difficult to compare a small window and a huge panoramic window almost the entire wall.
To make an adjustment for this parameter, first you need to calculate the so-called room glazing coefficient. It's easy - just find the ratio of the glazing area to the total area of the room.
kw =sw/S
kw- coefficient of glazing of the room;
sw- total area of glazed surfaces, m²;
S- room area, m².
Anyone can measure and sum the area of windows. And then it is easy to find the desired glazing coefficient by simple division. And he, in turn, makes it possible to enter the table and determine the value of the correction factor k10 :
Value of glazing factor kw The value of the coefficient k10 - up to 0.1 0.8 - from 0.11 to 0.2 0.9 - from 0.21 to 0.3 1.0 - from 0.31 to 0.4 1.1 - from 0.41 to 0.5 1.2 - over 0.51 1.3
- k11 - coefficient taking into account the presence of doors to the street.
The last of the considered coefficients. The room may have a door leading directly to the street, to a cold balcony, to an unheated corridor or entrance, etc. Not only is the door itself often a very serious “cold bridge” - if it is opened regularly, a fair amount of cold air will enter the room each time. Therefore, this factor should also be corrected: such heat losses, of course, require additional compensation.
The values of the coefficient k11 are given in the table:
This coefficient should be taken into account if the doors are regularly used in winter.
You may be interested in information about what is
* * * * * * *
So, all correction factors are considered. As you can see, there is nothing super complicated here, and you can safely proceed to the calculations.
One more tip before starting calculations. Everything will be much easier if you first draw up a table, in the first column of which you sequentially indicate all the rooms of the house or apartment to be soldered. Next, in columns, place the data that is required for calculations. For example, in the second column - the area of \u200b\u200bthe room, in the third - the height of the ceilings, in the fourth - orientation to the cardinal points - and so on. It is not difficult to make such a plate, having in front of you a plan of your residential properties. It is clear that the calculated values of the required heat output for each room will be entered in the last column.
The table can be compiled in an office application, or even simply drawn on a piece of paper. And do not rush to part with it after making the calculations - the obtained indicators of thermal power will still be useful, for example, when purchasing heating radiators or electric heaters used as a backup heat source.
To make it as easy as possible for the reader to carry out such calculations, a special online calculator is placed below. With it, with the initial data previously collected in a table, the calculation will take literally a few minutes.
Calculator for calculating the required heat output for the premises of a house or apartment.
