Dependence on the temperature regime of the heating system
The power of the radiators is indicated for a system with a high temperature thermal regime. If the heating system of your home operates in medium or low temperature thermal conditions, you will have to make additional calculations to select batteries with the required number of sections.
To begin with, let's determine the thermal head of the system, which is the difference between the average temperature of the air and the batteries. For the temperature of the heating devices, the arithmetic mean of the values of the temperature of the supply and removal of the coolant is taken.
- High temperature mode: 90/70/20 (supply temperature - 90 °C, return temperature -70 °C, 20 °C is taken as the average room temperature). We calculate the thermal head as follows: (90 + 70) / 2 - 20 \u003d 60 ° С;
- Medium temperature: 75/65/20, heat head - 50 °C.
- Low temperature: 55/45/20, heat head - 30 °C.
To find out how many battery sections you will need for 50 and 30 heat head systems, multiply the total capacity by the radiator nameplate head and then divide by the available heat head. For a room of 15 sq.m. 15 sections of aluminum radiators, 17 bimetallic and 19 cast iron batteries will be required.
For a heating system with a low temperature regime, you will need 2 times more sections.
Example of a simple calculation
For a building with standard parameters (ceiling heights, room sizes and good thermal insulation characteristics), a simple ratio of parameters can be applied, adjusted for a coefficient depending on the region.
Suppose that a residential building is located in the Arkhangelsk region, and its area is 170 square meters. m. The heat load will be equal to 17 * 1.6 \u003d 27.2 kW / h.
Such a definition of thermal loads does not take into account many important factors. For example, the design features of the structure, temperature, the number of walls, the ratio of the areas of walls and window openings, etc. Therefore, such calculations are not suitable for serious heating system projects.
Accurate heat load calculations
Thermal conductivity value and heat transfer resistance for building materials
But still, this calculation of the optimal heat load on heating does not give the required calculation accuracy. It does not take into account the most important parameter - the characteristics of the building. The main one is the heat transfer resistance of the material for the manufacture of individual elements of the house - walls, windows, ceiling and floor. They determine the degree of conservation of thermal energy received from the heat carrier of the heating system.
What is heat transfer resistance (R)? This is the reciprocal of thermal conductivity (λ) - the ability of the material structure to transfer thermal energy. Those. the higher the thermal conductivity value, the higher the heat loss. This value cannot be used to calculate the annual heating load, since it does not take into account the thickness of the material (d). Therefore, experts use the heat transfer resistance parameter, which is calculated by the following formula:
Calculation for walls and windows
Heat transfer resistance of residential building walls
There are normalized values of the heat transfer resistance of walls, which directly depend on the region where the house is located.
In contrast to the enlarged calculation of the heating load, you first need to calculate the heat transfer resistance for external walls, windows, the floor of the first floor and the attic. Let's take as a basis the following characteristics of the house:
- Wall area - 280 m². It includes windows - 40 m²;
- The wall material is solid brick (λ=0.56). The thickness of the outer walls is 0.36 m. Based on this, we calculate the TV transmission resistance - R \u003d 0.36 / 0.56 \u003d 0.64 m² * C / W;
- To improve the thermal insulation properties, an external insulation was installed - polystyrene foam 100 mm thick.For him λ=0.036. Accordingly R \u003d 0.1 / 0.036 \u003d 2.72 m² * C / W;
- The overall R value for exterior walls is 0.64+2.72= 3.36 which is a very good indicator of the house's thermal insulation;
- Heat transfer resistance of windows - 0.75 m² * C / W (double-glazed window with argon filling).
In fact, heat losses through the walls will be:
(1/3.36)*240+(1/0.75)*40= 124 W at 1°C temperature difference
We take the temperature indicators the same as for the enlarged calculation of the heating load + 22 ° С indoors and -15 ° С outdoors. Further calculation must be done according to the following formula:
Ventilation calculation
Then you need to calculate the losses through ventilation. The total air volume in the building is 480 m³. At the same time, its density is approximately equal to 1.24 kg / m³. Those. its mass is 595 kg. On average, the air is renewed five times per day (24 hours). In this case, to calculate the maximum hourly load for heating, you need to calculate the heat losses for ventilation:
(480*40*5)/24= 4000 kJ or 1.11 kWh
Summing up all the obtained indicators, you can find the total heat loss of the house:
In this way, the exact maximum heating load is determined. The resulting value directly depends on the temperature outside. Therefore, to calculate the annual load on the heating system, it is necessary to take into account changes in weather conditions. If the average temperature during the heating season is -7°C, then the total heating load will be equal to:
(124*(22+7)+((480*(22+7)*5)/24))/3600)*24*150(heating season days)=15843 kW
By changing the temperature values, you can make an accurate calculation of the heat load for any heating system.
To the results obtained, it is necessary to add the value of heat losses through the roof and floor. This can be done with a correction factor of 1.2 - 6.07 * 1.2 \u003d 7.3 kW / h.
The resulting value indicates the actual cost of the energy carrier during the operation of the system. There are several ways to regulate the heating load of heating. The most effective of them is to reduce the temperature in rooms where there is no constant presence of residents. This can be done using temperature controllers and installed temperature sensors. But at the same time, a two-pipe heating system must be installed in the building.
To calculate the exact value of heat loss, you can use the specialized program Valtec. The video shows an example of working with it.
Anatoly Konevetsky, Crimea, Yalta
Anatoly Konevetsky, Crimea, Yalta
Dear Olga! Sorry for contacting you again. According to your formulas, I get an unthinkable thermal load: Cyr \u003d 0.01 * (2 * 9.8 * 21.6 * (1-0.83) + 12.25) \u003d 0.84 Qot \u003d 1.626 * 25600 * 0.37 * ((22-(-6)) * 1.84 * 0.000001 \u003d 0.793 Gcal / hour According to the enlarged formula above, it turns out only 0.149 Gcal / hour.I can’t understand what’s wrong? Please explain!
Anatoly Konevetsky, Crimea, Yalta
Calculation of the number of heating radiators by area and volume of the room
When replacing batteries or switching to individual heating in an apartment, the question arises of how to calculate the number of heating radiators and the number of instrument sections. If the battery power is insufficient, it will be cool in the apartment during the cold season. An excessive number of sections not only leads to unnecessary overpayments - with a single-pipe heating system, residents of the lower floors will be left without heat. You can calculate the optimal power and number of radiators based on the area or volume of the room, while taking into account the features of the room and the specifics of different types of batteries.
Determination of the number of radiators for one-pipe systems
There is one more very important point: all of the above is true for a two-pipe heating system. when a coolant with the same temperature enters the inlet of each of the radiators. A single-pipe system is considered much more complicated: there, colder water enters each subsequent heater. And if you want to calculate the number of radiators for a one-pipe system, you need to recalculate the temperature every time, and this is difficult and time consuming. Which exit? One of the possibilities is to determine the power of the radiators as for a two-pipe system, and then add sections in proportion to the drop in thermal power to increase the heat transfer of the battery as a whole.
In a single-pipe system, the water for each radiator is getting colder and colder.
Let's explain with an example. The diagram shows a single-pipe heating system with six radiators. The number of batteries was determined for two-pipe wiring. Now you need to make an adjustment. For the first heater, everything remains the same. The second one receives a coolant with a lower temperature. We determine the % power drop and increase the number of sections by the corresponding value. In the picture it turns out like this: 15kW-3kW = 12kW. We find the percentage: the temperature drop is 20%. Accordingly, to compensate, we increase the number of radiators: if you needed 8 pieces, it will be 20% more - 9 or 10 pieces. This is where knowledge of the room comes in handy: if it is a bedroom or a nursery, round it up, if it is a living room or other similar room, round it down
You also take into account the location relative to the cardinal points: in the north you round up, in the south - down
In single-pipe systems, you need to add sections to the radiators located further along the branch
This method is clearly not ideal: after all, it turns out that the last battery in the branch will have to be simply huge: judging by the scheme, a coolant with a specific heat capacity equal to its power is supplied to its input, and it is unrealistic to remove all 100% in practice. Therefore, when determining the power of a boiler for single-pipe systems, they usually take some margin, put shutoff valves and connect radiators through a bypass so that heat transfer can be adjusted, and thus compensate for the drop in coolant temperature. One thing follows from all this: the number and / or dimensions of radiators in a single-pipe system must be increased, and as you move away from the beginning of the branch, more and more sections should be installed.
An approximate calculation of the number of sections of heating radiators is a simple and quick matter. But clarification, depending on all the features of the premises, size, type of connection and location, requires attention and time. But you can definitely decide on the number of heaters to create a comfortable atmosphere in winter.
Inspection with a thermal imager
Increasingly, in order to increase the efficiency of the heating system, they resort to thermal imaging surveys of the building.
These works are carried out at night. For a more accurate result, you must observe the temperature difference between the room and the street: it must be at least 15 o. Fluorescent and incandescent lamps are switched off. It is advisable to remove carpets and furniture to the maximum, they knock down the device, giving some error.
The survey is carried out slowly, the data are recorded carefully. The scheme is simple.
The first stage of work takes place indoors
The device is moved gradually from doors to windows, paying special attention to corners and other joints.
The second stage is the examination of the external walls of the building with a thermal imager. The joints are still carefully examined, especially the connection with the roof.
The third stage is data processing. First, the device does this, then the readings are transferred to a computer, where the corresponding programs complete the processing and give the result.
If the survey was conducted by a licensed organization, then it will issue a report with mandatory recommendations based on the results of the work. If the work was carried out personally, then you need to rely on your knowledge and, possibly, the help of the Internet.
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Appliance distribution
When it comes to water heating, the maximum power of the heat source should be equal to the sum of the powers of all heat sources in the building.
The distribution of appliances in the premises of the house depends on the following circumstances:
- Room area, ceiling level.
- The position of the room in the building. The rooms in the end part in the corners are characterized by increased heat loss.
- Distance to heat source.
- Optimum temperature (from the point of view of residents). The temperature of the room, among other factors, is affected by the movement of air currents inside the housing.
- Living quarters in the depth of the building - 20 degrees.
- Residential premises in the corner and end parts of the building - 22 degrees.
- Kitchen - 18 degrees. The temperature is higher in the kitchen room, as there are additional heat sources (electric stove, refrigerator, etc.).
- Bathroom and toilet - 25 degrees.
If the house is equipped with air heating, the amount of heat flow entering the room depends on the capacity of the air sleeve. The flow is regulated by manually adjusting the ventilation grilles, and controlled by a thermometer.
The house can be heated by distributed sources of thermal energy: electric or gas convectors, electric heated floors, oil batteries, infrared heaters, air conditioners. In this case, the desired temperatures are determined by the thermostat setting. In this case, it is necessary to provide such power of the equipment, which would be sufficient at the maximum level of heat losses.
Types of thermal loads for calculations
When making calculations and choosing equipment, different thermal loads are taken into account:
- Seasonal loads. having the following features:
- they are characterized by changes depending on the ambient temperature in the street; - the presence of differences in the amount of heat energy consumption in accordance with the climatic features of the region where the house is located; - change in the load on the heating system depending on the time of day. Since external fences have heat resistance, this parameter is considered insignificant; - heat consumption of the ventilation system depending on the time of day.
Permanent thermal loads. In most objects of the heat supply and hot water supply system, they are used throughout the year. For example, in the warm season, the cost of thermal energy in comparison with the winter period is reduced by about 30-35%.
dry heat. Represents thermal radiation and convection heat exchange due to other similar devices. This parameter is determined using the dry bulb temperature. It depends on many factors, including windows and doors, ventilation systems, various equipment, air exchange due to the presence of cracks in walls and ceilings. Also take into account the number of people present in the room.
Latent heat. It is formed as a result of the process of evaporation and condensation. The temperature is determined using a wet bulb thermometer. In any intended room, the level of humidity is affected by:
- the number of people who are simultaneously in the room; — availability of technological or other equipment; - flows of air masses penetrating through cracks and cracks in the building envelope.
Calculation of different types of radiators
If you are going to install sectional radiators of a standard size (with an axial distance of 50cm in height) and have already chosen the material, model and the desired size, there should be no difficulty in calculating their number. Most of the reputable companies that supply good heating equipment have the technical data of all modifications on their website, among which there is also thermal power. If not power is indicated, but the flow rate of the coolant, then it is easy to convert to power: the coolant flow rate of 1 l / min is approximately equal to the power of 1 kW (1000 W).
The axial distance of the radiator is determined by the height between the centers of the holes for supplying/removing the coolant
To make life easier for buyers, many sites install a specially designed calculator program. Then the calculation of sections of heating radiators comes down to entering data on your room in the appropriate fields. And at the output you have the finished result: the number of sections of this model in pieces.
The axial distance is determined between the centers of the holes for the coolant
But if you are just considering possible options for now, then it is worth considering that radiators of the same size made of different materials have different thermal output. The method for calculating the number of sections of bimetallic radiators is no different from the calculation of aluminum, steel or cast iron. Only the thermal power of one section can be different.
To make it easier to calculate, there are average data that you can navigate. For one section of the radiator with an axial distance of 50 cm, the following power values are accepted:
- aluminum - 190W
- bimetallic - 185W
- cast iron - 145W.
If you are still only figuring out which material to choose, you can use these data. For clarity, we present the simplest calculation of sections of bimetallic heating radiators, which takes into account only the area of \u200b\u200bthe room.
When determining the number of bimetal heaters of a standard size (center distance 50 cm), it is assumed that one section can heat 1.8 m 2 of area. Then for a room of 16m 2 you need: 16m 2 / 1.8m 2 \u003d 8.88 pieces. Rounding up - 9 sections are needed.
Similarly, we consider for cast-iron or steel bars. All you need is the rules:
- bimetallic radiator - 1.8m 2
- aluminum - 1.9-2.0m 2
- cast iron - 1.4-1.5m 2.
This data is for sections with a center distance of 50cm. Today, there are models on sale with very different heights: from 60cm to 20cm and even lower. Models 20cm and below are called curb. Naturally, their power differs from the specified standard, and if you plan to use "non-standard", you will have to make adjustments. Or look for passport data, or count yourself. We proceed from the fact that the heat transfer of a thermal device directly depends on its area. With a decrease in height, the area of \u200b\u200bthe device decreases, and, therefore, the power decreases proportionally. That is, you need to find the ratio of the heights of the selected radiator to the standard, and then use this coefficient to correct the result.
Calculation of cast iron radiators. It can be calculated by the area or volume of the room
For clarity, we will calculate aluminum radiators by area. The room is the same: 16m 2. We consider the number of sections of a standard size: 16m 2 / 2m 2 \u003d 8pcs. But we want to use small sections with a height of 40cm. We find the ratio of radiators of the selected size to the standard ones: 50cm/40cm=1.25. And now we adjust the quantity: 8pcs * 1.25 = 10pcs.
How to calculate radiator sections by room volume
This calculation takes into account not only the area, but also the height of the ceilings, because you need to heat all the air in the room. So this approach is justified. And in this case, the procedure is similar.We determine the volume of the room, and then, according to the norms, we find out how much heat is needed to heat it:
- in a panel house, 41W is required to heat a cubic meter of air;
- in a brick house on m 3 - 34W.
You need to heat the entire volume of air in the room, therefore it is more correct to count the number of radiators by volume
Let's calculate everything for the same room with an area of 16m 2 and compare the results. Let the ceiling height be 2.7m. Volume: 16 * 2.7 \u003d 43.2m 3.
Next, we calculate for options in a panel and brick house:
- In a panel house. The heat required for heating is 43.2m 3 * 41V = 1771.2W. If we take all the same sections with a power of 170W, we get: 1771W / 170W = 10.418pcs (11pcs).
- In a brick house. Heat is needed 43.2m 3 * 34W = 1468.8W. We consider radiators: 1468.8W / 170W = 8.64pcs (9pcs).
As you can see, the difference is quite large: 11pcs and 9pcs. Moreover, when calculating by area, we got the average value (if rounded in the same direction) - 10pcs.
What to do if you need a very accurate calculation
Unfortunately, not every apartment can be considered standard. This is even more true for private residences. The question arises: how to calculate the number of heating radiators, taking into account the individual conditions of their operation? To do this, you need to take into account many different factors.
The peculiarity of this method is that when calculating the required amount of heat, a number of coefficients are used that take into account the characteristics of a particular room that can affect its ability to store or release heat energy. The calculation formula looks like this:
CT = 100W/sq.m. * P * K1 * K2 * K3 * K4 * K5 * K6 * K7. where
KT - the amount of heat required for a particular room; P is the area of the room, sq.m.; K1 - coefficient taking into account the glazing of window openings:
- for windows with ordinary double glazing - 1.27;
- for windows with double glazing - 1.0;
- for windows with triple glazing - 0.85.
K2 - coefficient of thermal insulation of walls:
- low degree of thermal insulation - 1.27;
- good thermal insulation (laying in two bricks or a layer of insulation) - 1.0;
- high degree of thermal insulation - 0.85.
K3 - the ratio of the area of \u200b\u200bwindows and the floor in the room:
K4 is a coefficient that takes into account the average air temperature in the coldest week of the year:
- for -35 degrees - 1.5;
- for -25 degrees - 1.3;
- for -20 degrees - 1.1;
- for -15 degrees - 0.9;
- for -10 degrees - 0.7.
K5 - adjusts the need for heat, taking into account the number of external walls:
K6 - accounting for the type of room that is located above:
- cold attic - 1.0;
- heated attic - 0.9;
- heated dwelling - 0.8
K7 - coefficient taking into account the height of the ceilings:
Such a calculation of the number of heating radiators includes almost all the nuances and is based on a fairly accurate determination of the room's need for thermal energy.
It remains to divide the result obtained by the heat transfer value of one section of the radiator and round the result to an integer.
Some manufacturers offer an easier way to get an answer. On their sites you can find a handy calculator specifically designed to do these calculations. To use the program, you need to enter the required values in the appropriate fields, after which the exact result will be displayed. Or you can use special software.
When we got an apartment, we didn’t think about what kind of radiators we have and whether they fit our house. But over time, a replacement was required, and here they began to approach from a scientific point of view. Since the power of the old radiators was clearly not enough. After all the calculations, we came to the conclusion that 12 is enough. But you also need to take into account this point - if the CHPP does its job poorly and the batteries are a little warm, then no amount will save you.
I liked the last formula for a more accurate calculation, but the K2 coefficient is not clear. How to determine the degree of thermal insulation of walls? For example, a wall with a thickness of 375 mm made of GRAS foam block, is it a low or medium degree? And if you add 100mm thick construction foam to the outside of the wall, will it be high, or is it still medium?
Ok, the last formula seems to be solid, windows are taken into account, but what if there is also an external door in the room? And if it is a garage in which there are 3 windows 800*600 + a door 205*85 + garage sectional doors 45mm thick with dimensions 3000*2400?
If you do it for yourself, I would increase the number of sections and put a regulator. And voila - we are already much less dependent on the whims of the CHP.
The procedure for calculating the heat transfer of a heating radiator
The choice of heating devices for installation in a house or apartment is based on the most accurate calculation of heat transfer from heating radiators. On the one hand, each consumer wants to save on heating the home and therefore there is no desire to purchase extra batteries, but if they are not enough, a comfortable temperature cannot be achieved.
There are several ways to calculate the heat transfer of a radiator.
Option one. This is the easiest way to calculate heating batteries. it is based on the number of external walls and windows in them.
The calculation order is as follows:
- when there is only one wall and a window in the room, then for every 10 “squares” of the area, 1 kW of thermal power of heating appliances is required (in more detail: “How to calculate the power of a heating radiator - we calculate the power correctly“);
- if there are 2 external walls, then the minimum battery power should be 1.3 kW per 10 m².
Option two. It is more complex, but allows you to have more accurate data on the required power of devices.
In this case, the calculation of the heat transfer of the heating radiator (batteries) is carried out according to the formula:
S x h x41, where S is the area of the room for which the calculations are performed; H is the height of the room; 41 - the minimum power per cubic meter of room volume.
The result will be the required heat transfer for heating radiators. Further, this figure is divided by the rated thermal power that one section of this battery model has. You can find out this figure in the instructions supplied by the manufacturer with your product. The result of the calculation of heating batteries will be the required number of sections so that the heat supply of a particular room is efficient. If the resulting number is a fraction, then it is rounded up. A little excess of heat is better than a lack of it.
Simple area calculations
You can calculate the size of heating batteries for a particular room, focusing on its area. This is the easiest way - to use plumbing standards, which prescribe that a heat output of 100 W per hour is needed to heat 1 sq.m. It must be remembered that this method is used for rooms with standard height ceilings (2.5-2.7 meters), and the result is somewhat overestimated. In addition, it does not take into account such features as:
- the number of windows and the type of double-glazed windows on them;
- the number of external walls in the room;
- the thickness of the walls of the building and what material they are made of;
- type and thickness of the used insulation;
- temperature range in a given climate zone.
The heat that radiators must provide to heat the room: the area should be multiplied by the heat output (100 W). For example, for a room of 18 sq.m, the following heating battery power is required:
18 sqm x 100W = 1800W
That is, 1.8 kW of power is needed per hour to heat 18 square meters. This result must be divided by the amount of heat that the heating radiator section emits per hour. If the data in his passport indicates that this is 170 watts, then the next step in the calculation looks like this:
1800W / 170W = 10.59
This number must be rounded up to a whole number (usually rounded up) - it will turn out 11. That is, in order for the temperature in the room during the heating season to be optimal, it is necessary to install a heating radiator with 11 sections.
This method is only suitable for calculating the size of the battery in rooms with central heating, where the temperature of the coolant is not higher than 70 degrees Celsius.
There is also a simpler method that can be used for the usual conditions of apartments in panel houses. This approximate calculation takes into account that one section is needed to heat 1.8 sq.m of area.In other words, the area of \u200b\u200bthe room must be divided by 1.8. For example, with an area of 25 square meters, 14 parts are needed:
25 sq.m / 1.8 sq.m = 13.89
But such a calculation method is unacceptable for a radiator of reduced or increased power (when the average output of one section varies from 120 to 200 W).
Heat dissipation of batteries from different materials
When choosing a heating radiator, it should be remembered that they differ in the level of heat transfer. The purchase of batteries for a house or apartment should be preceded by a careful study of the characteristics of each of the models. Often devices similar in shape and dimensions have different heat dissipation.
Cast iron radiators. These products have a small heat transfer surface and are characterized by low thermal conductivity of the material of manufacture. The rated power of a cast-iron radiator section, such as MS-140, at a coolant temperature of 90 ° C, is approximately 180 W, but these figures were obtained in laboratory conditions (in more detail: “What is the thermal power of cast-iron heating radiators“). Basically, heat transfer is carried out due to radiation, and convection accounts for only 20%.
In centralized heating systems, the temperature of the coolant usually does not exceed 80 degrees, and in addition, part of the heat is consumed when hot water moves to the battery. As a result, the temperature on the surface of the cast-iron radiator is about 60°C, and the heat transfer of each section is no more than 50-60 W. Steel radiators. They combine the positive characteristics of sectional and convection devices. They consist, as seen in the photo, of one or more panels, in which the coolant moves inside. In order to increase the heat transfer of steel panel radiators, special ribs are welded to the panels in order to increase power, functioning as a convector.
Unfortunately, the heat dissipation of steel radiators is not much different from the heat dissipation of cast iron radiators. Therefore, their advantage lies only in relatively low weight and more attractive appearance. Consumers should be aware that the heat transfer of steel heating radiators is significantly reduced in the event of a decrease in the temperature of the coolant. For this reason, if water heated to 60-70 ° C circulates in the heating system, the indicators of this parameter may differ greatly from the data provided for this model by the manufacturer.
Aluminum radiators. Their heat transfer is much higher than that of steel and cast iron products. One section has a thermal power of up to 200 W, but these batteries have a feature that limits their use. It is used as a coolant. The fact is that when using contaminated water from the inside, the surface of the aluminum radiator is subjected to corrosive processes. Therefore, even with excellent power indicators, batteries made of this material should be installed in private households where an individual heating system is used.
Bimetal radiators. This product is in no way inferior to aluminum appliances in terms of heat transfer. The heat flux of bimetallic products is on average 200 W, but they are not so demanding on the quality of the coolant. True, their high price does not allow many consumers to install these devices.
Heat dissipation of cast iron radiators
The heat transfer range of cast iron batteries ranges from 125–150 watts. The spread depends on the center distance. Now you can do the calculation. For example, your room has an area of 18 m². If it is planned to install a 500 mm battery in it, then we use the following formula: (18:150)x100= 12. It turns out that in this room it is necessary to install a 12-section heating radiator.
Everything is simple. In the same way, you can calculate a cast-iron radiator with a center distance of 350 mm.But this will only be an approximate calculation, because for accuracy it is necessary to take into account the coefficients. There are not so many of them, but it is with their help that you can get the most accurate indicator. For example, the presence of not one, but two windows in the room increases heat loss, so the final result must be multiplied by a factor of 1.1. We will not consider all the coefficients, since it will take a long time. We have already written about them on our website, so find the article and read it.
What is all this for?
The problem should be considered from two points of view - from the point of view of apartment buildings and private ones. Let's start with the first.
Multi-apartment buildings
There is nothing complicated here: gigacalories are used in thermal calculations. And if you know how much heat energy remains in the house, then you can present a specific bill to the consumer. Let's give a small comparison: if centralized heating will function in the absence of a meter, then you have to pay for the area of \u200b\u200bthe heated room. If there is a heat meter, this in itself implies a horizontal type of wiring (either collector or serial): two risers are brought into the apartment (for “return” and supply), and already the intra-apartment system (more precisely, its configuration) is determined by the tenants. This kind of scheme is used in new buildings, thanks to which people regulate the consumption of thermal energy, making a choice between savings and comfort.
Let's find out how this adjustment is carried out.
1. Installation of a common thermostat on the "return" line. In this case, the flow rate of the working fluid is determined by the temperature inside the apartment: if it decreases, then the flow rate will increase accordingly, and if it rises, it will decrease.
2. Throttling of heating radiators. Thanks to the throttle, the patency of the heater is limited, the temperature decreases, which means that the consumption of thermal energy is reduced.
Private houses
We continue to talk about the calculation of Gcal for heating. Owners of country houses are interested, first of all, in the cost of a gigacalorie of thermal energy received from one or another type of fuel. The table below can help with this.
Table. Comparison of the cost of 1 Gcal (including transportation costs)
* - prices are approximate, since tariffs may differ depending on the region, moreover, they are also constantly growing.
Dependence of the degree of heat transfer on the connection method
The heat transfer of heating radiators is affected not only by the material of manufacture and the temperature of the coolant circulating through the pipes, but also by the chosen option for connecting the device to the system:
- Connection direct unilateral. It is the most favorable in relation to the indicator of thermal power. For this reason, the calculation of the heat transfer of a heating radiator is performed precisely with a direct connection.
- Diagonal connection. It is used if it is planned to connect a radiator to the system, in which the number of sections exceeds 12. This method allows you to minimize heat loss as much as possible.
- Bottom connection. It is used when the battery is attached to the floor screed, in which the heating system is hidden. As the calculation of the heat transfer of the radiator shows, with such a connection, the loss of thermal energy does not exceed 10%.
- Single pipe connection. The least profitable way in terms of thermal power. Heat transfer losses with a single-pipe connection most often reach 25 - 45%.
