Thermal radiator power: ways to count and select batteries

When choosing a heating radiator, the main attention should be paid to its heat transfer; this is the main parameter by which you can evaluate its performance. Given the variety of modern radiators, it is not difficult to choose the ideal option for any room.

Accepted terminology

Sometimes people far from physics confuse terms such as heat transfer, heat capacity and thermal conductivity. When heat radiators are considered heat dissipation is crucial.

But it will not be superfluous to understand these definitions:

• heat capacity - this concept means the amount of heat that must be expended to heat a substance by 1? С;

Note! The higher the heat capacity, the greater the inertia of the heater. That is, it will cool down more slowly, but it will not heat up quickly either.

• thermal conductivity - the higher this value, the faster the metal will warm up. For example, copper warms up much faster than steel or cast iron. So the bimetallic heater to the working temperature warms up many times faster than the cast iron or steel, only their price is much higher;

Note! With respect to batteries, the warm-up rate is not particularly important. The difference in the warm-up in a couple of minutes do not decide absolutely nothing.

• heat transfer - in general, this term refers to the heat exchange process, a hotter body cools down, and a cold one heats up until equilibrium is reached. The same thing happens when the house is heated, the battery cools down, and a comfortable temperature is maintained in the house.

Understanding the effectiveness of different types of batteries

Most modern batteries are manufactured sectional, so that by changing their number, it is possible to ensure that the heating capacity of radiators meets the needs. It should be borne in mind that the efficiency of the battery will depend on the temperature of the coolant, as well as on its surface area.

What determines the efficiency of heat transfer

The efficiency of the heating radiator depends on several parameters:

• on the temperature of the coolant;

Note! In the documentation on the heater, the manufacturer usually indicates the amount of heat output, but this value is indicated for normal temperatures (90? C at the supply and 70? C at the output). When using low-temperature heating systems, manual calculation is required.

• from the installation method - sometimes the owners, in pursuit of the beauty of the interior, close the batteries with decorative grilles, if the heat flux of heating radiators encounters a barrier in her face, then the heating efficiency will slightly decrease;

• from the connection method. With a diagonal connection (the supply pipe is connected from above), and the discharge one - from the bottom on the other hand, almost perfect battery operation is ensured. All sections will warm up evenly.

It is advisable not to be lazy and independently calculate the required power of the radiator, while it is better to choose a heating device with a certain margin. The reserve teploat of the radiator will not be superfluous, and if necessary, you can always install a thermostat and change the temperature of each individual heater.

Methods for calculating the required power

The calculation of the thermal capacity of radiators can be carried out by several methods:

• simplified - averaged index is used for a room with 1 door and 1 window. In order to estimate the number of the radiator section, it is sufficient to simply calculate the area of ​​the room and multiply the resulting number by 0.1. The result will be approximately equal to the required heating power of the heater; for insurance, we increase the resulting number by 15%.

Note! If the room has 2 windows or it is angular, the result should be increased by another 15%.

• by volume of the room. There is another dependence, according to which the 200-watt section of the radiator of the way to heat 5m³ space in the room, the result is quite inaccurate, the error can reach 20%;

• you can do a more accurate volumetric calculation with your own hands. View dependency is used

Q = S • h • 41,

the following designations are used: S is the area of ​​the room, h is the ceiling height, 41 is the number of watts per heating of 1 cube of air.

But it is possible to perform a more detailed calculation taking into account the method of installation of the radiator, the method of its connection, as well as the actual temperature of the coolant in the pipes.

In this case, the calculation instruction will look like this:

• first, the temperature head is calculated? T, the dependence of the form? T = ((T_pod-T_obr)) / 2-T_komn is used

in formula T_under - water temperature at the radiator inlet, T_arr - outlet temperature, T_room - the temperature in the room.

• then we calculate the required heater power Q = k • A •? T,

where k is the heat transfer coefficient, Q is the radiator power, A is the surface area of ​​the battery.

• The documentation usually indicates the information of radiators-teploatt-makers, so that Q is known and the corresponding temperature head. So it is possible to determine the value of k • A (this value is a constant for any temperature pressure);
• Further, knowing the product k • A and the real temperature pressure, one can calculate the radiator power for any working conditions.

And you can do even easier and use ready-made tables with the recommended number of sections of the radiator for a specific area. For example, the table of heat capacity of cast-iron radiators allows you to choose the right size of the battery without calculation. There are online calculators for easy calculation.

Choosing a radiator

From the point of view of heat transfer, bimetallic radiators can be considered the undisputed leader. The heat capacity table of heating radiators clearly shows that the heat output of such a design is about 2 times higher than that of cast iron.

But you need to take into account a lot of other details:

• the cost - cast iron classic radiators will cost at least 2 times cheaper than bimetallic;
• cast iron does not tolerate water hammer, and indeed, a rather fragile material;
• it is worth thinking about appearance. At an exorbitant price, you can buy cast iron radiators with a beautiful pattern on the surface. Such a heater in itself is a decoration of the room.

As for cost and efficiency, it is worthwhile to introduce such a concept as teploat of bimetallic radiators (or cast iron, steel). If we take into account the cost of the battery and its efficiency, it may turn out that the cost of teplomat of a cast-iron radiator will be lower than that of a bimetallic structure.

So do not discount the good old cast-iron heating device. The heat capacity of cast-iron radiators of heating completely allows to use them for heating houses, and with careful operation they can serve for more than a dozen years.

In conclusion

The heat capacity of a radiator is understood as the amount of heat that it is capable of delivering to a room under normal operating conditions. This is the most important parameter when choosing a heater for the house, the calculation of power is relatively simple, so that everyone can choose the best option for themselves.

The video in this article shows a detailed example of calculating the required heat output of heaters for a home.