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August 12, 2017 18:06

Calculation of radiators : the rules and examples

Sooner or later, the owners of apartments, cottages, as well as specialists of warehouse, retail, office and other rooms face the problem of acquisition of radiators.Regardless of changing the battery is installed or a new heating system, but educated calculation of the required number of partitions of any type of radiators will create an optimal climate for residence or temporary stay of people in the room, as well as to provide an optimum temperature for the storage of goods.But before you get your radiator, you need to determine the size of the product and the type of metal, because the thermal conductivity of the material is not the same at all.



radiators currently, the main material for the manufacture of radiators, a photo of which is presented in the article are the steel, iron and aluminum.Given that the different properties of the materials used in the manufacture of radiators affect the performance characteristics of the finished product is not the same, the diversity of batteries combined in 4 groups.

Cast iron radiators

batteries, made of cast iron, are in high demand for several decades.However, unlike the old specimens, the current models are more aesthetic and allow succinctly fit them into the interior of a different style orientation without the use of protective screens.

Cast reception 500x450


  • high resistance to aggressive coolant impurities;
  • ability to withstand significant pressure surges;
  • good heat-retaining capacity;
  • sufficient magnitude internal section eliminates clogging the radiator;
  • durability;
  • reasonable cost.

pros 2_500x450


  • duration of warm-up facilities during the initial supply of coolant;
  • need for periodic painting;
  • roughness of the inner surface promotes the formation of different kinds of sediments, slightly reducing the product performance over time;
  • complexity of installation, due to the greater weight.

cons 500x450

Despite all the advantages and disadvantages of cast iron radiators are ideal for both stand-alone and for the central heating system.

Steel radiators

huge variety of steel radiators, produced by domestic and foreign manufacturers, divided into:

  • panel.For other types of radiators are easy to design and more compact.heat Giving the majority of panel radiators based on the principle of convection, so that there is uneven heating of air masses.It would seem that the minimum number of welds should ensure good reliability of the design.However, a small section of the pipe leads to a rather rapid clogging of the radiator when using poor-quality coolant containing various impurities, so the panel radiators installed in multi-storey buildings is with caution;

  • tube.Advantageously, the tubular radiators feature is the absence of sharp corners and varied performance design.Unlike the panel instrumentation, heat transmission through radiation and larger cross-section pipes are less susceptible to clogging and waterhammer.Thus docking joints formed by spot welding after a short operating period allowed to flow.

Tubular 500x450


  • diverse range;
  • good heat dissipation at low thermal inertia;
  • wide price range depending on the battery type, size, and used in the manufacturing process technologies to minimize the various shortcomings.

pros pipe 500x450


  • high demands on the quality of the coolant;
  • low resistance to corrosion, especially when draining the heating system is more than 2 weeks;
  • need for periodic staining;
  • average lifespan seldom exceeds 10 years.

Panel in the context of 500x450

Steel radiators are most popular installation in private homes or rooms heated by an autonomous system.

Aluminium radiators

Batteries of aluminum began to produce relatively recently.Compared with products of iron, steel, aluminum batteries differ quite attractive design in the most diverse performance.


  • maximum heat level, carried out by convection and thermal radiation;
  • rapid heating of the premises;
  • excellent corrosion resistance;
  • light weight contributes to ease of installation;
  • reasonable cost.

alum 500x450


  • periodic airing system;
  • not resistant to waterhammer;
  • can not be used when installing copper elements of the system, which in the short term output of the battery system;
  • short operational period, rarely more than 10 years.

Aluminium 500x450

Despite a number of positive and negative aspects, some operational characteristics of radiators made of aluminum depends on the method of manufacturing the product.

Currently, aluminum radiators are manufactured by:

  • casting, when the required number of prefabricated sections connected into a single structure by means of steel nipples and gaskets.The main feature of the radiators, made by casting, is the release of products is quite complex shapes, which allows you to choose the size of the radiator, depending on the specific conditions for future use.At the same time the junction of the individual sections are rarely withstand test pressure of central heating systems;

al.sekts 500x450

  • extruded aluminum profile when passed through special equipment, is transformed into a finished product.Unlike injection molding, radiators manufactured by extrusion, are more resistant to changes in pressure inside the heating system.At the same time remove or add sections to the finished product is simply impossible.The amount of the finished radiator sections varies between 3-16.

monolith alyum_500x450

A variety of aluminum radiators are the anodized products, the production of which is made of metal, held a better cleaning and subjected to anodic oxidation.Unlike simple aluminum, anodized radiators have a relatively high resistance to chemicals present in the central heating coolants.Furthermore, the compound did not separate sections carried by nipples and couplers, latched externally product that increases the strength of the battery before the sharp pressure surges in the system.However, there are anodized devices much more expensive than their counterparts, so are not popular among a large number of consumers.

Anodized 500x450

Thus, it is not necessary to install aluminum radiators in rooms with central heating, and for uniform heating of premises, heated by an autonomous system, it is advisable to install a circulating pump.

Bimetallic radiators

With its ideal combination of steel and metal, bimetal radiators turn disadvantages used in the production of metals in the benefits of the finished structure, consisting of steel pipes for the movement of the coolant, which externally encased in aluminum.Along with aluminum devices, Bimetallic batteries are manufactured by molding and extrusion.

Bimetallic Monolith 500x450


  • aesthetic appeal;
  • excellent thermal conductivity, intrinsic aluminum batteries;
  • good strength characteristics;
  • high resistance to hydraulic shock;
  • low weight;
  • a long period of operation.

Sectional bimetal 500x450


  • possible clogging of the radiator due to the use of steel pipes of small diameter;
  • high cost.

Bimetallic 500x450

So, choose bimetallic radiators and other costs, taking into account the conditions of their future operation.For central heating systems is preferable to stop the choice on the cast-iron radiators and bimetal monolithic structure, while the batteries are suitable for stand-alone system, of any type of metal.We should not forget about the appropriate size of the radiator and liked the space reserved for the installation.

Dimensions radiators

For correct calculation sections radiators need to know the thermal conductivity of a single section, which depends not only on the material, but also on the size of the finished product.This radiator dimensions are selected based on the following factors:

Dimensions 500x450

  • Ideally, the length of the battery should take no less than 50-60% of the window opening.
  • optimum height of radiator = distance from the sill to the floor minus 15-20 cm, because the distance from the battery to the window sill during installation must be at least 8-10 cm and the distance from the floor to the lower boundary of the battery also vary8-10 cm.
  • battery thickness is determined by the peculiarities of planning, although the maximum heat output is achieved if the radiator appears to 4-5 cm beyond the sill.

Radiator Dimensions 500x450

Given the size of the product at the stage of the calculation of the required number of sections, the buyer in advance insures itself against the inaccuracies in determining the amount of heat required for a particular room.

Calculation radiators

optimal radiator power is determined for each room separately, since the volume of heated air in various premises is unlikely to be the same.Depending on the desired degree of accuracy of the final result, selects one of the calculation methods.

Calculation of

Square According to SNIP, for heating 1 m need 100 watts of heat energy, so:

Number of sections = room area * 100 W / heat output of the selected radiator section (taken from the documentation included with the radiator).

baht 500x450

example, for heating the room 3 m wide and 5 m long bimetallic radiator, the average power which section is 200 watts required: Number of sections = 15 * 100/200 = 7.5.Since the result is a fractional number, it shall be rounded to the nearest whole towards increase, ieheating room 15m² need 8 sections, which are divided into 2 radiator.

radiator Calculate the square belongs to a less laborious way, which leads to a rather approximate result.

calculation by volume

Guided SNIP, warm-1 m³ per panel, brick houses without additional insulation measures require 41 watts, and in insulated buildings equipped with modern double-glazed windows, enough to 34 watts.The calculation is as follows:

Number of sections = room volume (area * height) * 41 W (or 34 W) / power radiator section.


For example, the amount of room, located in the old Khrushchev, is 37.5 m³ (3 * 5 * 2.5).The acquisition is considered as a cast-iron battery with a heat transfer section 100 watts.Based on their data, the number of sections = 37.5 * 41/100 = 15,375.Round the result, we obtain the desired value of 16 sections.

In contrast to the previous method of calculation, the determination of the number of sections in terms of giving a more accurate result, but not the most reliable.

Using correction factors

method special is that when calculating the number of radiators are taken into account various factors that in one way or another affect the conservation of heat in the room.The calculation formula is as follows:

Required power radiator = Area * 100W (heat rate for 1 m²) * Ko * Ktep * CPL * Ktem * Ksten * Ktip * Kvys / power radiator section where:

  • Co. -glazing type (normal windows - 1.27; double glazing - 1.0, triple glazing - 0.85);
  • Ktep - thermal insulation of walls (low or without insulation - 1.27, and the average - 1.0, a high degree of thermal insulation, made with modern materials - 0.85);
  • CPL - area ratio of window openings to the floor space (10% -0.8; 20% -0.9; 30% -1.0; 40% -1.1; -1.2% 50);
  • Ktem - minimum outside air temperature at the coldest time (-10 ° C-0,7; -15 ° C-0,9; -20 ° C-1,1; -25 ° C-1,3;-35 ° C-1,5);
  • Ksten - the number of external walls (1-1,1, 2-1,2, 3-1,3, 4-1,4);
  • Ktip - factor correction required battery power, based on the room located on the premises (not heated attic - 1.0; Floor apartment - 0.8, heated attic - 0.9);
  • Kvys - ceiling height (up to 2.5 m-1.0, from 2.5 m to 3 m - 1.05; from 3 m to 3.5 m -1.1; from 3.5 to 4 mm - 1.15 m of 4.5 or higher - 1.2).

Steel panels 500x450

example, floor space, located on the 3rd floor of a 5-storey house is 15 sqm with room height of 2.5 m. The outer insulation is made using cheap thermal insulation materials.The room has one window with triple glazing and, accordingly, one outer ratio with the window opening - about 10%.In winter the temperature drops to -35 ° C.Radiator Power - 200 Watts.

required battery capacity = 15 * 100 * 0.85 * 1.0 * 0.8 * 1.5 * 0.8 * 1.0 / 200 = 6.12.

need for space heating radiator sections 7 200 watts.

Thus, the calculation of radiators with correction factors provides a more accurate result, which may well be less than the determination of the number of sections using approximate calculations.