How to choose bimetal heating radiators: technical specifications + analysis of all the pros and cons

Battery performance determines the speed and quality of heating. The market of modern equipment offers all kinds of solutions. One of the worthy options is bimetallic heating radiators that meet the main requirements of the heating system: strength, resistance to water hammer, high heat transfer and durability.

We will talk about how to choose the right heating device, in the manufacture of which two metals were used. In the article we proposed, the varieties popular among consumers are described in detail. Their technical characteristics are listed, leading manufacturers are listed.

The structure of bimetallic radiators

Externally, bimetallic models resemble ordinary ones. aluminum radiators. The difference lies in the internal content. The design of composite products consists of two basic elements: an internal steel pipe and an external figured-ribbed body made of aluminum panels. Some radiators use copper instead of steel.

The heat carrier circulates through an internal steel or copper pipe. Due to corrosion inertness, radiators do not rust and do not react with a chemically active heat carrier. The external elements and the internal collector are connected by spot welding or pressure casting.

According to their physical and operational properties, batteries are suitable for installation in multi-apartment buildings of any number of floors and the arrangement of a local heating system for cottage buildings.

The bimetallic structure determines the characteristics of the device.The steel core explains resistance to aggressive environments and endurance to pressure drops, an aluminum “shell” increases heat transfer and facilitates radiator

Features of different heating convectors

You should understand the differences between different types of batteries of two metals. It is customary to classify composite products according to the following criteria: composition of the inner core, external design and type of metal used.

Bimetal and semi-metal radiators

Users often confuse true bimetallic batteries with “half-breeds” - semi-metallic analogues.

Clean Bimetal

Aluminum is used to manufacture the outer casing of the device. The convector core is 100% stainless steel or copper. In the production process, pipes placed in special molds are filled with aluminum under pressure - a sealed structure is formed.

The outer shell is not in contact with the coolant and acts as a heat exchanger. The main feature of bimetallic radiators is high durability and a guarantee against leaks

High-grade bimetal withstands the pressure of a centralized and autonomous heating system.

Semimetal Batteries

The internal "skeleton" of the radiator is assembled from two metals: vertical guides - stainless steel, horizontal pipe - aluminum. A reverse combination is also possible.

Such an alliance of metals is not able to ensure the proper reliability of central heating communications. The coolant may contain alkali, which, in interaction with aluminum, provokes the appearance of corrosion. Destructive processes over time "pass" to the steel components of the radiator.

In addition, the integrity of the product may be in jeopardy due to the thermal expansion of metals - leakage is possible at boundary temperatures.

Externally, semi-metallic radiators do not differ from full-fledged bimetallic counterparts. "Half-breeds" produces lighter weight and lower cost

It is better to refuse to buy a low-quality composite, especially when it comes to centralized heating.

Sectional and monolithic models

Among the variety of bimetallic heating batteries, two types of structures are distinguished:

• sectional:
• monolithic.

Models assembled from sections are attracted by the variability of characteristics. They provide an opportunity to purchase a device with the exact heat transfer values ​​required for space heating. Monolithic do not have such advantages.

Typing systems

Collapsible radiators, the panels of which are connected using nipples. The horizontal pipe sections of the individual sections have multidirectional threads for joining the fastening nipples and the sealing lining.

Stacked models are more popular due to their practicality - it is possible to adjust the thermal power by adding or subtracting the desired number of sections. An additional plus - maintainability

Disadvantages of sectional radiators:

• joints - weak points of collectors where leaks are likely;
• limited working pressure - up to 20-30 bar.

Particular disadvantages include the partial contact of the coolant on the aluminum “jacket” during leakage.

Monolithic appliances

The listed disadvantages are devoid of whole modifications. Cast radiator is able to withstand pressure surges within 100 atmospheres.

Cons of monolithic batteries: there is no way to vary the thermal power, overpriced - 20-30% more expensive than sectional models with similar parameters

For high-rise buildings (10 or more floors), experts recommend choosing solid radiators, since there will be significant pressure in the heating system.

Copper or steel core?

Most manufacturers offer hybrid steel tube frame batteries. The main reason is the affordability of the metal and good strength characteristics. The symbiosis of steel and aluminum allowed to achieve resistance to vibrations pressure in the heating system, increase the level of heat transfer of the convector and reduce its inertness.

In copper + aluminum radiators, heat transfer tubes are made of copper. Heating panels - aluminum plates brazed to the inner copper frame

Advantages of copper core batteries:

• there is no chance of corrosion;
• the copper pipe transfers any water hammer - the best option for operation in domestic central heating systems;
• high efficiency of the device - the heat transfer of copper exceeds the performance of steel.

Copper-aluminum radiators are characterized by a service life of more than 50 years. The disadvantage of copper modifications is the high price.

Technical and operational characteristics

All basic parameters of the radiator are indicated in the passport of the heater.

In order not to make a mistake with the choice, you need to understand the meaning of the following characteristics:

• heat transfer;
• working pressure and temperature;
• center distance;
• dimensions;
• capacity, section weight.

Thermal power. The parameter indicates the amount of heat transferred from the battery to the room atmosphere at a given temperature coolant (+ 70 ° C). The indicator is measured in watts.

The average heat transfer of a composite radiator is 140-190 watts. The runaway of the values ​​is explained by the dimensions of the section and the features of the execution of devices from different manufacturers

Based on the thermal power of one section, the required battery performance for the entire room is calculated.

Performance indicators. The maximum coolant pressure depends on the thickness of the steel core. The choice of strength is at the discretion of the manufacturer. The parameter value ranges from 15 to 35 bar and is determined based on the operating conditions of the battery.

An important characteristic is the boundary temperature of the coolant. All high-grade bimetals are able to withstand + 90 ° C. Some manufacturers claim higher thermal resistance.

The maximum temperature stated in the passport of equipment of different trade positions: Global Style - 110 ° С, Tenrad - 120 ° С, Altermo - 130 ° С, Grandini - 120 ° C

Dimensions of the radiator. Dimensional characteristics include the following parameters:

1. Center distance - “mileage” between the axes of horizontal collectors. The standard size is 20-80 cm. Vertically oriented models with increased center distance are used if the layout of the room is not suitable for installing horizontal radiators.
2. Geometric parameters determine the height, width, depth of the section. The overall height of the radiator often exceeds the center distance by 6-8 cm. The traditional width of the ribs of bimetallic models is 80 mm.

The depth of the section is 75-100 mm. In addition to external panels, some manufacturers add parallel fins to the design to increase heating efficiency due to convection flows.

Overall dimensions: a - section height, b - distance between horizontal axes, c - battery depth, d - width of one section. The most popular products with a core height of 35 cm, 50 cm

Volume and mass. In bimetallic modifications, the coolant circulates around the core of circular cross section, in contrast to aluminum counterparts with an oval cross-section heat pipe. The capacity of one section of bimetal is less than the volume of the aluminum section with the same sizes.

For example, in convectors with an interaxial range of 500 mm, the coolant filling is about 0.2-0.38 l, with a core height of 350 mm - 0.15-0.25 l.

The weight of a standard bimetallic battery with dimensions of 580/80/80 mm (height / width / depth, respectively) and a center distance of 50 cm is 1.8-2 kg. Less weight is one of the signs of semi-metal.

Comparative analysis: bimetal and competitors

Before choosing a bimetallic or other radiator, it is desirable to compare its capabilities with its closest competitors. For composite convectors, these are aluminum, cast iron, steel batteries.

The assessment should be carried out according to the main criteria:

• heat transfer;
• endurance to pressure drops;
• wear resistance;
• ease of installation;
• appearance;
• durability;
• price.

Heat loss. In terms of heating efficiency, aluminum units are leaders, bimetal takes an honorable second place. Steel and cast iron radiators noticeably lose.

Aluminum is characterized by minimal thermal inertia - after starting the system, the air in the room warms up for 10 minutes

Resistance to hydroblow. The most hardy bimetallic units that can withstand up to 40 atmospheres (sectional models). The maximum working pressure on the aluminum heating system is 6 bar, steel - 10-12 bar, and cast iron - 6-9 bar.

It is bimetal that can withstand the numerous water hammer of a centralized heating system. This property is a key argument in favor of composite radiators for apartment buildings.

Chemical inertness. According to this criterion, the positions were distributed as follows:

1. Cast iron. Material is indifferent to adverse environment. Cast iron radiators have been used for decades, transporting an "alkaline", "acidic" environment.
2. Steel and bimetal. By itself, the steel core is resistant to the effects of aggressive components. The weak point of the steel pipe is the interaction with oxygen, contact with which leads to the formation of rust.
3. Aluminum. The metal reacts with various impurities in water.

Aluminum walls are especially susceptible to acidic conditions - the pH of the coolant must be within 8. Otherwise, corrosion develops actively.

Easy installation. In terms of installation, aluminum and bimetallic products are simpler. Cast iron radiators are more difficult to install because of their impressive mass.

In terms of durability, the leaders are composite and cast-iron batteries. Aluminum and steel products subject to operational requirements must be replaced after 10-15 years. Among the designated batteries, the most expensive bimetallic

It can be concluded. Buying a bimetallic radiator is clearly justified for assembling a heating network in a multi-storey building, where there are risks of pressure surges and coolant contamination. In a private house with stable operation of the boiler and filtering the incoming water, you can use heating device available aluminum batteries.

What should be considered when choosing a radiator?

To achieve the proper thermal effect, it is necessary to calculate the total battery power. Bimetal equipment is an expensive acquisition, so you should take care of its durability. Reliable performance of the radiator is guaranteed by trusted manufacturers.

Opportunity Assessment - Heat Calculation

Having determined the appropriate technical characteristics and dimensions of bimetallic radiators, it is necessary to calculate the required number of sections.

Basic formula: N = Ptot. / Ppas., Where Ptot. - the required battery power for the entire room, Pspasp. –Thermal power of the section according to accompanying documents

The heat transfer rate of the section is taken from the radiator's passport, and the total power must be calculated.

Area calculation

The normalized value of thermal power per 1 sq. M of living space for an average climatic zone, provided standard ceilings (250-270 cm):

• the presence of one window and wall with access to the street - 100 watts;
• there is a window in the room, two walls adjacent to the street - 120 W;
• several windows and "external" walls - 130 watts.

Example. Section power - 170 W, total area of ​​the heated room - 15 sq.m. Additional conditions: window - 1, external wall - 1, ceiling height - 270 cm.

N = (15 * 100) / 170 = 8.82.

Rounding is performed upwards. So, for heating a room, you need to use 9 sections of 170 watts.

Volume calculation

SNiP separately regulates the amount of thermal power per 1 cubic meter of premises in the amount of 41 watts.Knowing the volume of the heated room, it is easy to calculate the heat transfer of the entire battery.

Example. Room heating with previous parameters. For the purity of the experiment, the section power is left unchanged - 170 watts.

N = (15 * 2.7 * 41) / 170 = 9.76.

It is necessary to install a radiator in 10 sections. The second calculation is considered more accurate. In calculations, attention should be paid to the sources of heat loss indoors.

The calculated value must be increased by 10% if the apartment is located on the first / last floor, the room has large windows or the wall thickness does not exceed 250 mm

Avoiding fakes: radiator inspection

In addition to the analysis of passport data, it will be useful to conduct a visual assessment of the goods. In the pursuit of customers, some manufacturers tend to “embellish” their products by entering incorrect data into the documentation.

First of all, pay attention to the thickness of the core and the aluminum "shirt", overall dimensions, weight and quality of components.

Steel core. The minimum thickness of the steel tube is 3 mm. With smaller sizes, the declared product strength - resistance to water hammer and the development of corrosive processes.

The walls of the thin metal allow the coolant to access the aluminum “shell”, which, due to chemical activity, begins to rapidly collapse

The result of low-quality steel core is the formation of through holes and the creation of emergency situations on the heating system.

Radiator fins. Aluminum panels must be checked for strength - they should not be bent from the efforts of the fingers of one hand. The minimum thickness of the panels is 1 mm.

It is better to choose models with profiled channels between the ribs. Formed confuser increases the speed of air flow, increasing the intensity of convective heat transfer.

To reduce the risk of injury, the outer edges of the aluminum panels are rounded. On a surface there should not be streaks, roughnesses of coloring and "gaps"

Dimensions and weight. By individual order it is possible to produce radiators with a section width of less than 80 mm. However, store models with an inappropriate parameter are most likely a fake.

Some manufacturers to reduce the cost significantly reduce the width of the inner ribs, "masking" them behind the front panels of a standard size. This measure impairs the heat transfer of the bimetallic radiator.

Battery Accessories. It is almost impossible to check the quality of gaskets and nipples in place. You should rely on the name of the manufacturer and the warranty period. Trustworthy companies guarantee up to 15-20 years of trouble-free operation.

Rating of popular manufacturers

The review includes high-quality foreign heating systems and domestic products adapted to the changing conditions of heating systems.

In practice, the products of companies have proven themselves well:

• Global Style (Italy);
• Sira (Italy);
• Rifar (Russia);
• Tenrad (Germany).

Rank # 1 - Global

This is a recognized leader in the production of heating radiators.

The company produces three series of bimetallic batteries:

• Style - basic characteristics;
• Style Extra - compact dimensions;
• Style Plus - maximum heat dissipation.

The sections are connected by paronite gaskets, ensuring the tightness of the joints. Efficient heat transfer between metals is achieved by casting an aluminum “shirt” under pressure.

Additional characteristics: pressure - up to 35 atm, connection diameter - ¾ or ½ inch, coolant temperature - up to 110 ° С, outer shell - double color

Place # 2 - Sira

The Italian manufacturer is positioning its goods as premium products. Devices have gained popularity among consumers due to their durability and attractive design. The manufacturer provides a 20 year warranty on a series of full-fledged bimetal radiators Sira Ali Metal.

Characteristics of Ali Metal products: center distance - 350/500 mm, heat transfer models - 187/141 W (respectively center distance), pressure in the heating system - 35 atmospheres

Place # 3 - Rifar

Domestic manufacturer has developed a wide range of bimetallic radiators:

• Base - models with a center distance of 200/350/500 mm, a warranty from Rifar - 10 years;
• Forza - reinforced external coating resistant to scratches and mechanical damage;
• Alp - shallow depth (75 mm);
• Monolit is a one-piece radiator.

Monolit series batteries have the highest performance at high coolant pressure.

Technical data: operating pressure - 10 MPa, destructive pressure - 25 MPa, maximum temperature - 135 ° C, warranty period - 25 years

Place # 4 - Tenrad

German quality bimetal suitable for centralized and independent heating networks. It can be used in gravity, elevator and pump systems with one- and two-pipe wiring.

Distinctive features:

• the thickness of the vertical tubes is 1.8 mm, the walls of the collector are 3.6 mm;
• three-row finning;
• the side panels are sloped, which creates a diffuser effect for convective flow.

Two-layer enamel coating of high-quality coatings - when heated, the device does not emit harmful fumes.

Tenrad products are designed for operation in a system with a coolant pressure of up to 35 atmospheres. Bimetal radiators are certified and comply with the European standard EN442

With the rules for calculating the power and the number of radiators for the heating device will introduce next article, read which is before the acquisition of devices.

Conclusions and useful video on the topic

The video review clearly demonstrates the design features of composite radiators and the basic requirements that a high-quality device must meet:

High-grade bimetallic radiators combine the positive characteristics of both materials. Batteries are characterized by high thermal power, resistance to water hammer and excellent decorative properties. Their acquisition is a justifiable investment subject to the purchase of certified goods.

Tell us about how you chose a bimetallic heating device for your own apartment or country house. Share, which argument was decisive in your choice? Please leave comments in the block below, ask questions, post thematic photos.