How to choose bimetallic radiators of heating: technical characteristics + analysis of all pros and cons
The effectiveness of the battery determines the speed and quality of heating. The market of modern equipment offers all sorts of solutions. One of the worthy options are bimetallic radiators of heating that meet the main requirements of the heating network: strength, resistance to water surges, high heat dissipation and durability.
The choice of a hybrid battery is based on an evaluation of the technical characteristics with an eye on the manufacturer's reputation.
The structure of bimetallic radiators
Externally, bimetallic models resemble conventional 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 shaped-ribbed body made of aluminum panels.Some radiators use copper instead of steel.
The circulation of the coolant occurs through the internal steel or copper pipeline. Due to the corrosive inertness, the radiators do not rust and do not react with the chemically active coolant. The external elements and the internal collector are connected by spot welding or casting under pressure.
According to the physical and operational properties of the battery suitable for installation in apartment buildings of any heights and arrangement of local heating system cottage buildings.
Features of different heating convectors
Understand the differences between different types of batteries of two metals. Composite products are usually classified according to the following criteria: the composition of the inner core, the outer design and the type of metal used.
Bimetallic and polibimetallic radiators
Users often confuse true bimetallic batteries with "half-breeds" - semi-metallic counterparts.
Aluminum is used to make the outer casing of the device. The core of the convector is 100% stainless steel or copper. In the production process, pipes placed in special shapes are filled under pressure with aluminum - an airtight structure is formed.
A complete bimetal endures the pressure of a centralized and autonomous heating system.
The internal "skeleton" of the radiator is assembled from two metals: vertical guides - stainless steel, horizontal pipeline - aluminum. The reverse combination is also possible.
Such an alliance of metals is not able to provide adequate reliability of central heating communications. The coolant may contain alkali, which, in contact with aluminum, provokes the appearance of corrosion.Over time, destructive processes "move" to the steel components of the radiator.
In addition, the integrity of the product may be jeopardized due to thermal expansion of metals - leaks may occur at the boundary temperatures.
It is better to refuse purchase of low-quality composite, especially if it is a question of the centralized heating.
Sectional and monolithic models
Among the variety of bimetallic radiators there are two types of structures:
Folding radiators whose panels are connected using nipples. Horizontal pipe sections of individual sections have multidirectional threads for joining the mounting nipples and sealing lining.
Disadvantages of sectional radiators:
- joints - weak points of reservoirs, where leaks are likely;
- limited working pressure - up to 20-30 bar;
- partial hit of the heat carrier on aluminum "shirt" at course.
The listed shortcomings lack complete modifications. Cast radiator is able to withstand pressure surges within 100 atmospheres.
For high-rise buildings (10 or more floors), experts recommend choosing one-piece radiators, as 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 made it possible to achieve resistance to pressure fluctuations, increase the level of heat transfer from the convector and reduce its inertness.
Advantages of copper-core batteries:
- no chance of corrosion;
- copper pipeline carries any water hammer - the best option for operation in domestic central heating systems;
- high efficiency of the device - heat transfer of copper exceeds the performance of steel.
Copper-aluminum radiators differ in their service life - more than 50 years. The lack of copper modifications - 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 be mistaken with the choice, it is necessary to understand the meaning of the following characteristics:
- heat emission;
- working pressure and temperature;
- center distance;
- capacity, weight of section.
The parameter indicates the amount of heat transferred from the battery to the atmosphere of the room at a given coolant temperature (+ 70 ° C). The indicator is measured in watts.
Based on the heat output of one section, the required battery performance is calculated for the entire room.
The maximum coolant pressure depends on the thickness of the steel core. The choice of strength is at the discretion of the manufacturer. The value of the parameter ranges from 15 to 35 bar and is determined based on the operating conditions of the battery.
An important characteristic is the limiting temperature of the coolant. All high-grade bimetals are able to withstand + 90 ° C. Some manufacturers claim higher thermal resistance.
Dimensional characteristics include the following parameters:
- Center distance- “mileage” between the axes of horizontal collectors. The standard value is 20-80 cm. Vertically oriented models with an increased center distance are used if the room layout is not suitable for installing horizontal radiators.
- Geometric parametersdetermine the height, width, depth of the section. The overall height of the radiator often exceeds the center range 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. Some manufacturers, in addition to external panels, add parallel fins to the design to increase heating efficiency through convection currents.
Volume and mass
In bimetallic modifications, coolant circulates along a round section core, in contrast to aluminum counterparts with an oval section heat conductor. The capacity of one bimetal section is less than the volume of the aluminum section with the same frame sizes.
For example, in convectors with an inter-axial range of 500 mm, the fullness of the coolant 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. Lower mass is one of the signs of a polibimetal.
Comparative analysis: bimetal and competitors
Before you choose a bimetallic or other radiator, it is desirable to compare its capabilities with its closest competitors. For composite convectors it is aluminum, cast iron, steel batteries.Evaluation should be carried out according to the main criteria:
- heat emission;
- endurance to pressure drops;
- wear resistance;
- ease of installation;
According to the efficiency of heating, aluminum aggregates are the leaders; bimetal takes the second place. Steel and cast iron noticeably lose.
Resistance to water hammer
The most robust bimetallic units capable of withstanding up to 40 atmospheres (sectional models). The maximum working pressure on the aluminum heat network is 6 bar, the steel one is 10-12 bar, and the cast iron one is 6-9 bar.
It is the bimetal that is able to withstand numerous hydraulic impacts of the centralized heating system. This property is a key argument in favor of composite radiators for apartment buildings.
According to this criterion, the positions were distributed as follows:
- Cast iron.The material is indifferent to unfavorable environments. Cast iron radiators are capable of being used for decades, transporting an “alkaline”, “acidic” environment.
- Steel and bimetal.By itself, the steel core endures 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.
- Aluminum.The metal reacts with various impurities in water.
Aluminum walls are particularly susceptible to acidic conditions - the pH of the coolant should be within 8. Otherwise, corrosion is actively developing.
In terms of installation, aluminum and bimetallic products are simpler. Cast iron radiators are more difficult to mount because of their bulkiness.
It can be concluded. The purchase of a bimetallic radiator is definitely justified for assembling the heating network in a high-rise building, where there are risks of pressure surges and contamination of the coolant. In a private house, with stable boiler operation and filtration of incoming water, you can use available aluminum batteries.
What should be considered when choosing a radiator?
To achieve the proper thermal effect, it is necessary to calculate the full power of the battery. Bimetallic equipment is an expensive purchase, so you should take care of its durability. The faithful execution of the radiator is guaranteed by proven manufacturers.
Having decided on the appropriate technical characteristics and dimensions of bimetallic radiators, it is necessary to calculate the required number of sections.
The heat transfer rate of the section is taken from the radiator passport, and the total power must be calculated.
The normalized heat output per 1 sq. M of living space for an average climatic strip, provided standard ceilings (250-270 cm) are:
- the presence of one window and a wall with access to the street - 100 W;
- a window in the room, two adjacent walls - 120 W;
- several windows and "external" walls - 130 watts.
Example. The power section is 170 W, the total area of the heated room is 15 sq. M.Additional conditions: window - 1, outer wall - 1, ceiling height - 270 cm.
N = (15 * 100) / 170 = 8.82.
Rounding up. This means that for heating the room it is necessary to use 9 sections of 170 watts each.
Calculation by volume
SNiP separately regulates the amount of thermal power per 1 cubic meter of space 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. Heating the premises with the previous parameters. For the purity of the experiment, the power section is left unchanged - 170 watts.
N = (15 * 2.7 * 41) / 170 = 9.76.
It is necessary to install a radiator on 10 sections. The second calculation is considered more accurate.
When calculating, attention should be paid to sources of heat loss inside the room.
How to avoid fakes: inspection of the radiator
In addition to the analysis of passport data, it is useful to conduct a visual assessment of the goods. Some manufacturers in the pursuit of customers tend to "embellish" their products, introducing incorrect data in the documentation.
First of all, pay attention to the thickness of the core and aluminum "shirt", overall dimensions, weight and quality of components.
The minimum thickness of the steel tube is 3 mm. With smaller sizes, the declared strength of the product is significantly reduced - resistance to water hammer and the development of corrosion processes.
The result of a poor-quality steel core is the formation of through holes and the creation of emergency situations on the heating network.
Aluminum panels must be tested for strength - they should not be bent from the efforts of the fingers of one hand. The minimum thickness of the panels - 1 mm.
It is better to choose models with profiled channels between the ribs. The formed confuser increases the speed of the air flow, increasing the intensity of convective heat exchange.
Dimensions and weight
By the individual order production of radiators with a section width less than 80 mm is possible. However, store models with an inappropriate parameter are most likely fake.
To reduce costs, some manufacturers significantly cut the width of the internal fins, “masking” them behind standard-size front panels. This measure affects the heat output of the bimetallic radiator.
It is almost impossible to check the quality of gaskets and nipples on site. You should rely on the manufacturer's name and warranty period. Trustworthy companies guarantee up to 15-20 years of uninterrupted operation.
Rating of popular manufacturers
The review includes high-quality foreign heating systems and domestic products adapted to the changing conditions of heating networks.
In practice, the products of the companies have recommended themselves well:
- Global Style (Italy);
- Sira (Italy);
- Rifar (Russia);
- Tenrad (Germany).
Place # 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 with paronitic gaskets ensuring tightness of the joints. Effective thermal transfer between metals is achieved by casting an aluminum “shirt” under pressure.
Place # 2 - Sira
The Italian brand is positioning its product as a premium product. Devices have gained popularity among consumers due to the strength and attractive design.
The manufacturer provides a 20 year warranty on a series of full-fledged bimetallic radiators Sira Ali Metal.
Place # 3 - Rifar
The domestic manufacturer has developed a wide range of bimetallic radiators:
- Base - models with 200/350/500 mm spacing, Rifar warranty - 10 years;
- Forza - Reinforced scratch resistant and scratch resistant external coating;
- Alp - shallow depth (75 mm);
- Monolit - one-piece radiator.
Batteries of the Monolit series differ in the highest indicator of working capacity with a high pressure of the heat carrier.
Place # 4 - Tenrad
German quality bimetal is suitable for autonomous and central heating networks. It is acceptable to use in gravity, elevator and pump systems with one- and two-pipe wiring.
- thickness of vertical tubes - 1.8 mm, collector walls - 3.6 mm;
- three-row fins;
- side panels are located under the slope, which creates the effect of a diffuser for convective flow.
Two-layer enamel coating of high quality paints and coatings - when heated, the device does not emit harmful vapors.
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:
Full bimetallic radiators combine the positive characteristics of both materials. Batteries are characterized by high thermal capacity, resistance to hydraulic impacts and excellent decorative properties. Their acquisition is a justified investment subject to the purchase of certified goods.