Externally, electric convectors are not much different from each other. At the same time, the cost of comparable models in terms of power can differ significantly. It’s all about the type of heating element installed in a particular model. What heating elements are used in electric convectors, and how do they differ from each other? We will analyze in this material.
Needle heating element
By today’s standards, the design of the needle heating element looks rather outdated. No wonder: it appeared as part of electric convectors in the mid-1950s. The element is a dielectric base made of electrical cardboard or textolite. A thin nichrome strip or wire is tucked into its perforated holes.
A wire having a high electrical resistance is threaded into the holes of the base in zigzags. As a result, “stitches” of the heating strip are formed on both sides of the structure, shaped like needles. For this method of laying the heating strip, this type was called needle.
This type of heater can be called differently. Translated from English, stich means stitch, therefore such heating elements are also called stitch heaters .
The surface of the wire or strip of the stitch heater is covered with a thin layer of high-temperature insulating varnish. This protects against short circuits between adjacent “needles”. And at the same time it allows you to get the required power of the heating element.
Needle heating elements are cheap and heat up to operating temperature instantly. This is where the advantages end, and then only the disadvantages follow. They are mainly caused by the archaic design.
Strong heating of the metal part of the heater. As a rule, the strip is heated up to 250-300 °C. This results in an unpleasant odor from combustible dust and pet hair.
Do not use the electric convector in damp and damp rooms. Moisture on the coil can cause a short circuit inside the device or electric shock to the user.
The fragility of the heating element. From local overheating in the place of accumulation of dust or wool, it can simply burn out.
Low efficiency. The energy consumption of the heating element is not commensurate with its efficiency in terms of heat output.
No heat storage. As soon as the power supply stops, the heater instantly cools down.
Convector Aceline CV-2000SWYL
The design of a tubular electric heater (TEN) was invented more than 160 years ago. The patent for the invention belongs to the American George Simpson, who received it in 1859.
The heating element is a tube made of carbon or stainless steel. Inside it is a conductive thread, usually made of nichrome (an alloy of nickel and chromium) or fechral (an alloy of iron, chromium and aluminum). The thread has a high resistivity. To exclude direct contact of the thread with the walls of the tube, the cavity of the latter is filled with a dielectric insulator with high thermal conductivity. As a rule, it is made from periclase (magnesium oxide in crystalline form). After filling the internal volume of the tube, the insulator is compressed.
It turns out a fairly solid monolithic structure, which heats up when an electric current flows through the heating element spiral. The tubular heater has a larger heating surface than the needle heater. This has a positive effect on its characteristics.
To increase the heat removal area, aluminum plates are installed on the tube. They have a significantly larger surface area than the heating element housing tube itself. The solution is simple but effective. The heating efficiency increases: the air, passing inside the electric convector, comes into contact with the hot surface of a much larger area.
Due to the additional ribs, the overall efficiency of the heating element is increased. Convectors with heating elements can be used in rooms with high humidity, since the design of the element is sealed. The temperature of the element rarely exceeds 120-150 °C, which makes it relatively safe.
The only significant drawback is the noise during operation. The fact is that steel and aluminum expand at different rates with a change in temperature. This causes characteristic clicks as the element heats up and cools down. In the daytime, this may not be much of a problem. But at night this can become a serious problem. Especially for people with light sleep.
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Monolithic heating element
Monolithic heating elements are a logical development of the heating element technology with additional fins for heat dissipation. They are deprived of the main drawback of their predecessors – noise during operation.
The design of a monolithic heater contains the same heating element, however, it is enclosed not in a steel tube, but in a monolithic aluminum case with ribs. The shape of the heating element can be any: it depends to a greater extent on the design of the electric convector and the technological features of the manufacture of heaters. The most widespread are:
monolithic heating element made in the form of a flat panel;
monolithic heater with two fins for heat removal (V-shaped heating element);
monolithic heater with four heat sink fins (X-shaped heating element).
The large surface area of the heater ensures high efficiency and energy efficiency. It is worth remembering that the element has a low heating temperature: it rarely exceeds 120 ° C. This makes the devices safe. Dust does not burn on the ribs of the element, local overheating is excluded.
Monolithic heating elements are the most durable. Many manufacturers claim that the service life of the elements is 20-25 years.
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Micathermic heating element
Micathermal heating elements are very different from other types of heating elements. Needle, tubular and monolithic heaters provide convection heating of the air in the room, while the micathermic one creates heat to a greater extent due to infrared radiation.
80% of the heat is generated by infrared waves, and the remaining 20% is due to convection heating. You can read more about the principles of infrared heating in this article.
This is how a micathermic heating element works.
In fact, this is a five-layer sandwich panel. The central layer is represented by a nickel plate, which is the heating element of the entire structure. On both sides it is covered with oxides of tin, zinc and iron. The purpose of these layers is the electrical isolation of the central heating element and the “organization” of the flow of directed infrared radiation.
As the outer layers of the “sandwich” is a special mica with a thickness of 0.03 mm. It is a good conductor and emitter of infrared waves, which quickly heats up to 200 ° C. To protect users from accidental contact, the micathermic element is necessarily protected by a grill. At the same time, the temperature of the convector body rarely exceeds 60 °C.
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Electric convectors with a mikathermic element are considered the most economical. Space heating consumes the least amount of electricity. However, it should be borne in mind that infrared radiation does not heat the air, but objects and objects that are in its path.
For safety reasons, do not bring the electric convector closer than 0.5 m to interior items.
As the distance to the heater increases, its efficiency also decreases. It is rather difficult to heat a large area with a device with mikathermic elements.
The type of installed heating element determines the efficiency of the convector, its energy consumption, durability and safety. Manufacturers of electric convectors do not always indicate the type of installed heating element in the characteristics of the device. Even though this parameter is key.
To definitely determine the type of heater installed in the device, it is enough to look into its ventilation openings for air intake. They are usually located at the bottom of the case.