The heat cycle in the apartment: an overview of modern electrical convectors

convectors are today’s most “advanced” type of home heater. What is this technique, what are its advantages, how to choose an electric convector?

In recent years, great importance is given to environmental friendliness of the air in the room. Latest research shows: when the temperature of heating surfaces exceeds 150° C, not only does it burn the oxygen in the air and dehumidify it, but it also creates products of combustion that are harmful to health, such as dust. Such a surface temperature, for example, in oil radiators, and spiral heaters – several times higher.

A little insight into physics

If you remember from your school physics class, the heated air rises. Through expansion, its density decreases, and so it is forced out by cooler air layers. This is how winds and cyclones appear in the Earth’s atmosphere: warmed air rises above some parts of the surface, and it is replaced by air masses from colder regions.

Same thing can happen in a closed apartment or office, but at a much lower volume. This process is called convection, and convectors exist to create and control convection for heating apartments and other rooms.

The ingenious thing is simple

The design of any convector is simple to the extreme. in fact it consists of just two parts – the housing, usually flat rectangular in shape, and the heating element. At the bottom of the hollow case there are holes for cold air intake and holes for heated air outlet at the top of the case. The heating element is located inside the case, usually at the bottom of it. It heats the air between the walls, and then this air rushes upwards.

The walls of the housing act as aerodynamic guides for the flow, creating the same draught as in the chimney. The heated air comes out through the vents, usually oriented at a slight angle to the vertical, rises up toward the ceiling along a parabolic path, cools down gradually, and sinks to the floor. After that the cycle is repeated.

Warm and safe

With convection, the heated air is distributed evenly and silently throughout the entire volume of the room. In some models of convectors for acceleration of process the fan is provided, but it is recommended to include it only in an initial stage of heating as at its work about silence is already impossible. Besides convection, the walls of the convector body play a certain role in heating, and their temperature usually does not exceed 60°C.

This makes convectors very different from oil radiators and conventional spiral heaters: Children and pets don’t risk getting burnt. Some manufacturers, such as Timberk and Ballu, in some models, use tempered black glass as material for the front of the body, which heats softer and more even than metal, as well as very aesthetic and modern-looking.

And instead of a heart – flame? No, not flame!

“The heart of any heating appliance is the heating elements. Let us dwell on them in detail.

Three types of electric heating elements are used in convectors: band needle , tubular and monolithic. The ribbon-needle heating element is a narrow dielectric plate with chromium-nickel wire loops protruding on the sides. With their low cost, almost complete absence of thermal inertia it takes a few seconds to heat and cool the heating element and high heating temperature, their wire loops are too fragile, so ribbon heating elements are rarely used in modern models of convectors.

Tubular heating elements heating elements are a nichrome filament inside a tube, along the entire length of which there are aluminum fin plates. The efficiency of heat transfer from the heater to the air depends on the number, location and area of the plates, as they heat the air. The surface temperature of the tube is much lower than the temperature of the nichrome filament, and this is an important advantage of heaters. There is also a disadvantage: it is the difference in thermal expansion of the tube and plates, due to which in the process of operation you can hear a crackling.

Monolithic elements do not have this disadvantage, because the nichrome filament with dielectric filling is placed in a cast aluminum housing, and the finned plates are an integral part of it. The work of all-metal heating elements is noiseless due to the lack of difference in temperature expansion, the intermediate heat loss is minimal, and the relatively low temperature of the heating plates allows you to reduce the temperature of the body convector. The surface of modern monolithic elements is rough, which increases the efficiency of heat transfer.

Consumer’s Choice:

“Yes: monolithic heating elements.

“Possible”: tubular heating elements crackle

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“Not worth it”: ribbon-needle heating elements too fragile .

Wings, legs… Most importantly, brains!

Despite the overall simplicity of design, the automatics, in which convectors are equipped, is not at all simple and very diverse. After all, the device should maintain the desired air temperature, choose the optimal mode for energy saving, to shut off at a given time, to have protection against power surges, overheating and icing, against falling for floor standing versions and against moisture.

To support the desired temperature there are two types of thermostats – with mechanical and electronic control. Mechanical thermostats are cheaper but have a lower temperature tolerance +/- 1°C and consume more electricity as a result. In addition, when you turn on off the mechanical thermostat is a characteristic click, which is unlikely to enjoy at night.

Electronic thermostats are noiseless, maintain a given temperature with an accuracy of 0.1°C and consequently make the convector more economical. Added convenience and the possibility to control the convector with an electronic thermostat with the remote control.

On a number of models of convectors there are several operating modes – “economy”, “maximum”, etc. d. It allows to save the electric power on simpler models, but with modern programmable electronic thermostats, the power consumption is optimized automatically.

Modern convectors, regardless of the model and manufacturer, are necessarily equipped with protection against overheating, moisture protection and electrical protection of the housing of the corresponding classes.

Consumer’s Choice:

“Yes: Electronic thermostats: Quiet and economical

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“Possible”: mechanical thermostats.

On the wall or on the floor?

Flat rectangular shape of most convectors was literally born to be placed on walls, in the same place where central heating batteries are usually located. Fortunately, the low temperature of the device body allows you to place them on the walls: they do not spoil their surface. Our convectors do not take up much room space and provide the most efficient air convection. That is why many convector models are designed exclusively for wall mounting Stiebel Eltron CNS, AEG VKL, Noirot .

However, this is not always possible, for example, if there is no access to the walls or convector is an additional source of heating. Therefore, there are also floor convectors that are easy to move or roll into place. At present, the leading manufacturers switched to the production of convectors with two installation types – in addition to brackets for fastening to the wall, the set includes removable legs with castors, which greatly increases the options for their use.

What to pay attention to when choosing a convector

After reading all of the above, you can arm yourself to choose the convector. So, a modern quality convector, regardless of the firm-manufacturer must be equipped:

Mandatory:

– A monolithic one-piece heating element.

– Electronic thermostat.

– an overheat protection system.

– The system of protection against freezing for our latitudes it is not unimportant .

– Tilt sensor for floor standing models .

– IP-24 electrical protection class.

– moisture protection class I.

Desirable:

– A timer for switching off.

– Remote control

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– The possibility of installation both on the walls and on the floor.

– Display with temperature and mode indication

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– Possibility of programming modes during the day, when nobody is at home, a lower temperature is maintained, and at other times – a comfortable one

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Power of convector is chosen depending on the area of heated room and is calculated quite simply – 100 watts per 1 square meter. So a 1000 watt heater is needed for a 10sqm space, a 1500 watt heater for a 15sqm space, and so on. d. This calculation option is suitable when the convector is the main means of heating. If it only complements the existing ones, you can divide the power indicator by two.

When choosing should give preference to brands of well-known manufacturers, yet the guarantee and reliability – is not just empty words. It is worth to note, that European firms Timberk, Nobo, Noirot obligatory equip convectors with anti-freeze system and switch-off sensor in case of tipping over, and purely Chinese and other Asian with equal or better design and more sophisticated electronic stuffing often ignore this function. The “Europeans” have also got higher warranty period, although it is not so essential – almost all convectors can work for 15-20 years, and it is possible that during this period something more perfect will appear on the market.

DO YOU KNOW..

Why convector??

Really, there are oil radiators, heaters, infrared radiators… And the thing is, that convectors are simply better on the total set of merits and demerits. Oil radiators are cumbersome, the temperature of their working surface is high you can get burned , because of the undirected convection the air is heated slowly. Fan heater warms up the air faster than others, but they create noise, their open heating elements ruthlessly burn oxygen together with dust and dry the air. This is acceptable, for example, for the workers’ huts, where the builders came to get warm with frost, but for the apartment, such heating is not recommended.

Infrared emitters have a number of advantages, but still their main purpose – heating of open and semi-open spaces, such as glazed gazebos. When they work, there is no air circulation, which is so important for the apartment. The bottom line is convectors – fast heating due to convection, safe surface temperature, environmentally friendly, the possibility of using them as a primary heater.

There are also combined variants, when the infrared emitter is located in the convector body, such as presented in the table models Polaris, Ballu, Electrolux. They have several advantages, such as fast heating up, low surface temperature of the device, but the convection itself in this case is of secondary importance and accounts for about 20% of the heat it receives. The correct choice depends on the type and purpose of the room to be heated.

The table of characteristics of the most popular and recently on sale electric convectors.