Fixed or mobile, electric convectors offer identical performance. 1 kW consumed = 1 kW of heat. This thermal efficiency may seem high, compared to the 70 to 90% efficiency of traditional thermal boilers, but it is modest, compared to that of inertia electric radiators and downright derisory, compared to heat pumps delivering up to 6 times more heat. energy than they consume!
This does not imply that these heaters are totally devoid of interest, under certain conditions of use.
Electric heater operating mode
The principle of operation of the electric convector is comparable to that of an open fireplace. Physically, the convector consists of a built in metal, solid on the 4 vertical sides (the duct), with a screened air inletlocated at the base, near which is deployed an electrical resistance (the hearth) and a upper grid (the evacuation stump). Like the smoke in the chimney, l’air lighter, because heated by the resistance, gets up in the frame, then disperse in the room through the grid high. The depression thus created sucks in cooler ambient air through the low grille, which, warming up in turn, naturally maintains this movement as long as the resistance remains under tension. When the ambient air reaches the desired temperaturethe thermostat turns off the resistance, which interrupts the cycle. The ambient air therefore cools, until it reaches the resistance replenishment signal. This cycle perpetuatesas long as the electricity source is available.
State of the commercial offer of electric convectors
The market segment of electric convectors is divided into 3 main groups:
- Mobile, static or fan convectors;
- Wall convectors;
- Wall convectors with radiant panels.
The usual power of the devices ranges between 500 et 2 000 watts, in steps of 250 Watts, but some manufacturers still offer higher powers. Despite a drastic downturn in the global market, due to the age of technology, the number of mobile electric convectors sold worldwide remains stable. We must look for the reason for the good health of this market segment, in the character nomadic of these light materials and sans true concurrence in heatingappoint. Wall convectors are gradually disappearing from our walls. Without being prohibited, their utilisation already heavily penalized by the 2012 thermal regulations (RT 2012), is today anecdotalbecause RT 2020, in force since 1is January 2021, mimics building heating consumption at 12 kilowatts per hour of primary energy, per square meter (kwhep/m²). Knowing that 1 kW of power from an electrical appliance is equivalent to 2.58 kwhep/m², current buildings must not only further reinforce their insulation, but are required to produce calories from an energy primary (solar, geothermal, hydraulic), to compensate for incompressible consumption. New buildings simply can no longer afford the luxury of using heating methods energy guzzlers. Despite thecraze current electric heaters inertiathe renewal market in old housing still supports production, falling regular, from wall convectors to radiant panelreputed to be more comfortable.
Advantages of electric convectors
The major advantage of electric convectors lies above all in the modesty of the prix, both for purchase and installation. The public price of a medium power convector (between 40 and 200 €), represents an investment 8 and 10 times less only for the acquisition of an inertia radiator of similar heating power!
Other advantages of the electric convector:
- climb in room temperature fast ;
- simplicity of use;
- regulation relative to thehumidity ambient;
- montage on the site simple, fast and without any other constraint than a power supply and a wall bracket;
- No fuel handling.
Disadvantages of electric convectors
Electric convectors have more or less troublesome defects and dangers that should be developed:
1 – Prohibitive operating costs.
The main defect of the electric convector is, without possible dispute, the cost of its power consumption. With equal insulation, the amount of the energy bill can be, at best, 20 to 25% higher than with any other device. Compared to heat pumps, hybrid heaters or some modern biomass heaters, the numbers soar downright to amounts 2 to 5 times higher. However, this data must be modulated by device category. Wall-mounted convectors, for example, can be fitted with high-performance on-board regulation devices or decentralized programmers, enabling their operating bills to be reduced by 7 to 10%.
2 – Impact on the health of the occupants
The financial argument is not the only obstacle to the use of the electric convector. The principle of convection imposes a brewing fast permanent ambient air. This current of air raises and transports in the atmosphere of the room, an infinity particles fine (dust, hair, organic waste, textile filaments, pollen, etc.). This pollutionpotentially dangerous for people with respiratory deficiency or diseases, can also cause allergic reactions the severity of which is difficult to predict.
Another cause for concern or discomfort is some of the airborne impurities, build up on the heating element, during thermostatic breaks or when the appliance is stopped. They are burning invariably, during the re-ignition of the resistance, of the “red filament” type, like those of a toaster. This phenomenon gives off a odour particularly unpleasantespecially in the presence of animals, whose hair remains suspended in the air and raises questions about the harmfulness of the calcined nanoparticles inhaled by people.
The drying of the air, useful in rooms storing humidity, becomes harmful and irritant for the ENT sphere.
3 – Impact on comfort
By definition, convection creates a vertical stream of warm air that collects near ceilings. Under the effect of the heat exchanges with these walls, it releases calories, becomes denser, and therefore heavier, generating a new flow of descending air, which, swallowed and reheated by the convector, creates a permanent aeraulic loop. These movements create thermal strata in the living room. The temperature difference of several degrees, between the floor and a man’s height, causes a permanent feeling of discomfort for the occupant, which encourages him to increase the ambient temperature excessively.
Radiant panel convectors partially solve this major defect, because radiation, even modest, does not heat the air, but the objects or bodies within its radius of action, thus limiting uncomfortable thermal layers near the ground.
4 – Effects on the environment
The abnormally dry air accentuates the concentration of volatile dust, which settles on the walls, forming large black marks. This lack of hygrometry, alternating with the natural humidity of mid-seasons, tends to deform the wood of furniture and joinery.
The choice of electric convector
Given the sharp increase in the price of electricity observed in recent years and the pessimistic forecasts in this area, the electric convector has become the ultimate option of choice for permanent heating. In replacement of devices, choose a model of the same power, imperatively equipped with a precise electronic temperature regulator. Piloted by a programmer, it will better meet the needs and will be more economical in consumption.
Mobile convectors should be light. For sporadic use, do not hesitate to overestimate the power, to allow rapid rises in temperature. Prefer electronic thermostats which are much more precise than mechanical ones.