The principle of the inertia radiator is as old as heating. As soon as the men lit a fire to warm themselves, they never stopped retain heat, in order to put the drudgery of refueling into perspective. We can think that the men of prehistory heated, in the brazier, large pebbles which continued to give off their heat, although after extinction fires. The Scandinavian peoples who, from the Middle Ages, stuffed their heaters with volcanic stones had no other aim. Today, to obtain heat, it suffices to press a button, or better, to delegate this task to an automaton. We operate, however, always thermal inertia materials or fluids, to gain in comfort or to save energy, heavy for the balance of budgets and for the ecology of the planet.
This double observation is at the origin of the unprecedented development of electric inertia radiators, dealt with in this dossier.
Mode of operation of the inertia radiator.
Inertia radiators are made with materials densewhich have the particularity ofstore heat. They can be compared to batteries for electricity or tanks for fluids. inertia radiators, recover, then store, the unused calories, to restore them gradually, when the energy source is cut off. This characteristic applies equally to radiators with dry inertia or inertia fluidbut also to water or steam central heating radiators, to solar or geothermal installation radiators, to gas radiators or for that matter to all other calorifiers.
Performance of inertial radiators
The assessment of the performance of an inertia radiator is based on 3 main criteria:
- the Powerful and Watts;
- the type of material the heating core;
- the type and functions of the controller or programmer.
Heating body materials
The material constituting the heating body depends on the calorie storage capacity. Electric radiators, which exploit the inertia of fluids and dry inertia, share common advantages and disadvantages, although each brings its own particularities.
Common advantages:
- gentle warmth and comfortable provided in a way homogeneouswithout drying the air;
- heat emission long after extinction heating element;
- savings energy to operation;
- limited maintenance periodic dusting;
- ravidity and ease of installation;
- low cost installation, without degradation of the site;
- Very large choice powers, models and finishes.
Common disadvantages:
- prix high buy;
- device heavy (weight increases with storage efficiency);
- poorly suited to rooms with intermittent use (bathrooms, toilets, laundries, etc.);
- strong marketing promotion at the veracity sometimes
Advantages and disadvantages of fluid inertia radiators
In these devices, the storage element is the heat transfer liquid circulating in the heating body, generally in steel or in fonte d’aluminium. It is the system approaching, at best, central heating.
Advantages of fluid inertia:
- climb in temperature more fast ;
- weight less raised.
Disadvantages of fluid inertia:
- less durability;
- heat transfer liquid gras, aggressive et not very ecological ;
- possible noises fluid circulation;
- lower reliability.
Advantages and disadvantages of dry inertia radiators
In these heaters, the heat is retained in the mass of inert and dense materials making up the heating body, either by Ascending storage efficiency:
- fonte d’aluminium ;
- cast iron;
- natural stones (lava, granite, etc.);
- natural or composite refractory materials (bricks, ceramics, steatite).
Advantages of dry inertia:
- grande thermal stability ;
- slow playback and gradual increase in stored calories;
- reliability and durability exceptional;
- no noise Operating ;
- no risk for the environment ;
- only electrical devices are subject to aging.
Disadvantages of dry energy:
- climb in temperature more spring ;
- heavy to very heavy appliances.
Dry inertia radiators sometimes include, on the front, a radiant heat emitterensuring the rapid rise in room temperature.
Regulation of inertia radiators
Modern inertia radiators have a system of electronic regulationoften supplemented by a scheduledur. They sometimes incorporate presence devices to automatically reduce the ambient temperature during periods of non-occupancy. Centralized or embedded, programmers are the main vector ofenergy savings. They are capable of adjusting ambient temperatures, in steps of 1/10°C, hours by hour, room by room, over weekly or monthly periods. Some, compatible with GSM, can be controlled remotely, using a simple telephone.
Ambient temperature sensors deported of the radiator are more efficient.
The power of the inertia radiator
The power, expressed in Watts (nominal power), corresponds to the maximum heat delivered each hour by the radiator. She compensates for heat loss of the room. The most efficient devices modulate this power, to better exploit the orders sent by the regulator (or the thermostat).
The nominal power of domestic electric inertia heaters ranges between 500 W and 3000 W, in steps of 250 to 500 W, depending on the manufacturer.
Choose an inertia radiator
The choice of a heating device can’t be separated of the’environment in which it is installed. The prohibitive operating cost prohibits the development of electric heaters for buildings that are poorly insulated and very permeable to air, whose construction is prior to the thermic regulation (RT) in 1989. The “all-electric” revolution only came with the RT 2005limiting the heat loss of new buildings, in a modest way, to the energy consumption of 190 kWh/(m².in). The gentle heat of inertia radiators only finds its true interest from RT 2012limiting thermal consumption to 50 kWh/(m².in). It should be noted, however, that some homes renovated or built before this date have comparable or superior thermal performance.
The evaluation of the heat losses of the part to be heated constitutes an essential preliminary, to determine, with rigor, the power of the radiator with inertia. However, use validates empirical modes, based on the local climate, the level of insulation and the volume to be heated.
Simply estimate the power of the radiator, using the empirical method:
1 – poorly insulated building (< 2005):
- 60 W/m3 for harsh climates (continental and low mountain);
- 50 W/m3 for temperate climates (oceanic and semi-oceanic);
- 40 W/m3 for mild climates (Mediterranean).
2 – moderately insulated buildings (2005 to 2011):
- 50 W/m3 for harsh climates;
- 40 W/m3 for temperate climates;
- 35 W/m3 for mild climates.
3 – well insulated buildings (≥ 2012)
- 40 W/m3 for harsh climates;
- 35 W/m3 for temperate climates;
- 30 W/m3 for mild climates.
Example of estimated power the radiator needed to heat a moderately insulated room, located in Nice, of 4.00 mx 3.00 m and 2.5 m ceiling = (4 x 3 x 2.5) = 30 m3 x 35 = 1,050 W,
That is, power reduced to the higher commercial power: 1 250 W.