It is hard to divide storage heating stoves into categories of various overall dimensions and power ratings. As it was previously mentioned, TermoKaust® is a ready-to-use stove that resembles a fireplace and provides a view on real fire. Heat-accumulating mass meets average values of thermal energy collection in chamotte and it gives up heat to rooms of typical volumes, which constitute current standards in energy-saving construction industry and amounts to 80-100 kg of the stove's weight per 1 kg of wood for combustion.
If we expand it by the weight of mortar and ceramics, which take part in heat accumulation, we will get about 120 kg of weight per the same kilogram of wood. As far as heat accumulation is concerned, the weight should be as large as possible. However, as the weight of accumulating materials increases, we observe higher resistance values. Thus, we should select the best possible coefficient. We named it "the comfort of use coefficient" and we created a practical dependence between the size of furnace, its surface, heating mass and amount of fuel, and then we compared them with the demand for comfort of use and acquiring heat in a given time.
The demand and customer's preferences decide on the manner of operation and thermal energy collection of the stove. Size and weight of the stove are appropriate for medium rooms of today's single-family houses. The size of furnace is appropriate for burning a batch of wood during the specified cycle and time. We assumed that the demand of your rooms is 40W/m2 at the temperature of -16oC outside. Let's stock our homes with wood according to the above calculation. At average temperatures the above data are always working to our advantage and we actually need less energy. However, there are winter times when the device needs to work more. That is why its parameters should be counted in the same way. Average temperature in Poland during a heating season amounts to 3-5oC. Our stove is capable of producing over 40kWh (accumulated nominal value when starting with a cold stove) of thermal energy by burning 11 kg of firewood during 3 hours and 12 hours of accumulation. Thus, we may assume that we acquired an average of 3.3kW/h. During first hours and at higher temperatures, the values would be higher, and at the final stages they would be smaller.
This energy covers about 80m2 of our room. In practice, these values vary. They depend on many factors, type of floor, how often we come in and go out of the room, whether there is a dinette or not, whether we ventilate often or not and how efficient is the ventilation. Each instance would be different, and that is why firewood consumption will also vary. On the example of operation of our TermoKaust stove, we may assume correct operation for the maximal 90m2 of surface in an open living room of an energy-saving house. Of course, this applies to continuous heating (do not mix it up with continuous burning!)
Let's get back to different dimensions, sizes and power ratings of the stove.
Generally, series of types imply differences in power, appearance and trimming.
Our stove is encased with tiles, and each casing is unique. Furnace, combustion conditions as well as - which is most important - the repeatability of heating levels are stable.
Stoves "create" power and accumulate it. Then the power "charges" the mass. If we put some more firewood, we will waste a lot of energy during violent combustion. On the other hand, if we put too less, we will not reach enough temperature for proper combustion and heat accumulation. The flow of flue gas plays an important role here. It transfers thermal energy onto walls and should amount to 1.5m/s in storage heating. Such a speed of gas flow transfers heat continuously and beneficially.
Modern stove-fitting and stove industry pay great attention to the above.
The second parameter that plays a role in keeping energy inside the stove is the outlet temperature measured in the chimney, which should amount to 120-160oC. Greater power of a furnace means larger chimneys, violent combustion and a rapid increase of gas flow speed, which in turn lead to higher resistance rates. Therefore the diameters of outlets in chimney liners are so large and their relatively low convection heating power. A single glass in furnace door rather decreases temperature inside and impair combustion process. This is observed in case of cheaper liners.
A 24-hour heating cycle should progress similarly in order to make the residual heat from previous combustion noticeable. Constant operation during a heating season would be beneficial in terms of heating costs counted at the end of the heating season. The power of the device is always assigned to volume of a room, which we want to heat. In practice, we will need more or less firewood.
Here our series of types, various power ratings and overall dimensions meet in a single device.
While using the TermoKaust stove we always can control heating levels freely, and what is more important - it is possible at high thermal inertia.