We speak of "pure wood burning" when a stove has no grate and consequently no primary air. This form of burning is particularly clean. Strictly speaking, it is not the wood that burns, but gases that escape from the wood. Since these gases are on the surface of the wood, there must always be enough combustion air from above at this point - the secondary air. Air from below - i.e. primary air - is only a disruptive factor for this process.
Primary air, however, facilitates the heating process. To bring the stove up to temperature quickly, the air from below helps.
With its two-part cast-iron grates, DROOFF combines convenient heating with primary air with the possibility of pure wood burning. The grates can simply be pushed shut after the fire has been lit. In the start-up phase, the fire benefits from the primary air from below, and after lighting up, the stove burns only cleanly with secondary air.
Another advantage is that once the grate is closed, no more ember particles can fall into the ash box, unlike with conventional grates. This is because embers in the ash pan smoulder with too little oxygen, which can produce considerable emissions.
Of course, the upper part of the DROOFF grate is rigid and the lower part can be moved to close the grate openings. In this way, the ember bed and fire are not moved. A so-called "vibrating grate" is not only useless, but also harmful to the environment. Shaking only raises dust and increases emissions.