Construction, low pressure in the chimney, wood moisture, wood amount and operation are the key factors influencing clean panes.
BRUNNER has designed the combustion air guide in such a manner that the inflowing air in front of the viewing glass reduces the accumulation of soot and dust. The door-profile and the pane construction prevent the protection shield of interferences due to leaks. The panes stay clean and soot-free. The pane-geometry has a major impact, too. Small, straight pane-formats remain clean for longer. In comparison two- or three-side glass constructions (Corner- and Panorama- fireplaces) with turbulent airflows in the corners have to be cleaned more frequently.
Chimney negative pressure:
It is not possible to compensate too high or low negative chimney pressure with adjustable combustion air openings. Under these boundary conditions flow conditions can cause increased soot deposits.
In case of low negative pressure not only the combustion air cannot be sucked in sufficiently, but also the pane flushing air is blown in too weak. The air flows over the panes with an insufficient throw distance.
In case of too high negative pressure the “suction” sucks the inflowing air at the top into the coupler area. As a result the flushing air cannot flow over the pane in order to fulfil its protective effect.
In both cases a turbulent and unstable combustion arouses, which results the accumulation of unburned gas particles on the viewing glass. Consequently, the panes are filthy.
With technical measures it is possible to optimise these circumstances (i.e. Sissi flap for too high chimney negative pressure). Unfortunately unpredictable weather-related bad operating conditions can never be avoided and must be accepted as an exception.
Wood moisture, wood amount and operation
The fuel quality and quantity also has a large influence on clean panes. A basic condition is dry wood with residual moisture of under 20%.
Furthermore required temperatures and airflows for flushing air can only be achieved when specific filling quantities are adhered. In case of too low temperatures in the combustion chamber heating gases condense on the cold panes. In this case they soot and fog-up.
During burn-off the intended operational mode is essential. If the device is used by different people we recommend the automatic combustion air system EAS/EOS. This system guarantees optimal combustion air guidance and helps to avoid operating errors.