The ANTONINI lehr heating system may be either direct, indirect, electrical or even combined.
• Direct system. The heat from the burner flame is sucked in by the impeller of the air-circulator, then pushed into the circulation channels along the sides of the tunnel, and finally crosses the tunnel and the glass from the bottom upwards, until it is once again sucked in by the impeller itself. Therefore, the hot combustion air is mixed with the air of the tunnel.
• Indirect system. It uses heat exchangers called “radiant tubes”. The burner flame develops inside these tubes and never comes into contact with the tunnel air. The air that is circulated inside the tunnel by the circulators passes first above the exchangers and then through the tunnel and the glass, still from the bottom upwards. The combustion fumes are thrown-out in special collectors.
• Electrical system. It is simpler than the above-described ones and uses the same air circulation system as the two systems described previously. Electrical elements provide the required heat. These heating elements are special, wrapped in air, to guaranty maximum heat transfer efficiency. The type of element and the quality of the material guaranty a practically unlimited and maintenance-free service life.
• Combined system. It bears this name as it combines two of the above systems in the same lehr. Due to production requirements or to the availability of energy sources, it may be necessary to equip the same lehr with both a direct (gas or electric) and an indirect heating system, making the best possible use of the features of both systems.