Heat losses by radiation can occur via furnace openings for loading/unloading. This i s especially significant in furnaces operating above 500 °C. Openings include furnace flues and stacks, peepholes used to visually check the process, doors left partially open to accommodate oversized work, loading and unloading materials and/or fuels, etc.
燃燒爐開口在打開充裝料或卸料時熱能會以輻射熱的方式洩漏造成熱損失，尤其是燃爐操作溫度超過500 °C以上時。
這些開口包括燃爐煙道及煙囪、用來檢查製程的窺視孔，裝料或送燃料的開口，或調整過大工作時半遮半掩的爐門。
