After a time the flow is reversed,the newly heated bricks being used to preheat the air and gas, while the exhaust reheats the checker chambers which have cooled during the first phase.

• 间隔一段时问，气流改变方向，利用新加热的格子砖来预热空气和煤气，而废气又把前一阶段已冷却下来的蓄热室再加热。