Boilers can also be further classified on the basis of the construction of the reversal chamber in fire tube design Reversal Chamber This is the posterior portion of the combustion chamber through which the flue gases travel from the first pass (furnace) to the second-pass tubes. 3 PASS Wet Back Boilers In 3 pass wet back boilers as the name suggests the reversal chamber is surrounded by water. Refer the fig. As we can see in the fig, the combustion reversal chamber is surro