what are vent stacks
In this corner: a vent stack is series of vertical pipe vents that passes through at least two stories and is meant to maintain atmospheric pressure in the drainage system. The vent stack usually runs parallel with the soil/waste stack and may either extend up through the roof or connect to a stack vent. And in this corner: a stack vent is the uppermost portion of a soil/waste stack that continues the pipe from above the highest connected fixture out the roof.