the period of time, the sidereal day, during which the earth makes one complete revolution on its axis relative to a particular star. The mean sidereal day lasts 23 hours 56 minutes 4.1 seconds of the mean solar day.
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.
Roof vents. 1  Air intake and exhaust vents are used in ventilating steep-slope roof assemblies to provide a means of allowing outside air to enter and exit attics and ventilation spaces. Intake Vents: Air intake vents are used to allow outside air to enter into attics and ventilation spaces.