Plumbing Terminology - M

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The main is the primary artery of supply of the water supply or drain system in which all the branches connect. In the case of drains, known as the Main Vent.

Main vent

The main vent is the pipe that runs vertically beside the soil stack. The branch and fixture vents are connected to the main vent, and through it each trap is supplied with air by the outside atmosphere. The main vent is connected to the outside either by being extended through the roof separately or by being run back into the soil or waste stack at a point above the highest fixture connection.


The wiring, plumbing and heating and cooling systems in a building; also the components with moving parts such as furnaces, plumbing fixtures, etc.