Roof plumbing vents and methods including for tankless water heaters with concentric venting

A concentric vent assembly comprising:

• an outer housing having an inner surface and an intake passageway, the intake passageway extending away from the outer housing and in communication with the inner surface of the outer housing;
• a main housing having an upper end and lower end, the main housing have a flex cap disposed around the main housing and between the upper end and lower end of the main housing, the main housing being disposed within the outer housing and defining a flow passageway between an outer surface of the main housing and the inner surface of the outer housing, the flow passageway extending from an upper end of the outer housing to the intake passageway;
• and
• an umbrella assembly including a central rod having an upper end and a lower end, and a flexible upper cover attached proximate the upper end of the central rod, the umbrella assembly having a first position in which the flexible upper cover is disposed within the outer housing and a second position in which the flexible upper cover is in a deployed state above an upper end of the outer housing.

A method of establishing a vent for an item of equipment located within a building, the method comprising:

• positioning a first housing through an exterior surface of the building, the first housing having a first end located outside the building and a second end located inside the building;
• moving a flexible upper cover from a first position inside the first housing to a second position outside the first housing and outside the building, the flexible upper cover being in a collapsed state in its first position and a deployed state in its second position;
• and
• connecting the second end of the first housing to an exhaust port of the item of equipment.