TYPE B - GAS VENT 90 Degree Elbow 4.5"

The Type B 90° elbow is a double‑wall venting component designed to change the direction of flue gas flow by 90° (a right angle) in a chimney / gas vent system for gas‑fired appliances (Category I, draft‑hood equipped). It is part of a “B‑Vent” (or “B gas vent”) system, which uses a concentric double‑wall pipe: an inner liner to carry the hot flue gases, and an outer shell with an insulating airspace to limit heat transfer to surrounding structure. A 4.5‑inch outer diameter variant suggests a nominal 4″ inner flue diameter. This elbow allows installing a right-angle turn in the vent run—for example, to route around obstacles, penetrate wall or ceiling offsets, or align with vent terminations. The elbow must maintain proper clearances to combustibles, be supported, and be compatible with the rest of the Type B system. In many installations, the elbow is adjustable (0°–90°) or comes with swivel or rotatable joint to facilitate alignment. It joins to other vent components via twist-lock, snap-lock, or locking tabs. One actual product, the Metalbest 4RV 90° Type B adjustable elbow, lists an outer diameter of 4.5 in and inner pipe (flue) diameter of 4 in.