Single Branch & Y-Branch Fittings
The branch is how an appliance or a secondary run joins the main stack. Marley single branches are available at 87.5° and 45°, in equal and unequal patterns, so the connection can be made swept into the direction of flow.
Also searched as: Y branch, single branch, tee, swept tee, junction, branch fitting, 45 degree branch
Equal and unequal branches
An equal branch joins two pipes of the same diameter — 110 × 110mm is the most specified. An unequal branch reduces at the inlet, for example 160 × 110mm where a floor stack joins a main collection run, or 110 × 82mm for a smaller branch. Ordering the unequal pattern avoids a separate reducer and one extra joint.
45° versus 87.5°
The 45° branch, often called a Y-branch, sweeps the incoming flow into the direction of travel and is the correct choice on horizontal runs and at the foot of stacks. The 87.5° branch is used for appliance connections into a vertical stack where space is tight. Always connect a horizontal branch into the direction of flow, never against it.
Branch connection zone
On a vertical stack, do not connect a branch within the restricted zone opposite and below the WC connection — the Technical Manual sets out the dimensions. Ignoring it is a common cause of cross-flow and of foul water discharging into an opposite appliance.