What size branch is used for a 2" trap in a combination fixture?

The size of the branch used for a 2" trap in a combination fixture is determined by plumbing codes and standards that ensure adequate flow and minimize the risk of blockages. A 2" trap requires a corresponding 2" branch to maintain proper drainage and prevent backpressure issues.

Using a 2" branch allows for the appropriate volumetric flow rate needed to effectively remove wastewater from the fixture without causing undue stress on the plumbing system. Ensuring that the branch matches the trap size is crucial for maintaining the efficiency of the drainage system and preventing clogs that might arise from using a smaller diameter branch. Therefore, the standard practice is to use a branch size that matches the trap, which in this case, is 2 inches.