Plumbing Size

Refers to the inner diameter of the pipes used in your system (see diagram below).

Pipe Size

IMPORTANT! It's best to enter the INSIDE diameter of your pipe fittings here. However, if you taking your measurements from the wet end, A 3" overall OUTSIDE diameter translates to 2.0" plumbing size while a 2 3/8" OUTSIDE diameter translates to a 1.5" plumbing size.