Combination Waste and Vent (Floor and Hub Drains Only)

Section 890 Section 890.1590  Combination Waste and Vent (Floor and Hub Drains Only) A combination waste and vent system consisting of floor and hub drains may be installed when structural conditions preclude conventional plumbing. Appurtenances delivering large quantities or surges of water shall not be discharged to a combination waste and vent. a)         The waste piping and trap in a combination waste and end-vented (both ends) system shall be a minimum of 4 inches in diameter.  The vents in the system shall be a minimum of 3 inches in diameter.  Only one floor drain shall be connected to each branch of a combination waste and vent. b)         A branch more than 15 feet in length shall be separately end vented. The minimum area of any vent installed in a combination waste and vent system shall be half the area of the drain pipe served. c)         Sinks, lavatories and other fixtures that are roughed in above the floor shall not be permitted on a combination waste and vent system. d)         Long mains shall be provided with additional relief vents located at intervals of every 100 feet.  (See Appendix K.Illustration FF.)