Section 890.1520  Circuit and Loop Venting

a)         Battery Venting.  A soil or waste branch to which two but not more than eight of the same type of floor outlets or fixtures, such as eight water closets, eight pedestal urinals, eight shower stalls or eight floor drains are connected in battery, may be vented by a circuit vent that shall take off from in front of the last fixture connection.  Blowout type fixtures are prohibited.  Lower floor branches serving more than three water closets shall be provided with a relief vent taken off in front of the first fixture connection.  The horizontal branch for its full length to the farthest fixture opening shall be uniformly sized based on the total drainage fixture load as listed in Appendix A.Tables G, H and L. (See Appendix K.Illustration Y.)

b)         Dual Branches.  When parallel horizontal branches serve a total of eight water closets (four on each branch), each branch shall be provided with a relief vent at a point between the two water closets most distant from the soil stack.  The horizontal branch for its full length to the farthest fixture opening shall be uniformly sized based on the total drainage fixture load as listed in Appendix A.Tables G, H and L.  Intermediate floor branches shall be provided with a relief vent taken off in front of the first fixture connection.  If traps other than water closets discharge above the horizontal branch, each such trap shall be provided with a continuous vent.  (See Appendix K.Illustration Z.)

c)         Vent Connections.  When the circuit or relief vent connections are taken off the horizontal branch, the vent branch connection shall be taken off vertically from the top of the horizontal branch.  (See Appendix K.Illustration AA.)

d)         Fixtures Back-to-Back in Battery.  When fixtures are connected to one horizontal branch through a double wye, a sanitary cross in a vertical position, or a manufactured fixture carrier, a common vent for each two fixtures back-to-back shall be provided.  (See Appendix K.Illustration BB.)

e)         Fixture Connections.  Branch wastes and fittings for circuit vented fixtures shall be installed so that the fixture drain enters the side of the branch drain.  (See Section 890.1320(i) and Appendix K.Illustrations Y and CC.)

f)         Circuit and Loop Vented Fixtures.  For circuit and loop vented fixtures are installed in a multi-story building, a relief vent shall be provided at the base connection into the horizontal by connecting the vent stack, full-size, into or near the base of the soil stack, or by connecting the vent stack directly into the horizontal branch near the soil stack.  The vent shall be carried full size.  (See Appendix K.Illustration DD.)

(Source:  Amended at 38 Ill. Reg. 9940, effective April 24, 2014)