Marty,
Thanks, that's an excellent point. I was planning to do it inline but that does make sense from both a code and manufacturing standpoint to use a 8x4 conc reducer.
I've got a code issue at work with regards to making a condensate drain tank. The tank is made out of 2 pipe caps and a 1-1/2' section of pipe, all 8" nominal diameter, schedule 40, with 1" NPT half couplings as inlets and outlets, and a 4" ANSI 150# pipe flange on top that's met by a blind...