I’m replacing a 40+ year old shower with a new one. Of course the drain/trap isn’t in the same place. I don’t have enough vertical clearance to install an up/right pvc elbow to a male-copper-threaded trap end and then go over and install an left/up elbow. Is installing a double trap recommended in this or any case? Would it slow or stop the shower drainage flow? Or should I redo(cut,T, and re-sweat) the shared copper drain line? Hope this makes sense. I’m not a plumber, but just trying to do-it-myself. Thanks.
DYIMAN, a basic rule of plumbing is that you never, ever, double trap a fixture. The result would be that the drain would become “air-bound” and would drain very poorly. Since you do not have the clearance to offset the drain, your best option is to do what you obviously don’t want to do: cut the copper and extend the p-trap to the new shower drain. If there are other fittings involved, it becomes more complicated, but if you are a real do-it-yourselfer, you should be able to handle it, assuming that you can handle sweating copper. A simpler alternative to sweating the copper is to buy some clamps and PVC at your hardware store, but it would not make nearly as good a job, and I am sure that you want this to be lasting and leak-free.