Tub to Shower Conv - Need Advice on Drain

[execdawg92]

Hello Everyone - I a DIY'er with many projects under my belt. I've come across something on this project where I need some input. I have a home built in 1984 and I'm remodeling a bathroom, removing the tub and making a shower.

This weekend I dug out the hole around the tub drain to find that I do not have the room I thought I would to install a 2" line. I was hoping I would have enough room to take out the 1 1'2" line for a 2" shower drain.

(See pic)

With some research, I found that my City has adopted the 2009 IPC so I can use a 1 1/2" P trap and drain. (I know it's not ideal, but it will meet code.)However, the issue I have is my A/C unit drains into this line from the attic. It drains into the back of the tub drain (see pic). So, my question is the following:

1) Should I leave the existing P trap, cut it and put a 'T' connector on the end to attach the shower drain and the A/C drain? Makes sense to me because it will block the sewer smell up the A/C and Shower lines. However, I didn't know if it is ok to have the P Trap away from the actual shower drain? I have always installed the P Trap directly underneath the shower drain. Would it be a problem to unclog if it was set-up this way? The shower drain would be 12" - 24" inches from the P Trap (I haven't decided on the exact location yet.)

- or -

2) Install an extra P trap - leave the existing one and install one under the shower drain. Tee in A/C line near exisitng P Trap. I just thought the P Trap under he shower drain would be the first to clog making access easier for clean out. The exisitng P Trap left in place to block sewer smell up A/C line into the attic.

- or -

3) Cut out old P Trap and install new one under the shower drain. Tee in the A/C line connection into shower drain line near the old P Trap location. My concern here is that I would have to install a P Trap in the 3/4" A/C drain line to keep sewer smell from going up the A/C line.

Thanks for the assistance.

[jadnashua]

Two traps in series is never allowed, and would create poor drainage. Draining it in front of the trap is potentially a possibility, but really messy, so likely not a great idea. You might solve all of this if you used a linear drain rather than a traditional one, as that would allow you to place the drain in nearly the same position as it is now. The floor becomes easier, too, since it only needs one slope, and is truly flat, rather than a bowl. A long trap arm means a long pipe that can accumulate soap scum, dead skin, hair, etc., and start to smell. Yes, some of it will wash away, but not all, and the trap right beneath the drain minimizes that dirty pipe smell/mess, and stuff 'falls' easier than it is pushed.