My plumber just installed the fixtures in my shower/tub and the shower stays running when the tub spout is running. I can tell he didn't even test it because when I turned on the water, I could hear the air getting flushed out. Even with the tub spout running at a low flow, the shower still leaks. All parts are brand new and I highly doubt the diverter is defective. Any feedback or tips would be appreciated. I called the plumber but he hasn't gotten back to me yet.
So it looks like it was a bad part, see the o-ring missing below. BTW, you just need a deep socket wrench to remove the diverter, I wasted a few hours looking for plumber's wrenches before figuring this out...lol.
Glad it's working now but this valve kit was brand new, seems odd that something so critical would be missing. Also the part that I pulled seems used or refurbished (see discoloration). I hope the rest of the valve is ok.
If the plumber didn't check for leaks he probably didn't let the water flush-out any pipe debris or other particles from the supply lines. Check for obstructions at the valve body. Also check the diverter for proper function with the valve fully opened. The more water pressure the tighter the seal.
1: It's called brand-new-broken. Get on the horn with the manufacturer of the valve.
2: If it was the plumber's fault, they melted a seal or something while soldering.
After being advised by both of these parties, you'll know better about who gets to pay to fix it. If it's #1, you might have to eat the labor on it yourself, less the cost of the new valve, plus you get to re-tile. If it's #2, you have to "play nice" or call lawyers.