I'm removing a stackable washer/dryer and installing a vanity sink for my daughters art studio. All the lines are in place, hot & cold water lines and vent pipe (washer's waste water pipe), however as I opened the wall to relocate the valves and tap into the washer's vent line, I came across the following.
As you can see in the sketch, "Current" shows an existing p-trap from the washer's vent line, in the wall. I've read various "not a good idea to have two p-traps on the same line" scenarios due to potential lack of pressure and possible backwash, etc.
Any how, what I'd like to do, and know if it's within code, "Upgrade" is add a vent line for the vanity on the existing vent pipe, just above the washer's vent line?
A bit off topic but... I also noticed that there's only one shut-off valve (hot water line) on the water heater, and nothing for the cold one; is this normal? How do you go about turning the cold water off to run new lines?