Drain pipe for washing machine

[Whatnot]

I am wanting to put a washing machine in an upstairs room that is next to the bathroom. I originally thought it would be simple because the plumbing is right in the wall.
I have 3 drain pipes in the wall but not sure if I can use any of them. One is a 1-1/2", one 2"
and one 3".
The 1-1/2" is the vent for the bathtub drain.
The 3" is the vent for the toilet and I think the main pipe that all the vent pipes tie into up higher.
The 2" goes all the way down to the basement and connects in just after the toilet pipe for the bathroom on the main floor. Is that the vent for that toilet?

Is it possible to use any of these pipes for a washing machine drain?

 

[Breplum]

Not without connecting below the toilet

 

[Sponsor]

 

[Helper Dave]

Vents aren't drains. Laundry needs 2" pipe minimum, so the 1 1/2" is out. Really sounds like the 2" is only a vent ( would help to see how it connects to confirm). The 3" doesn't serve as a drain to anything above? Is it just a 1-story house?

Might have to drill another hole down, and connect somewhere in the basement from the aounds of it, though.

 

[Whatnot]

It is a 2 story house. The upstairs bathroom is directly above the lower bathroom.
I am not exactly how all the piping is routed because it is inside the walls and ceiling/floor. The 3" pipe and the 2" pipe are the only pipes in this wall that come all the way from the basement. (the shower and sink in the lower bathroom and the sink in the upper bathroom are on the opposite side of the rooms)

The bathtub and the toilet both have horizontal pipes connecting into the 3" pipe that goes from the basement up through the roof. That piping is under the floor so can't see exactly how it is connected.

It seems weird that they didn't put any laundry plumbing in this house. I was hoping that the 2" pipe was meant for it when I first found it. The previous owner had a washing machine in the basement but it was not connected and the only place it could have drained to down there would have been the sump pit.

I will try to get some pictures of the pipes in the basement.

 

[Whatnot]

Ok, after a lot more research, hopefully I have it figured out. The 2" pipe did turn out to be the vent for the toilet on the main floor.

My plan is to cut open the wall so I can put a wye in the 3 inch pipe below where the upstairs toilet and bathtub tie into it. Then put a 2" street 45 in it so the 2" new pipe can run up parallel to the existing pipes.
Then then cutting into the 2" vent from the lower toilet to tee in the vent for the new washer drain. Is that acceptable.