I am installing 2 new washers and dryers on each floor in our two flat in a kitchen pantry (the building is 120 year old frame building.)

We are installing the wall insert that has the hole for the water coming in and a hole to put the drain hose going out. I know it has to be about 42" off the floor, but do these drains also need to have pea traps and a vent pipe?

If so, how far down do I need to put the pea trap? And then where do I need to put the vent? I am using 3" PVC for the drain and 2" PVC for the pea trap and vent if needed.

This is the drain where the rubber hose from the washer is inserted into it so it drains down and into the basement drain.

We are using 3" drain pipe because we don't want problems if both washers are ejecting water at the same time - they'll be on the same drain.

Thank you!

- Jim