wye

I am confused about SanTs and Wyes. I understand SanTs cannot be used on their backs, so they cannot be used to connect a vertical drain to a horizontal drain pipe. For this, a wye plus 45-degree elbow must be used. Where my confusion lies is with connecting a horizontal drain pipe, into a...

I am doing a bathroom add-on to the second floor of a two-story home. Thus, my options are a bit limited as far as where I put the drain lines and drain stack. This all boils down to the use of a wye to combine the toilet drain and other bathroom drains on a horizontal. I just don't know how to...