Downstream from my sink trap I am required to vent the drain - I am accomplishing this with a studor (air emittance) valve. In order to install this valve I must tee into the horizontal line. Which fitting do I use in this instance? I have been told a sanitary tee is not to code but also recall that a wye is not to be installed 'laying on its back'. That leaves only the vent tee but I think that is also a misapplication. If the wye is the correct answer, in which orientation is it to be set? Help!