Hello am wondering if I can use a 3-3-2 Low Heel elbow to vent a WC? If I'm not using a standard description, this is a 3" elbow with a 2 " take off (sort of a 'Y' fitting) The elbow would be oriented vertically with the 2 " on the 'upstream' side. This will be connected directly below the WC. My issue is a spacing one, can't fit the necessary vent down stream of the elbow. Is is appropriate to have a vent 'upstream' of the fixture?
Thank you.
Tim