: I have a question that might not have an answer (or at least not one I like). I installed a sink/sink pump combination in my basement. I was having difficulty getting to the venting stack with the sink plumbing, so I used a mechanical vent (Studor) coming off the sink pump basin. The drainage seems to be working fine, but the sink was draining very slowly. With some experimentation, I noticed that everything drained fine when I removed the mechanical vent. What I assume is happening is that the sink is try to expel air as the basin fills and the mechanical vent is keeping this from happening. Is there an easier way to do this without running another line to try to find a vent stack? Can the pump just be vented into the open air of the basement? (It's only a sink.) Any help would be greatly appreciated... Thanks!
Reply: Found this at www.libertypumps.com
"An automatic or mechanical vent device can not be used since this type of vent typically allows air to pass only one way. Pump systems require venting in both directions. The system must be vented directly to the atmosphere in accordance with national and local plumbing codes (Please note that sump pumps do not require vents). Using these types of vents may cause improper drainage of the fixture or affect pump cycling."