We just bought a house and are getting a new washer/dryer setup, but the old one is slightly confusing. There is a switched pump to pump out the laundry water. I don't know if this open pipe above the washer is a vent or if it was just the old homeowners way of initially tying into the sewer line prior to the installation of the pump. It looks like it has a P-trap, so I'm not sure if it is a vent or the initial drain attempt. This is in a basement below grade and main line, so I know the water must be ejected upwards. Does anyone have any ideas on this pipe and if I can get rid of it when rerunning the new drainage setup? I am thinking of a laundry sink with an auto pump, a check valve to prevent backflow, and a ball valve to limit flow and prevent the pump from burning out. Thanks so much for any help you can offer!
Without the sink and pump, usually the washing machine discharge hose would be inserted in the top of that open pipe. It is above the level of the exit pipe, and has a trap to prevent outgassing.
I would think the pump would have a similar connection (e.g. connection above drain with trap), if there were other users of that drain line. But I guess not in this situation. Perhaps that was added later.