Hi everyone, thanks in advance for any guidance you can provide. I recently finished half of my basement and I decided to add a small laundry room on the finished side. I added a new utility sink and installed a Liberty 404 pump to pump the water to my main line. I plumbed the discharge and vent from the pump to the 1.5” drain for the powder room sink. Everything drains well but when the pump kicks on it makes a gurgling sound in the powder room sink. My questions are:

(1) Should I run the discharge and vent to a 2” pipe on the other side of the basement?

(2) can I install an AAV on the discharge close to where it ties into the powder room drain?

Would either of these solve my problem or am I way off? Running a new stack through the roof isn’t an option unfortunately. Thanks again for your help, I really appreciate it.

Ben

if the powder room sink is vented properly then discharging the pump into the 1 1/2 sink drain should not make any sound.
the water you are pumping into the sink drain is sucking for air (normal function).
if the sink is vented the pumped water will suck air from the sink vent. it is sucking water from the sink trap.
you realize this is just an educated guess.
your pump vent can not tie into the sink drain. that does no good and in fact may make the situation worse.
try cutting the pump vent to let it suck air from the finish area. that may solve the problem ??
an AAV down at the pump will do no good.
set the vent like this. there will be now sewer gas because of the check valve. there will be no foul smell because there is no toilet involved.

Packy thanks so much for your response. Next weekend I will do what you suggested. I’ve still got the old sink with another pump installed about 15 feet away on the unfinished side. I think I’m going to cut the vent on the unfinished side and run it to that sink. Do you see any issues with that? Also, the vent doesn’t have to pitch correct? I can just run it under the joists and down into the old sink? The only reason I’m thinking about running it to the old sink is because I would get a foul smell from time to time from the stagnant water I think because the old sink is installed the way you recommended. Thank you again, I really appreciate you taking the time.

The flow of water past the sink connection is creating a venturi action, which is sucking the water from the trap.
I once had a customer where the installer of their remote bathroom, connected the pump discharge into the toilet's vent and everytime the pump turned on it sucked the water out of the toilet. The only cure is to find a "proper' location for the pump's connection.

Thanks HJ I’ll run the drain to the old sink this weekend and hopefully that will solve the problem. I appreciate you responding.