We're in a loft-style space with lots of old, patched-together plumbing. We recently added a washing machine to the end of the bathroom/kitchen drain lines, and it's created a suction problem.
All three run along a straight wall. The main drain out of our 3rd floor unit has a vent stack above it.
Going along the wall from the main drain, at about 6 ft, we have toilet with a full-size soil line to the main drain (and a bathroom sink about 4 ft away, with a totally separate 1.5" drain that runs directly to the main drain, so I don't think it's relevant).
Another 14 feet along the wall - about 25 feet from the main drain - is the kitchen sink, with a 1.5" drain that runs about 20 ft until it ells down into the toilet's soil line.
We added a washing machine at the end of the line - about 14 ft beyond the kitchen sink - by replacing the elbow that connected that sink's trap with a tee to a 1.5" PVC pipe that runs along the wall to an elbow (We gave that pipe about 6" of rise before the elbow) that connects to the p-trap and then to the standpipe for the washer drain.
Everything drains OK, but when the washer is draining it dumps a bunch of water in the drain and when that flow stops, the kitchen sink gurgles and the water in the trap is sucked out.
After the wash load finishes, the first time we use the kitchen sink we can hear the flow through that trap sucking the water from the washer's trap.
I added a wye to the top of the standpipe - with the washer outlet going into one arm of the wye and the other left open - to see if allowing more air into that pipe along with the water would help, but if it made any difference it wasn't enough to fix the problem.
Is this a situation where an air-admittance valve might help?
Would having LESS rise between the kitchen and washer help, maybe?
All of this is in a 20 by 60 foot room with 11 ft ceilings and no insulation, and on the top floor of the building, so I'm not super-worried about gas accumulating, but I would like to fix it.
Any suggestions appreciated! I can upload a drawing or photo it if any of the descriptions are confusing.
All three run along a straight wall. The main drain out of our 3rd floor unit has a vent stack above it.
Going along the wall from the main drain, at about 6 ft, we have toilet with a full-size soil line to the main drain (and a bathroom sink about 4 ft away, with a totally separate 1.5" drain that runs directly to the main drain, so I don't think it's relevant).
Another 14 feet along the wall - about 25 feet from the main drain - is the kitchen sink, with a 1.5" drain that runs about 20 ft until it ells down into the toilet's soil line.
We added a washing machine at the end of the line - about 14 ft beyond the kitchen sink - by replacing the elbow that connected that sink's trap with a tee to a 1.5" PVC pipe that runs along the wall to an elbow (We gave that pipe about 6" of rise before the elbow) that connects to the p-trap and then to the standpipe for the washer drain.
Everything drains OK, but when the washer is draining it dumps a bunch of water in the drain and when that flow stops, the kitchen sink gurgles and the water in the trap is sucked out.
After the wash load finishes, the first time we use the kitchen sink we can hear the flow through that trap sucking the water from the washer's trap.
I added a wye to the top of the standpipe - with the washer outlet going into one arm of the wye and the other left open - to see if allowing more air into that pipe along with the water would help, but if it made any difference it wasn't enough to fix the problem.
Is this a situation where an air-admittance valve might help?
Would having LESS rise between the kitchen and washer help, maybe?
All of this is in a 20 by 60 foot room with 11 ft ceilings and no insulation, and on the top floor of the building, so I'm not super-worried about gas accumulating, but I would like to fix it.
Any suggestions appreciated! I can upload a drawing or photo it if any of the descriptions are confusing.
