This is my first post. I joined purely to solve this problem. I have attached a crudely drawn, in Paint, layout of the washing machine standpipe inside of the house and out. This is an old house (50 years) and when I had it inspected to before buying, he said the standpipe needed to be repaired because it drained into an open sewer pipe on the exterior of the house. So it was fixed, and that is the drawing I have attached. These pipes were just installed and never used so I doubt it is a clog.
I went to do my first load of laundry and water began overflowing from the standpipe. The height of the pipe is 39" from the floor, so that seems correct. My friend and I did some tests and it seemed to drain just fine when the exterior screw cap (see drawing) was removed. As if it let air out of the system. So I screwed the cap back on while the washer was expelling water and it immediately backed up. SO I took the AAV of the line and it drained just fine.
However, this pipe, as previously mentioned, drains directly to the sewer line under ground. So removing the AAV may allow gases to come into the house.
My problem is that every test I have done shows that air needs to get out for the water to drain properly. The AAV only lets air in. And every article I've read shows this setup being correct.
Could you please help me?
Thanks
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