Help with a Washing Machine?

[ShannonChuy]

Okay so my washing machine is overflowing the standpipe when it drains, it was doing this a while ago and then it stopped but now it's doing it again. The washing machine is on the main floor in the middle of the house (it is supposed to be for a stackable but my dryer is in the basement), the drain pipe runs probably 20-25 ft until it reaches the main stack. It's a 1 1/2" pipe with no other fixtures plumbed into it. There is no vent on this line, and no vents near it to tie into (everything else vents through the main stack but they're much closer). Standpipe is probably about three feet high and is connected to a 90 which immediately goes into the p-trap (these connections are under the main floor in the basement). I've tried snaking the drain and didn't find any obstructions. I do not believe this plumbing was done by a licensed plumber and I can't figure out how to fix this. Do I need to change the drain to 2"? Can the standpipe act as the vent? Or is the whole thing a giant headache? I'm in Massachusetts and am unsure of the current code.

 

[Standardairconditioner]

You may to check with MA state law and see if this qualifies for a "repair" which you can do yourself, or a "new install" which I believe you must get a permit and have it done by a licensed professional, or have a licensed professional agree your work meets MA state rules.

An unvented trap can be very slow to drain.

Standpipes are not vents. They are a substitute for your washer emptying into an open sink, and the sink is both trapped AND vented.

That means your standpipe needs a vent soon after where its trap ends.

Did you snake properly with motor tool like a SuperVee? A manual hand snake is useless for a long run of 25 ft.

Youtube is your friend.

 

[Sponsor]

 

[Cacher_Chick]

The newer washers do not use much water, but the water that is in them drains quickly. I would start by rodding the horizontal section of pipe to the stack, and then reworking your standpipe so that it drops directly into the trap, and then install another riser for an AAV within 2-3 feet of the trap. If you are in the USA, the trap and vent must be on the same floor as the standpipe to meet the minimum code requirements. If you have access, converting the entire drain to 2" is a great idea, as it is how things have been done here for many years.