Washing machine has no trap, what should i do to correct

[joesiah]

Hi while doing a remodel i notice that my washing machine has no trap, it shares a drain line with the bathroom sink, the sink has a ptrap under the sink but there is not one for the washing machine. They both have a 1-1/2 inch pipe which is goes into a 2" with a aav then in to a 3" into the main sewer line. My questions are does the washing machine need a 2" pipe, and if not can i just put a ptrap down the line from both drains to fix the problem. I am attaching a picture of the connections and a drawing of how it is set up.. thanks. I can upload a video if it will help..

[hj]

IF that piece with the 45 on it is the washer drain, then it DOES need a trap, but NOT like you show putting one in.

[cacher_chick]

The fixtures must be trapped individually and each trap will need it's own vent. A proper laundry drain is 2" What you are proposing with the running trap would not be approved anywhere in the U.S.A.

There are several good threads with pictures here in the forums showing how to properly plumb a washer. Take your time and look around.

[joesiah]

Okay so i need to remove whats there and go with a 2" for the washing machine, that is fine, before i do i want to make sure what im putting in is code or as close as I can get.. don't want any problems in the future. i have made a drawing of what im thinking about setting up.. drawing is looking down on the pipe.. please let me know if this will work?.. thanks.

[jadnashua]

AAV's are not allowed everywhere, the drain system needs at least one atmospheric vent, and if there's a reasonable way to vent what you're doing atmospherically, the inspector will probably require it to be done that way. An AAV is mechanical device that will eventually fail, needs access for that eventuality, and doesn't work in all situations. It can only let air in, and a washing machine's pump may end up pressurizing the pipe with no place for that air to go, thus, the AAV won't work and you'd end up gurgling and spitting in the lav sink.

[joesiah]

There are several vents in the system going out the roof, at least 3, main, kitchen and bath.. do i still need to add one to this part of the system?

[hj]

You have to understand that an AAV can CAUSE as many problems as it cures, depending various circumstances that can occur over time. IF you installed it EXACTLY as you have drawn it, you would create TWO "running traps". Actually, that "washer drain" looks like it was originally the vent for the sink so there may be a pipe that it was connected to at the ceiling somewhere.

[joesiah]

Two Running Traps? What is that? is that a bad thing? The washer drain was not a vent pipe, I know this for sure because this is an old remodel job, which obviously was not done correctly... don't know how it got past the inspector this way... I haven't had any sewer gass issues or drain issues so far, just noticed it and thought i should correct it, I just want it fixed and i can't go through two floors and the roof to vent... So what is my best option??

[cacher_chick]

A running trap is a trap that is installed in the horizontal drain, and is not allowed. The fixture drain needs to drop vertically into the trap.

It is pretty hard to say what your best option is without being there to see where all the walls above are, where other plumbing is routed, and what the obstacles are.

To say you "can't" doesn't mean it cannot be done.

This is in a finished basement?

[joesiah]

Here is a video,
I think I’m just going to add a ptrap to the washing machine and tie back into the existing pipe..

[cacher_chick]

The washer will siphon it's trap, so you would not be accomplishing anything.

If I could for some reason not install a proper vent there, I would install a 2" washer standpipe and trap, draining into a new 2" horizontal pipe running below the sink's drain pipe into a new sanitary tee installed below the existing one.

The new trap would be vented by a riser which goes up to a point near the ceiling with the AAV as high as possible on the top. I would install the new vent riser within a couple feet of the trap.

[joesiah]

how about this?
i think this will be the quickest way ..

[jadnashua]

EACH fixture needs it's own, separate (they can be combined higher, if done right) vent. No, that is not better. Often, the easier route does not work.

[joesiah]

I talked to a local plumber and he said i could do this.. any thoughts.. thanks.

[cacher_chick]

Your drawing does not portray the actual layout very well.

There is little to say you would not be allowed to connect it in that manner, if the washing machine standpipe and branch drain were all 2", and someone made a double-fixture fitting in that size.

If the line ever becomes restricted, the washer is going to pump it's entire load into your bathroom.