drainoverflowwasher
There is a similar thread on this topic. I've got a new LG WT1101CW top load washer and our drain pipe can't keep up with the flowrate coming from the washer. It's a great idea to add a larger diameter tube to the drain pipe to allow the excess water time to drain away.
Is there any significance to the second 2" pipe at the outlet side of the trap? Or is this just another drain pipe coming from "upstairs"?
When drain water from one fixture comes back out another fixture, it means your blockage is beyond the point where those drains meet.
You need to get a good look at the topology of your waste plumbing, to get some ideas about where the blockage is. Clothes washer -> bathtub is a common symptom, because the clothes washer drains a lot of water up high (it has a pump) and the tub drain is down low.
Snaking down a drain is really hard, because of all the curves of the P-trap. If you're lucky, you have a clean-out somewhere, like under the house or behind a wall. Otherwise, you can try removing a P-trap to get the snake in, or removing a toilet. Removing a toilet is not very hard, but can be daunting.
We had a similar problem in this house. There were a few clean-outs accessible in the crawlspace, and our landlord used a hand-held snake in them, but didn't have much luck.
They hired a professional plumber. He pulled a toilet out and ran a huge snake down the drain (not one of the handheld units, but a huge, loud, floor-standing model heavy-duty cable). After running all 75' out, he borrowed another snake from his colleague, for 150' of snaking. This is a single-story house, on a 50'-wide lot, so the snake was well in to the street!
He said he pulled out a lot of roots. This is apparently common in older plumbing. They develop a small leak, and nearby plants grow after the nutrient-rich water, and find their way in to the pipe. It took him about 4 hours.
Plumbing is simple. There aren't a lot of rules to follow. Everything works in obvious ways. You don't need a lot of expensive, complicated tools, and if you do need something big, you can rent it. Anyone can fix plumbing.
But it can also be unpleasant. Screw-on connections may be rusted in place - hacksawing is often easier. There's the spectre of old poop and hair. Things may be difficult to reach - in a cabinet behind a sink basin or in a muddy crawlspace full of rat droppings.
If the job takes a few days, and you're unaccustomed to living without plumbing, it can be a trying time. Especially if there's a whole family in the house, and they aren't sympathetic. A pro will get the job done much faster, since they arrive with the right tools, parts, and experience.
There's a lot of instructions out there, on the internet, at the library, at the hardware store. If you decide to get your feet wet (get it? ha ha) then you will be able to find the information you need.
Ideally, you should move the P-trap upstairs, and vent through the roof. Under no circumstances should you have two p-traps in one line. You get an air-lock between the two, and funny stuff happens.
You want something like this:
Best Answer
No. The vertical pipe downstream of the trap is either another drain coming in from above or a vent stack. It isn't involved with the capability of the 3" section to provide some surge capacity for the draining washer.
(Well, I suppose it does add a little bit of capacity, insofar as water can fill that drain/vent pipe up to the level of the opening at the top of the 3" section. So that's a little bit of surge capacity. But it isn't its primary purpose.)