[balesmachine]

I have read several posts here and it appears that you know what you are doing - and I don't! But I am real good at visualizing things. Here is my problem.

I have lived in the same house for 20 years, and have never had a problem with the drain I speak about. We DID get a new washing machine a few years ago, and I THINK that our problem started then. We have a single story house on a slab. The drain is set into the wall in a little aluminum box with a open front. The wall has sheet rock on the inside, and brick on the outside, which is the back porch. The box houses the open end of the drain pipe, and the hot and cold water supplies for the washer. Looks like the box is designed to catch small leaks from the water line valves, and let them go into the drain rather than on the floor, in the wall, or other places. The drain pipe is 1-1/2 " inside diameter, and is about 32" off the floor. I can't look very far into the drain pipe, but I can look far enough to tell that the drain is PVC and has what looks like a 45 degree bend about 6 to 10 inches from the top opening. I first noticed the leak because the porch would be wet at the bottom of the brick. The water is leaking in the wall, and running out the weep holes in the brick onto the porch. So far, I have not noticed any leaking inside the house, and also the sheet rock hasn't showed any water staining.

Here is what I have done. I ran a snake in the drain pipe and it was perfect, with absolutely no hint of blockage. I ran it down 10 feet or so. I have a clean out access near the washer and can observe the water running real fast, when it is draining. The washer drain T's into the pipe from the bathroom sink to the toilet, and then all go outside, where there is a cleanout plug. I have cleaned out the vent a bunch of times, but have never found any obstructions in it.

Here is what I think, and tell me if this makes any sense. I have read that the new washer discharge flow is much faster than the old ones. Since we only have a 1-1/2" dia pipe, it simply cannot handle the faster discharge rate. Seem to me when I watch it, there is so much water dumping from the washer, the air is blocked between the rubber hose and the p trap. Since the vent (through the roof) is beyond the P trap, it really does not come into play. I have heard that alot of newer homes use 2" pipe for washer drain pipes.

What do you think. The house was built in the early 70s.

[iamgrowler]

If it's feasible to do so, you should consider upgrading the trap, trap arm and drain to 2".