My father had the sags in his later sewer line fixed, but he still has sewer gas coming out of the floor drain in his laundry room.

Looking from below at the way the floor drain is plumbed, it has no source of water coming into it. The washing machine drains into the same drain, below the p trap. He has tried adding water, sometimes gallons at a time, but this hasn't helped.

There are a few things that may be wrong. First, I do not see a vent. There may be a vent connected above the washing machine drain, inside the wall, but if there is one I cannot see it.

I'm wondering if the p trap (white pipe at the top, tiled in) is installed incorrectly. It's hard to see the way it goes through the TGI, but it may be a complete "S".

There is a second p trap, which I did not install, which looks ridiculous.

I'm wondering, is it possible to route some of the water from the washer drain through the p trap to keep water in it, without using some model of p trap primer?

What is the best way to stop the sewer gas from coming up?

That looks likes some DIY f-up. If there is no vent, the trap could be getting sucked dry.

^^Exactly, and frankly I was embarrassed to post the photo, a little less since that isn't my work, but still.

I wish I knew how to tell if there was a vent connected there. The washer drains fine, no issues.

It does appear the water is getting sucked out of the p trap. I've read that if the p trap is a complete "s", this can happen.

Which drain is the laundry tub stand pipe?

The left horizontal, the center vertical thru floor, or is it connected to the horizontal disappearing to the right?

The standpipe is sucking air from the closest source, and I'd guess the standpipe is the center drain against the wall.

To fix that issue, you'd cut a tee on the stack and repipe the floor drain to the stack.

This is on my list of reasons why I hate plastic, but you can probably use a Furnco at the floor drain if there is no plastic upon which to get a pvc joint.

As it is piped now, it looks like the left horizontal into the wall is the vent, then you have three branches on a single pipe. The right one is a laundry tub?

Can't have a branch off a branch. The floor drain is double trapped, and if there is a standpipe trap above the floor, the standpipe is also double trapped.

quote:

Originally posted by Woodman:
Which drain is the laundry tub stand pipe?

The center vertical through pipe (white), to the right of the TGI is the laundry tub stand pipe.

So far as I know, the one to the left that goes into the wall (with the hot and cold supply lines on either side) is the drain pipe for the utility sink in the garage.

When you say to cut a tee into the stack, will this address the fact that no water flows into the floor drain?

If there ends up not being a vent, will a pop up vent work? There are pop up vents attached to each of the drains of his main kitchen sink and his island sink on the same level.

One of those three has to be a vent. The one on the left, does it run thru the wall right out to the utility sink? Sometimes they go thru a wall then straight up to a tee, pick up a sink, and continue up thru the roof (look from outside).

The one on the right, what is it doing?

Yes, you can change the trap to one which will receive an automatic trap primer. If the floor drain had a deeper trap it would help contain the water. If the floor drain is never used, you could eliminate it. I'd avoid a trap primer.

If it were my house and there was no vent, I'd move the floor drain to the "stack", add a tee on the line on in the garage, and stub from the tee into the garage rafters.

If the garage drain line is venting the whole stack, then just move the floor drain to the stack.

If he is not using the floor drain, just eliminate it?

I have mocked up a possible solution to this issue. The dimensions are close, some pipes are tilted as nothing is glued.

Can someone please look at this and see if there is anything wrong with cutting out the existing pipes and replacing it with something like this? I'm not sure about the area to the right of the p trap.

Thank you for your help.

In commercial work that I have been involved in the floor drains are always specd. with trap primers for this reason.
The trap primer has a water line attached to it which adds a small amount of water to the trap when someone else uses a plumbing fixture.

"A" for effort, deepocean. If the trap cannot keep up with washer discharge water will rise out of the floor drain. Maybe best to either eliminate the floor drain or avoid a "branch off a branch"?

quote:

Originally posted by Woodman:
"A" for effort, deepocean. If the trap cannot keep up with washer discharge water will rise out of the floor drain. Maybe best to either eliminate the floor drain or avoid a "branch off a branch"?

Thank you for your kindness in saying that, considering how it probably looks to a plumber. The floor drain at issue serves to provide a path for to remove water from the laundry room in the case of a catastrophic leak from the washing machine tub, filler lines, or drain pump.

I had hoped for a way to use some of the water from the washing machine to avoid installing a p trap primer.

Is there no other way to put water in the floor drain p trap without using p trap primer? A lot of people seem to have p traps in their laundry rooms without having this problem. There's a floor drain cemented into the basement floor in that house which has never had this issue.

The ABS looks fantastic, truthfully. But a washer standpipe is tall for a reason.

You could put the floor drain on the stack and create a "deep seal trap", meaning make the trap hold a tall column of water - think 12". A pouring of cooking oil into the trap can also help prevent evaporation and subsequent loss of trap seal. Those "waterless urinals"? They use a "proprietary" liquid very similar which keeps the smell out of the bathroom and prevents evaporation.

The old Philadelphia Plumbing Code called for cast iron deep seal traps at the base of rain leaders - an item virtually impossible to get these days. But the old way certainly worked.

Looking at the solution you put together, I think I would flip it around to have the washer drain fall strait into the trap and have the floor drain take that 90 degree turn over to the right. My thinking is that you'd want to get that washer drain water moving with some force to help evacuate it more efficiently. That would hopefully negate the possibility of it backing up out of the floor drain.

But I'm no plumber.

quote:

Originally posted by Skull Leader:
Looking at the solution you put together, I think I would flip it around to have the washer drain fall strait into the trap and have the floor drain take that 90 degree turn over to the right. My thinking is that you'd want to get that washer drain water moving with some force to help evacuate it more efficiently. That would hopefully negate the possibility of it backing up out of the floor drain.

But I'm no plumber.

I will try to mock that up, and post another photo.

Make two separate drops.

Fill the trap with RV antifreeze (google it, NOT auto antifreeze.)

Some use vegetable oil (I have in an unused shower) but it can go rancid.

Woodman, thank you for all your replies.

quote:

Originally posted by cparktd:

Fill the trap with RV antifreeze (google it, NOT auto antifreeze.)

I have thought of this, however it seems water gets pulled out of the p trap a few days after it is filled. Sometimes. Other times, not.

quote:

Originally posted by deepocean:

quote:

Originally posted by cparktd:

Fill the trap with RV antifreeze (google it, NOT auto antifreeze.)

I have thought of this, however it seems water gets pulled out of the p trap a few days after it is filled. Sometimes. Other times, not.

Your vent is clogged. Try snaking your vent from the roof, or run a garden hose down the roof vent and see if it drains. Since the plumbing cannot vent it sucks the water out of the trap and then is venting from the laundry room sink.....

I have wondered about the vent. Now I am curious as to whether or not there is a pop up vent under the laundry sink. I will check that tomorrow.

quote:

Originally posted by Woodman:
You could put the floor drain on the stack and create a "deep seal trap", meaning make the trap hold a tall column of water - think 12".

When you say put the floor drain on the stack, can you please explain what you mean? I'm really motivated to do any reasonable thing to get this fixed for them and move on to something else.

Seriously. Take a look at trap primers. Keeping the trap full of water is what they are designed to do.
I am sure you can retrofit without having to remove old floor drain since you have access underneath.