Washing machine stinks during Drain Cycle

[Hos]

Hi All,

We recently purchased a home (first home) and settled in comfortably. Everything has been great with the exception of the Laundry room/drain.

Every time the washing machine goes into the drain cycle we can smell a terrible musky, eggy, gross odour. The smell lasts for about 15-20 second and quickly fades away.

I thought it was coming from the laundry tub, but it doesn't seem so.

I removed the laundry tub and took a picture for reference.

No other sink, toilet or drain smells musky/eggy.

Attached is a picture of what seems to be a butcher job.

 

[Reach4]

Pour a pint of water into the laundry tub drain once per month, or cover that open pipe to prevent gas escape.

 

[Sponsor]

 

[Hos]

Pour a pint of water into the laundry tub drain once per month, or cover that open pipe to prevent gas escape.

My apologies. The open drain pipe you see did have a the laundry tub attached to it. I removed it just for the picture and put the tub back on.

Is that the "open pipe" you are referring to? If so, it's closed. It also still stinks during the drain cycle. We actually use the laundry tub toughly once a week.

 

[Reach4]

Is that the "open pipe" you are referring to?

Yes. Dang. Thought it would be an easy fix.

 

[Jadnashua]

I see two problems...your standpipe for the washer is too short, and your laundry tub is not vented properly. Once a pipe becomes a drain, it cannot also be a vent line with few very specific situations (and this isn't one of them). You'd need to revent that line above where the WM enters. If that line going up is also a drain for things above, then neither of the two things are properly vented. On the laundry tub, ideally, you'd not have as long of a riser from the trap since anything there can start to smell if it gets a coating of say soap scum, etc., but it's probably not the source of the problem.

 

[Hos]

I see two problems...your standpipe for the washer is too short, and your laundry tub is not vented properly. Once a pipe becomes a drain, it cannot also be a vent line with few very specific situations (and this isn't one of them). You'd need to revent that line above where the WM enters. If that line going up is also a drain for things above, then neither of the two things are properly vented. On the laundry tub, ideally, you'd not have as long of a riser from the trap since anything there can start to smell if it gets a coating of say soap scum, etc., but it's probably not the source of the problem.

Thanks very much for the feedback. The washer and tub are both located in the basement of the house (if it matters).
How should the laundry tub be vented? There is a floor drain within 5 feet of the plumbing in the photo.

Would it make sense to have the washer just drain in the rub and eliminate p-trap for the washer?

Also, what's that thing at the top of the pipe? Is is an AAV (found a similar photo online).

 

[Reach4]

Try rubber-banding a piece of plastic bag material over the laundry tub drain if it is loose as pictured, or if the tub is back in place, put a stopper in the laundry tub and an inch of water in the bottom of the sink before trying a wash. If that cures the problem, add an AAV to the sink trap arm.

If the temporary plugging does not cure the symptom, there may be an air leak in your piping. Things don't look totally straight in the photo, and it almost looks like a compression drain fitting at the floor. But it is probably just a coupling. Not sure what I am seeing. That thing that you don't know what it is could be a union. So something could be leaking. But temporarily plugging up the laundry tub exit for the test should be informative.

I don't think the standpipe height being under the specified 18 inches is contributing to the odor symptom.

 

[Hos]

Try rubber-banding a piece of plastic bag material over the laundry tub drain if it is loose as pictured, or if the tub is back in place, put a stopper in the laundry tub and an inch of water in the bottom of the sink before trying a wash. If that cures the problem, add an AAV to the sink trap arm.

If the temporary plugging does not cure the symptom, there may be an air leak in your piping. Things don't look totally straight in the photo, and it almost looks like a compression drain fitting at the floor. But it is probably just a coupling. Not sure what I am seeing. That thing that you don't know what it is could be a union. So something could be leaking. But temporarily plugging up the laundry tub exit for the test should be informative.

I don't think the standpipe height being under the specified 18 inches is contributing to the odor symptom.

Thank you very much.
The tub is back in place. I'll try putting a rubber stopper on the laundry tub drain when we do our next load of laundry.

I googled the model number found on the "thing I don't know" and the result came back as this: http://osb.ca/products/etc-misc/air-admittance-valves/VA55.php

You're right. the long pipe from the basement floor is not straight, but everything seems tight and feels like hard plastic (abs).

I'll post back my results with the tub drain plugged.

 

[Reach4]

Since that is an AAV (air admittance valve), that would seem to bring up another possibility -- that the AAV has failed. Those are intended to admit air but not release air. You could try sealing a plastic bag over that during your test to insure that the AAV is not what is letting the gas out. In fact, you might want to just replace the AAV (easy to do and not very expensive) or at least figure out a test of that device. You don't have to use the same model. Studor is the leading name. Those thread in, and I think the thread is standardized. You would want to be sure that there is enough room between the pipe and the wall, since the outer diameter of the units vary.

The more I think of it, the AAV seems like the prime suspect.

 

[Terry]

The washer siphons the trap on the laundry tub.
The washer should have a 2" drain, p-trap and standpipe. The vent can be 1.5"
The laundry tray needs it's own p-trap, which you have, but should also have it's own vent, which can tie back in at 42".
If you have an AAV for that, you may consider getting a better one. Not all AAV's are equal.

 

[Hos]

The washer siphons the trap on the laundry tub.
The washer should have a 2" drain, p-trap and standpipe. The vent can be 1.5"
The laundry tray needs it's own p-trap, which you have, but should also have it's own vent, which can tie back in at 42".
If you have an AAV for that, you may consider getting a better one. Not all AAV's are equal.

Thanks Terry.

So are you also recommending I change the AAV first?

Would make more sense to do something like the attached instead (although I don't think my washer drain hose is long enough). This way I can eliminate the washer p-trap and "clean up" the area a little? It looks like a disaster right now.

 

[Reach4]

Draining the washer into the laundry tub is common and permissible. What you propose is not.

 

[Hos]

Alright. So I'm thoroughly confused now.
I would really, really, really appreciate if someone could do up a MS Pain drawing to give me a better understanding of what needs to be done.

My wife likes the idea of NOT having the washer drain in the laundry tub, so I'd like to keep it clean like the way it is...but the smell needs to go.

From my understanding based on these messages, I need to have a vent for the washer p-trap and another vent for the tub. If that's the case, my only option would be to use 2 x AAVs, as the previous owner finished the basement and all other plumbing is covered up.

I'm a visual person, and i'm having a hard time visualizing what this should look like.

 

[Reach4]

Choices include a

• single AAV over a "double fixture fitting". The 2 trap arms go into the double fixture fitting. but that may not fit your corner location. Also, usually those would have a 2 inch outlet, so I don't know if you could do this with your 1-1/2 drain pipe..
• One AAV for each trap arm.
• Separate verticals that join high enough and tee to a single AAV.

https://terrylove.com/forums/index.php?threads/adding-utility-sink-to-laundry-room.57855/
https://terrylove.com/forums/index.php?threads/washing-machine-slop-sink-aav.46581/

When you build your new plumbing tree, attach it to the walls securely.

However I think you should just start with a new Studor AAV on your old system. You can reuse that if you build a new tree.

 

[Hos]

Choices include a

• single AAV over a "double fixture fitting". The 2 trap arms go into the double fixture fitting. but that may not fit your corner location.
• One AAV for each trap arm.
• Separate verticals that join high enough and tee to a single AAV.

https://terrylove.com/forums/index.php?threads/adding-utility-sink-to-laundry-room.57855/
https://terrylove.com/forums/index.php?threads/washing-machine-slop-sink-aav.46581/

When you build your new plumbing tree, attach it to the walls securely.

OK. I think I understand what the first option would look like, but I have another question re: option 1.

It it possible to run the 1.5" pipe that connects to the Double Fixture Fitting further down before connecting the p-trap. Basically, I want to be able to get the drain hose from the washer closer to the actual drain pipe. Right now it's just barely reaching.

I've attached a picture of what I mean. It is a tight corner, so it would be nice if I could run the pipe along the left wall you see in my first picture, then place a p-trap and vertical pipe for washer drain.

Thanks again for the help. I appreciate all the replies and tips as I learn.

 

[Jadnashua]

Does anything from upstairs drain into that pipe? Or, does it go up as a vent all the way? The picture cut off, so it wasn't obvious what was going on above. If it is a drain for something above, the WM is NOT vented properly. With few exceptions, once something is used as a drain, it cannot also be a vent.

If the AAV is working, you could add another vent line from the sink, then join that vertical and only need the one AAV. Code calls for that to be at least 42" above the floor, which Terry mentioned.

 

[Reach4]

Here is a straw man idea. The trap arm B should be no longer than 3 ft for 1-1/2 for some codes (remembering that the drain line (H) thru the floor is only 1-1/2. Using a separate wye and sweep, or combining those with a combo, as I drew, will get the water from the washer zipping along in the correct direction. This also allows independent angling of the pipes.

The double fixture fittings I think presumes that it will do the venting, and your proposed standpipe location would be too far away. Some codes allow more -- I am thinking 5 ft, but I think your proposed location was farther than that too.

What flaws? Rocks invited.

 

[Jadnashua]

The problem with a WM drain is that when there's only an AAV, since the water is pumped, the velocity is high and it tends to push some air in front of it...an AAV only lets air in, not out. It works with vacuum, not pressure. An atmospheric vent would let air in or out. Especially with a 1.5" line (code in the USA on new stuff would force that to 2", but that would be REALLY expensive to remedy), the WM can nearly fill the pipe and it acts like a piston.

It would be much simpler to drain the WM into the sink.

 

[Hos]

Here is a straw man idea. The trap arm B should be no longer than 3 ft for 1-1/2 for some codes (remembering that the drain line (H) thru the floor is only 1-1/2. Using a separate wye and sweep, or combining those with a combo, as I drew, will get the water from the washer zipping along in the correct direction. This also allows independent angling of the pipes.

The double fixture fittings I think presumes that it will do the venting, and your proposed standpipe location would be too far away. Some codes allow more -- I am thinking 5 ft, but I think your proposed location was farther than that too.

View attachment 33902

What flaws? Rocks invited.

Oh man...this is EXACTLY what I need. This would work perfect for the limited space in the area.

If I do it as you've sketched out, I'd even be able to hide the plumbing between the wall (it's really a pain too look at right now).

Doing it this way will obviously be more work and money (and we're limited on funds since we just spent it all on the house), but it will definitely look MUCH better !

The length of the wall is on the left is roughly 3.5ft, so I think this will work perfectly.

 

[Jadnashua]

Good luck...let us know if it works...it's by no means a certainty. Verify that the existing AAV is still working properly. If you seal a plastic bag over it, you'd be able to see if air is sucked in, or pushed out if the bag is not full (none should get out, if it does, that's likely the source of the smells).