P trap drys out after 3-4 days.

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JohnB

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Laundry room p-trap:

1. After washing, the p-trap is definitely filled. I have a cheapo USB sewer cam to confirm.
2. Within a few days--usually 4, the trap is dry enough to let fumes into the laundry room. This seems way too short, yes?
3. I'm tried flushing the nearest toilet to see if it is siphoning the laundry room trap. It isn't.
4. There is a vent. The vent appears to be clear--I didn't snake it but I did run a garden hose down it full blast from the roof.
5. The trap isn't leaking--I have the dry wall removed on the other side of the wall.

So....any other ideas besides the usual above? This is baffling me.

Thank you.
 

Jadnashua

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Post a picture of the plumbing for the laundry. Unless things are really hot, a trap like that won't evaporate in a few days. The alternative is siphoning. It might take a combination of things draining (say shower, and maybe something else). I might be missing something.
 

JohnB

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Laundry room p-trap:

1. After washing, the p-trap is definitely filled. I have a cheapo USB sewer cam to confirm.
2. Within a few days--usually 4, the trap is dry enough to let fumes into the laundry room. This seems way too short, yes?
3. I'm tried flushing the nearest toilet to see if it is siphoning the laundry room trap. It isn't.
4. There is a vent. The vent appears to be clear--I didn't snake it but I did run a garden hose down it full blast from the roof.
5. The trap isn't leaking--I have the dry wall removed on the other side of the wall.

So....any other ideas besides the usual above? This is baffling me.

Thank you.
 

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JohnB

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I added pictures to the original post. Sorry, water heater is nearby so photo angles are odd. In case any of you are wondering what the expandable foam is for--it is just sealing around the plastic washer box to the drywall.
 

Jadnashua

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If you're positive nothing flows into that vent from above, I do not know what may be causing your problem. For the most part, a vent cannot be used as a drain and vice-versa. There are exceptions, but this does not appear to be one of them.
 
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If that "vent through roof" is a dedicated vent just for washing machine trap, it is very possible your Las Vegas Nevada climate is evaporating the trap.

Let's take advantage of the removed drywall and the vent's coupler that can be easily removed.

Get an AAV on a pipe about a foot long, and put that in place of the galvanized "vent through roof". That's cheap and easy to DIY.

If your trap still dries out with the AAV test, you might want to install a trap primer.

If your trap stays full after 4 days, marvel at your DIY work.
 

JohnB

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If that "vent through roof" is a dedicated vent just for washing machine trap, it is very possible your Las Vegas Nevada climate is evaporating the trap.

Let's take advantage of the removed drywall and the vent's coupler that can be easily removed.

Get an AAV on a pipe about a foot long, and put that in place of the galvanized "vent through roof". That's cheap and easy to DIY.

If your trap still dries out with the AAV test, you might want to install a trap primer.

If your trap stays full after 4 days, marvel at your DIY work.
Not a bad idea. It appears the county allows AAVs. In fact I may do something even less invasive--I might try temporarily capping off the vent and not use the washer for several days to see if the trap evaporates. I'm not worried about fumes since that is already the problem. Still, none of the other fixtures are drying out--there is another vent very close to this one for the guest bath that doesn't get used every day.
 

Jadnashua

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HJ lives and works in the desert SW...you might ask him if he sees traps drying out after 3-4 days...I think it would take a really unusual situation for that to happen. As to there being a smell...consider that the insides of galvanized piping after a number of years is likely starting to rust and be rough, at least at the joints, and will trap all sorts of lint and deposits from the detergent and softeners you may use in your laundry. The tall stand pipe could have a coating of that organic residue on it, and be smelling, and have nothing to do with the trap being dried out. Have you actually verified that it is dry by poking something down in there, or looking with a good light? It may not be dry. Doing a load would wash away some of that debris, but by no means all of it, and it might just be taking that long for things to 'fester' again.
 

Cacher_Chick

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It is also possible that the galvanized piping is full of rust scale which is retaining a lot of fiber and lint from the washer. The fibrous buildup can wick the liquid from the trap. Replace the standpipe, trap, and sani-tee with new PVC or ABS and your problem might be solved.
 

JohnB

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It is also possible that the galvanized piping is full of rust scale which is retaining a lot of fiber and lint from the washer. The fibrous buildup can wick the liquid from the trap. Replace the standpipe, trap, and sani-tee with new PVC or ABS and your problem might be solved.

Since I have the wall open anyway, I will probably do that.
 

Jadnashua

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IMHO, galvanized piping is a problem waiting to happen, and I'd get rid of any that was easily accessed. Cast iron is still a premium product, and can last eons. PVC is much easier to install, and remains smooth most of the time except if it is abused by dumping something it's not designed for down it.
 
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