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Backing Up Washer Drain

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ksteen148

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Hello everyone,

I recently put together a drain system for my washer (see attached picture). However, it keeps backing up... did I do something wrong?

E6E735C1-80C9-475D-B5C2-3AB6CA4860F9.jpeg
Please help!

Thanks for your ideas and comments.
 

voletl

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First things first and that stutter vent needs to be moved much higher it needs to be at least 6 in above the standpipe height also you cannot connect the P-trap to the drain with a Wye it must be done with a tee

If the drain continues to backup you might have a partial blockage down in the Line open up that clean out and start snaking
 

CT18

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What is that 2" connected to. In many areas the 2" from the washer needs to tie into a 3" line. These new machines move a lot of water quickly
 

Diehard

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While you're at it, raising the top of your standpipe to it's maximum height(probably 48" above the floor for you), would reduce the flow rate discharging from your washing machine. If you think that a high flow rate may be contributing to the back-up.

Here's an interesting article...
https://www.pmmag.com/articles/85477-it-s-not-the-plumbing

Also, the reason for a tee connection...
fixture_arm-trap-weir-not-higher-than-vent.jpg

EDIT: Although a good idea, an AAV for a washing machine does not have to be 6" above the flood rim level.
AAV.jpg
 
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ksteen148

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Thank you for all of the tips!
I rebuilt the standpipe according to everyone's advice, but I'm still having issues. I think it's still not getting enough air. I'm going to try to extend the vent up into the attic space... unless anyone else has another suggestion?
 

Diehard

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Not sure if you mean extend the vent up to the attic WITH OR WITHOUT the AAV.

I'd suggest you try it with the AAV removed, without extending the pipe, to test/confirm your suspicions.

The trouble with AAV's they can remain closed if they don't sense a negative pressure. And a high volume from a washing machine could cause that , particularly if that 2" line is not dumping into a 3" line.

You may see water backing up that open vent line if that was the case.
 

ksteen148

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Not sure if you mean extend the vent up to the attic WITH OR WITHOUT the AAV.

I'd suggest you try it with the AAV removed, without extending the pipe, to test/confirm your suspicions.

The trouble with AAV's they can remain closed if they don't sense a negative pressure. And a high volume from a washing machine could cause that , particularly if that 2" line is not dumping into a 3" line.

You may see water backing up that open vent line if that was the case.
I tried removing the AAV when I rebuild the standpipe and water was still backing up. Are you saying that whether the vent is 12” or 12’ above the standpipe it wouldn’t make a difference? Thanks again for your help.
 

Diehard

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Assuming the arrangement was as I see it, where the vent height is shown lower than the standpipe, I assume it was coming out of the vent pipe. Which means it was not due to the lack of air. It means it's not flowing due to restrictions in the drain line.(Partial blockage or pipe too small.)

Have you tried snaking the drain line for possible partial blockage?

Can you determine if that 2" line connects to a 3" nearby? (Too bad they do indicate how close the 3" pipe should be.)

Options to improve, if not partially blocked.(After snaking)
Raise stand to 42" above trap weir.
Raise AAV to 6" above the top of the standpipe.
Or add a laundry sink and dump washer into that.

Code wording:
"Standpipes shall be individually trapped. Standpipes shall extend not less than 18 inches (457 mm) but not greater than 42 inches (1066 mm) above the trap weir. Access shall be provided to standpipes and drains for rodding."
 

Diehard

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Just saw you previous posts on this subject. From April I believe.
So I must ask, since you didn't do what frodo had suggested. i.e. install stand pipe directly into old shower trap. Or maybe you didn't fully understand what he was suggesting.
Did you remove the shower trap or is it now double trapped. Which of course is a no-no.

The 2" shower drain it itself may have caused a problem. That we can't say at this point but I think 2 traps have a worse potential effect.
 
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ksteen148

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Assuming the arrangement was as I see it, where the vent height is shown lower than the standpipe, I assume it was coming out of the vent pipe. Which means it was not due to the lack of air. It means it's not flowing due to restrictions in the drain line.(Partial blockage or pipe too small.)

Have you tried snaking the drain line for possible partial blockage?

Can you determine if that 2" line connects to a 3" nearby? (Too bad they do indicate how close the 3" pipe should be.)

Options to improve, if not partially blocked.(After snaking)
Raise stand to 42" above trap weir.
Raise AAV to 6" above the top of the standpipe.
Or add a laundry sink and dump washer into that.

Code wording:
"Standpipes shall be individually trapped. Standpipes shall extend not less than 18 inches (457 mm) but not greater than 42 inches (1066 mm) above the trap weir. Access shall be provided to standpipes and drains for rodding."
The arrangement you see in that picture is no longer. I have corrected as everyone has suggested in previous posts-- it is done properly.
I have already attempted to snake the drain without any change.
It is hard to tell where the 2 in. becomes 3 in., but I believe it is less than 8 feet.

I'm trying to avoid the laundry sink if possible. I'll give your additional suggestions a try. Thanks.
 

ksteen148

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Just saw you previous posts on this subject. From April I believe.
So I must ask, since you didn't do what frodo had suggested. i.e. install stand pipe directly into old shower trap. Or maybe you didn't fully understand what he was suggesting.
Did you remove the shower trap or is it now double trapped. Which of course is a no-no.

The 2" shower drain it itself may have caused a problem. That we can't say at this point but I think 2 traps have a worse potential effect.
Yes, I jackhammered out the floor, removed the trap, and connected directly. It is not double trapped.
 

Diehard

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So then my question should have been, was the water coming out of the vent line when you removed the AAV, and was it still lower than the top of the standpipe?
Either way, it still a sign of a restriction.
The reason I suggested to raise the standpipe to it's maximum allowed height was to reduce the water flow. In other words the high the washing machine pump has to lift the water the lower the flow rate should be.

Did you ever look to see if you washer is one of those that have a much higher discharge rate?

oops! sorry I missed your answer on the traps until I refreshed the screen.
 
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ksteen148

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So then my question should have been, was the water coming out of the vent line when you removed the AAV, and was it still lower than the top of the standpipe?
Either way, it still a sign of a restriction.
The reason I suggested to raise the standpipe to it's maximum allowed height was to reduce the water flow. In other words the high the washing machine pump has to lift the water the lower the flow rate should be.

Did you ever look to see if you washer is one of those that have a much higher discharge rate?

oops! sorry I missed your answer on the traps until I refreshed the screen.
Water was not coming out of the vent line when I removed the AVV... and no, I corrected the AVV placement, it is now 12" above the standpipe.
That is a good idea, I'll raise the standpipe to it's max.
I'll look into the discharge rate of the washer... but as of right now, the line is backing up with just a hose.
 

Jeff Handy

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This is probably not critical, but your Studor vent looks undersized.

It looks like you have a reducing fitting on the 2” pipe, then the small AAV fits inside that reduced fitting.

So you are no way getting a 2” cross section of venting air.

I don’t know any code requirements, but common sense tells me it is too choked for vent air.

So if anything, I would suggest an increaser fitting, then a bigger AAV.

Not that this is causing your backup now, but it should help for long term.

And post a new pic of how everything looks now, if it is still not draining right.
With the washer hose installed as you are using it.
Maybe add a video too, showing the backup.
 
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ksteen148

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This is probably not critical, but your Studor vent looks undersized.

It looks like you have a reducing fitting on the 2” pipe, then the small AAV fits inside that reduced fitting.

So you are no way getting a 2” cross section of venting air.

I don’t know any code requirements, but common sense tells me it is too choked for vent air.

So if anything, I would suggest an increaser fitting, then a bigger AAV.

Not that this is causing your backup now, but it should help for long term.
I really screwed up on that first one, just threw it together without doing any research.
But that makes sense, I'll also try a bigger AVV. Thanks.
Do you think increasing the height of the vent line would make a difference? Would that allow more air flow?
 

Diehard

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It won't allow more air in than when you had the AAV completely removed.:eek: I think Jeff probably missed that.
It also won't let more air in if you raise it. In fact, theoretically, by making the vent pipe longer would only decrease the amount of air. Although insignificantly.(friction loss.)
You may also want to look at the owners manualto see what it says for maximum height you can raise the hose above the machine. That would give use an idea as to how much pressure it's capable of, safely.
Because the next step MAY be restricting the flow a little more by other means.

What's the name and model no.? I may try to check on that through the manufacturer.
 

Jeff Handy

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I had said,

“This is probably not critical, but your Studor vent looks undersized”.

I also said,
“Not that this is causing your backup now, but it should help for long term”.

I knew the backup still occurred even with no Studor vent at all.

I just felt that it would be less prone to clogging in the future, once the other issues are worked out, if it had a bigger source of vent air to keep lint etc moving along as fast as possible.
 

ksteen148

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It won't allow more air in than when you had the AAV completely removed.:eek: I think Jeff probably missed that.
It also won't let more air in if you raise it. In fact, theoretically, by making the vent pipe longer would only decrease the amount of air. Although insignificantly.(friction loss.)
You may also want to look at the owners manualto see what it says for maximum height you can raise the hose above the machine. That would give use an idea as to how much pressure it's capable of, safely.
Because the next step MAY be restricting the flow a little more by other means.

What's the name and model no.? I may try to check on that through the manufacturer.
LG WT7100CW... I’ll call them today. Thanks.
 
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