Replacing PVC drain pipe for washer

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imaltesers

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Hi everyone,

I opened the wall in my laundry room and discovered that the drainage pipe for the washer is 1.5" PVC. Brief online search says that it needs to be 2". The pipe extends down into the basement and connects via tee fitting to another 1.5" pipe, then it finally reaches a larger 3" pipe. I have a new washer that isn't installed yet so no idea if this is an issue or not.

Questions:
Can I leave this as is?
If I should replace it, can I replace the pipe up until the 1.5" tee and just replace with a 1.5" x 2" tee? Or do I need to replace all the pipes up until the 3" pipe?
If I need to replace all the 1.5" pipe, how can I connect to the 3" tee without having to cut it out?

TIA
 

imaltesers

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washer drain pipe.jpg
 

wwhitney

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Ah, that all needs to come out back to the 3" wye. There's two current problems: there's no vent for the standpipe trap, and the standpipe trap arm would need to connect to the horizontal branch with a combo, not a san-tee on its side.

Assuming you are under the IPC, then a standpipe needs to be 18" to 42" in length above the trap (weir). So depending on where you want the top of the standpipe, the trap should probably be above the floor. Then you can have a san-tee above the floor with a dry vent off the top (could be an AAV) and the drain going down through the floor. That could hit an upright combo to join the kitchen drain coming in, and the branch can go into your 3" wye.

Cheers, Wayne
 

imaltesers

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Thanks for the response. Moving everything upstairs would be a huge project for me, not very confident as a new DIYer o_O

Just for my knowledge, the current standpipe is well beyond 42" since it's going into the basement, so what's the risk with this setup?
 

Terry

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There have codes requiring that the washer p-trap be on the same floor and that the standpipe is with standard lengths. That's to prevent siphoning of the p-trap.
If the trap siphons, you will be wondering why you have a smelly home.

The washer and the kitchen sink line are 2" by code. Why in blazes was that run with 1.5"?

A RamBit can drill out the reducing bushing and then you can glue in the correct size.
 

imaltesers

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House was built in the 70s and seems to have gone through a remodel before we acquired it. Couldn't tell you why the pipe is 1.5", maybe it was DIY. But kitchen sink drain can be 1.5" right?

Thanks for the tip about the RamBit!
 

Jeff H Young

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Why the 3 inch santee on back ? I guess , hope vent only .
I think back East they allow 1.5 on kitchen drain but definitely not wash machines. but 1 .5 on a kitchen sink is illegal here and considered hack why anyone would use it here ? but you have a different culture due to it being legal for us plumbers in the West its ingrained as sub standard poor workmanship.
 

Terry

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I'm not liking the 3" santee on it's back either.
Is that for a vent, weird if it is, or is it a toilet dropping down, not good if that's the case.
 

imaltesers

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I believe the 3" vertical is a vent but not sure if other fixtures are connected to it, I'll try to find out.

So here are some photos and sketches of what I'm planning to do, please let me know if it checks out?

washer drain plan 1.jpg
The washer outlet box will be lowered a notch and resulting standpipe will be 22" tall. Dryer box in the way makes the horizontal just shy of 4" so hence the bend in the standpipe, if that's not enough then I'll move the entire box to the left and redo the water supply lines. Cold water line (red) will need to wrap around the back to get out of the way. AAV will be as tall as the standpipe for easier access. All 2" PVC.

washer drain plan 2.jpg
Kind of difficult to get an accurate angle on this, but essentially the pipe will come down from around the same location as the electrical wire, then a slight bend (not sure what angle exactly) before meeting the kitchen sink drain at a 3" combo wye. Leaving the kitchen sink pipe at 1.5" so using a bushing to connect that to the wye. I'm actually not too sure if this will fit, going to buy parts and dry fit tomorrow.
 

wwhitney

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Dryer box in the way makes the horizontal just shy of 4" so hence the bend in the standpipe
The 4" is measured from the inside vertical face of the trap outlet elbow to the inside vertical face of the san-tee. So you only need ~2" of exposed pipe between the fitting hubs.

As to dry fitting, if you don't want the fittings to move when you make up the joints, you'll need to recut slightly longer pipes for the final glue up. Dry fits are never full depth.

Cheers, Wayne
 

Jeff H Young

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If you are replacing the box you could use one with a waste outlet left side but putting a couple 22s or 45s on the standpipe would be no issue either just if your replacing it anyway I'd then use a left side waste
 

imaltesers

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The 4" is measured from the inside vertical face of the trap outlet elbow to the inside vertical face of the san-tee. So you only need ~2" of exposed pipe between the fitting hubs.

As to dry fitting, if you don't want the fittings to move when you make up the joints, you'll need to recut slightly longer pipes for the final glue up. Dry fits are never full depth.

Cheers, Wayne
Good to know, maybe I won't need to bend the standpipe then.
So when dry fitting the straight runs will be shorter than what is actually needed when gluing? Is it better to go by measurement then?

if you are replacing the box you could use one with a waste outlet left side but putting a couple 22s or 45s on the standpipe would be no issue either just if your replacing it anyway id then use a left side waste
Yes I am replacing the box, will consider this idea!
 

Jeff H Young

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I see your space is kind of tight because you are going to penetrate floor about a foot to the right. but I also notice the dryer is so close to washer space might consider move washer box over to the next stud bay to left . copper appears in way underfloor when waste comes up to the right
 

John Gayewski

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Also what would be the best order to assemble this? Should I start at the 3" pipe and work my way up?
Generally start at the lowest point and work your way up. Sometimes existing conditions require creative assembly, but generally work from the bottom up.
 

imaltesers

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Actually...I think I spoke too soon. There were two places where the pipes were just slightly offset, so a family member suggested using a Fernco coupling. At that point I was pretty flustered and wanted to get it done, so I didn't think much of it...but after researching a bit more I'm pretty sure this isn't allowed.

camphoto_1450712544.jpeg
What should I do now? Can I replace the couplings with the shielded type? Or does it need to be redone?
 
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