How can I connect a standpipe here?

[Ramjam]

Hello,

I'm currently renovating my laundry room. Previously the washing machine emptied into a laundry tub. I would like to install a standpipe for it to drain into instead.

I've attached a picture of the plumbing I currently have. In the picture you will see the old drain for the laundry tub, a line that connects to the left which comes from the kitchen sink upstairs, and a line on the right which is a vent. Would it be correct to connect the standpipe via a Y onto the horizontal part of the drain line that runs to the laundry tub? My limited knowledge tells me this will work however I am worried that this would cause the water being dumpved by the washer to back into the sink.

The only other option I can think of is connecting it onto the vertical part of the drain line that comes from the kitchen sink, however doing this would result in the stand pipe trap being over 18 inches from the floor which from my understanding is not allowed?

Thanks for the help!

 

[Ramjam]

Does anyone have any input at all? I'm at a standstill on this project until I figure this out. My fault for waiting until the last minute to look into this I know...

 

[Sponsor]

 

[Stuff]

Need some clarification. Are you planning on still having both a laundry tub and a standpipe?
Is this going to have a finished wall with a laundry standpipe and water connections?

 

[Ramjam]

Need some clarification. Are you planning on still having both a laundry tub and a standpipe?
Is this going to have a finished wall with a laundry standpipe and water connections?

I plan to have the laundry tub and the washer yes. I will finish the wall with a laundry standpipe and water connections. Here's where I'm at so far; I decided to re-plumb the vertical part of the stack. Now, the lower connection comes around to the sink stub out (plumbed in the picture), from here, as far as I know, I will continue to the right, add a Sanitary tee to connect to the existing vent, and then continue to the standpipe. Does this sound right? Quite honestly I think I need this extra vent but I am not quite sure seeing as how there is a vent connection on the top of the vertical part of the stack in the picture.

 

[Stuff]

What you propose would be a wet vented laundry tub which wouldn't work right. The washing machine could move enough water to suck out the tub's trap.

You want something more like this (Terry's pic). What you are doing is more complicated but I have a couple of ideas. To tie in the kitchen sink drain put a horizontal t-wye under the tub san-t pointed left to go around the corner. That might raise the tub drain too high so may use a long sweep elbow below the stacked san-t's instead. Kind of goofy - maybe someone else could chime in.

 

[Ramjam]

What you propose would be a wet vented tub which wouldn't work right. The washing machine could move enough water to suck out the tub's trap.

You want something more like this (Terry's pic). What you are doing is more complicated but I have a couple of ideas. To tie in the kitchen sink drain put a horizontal t-wye under the tub san-t pointed left to go around the corner. That might raise the tub drain too high so may use a long sweep elbow below the stacked san-t's instead. Kind of goofy - maybe someone else could chime in.

I'm not sure I understand why the laundry tub would be wet vented in my plan. Could you explain this to me? As it stands now the vent connect vertically on top of the Sanitary T that connects the laundry tub (and future standpipe) and also on top of the San T that connects the upstairs kitchen sink. What I was planning is putting another vent to the right of the sink, so basically the vent would be in between the standpipe and the laundry tub. You don't think this will work?

 

[Stuff]

From what I understand of your setup - the pipe section between the laundry tub and the vent to the right would also have water in it when the standpipe drains. If so this section would be a vent for the laundry tub and a drain for the washer standpipe - thus a wet vent.

From a quick search it seems that Ontario codes do allow this wet vent. Other areas don't. So I should not have said that it wouldn't work, just that it wouldn't pass code in many places. If this has a permit and will be inspected you might want to show your proposal to the inspector first.

 

[Jadnashua]

First, your WM standpipe should be 2" while the laundry tub can be smaller. EACH of them needs to be vented. In your last picture, neither is...the vent line needs to come off of the trap arm before the drain turns down. You can combine the vents and only still need one to go up, but each trap should be vented separately. Study that picture Terry supplied, and I think you'll see what we're talking about.

 

[Terry]

You can't dump the kitchen sink from upstairs over the laundry tray and washer.
What you had to start was kind of workable, and then you turned it into something that didn't work at all.
The waste from upstairs comes in "below" any plumbing on the first floor.
The laundry tray trap arm can only have 135 degrees of change before it hits the vent. You have 180 degrees of change. Nope!

Cut the upstairs in near the floor, then add the plumbing for the tray and washer, venting both, not wet venting. By the way, wet venting is for bathroom fixtures on the "same" floor. Venting for the tray and washer uses the previous vent, and can be revented at 42" above the floor, not below that height.

 

[Ramjam]

From what I understand of your setup - the pipe section between the laundry tub and the vent to the right would also have water in it when the standpipe drains. If so this section would be a vent for the laundry tub and a drain for the washer standpipe - thus a wet vent.

From a quick search it seems that Ontario codes do allow this wet vent. Other areas don't. So I should not have said that it wouldn't work, just that it wouldn't pass code in many places. If this has a permit and will be inspected you might want to show your proposal to the inspector first.

You seem to be understanding my setup correctly. Yes this section of pipe would have water in it when the standpipe drains. Thanks for explaining the wet vent concept I understand that now.

 

[Ramjam]

First, your WM standpipe should be 2" while the laundry tub can be smaller. EACH of them needs to be vented. In your last picture, neither is...the vent line needs to come off of the trap arm before the drain turns down. You can combine the vents and only still need one to go up, but each trap should be vented separately. Study that picture Terry supplied, and I think you'll see what we're talking about.

In looking at the picture I think I'm starting to get an understanding. SO from where the horizontal pipe is currently, I can install a Y fitting for the sink, and then run pipe horizontally a few inches, then a T going to the stub out and the top of the Tee connecting to the vent? I can then add a second vent on the horizontal line close to the stand pipe and be ok that way?

 

[Ramjam]

You can't dump the kitchen sink from upstairs over the laundry tray and washer.
What you had to start was kind of workable, and then you turned it into something that didn't work at all.
The waste from upstairs comes in "below" any plumbing on the first floor.
The laundry tray trap arm can only have 135 degrees of change before it hits the vent. You have 180 degrees of change. Nope!

Cut the upstairs in near the floor, then add the plumbing for the tray and washer, venting both, not wet venting. By the way, wet venting is for bathroom fixtures on the "same" floor. Venting for the tray and washer uses the previous vent, and can be revented at 42" above the floor, not below that height.

So if I understand this correctly, I basically need to switch where the upstairs drains with where the tray and washer will drain? I also need to add two vents on my horizontal line; one before the laundry tray trap arm (to vent it prior to it turning 180 degress) and then another past this but before the standpipe. Will that be ok?

Out of curiosity, can I ask what the reasoning is as to why the upstairs needs to drain below the downstairs? Just trying to get a grasp of this for the future.

Thanks!

 

[Breplum]

The basic concept of why the upstairs 2" drain is required (Uniform Plumbing Code) to is to prevent a slug of water from acting like a siphon upon the water in the traps and potentially draw/suck out the protection they afford.

 

[Ramjam]

The basic concept of why the upstairs 2" drain is required (Uniform Plumbing Code) to is to prevent a slug of water from acting like a siphon upon the water in the traps and potentially draw/suck out the protection they afford.

I understand your point here and wish I would've thought of that earlier! The fact that my vent connects right above the Y from upstairs wouldn't prevent this I assume?

 

[Jadnashua]

Except in very few, specific situations, once a pipe becomes a drain, it cannot also be a vent. The vent needs to be designed so that it stays dry with no water flowing through it.

 

[Ramjam]

Except in very few, specific situations, once a pipe becomes a drain, it cannot also be a vent. The vent needs to be designed so that it stays dry with no water flowing through it.

Ok, so this vent which is directly above the Y for the upstairs sink is a dedicated vent, no water running through it. Does this help my situation re: It being plumbed in above the washer and laundry tub?