A DWV Question That Puzzles Me

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Bird Doo Head

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Jan 11, 2010
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Hi Everyone
I'm new at this forum and am not certain if I am in the correct area, or if this question belongs in Tubs & Showers. Please pardon me if I'm incorrect.
I tried to keep the post short, but wanted to give you professionals as many details as I could think of.

My situation is that we have an elderly resident in our home who can no longer get into the 1st floor bathtub, as it is a 4 foot Kohler Greek & the apron is high. Since the room has space, my (genius?) plan was to put in a low curb shower stall next to the tub, as I want to keep the tub. Alternatively, I will "pan & pitch" the room and make the entire space a shower.

The DWV arrangement has me questioning my idea:

EXISTING SET-UP:
Existing, in the basement below the bathroom, there is a 3" stack with a "tree".
A) Into the top branch is a 2" line which goes up, catches a 1 1/2" line with a 1 1/4" lavatory. From there, it ties to the VTR above the first floor.
(3"- Becoming 4" 18" below the roof.)
B) Into the "Side" branch is a 3" line to a 3x4 closet bend for that bathroom's toilet. The length is 60" from CL Bend to CL Stack.
C) Into the "Front" branch is a 1 1/2" pipe (30" long) going to (wye facing almost vertical) a 1 1/2" trap for the existing bathtub. There is a clean out at the end of the wye.
D) Into the bottom, 3" extends below the basement floor to a Wye & 1/8 Bend which enters a 4" line to the street. There is a clean out before it enters the concrete. The only things after the stack on the main building drain line are a clean out, a building trap, (old house) and a tie in for the weep tiles around the footings and criss crossed under the basement floor (really old house)

THE GRAND PLAN:
Replace the 1 1/2" to the tub with 2" (The tree's branch socket is 2")
Replace the clean out at the end with a 2" and keep 1 1/2" to the tub (tub-shower would be more correct).
Tie the new shower, with a 2" P Trap because it is a shower, into the new 2" somewhere between the tub and the stack. The length of this from the trap to the stack will only be about 24". I can't make it much longer. I would make the connection with a wye and 1/8 bend into the side of the existing pipe.

I can't enter the stack below the tree because the pipe would be in the way of built in cabinets (or are the cabinetsin the pipe's way?) I also can't realistically make a new tap to the below-floor line, as more built in cabinets are in the way. I do have a clean-out for the main line about 3 horizontal feet and 7 vertical feet from the proposed new shower drain. It is 4", but is not vented.

SIX MILLION QUESTIONS ABOUT THE PLAN:
Does this sound proper?
Does it sound like it would work, or when the tub is emptied, will it back up into the shower pan?
Should I reverse the tap order on the 2" and put the shower in first, tub in after the shower (tub closer to stack)?
Should I re-vent the new shower drain line? Is it close enough to the tree to eliminate the need for a re-vent?
Venting will be quite a challenge, as all the walls are finished on its way to the stack. (Of Course!) Also, there is no way to run it above the flood rim before it has to go horizontal- The drain will be 2' into the room and there is no wall above before the stack.
I possibly could install an AAV in the wall of the bathroom, above the flood rim of the shower, with minimal damage. (Assuming it would get enough air inside the wall. I could leave an access plate for service.) But, the pipe to it would travel horizontally before it could go vertical. (Again, no wall between the stack and the trap.)

Side Note: The vent on this stack actually travels horizontally about 18" before it goes "up". I think it is called a "wet vent" because of the lav that drains into it.

What do all of you think? Sadly, the budget doesn't allow for a professional plumber to do the work. The house is too small for another shower room. (We tried to figure this out. We even considered a tub lift, but the person can't process information well enough to operate one. Assisting her in and out takes some more of her dignity away. Step in shower sounds like the answer until the next down-turn.

Is this a hopeless conundrum? I really hate to remove the tub in that room. I don't fit, but my wife sure enjoys it!

I wish I could photograph the tree and attach it, but that would require a trip to a computer forum and a camera forum. I can sketch it as CAD if it helps. (Only if someone can tell me how to attach a pdf to a post. I'm over the age limit for learning to much on computers!)

Again, I want to thank you all for your help in keeping this person living in our home as long as possible. A shower is one giant step in maintaining a little piece of what is left of her independence!

Paul
 
I just joined the forum about 20 min ago. Let's see if I can help.


Hi Everyone

EXISTING SET-UP:
Existing, in the basement below the bathroom, there is a 3" stack with a "tree".
A) Into the top branch is a 2" line which goes up, catches a 1 1/2" line with a 1 1/4" lavatory. From there, it ties to the VTR above the first floor. (3"- Becoming 4" 18" below the roof.)

Let's try and clarify what you have.Do you have cast iron pipe with hubs and lead joints or is it DWV Copper. Is the side branch for the toilet the same fitting as the front branch. The 2" line is on top of the 3" tee going up through the floor. this would be the vent.
B) Into the "Side" branch is a 3" line to a 3x4 closet bend for that bathroom's toilet. The length is 60" from CL Bend to CL Stack.
C) Into the "Front" branch is a 1 1/2" pipe (30" long) going to (wye facing almost vertical) a 1 1/2" trap for the existing bathtub. There is a clean out at the end of the wye.
D) Into the bottom, 3" extends below the basement floor to a Wye & 1/8 Bend which enters a 4" line to the street. There is a clean out before it enters the concrete. The only things after the stack on the main building drain line are a clean out, a building trap, (old house) and a tie in for the weep tiles around the footings and criss crossed under the basement floor (really old house)

THE GRAND PLAN:
Replace the 1 1/2" to the tub with 2" (The tree's branch socket is 2")
Replace the clean out at the end with a 2" and keep 1 1/2" to the tub (tub-shower would be more correct).
Tie the new shower, with a 2" P Trap because it is a shower, into the new 2" somewhere between the tub and the stack. The length of this from the trap to the stack will only be about 24". I can't make it much longer. I would make the connection with a wye and 1/8 bend into the side of the existing pipe. Should work Okay But you will need a vent just after the new P-trap

I can't enter the stack below the tree because the pipe would be in the way of built in cabinets (or are the cabinetsin the pipe's way?) I also can't realistically make a new tap to the below-floor line, as more built in cabinets are in the way. I do have a clean-out for the main line about 3 horizontal feet and 7 vertical feet from the proposed new shower drain. It is 4", but is not vented.

SIX MILLION QUESTIONS ABOUT THE PLAN:
Does this sound proper?
Does it sound like it would work, or when the tub is emptied, will it back up into the shower pan? NOT unless the tub is lower than the showerShould I reverse the tap order on the 2" and put the shower in first, tub in after the shower (tub closer to stack)? NO
Should I re-vent the new shower drain line? Is it close enough to the tree to eliminate the need for a re-vent?
Venting will be quite a challenge, as all the walls are finished on its way to the stack. (Of Course!) Also, there is no way to run it above the flood rim before it has to go horizontal- The drain will be 2' into the room and there is no wall above before the stack.
I possibly could install an AAV in the wall of the bathroom, above the flood rim of the shower, with minimal damage. (Assuming it would get enough air inside the wall. I could leave an access plate for service.) But, the pipe to it would travel horizontally before it could go vertical. (Again, no wall between the stack and the trap.)

Side Note: The vent on this stack actually travels horizontally about 18" before it goes "up". I think it is called a "wet vent" because of the lav that drains into it.

What do all of you think? Sadly, the budget doesn't allow for a professional plumber to do the work. The house is too small for another shower room. (We tried to figure this out. We even considered a tub lift, but the person can't process information well enough to operate one. Assisting her in and out takes some more of her dignity away. Step in shower sounds like the answer until the next down-turn.

Is this a hopeless conundrum? I really hate to remove the tub in that room. I don't fit, but my wife sure enjoys it!

I wish I could photograph the tree and attach it, but that would require a trip to a computer forum and a camera forum. I can sketch it as CAD if it helps. (Only if someone can tell me how to attach a pdf to a post. I'm over the age limit for learning to much on computers!)

Again, I want to thank you all for your help in keeping this person living in our home as long as possible. A shower is one giant step in maintaining a little piece of what is left of her independence!

Paul


If I read this right, the 1 1/2" tub drain goes turns up into wall with a wye and picks up p-trap on a santee and continues up as a vent.
If you increase the 1 1/2" line to the stack you can add a wye fitting lying on it's side to the 2" to pick up the shower. ( believe this was what you had in mind) But you have to add a vent after the new p-trap.

If you can change the santee (where the tub p-trap connects) to a "double santee". You can use the same vent. 2" shower one side and 1 1/2" tub on the other side
 
Last edited:
Thanks for your response, Kilroy.
I think I didn't explain too well. The stack plumbing and tree are PVC, so when I say "change to 2"" I guess I mean cut it all out and replace, as the reducing bushing is glued in.

The top of the stack (I call it a tree) has just two side lines coming out: One is 3" to the toilet and one is 2" (reduced to 1 1/2) to the tub. The tub goes from trap to the stack. It doesn't go up the wall.

The top of the stack fitting is bushed down to 2" and goes up the wall. It picks up the lav with a 1 1/2" santee (lav trap is 1 1/4"). After the lav is picked up, the 2" keeps going up, eventually changing to 3", then 4" and through the roof.

You mentioned venting the new trap. Am I correct that the vent can not go horizontal unless it is 6" above the flood rim of the shower? If that's the case, I'm in trouble! The line form the new shower wouldn't pass under a wall on its way tot he stack. (The stack isn't under a wall either. Its vent goes horizontal for 18" to the nearest wall to go up.

If I can figure out how to get a vent to a wall, should it tie into the existing vent above or below the lav which empties in to the vent now? I'm guessing above and don't re-vent the lav?

Thanks Again!
Paul
 
Thanks for your response, Kilroy.
I think I didn't explain too well. The stack plumbing and tree are PVC, so when I say "change to 2"" I guess I mean cut it all out and replace, as the reducing bushing is glued in.

The top of the stack (I call it a tree) has just two side lines coming out: One is 3" to the toilet and one is 2" (reduced to 1 1/2) to the tub. The tub goes from trap to the stack. It doesn't go up the wall.

The top of the stack fitting is bushed down to 2" and goes up the wall. It picks up the lav with a 1 1/2" santee (lav trap is 1 1/4"). After the lav is picked up, the 2" keeps going up, eventually changing to 3", then 4" and through the roof.

You mentioned venting the new trap. Am I correct that the vent can not go horizontal unless it is 6" above the flood rim of the shower? If that's the case, I'm in trouble! The line form the new shower wouldn't pass under a wall on its way tot he stack. (The stack isn't under a wall either. Its vent goes horizontal for 18" to the nearest wall to go up.

If I can figure out how to get a vent to a wall, should it tie into the existing vent above or below the lav which empties in to the vent now? I'm guessing above and don't re-vent the lav?

Thanks Again!
Paul

That makes more sense.The tub p-trap arm goes directly into the stack The 2" going up w/ an 18' offset to wall is the vent. the lav drain connects to the vent making the vent for the toilet and tub a wet vent.
The 1-1/2 " from the tub p-trap is a trap arm until it connects to a vent.
You can't put 2 p-traps on one trap arm.

Good luck
 
Great Information!
Thanks very much.
It's off to Plan B (What ever that will be!)
Paul
 
Consider swapping out the tub with a tub that has a door on the side. They are available from a variety of manufacturers and they are referred to as walk-in tubs. However, make sure there is a single handle faucet on the tub/shower controls with a maximum temperature limit stop to prevent scalding conforning to ASSE 1016 or provide an ASSE 1070 compliant temperature limiting in-line mixing valve on the hot water line to that fixture to mix CW with the HW and limit the hot water temperature to a maximum of 120 degrees F or whatever temperature below 120 you feel safe with, comming from the tub spout to prevent scalding.

Caution: I am aware of many of the walk-in tub manufacturers that sell the tub with a non-code compliant two-handle tub filler valves.
I have been an expert in litigation where elderly people receive horrible scald burns after turning off the cold water before the hot water when the hand held shower was still spraying. Its not a pretty sight.

I like the whirlpool tubs and bathtubs with gasketed doors they provide elederly persons with access to the tub and they can connect to existing plumbing. (just make sure there is a thermal limiting faucet or temperature limiting mixing valve)
 
Thanks to you both for the information & helpful ideas.
Regarding the walk-in shower, we are actually looking in that direction. Our problems, so far, are space in the room (tub would have to go) and lifting of feet. I do, however, think we will still consider that option.

Thanks, too, for making absolutely certain I knew to put in a safe, anti scald valve. I changed my father's shower valve to one when I re-tiled his shower. I didn't mention it, but he noticed and thanked me. As he aged and his mind slowed down, he mentioned that he would scald himself before he remembered to turn down the temp. Thank Goodness for those items!

Funny story: When I was working on my dad's shower, I'd drive there after work (about an hour) and work as late as I could each evening- say 12 or 1 am. then I'd drive 1 1/2 hours home. Well, the day I sweat in the valve, I decided to test it before I left for the night. I turned on the hot line shut off valve. Checked the shower...Nothing! Hmmm... What could it be? I took the new shower valve apart- No problems there. I tried everything I could think of until I decided I must have put so much solder I plugged the inlet. So I un-sweat the thing, opened the shut off & had full flow. I was stumped. Now, it was past 3 am & I had a long drive home & had to be at work at 8am. I decided to think about it tomorrow. In the middle of my short night' sleep it came to me: Anti scald valve, right? I tested the hot side, but the cold shut off was still off. Of course water wouldn't flow! The next night, I tested the valve with BOTH shut off valves open. It worked like a champ! That, my friends, is what happens when an electrician tries to be plumber!
 
Can someone suggest a good manufacturer of these walk-in tubs? This would also work for kids' baths, right?
 
tthe problem with a walk in tub is that when done using the tub the occupant must wait for the tub to completelly drain and often elderly people complain about getting cold when they are waiting for the tub to drain.
 

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