Long drain pipe with no slope

[gwills]

I am installing a one piece bathroom counter/sink. This is a remodel and the existing iron pipe is in the wall that is 36" to the left of the sink tail piece. A studor valve will provide make-up air. My original plan was to run 1.5" sch 40 PVC from the elbow on the iron pipe to a T with a AAV and another piece of PVC that will terminate in a 1.5 x 1.25 metal P trap. A 12" tail piece should be long enough for the proper 1/4" slope. The problem is that the 1.5" PVC is dead level. What is the best way to get the required slope?

Thank you in advance for any advice.

Gene

 

[Reach4]

I am thinking to cut the tailpiece about 1 inch shorter-- 1/4 inch fall from the tailpiece to the wall, and another 3/4 to go 3 ft left to the steel pipe. If there is a pvc pipe that is dead level, change that to get the right slope.

If that is not the kind of answer you were thinking of, how about a photo or a sketch?

Depending what is off to the left, you may not need an AAV. If you do need an AAV, there may be an easy way.

 

[Sponsor]

 

[Jeff H Young]

it should be apparant but basicaly raise it to where it has fall. it may require removing a strap. removing the pipe and notching out one or 2 studs if the holes were drilled level as opposed to having fall. but you dont describe it very well. pretty easy stuff

 

[gwills]

I am thinking to cut the tailpiece about 1 inch shorter-- 1/4 inch fall from the tailpiece to the wall, and another 3/4 to go 3 ft left to the steel pipe. If there is a pvc pipe that is dead level, change that to get the right slope.

If that is not the kind of answer you were thinking of, how about a photo or a sketch?

Depending what is off to the left, you may not need an AAV. If you do need an AAV, there may be an easy way.

I am attaching a couple of photos that may do a better job of explaining the issue. I know that the photo shows that the trap is too high but I plan on getting a longer tail piece so that the trap and drain pipe line up. I could hang a support strap in the cabinet but I would need to put a lot of upward pressure on the 36" run of drain pipe.

 

[wwhitney]

So, are you at a point where you can pull out the vanity without a huge hassle? If so, take a look at what's in the wall and see how you can adjust/wedge the pipe coming out to be at 2% slope, rather than level. You'll have to enlarge the hole at the vanity for the pipe to accommodate the higher elevation at the plane of the vanity side wall, but an escutcheon should cover it.

If not, carefully enlarge the hole at the top while the pipe is still in place. Wedge the pipe upwards against the bottom of the hole. If you can't get the full slope you need this way without excess stress on the pipe, then cut the pipe about 4" from the hole, and glue in a coupling. The coupling should give you a little play so you can "kink" the connection upwards as you make up the joint and get the right slope. [Or just glue on a trap adapter and switch to tubular, I expect that the tubular compression joint would accommodate the required "kink"]

BTW, what is up with the tee on the end of the pipe? That style of tee is not for use with drains.

Cheers, Wayne

 

[gwills]

Wayne,

Thank you for the reply. I really appreciate your taking time to share your experience.

The walls are finished and the galvanized pipe is set in a concrete slab so moving the pipe would be difficult.

What about heating the PVC and pushing it up to a 2% slope? Or, how about moving the T closer to the wall and using it to get enough flex for the slope?

The T is for the AAV. Should I have used one with a sweep towards the drain or T’ed off of the tail piece instead of the drain pipe? Is there a better configuration?

There isn’t any vent pipe connected to the galvanized pipe in the wall and the existing vent pipe does not supply enough air when the Kohler toilet is flushed on the second floor. The Kohler flushes all of the water in one big swoosh which sucks the water out of the traps. I didn’t have this issue with other toilets and I plan on replacing it with the next remodel.


Gene

 

[gwills]

Wayne,

I understand your point about the T, I will get one with a sweep. Thanks for pointing out my oversight.

 

[Reach4]

I understand your point about the T, I will get one with a sweep. Thanks for pointing out my oversight.

Usually you are better to put a trap adapter near the sink area, and use slip joint drain parts. Those are much easier to adjust and get right than are glued pieces.

 

[gwills]

Reach4,

Are you suggesting that I put the T for the AAV close to the wall and then use slip joints the rest of the distance (about 24") to the trap?

 

[wwhitney]

You can get an AAV for tubular, I believe Magic Trap is one that Reach4 often points to. I suggest putting the trap adapter 2" - 4" from the sidewall and doing everything else inside the cabinet in tubular.

Cheers, Wayne

 

[gwills]

Wayne,

I guess that heating the PVC pipe was a "no go"?
I understand your recommendation. Thanks again for your help.

Gene

 

[Reach4]

Are you suggesting that I put the T for the AAV close to the wall and then use slip joints the rest of the distance (about 24") to the trap?

I was not thinking about the AAV. I don't know that you need one, but an extra will not hurt.

You can get an AAV for tubular, I believe Magic Trap is one that Reach4 often points to. I suggest putting the trap adapter 2" - 4" from the sidewall and doing everything else inside the cabinet in tubular.

If not raising the pipe behind the wall by removing some wood above the pipe, putting a santee (PA is on IPC) on its back a few inches from the wood would give two joints to try to raise the pipe trajectory a degree or two. I don't know how well that idea works. The AAV would go on top. Then I would run pvc horizontally and strap it up. Near the drain area, I would glue the trap adapter.

Use a long string of slip joint extensions? I don't know. I guess it would be easier to get the slope. I would need hangers across.

If I used the Rectorseal Magic Trap, I would still want the trap adapter close enough to the drain area, and support the pipe on its slope. The slip joints shine when trying to change angle and lengths to make a trap align with a tailpiece.

Rectorseal 97402 Magic Trap with the Rectorseal 97400 AAV. .
https://rectorseal.com/product/magic-trap/

 

[Reach4]

I guess that heating the PVC pipe was a "no go"?
I understand your recommendation. Thanks again for your help.

Maybe. Not official. Nobody is likely to notice if you don't discolor the plastic or bend it a lot. But it is not going to help the section behind the wood. I am not a pro.

If there is no story above, the connection in the wall may be a sanitary tee with a proper vent, and you could get the pipe slope corrected. In that case, an AAV would be superfluous.

What tool would let you remove a bit of wood with access to one side only? 1/16 could be enough if the santee is nearby, which seems probable. A multitool could plunge cut, but would remove more wood than needed. Exacto knife would be tedious.

 

[gwills]

Reach4,

I gutted the room and rebuilt the walls, ceiling and floor so I know for sure that there is no vent. I have a lot of practice heating PVC for conduit so I think that I could do a nice job but I agree it is not a prescribed solution.

It is starting to feel like the best approach is to put the AAV T close to the wall (36" from the tail piece) then use a trap adapter to allow for some play in the tubular that connects to the trap. I have not been able to find tubular in lengths greater than 24" so I will have to make up the other 12" with PVC and the AAV T. Does this make sense?

 

[wwhitney]

What tool would let you remove a bit of wood with access to one side only? 1/16 could be enough if the santee is nearby, which seems probable. A multitool could plunge cut, but would remove more wood than needed. Exacto knife would be tedious.

- Get escutcheon, slip over pipe, trace outline
- Bear in mind that with the pipe raised, the escutcheon will be raised, too
- Get metal half pipe shield, slip between plastic and wood to protect plastic pipe.
- Use narrow blade in oscillating tool, narrow minimizes overcutting. Enlarge hole to allow pipe to move up to 1/8" upward
- Shim pipe as required, cut shims flush
- Install escutcheon

Cheers, Wayne

 

[wwhitney]

I gutted the room and rebuilt the walls, ceiling and floor so I know for sure that there is no vent. I have a lot of practice heating PVC for conduit so I think that I could do a nice job but I agree it is not a prescribed solution.

So what is the connection to the galvanized stack?

If it's a threaded connection (PVC male adapter into a thread tee on the stack), can you unscrew the connection, pull out the pipe, enlarge the hole a little, and screw in a new pipe where you've glued the male adapter on slightly cocked so that the pipe end up with the slope you need?

That might be all doable within the access area covered by a standard escutcheon, but it is also worth considering cutting a large access if necessary. You could make up a wood access panel that covers your access hole and screws the remainder of the plywood vanity side.

Cheers, Wayne

 

[gwills]

Wayne,

The 1.5" PVC pipe has a male adapter glued to the end in the wall so I can easily unscrew the PVC pipe. It would probably be easier to switch to 1.25" pipe, glue on a male adapter and screw it into the galvanized elbow.

How do I get the proper slope without putting a strap on the pipe and forcing it upward?

The wall is 1/2" drywall covered with 3/4" oak boards. The interior of the cabinet is 1.5" away from the exterior of the wall so that adds up to 2.75" between the galvanized elbow and the inside of the cabinet. Not sure that I could ever get the proper slope on the last 3-4" of the drain pipe before it enters the vertical drain pipe.

 

[gwills]

How do I cock a PVC connection? If the pipe is fully inserted into the male adapter there is no play.

 

[wwhitney]

The 1.5" PVC pipe has a male adapter glued to the end in the wall so I can easily unscrew the PVC pipe. It would probably be easier to switch to 1.25" pipe, glue on a male adapter and screw it into the galvanized elbow.

Elbow? Not tee? A non-flat elbow means you you definitely need an AAV. And if it's a flat galvanized elbow, does it have the proper sweep?

How do I cock a PVC connection? If the pipe is fully inserted into the male adapter there is no play.

Well, my experience is much more with ABS than PVC, with ABS you can get a little play. You may not be able to get any play dry fitting, but the solvent cement should increase the play. You'd need to be able to get a good handle on the male adapter, maybe thread on a temporary coupling and extension.

If that doesn't work or isn't sufficient, and your threaded entry is dead level, I like the idea of heat bending. Or even better, go to a supply store and find a piece of PVC pipe that already has a little bend in it, and use the existing bend strategically.

Cheers, Wayne

 

[gwills]

I have to be making this harder than it needs to be.