Long drain pipe with no slope

[wwhitney]

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

Interfacing with galvanized is the difficulty. Best practice when opening up walls would be to replace all galvanized with new plastic pipe. A shielded rubber coupling for galvanized to PVC would give you a little play.

Cheers, Wayne

PS If it's a flat galvanized elbow, then the solution is to tighten/loosen it a little so the threaded entry is not level.

 

[gwills]

Yep, definitely an elbow then straight down into the slab.

I am going to the shop and heating up a piece of 1.25" PVC. That will give me a slope all the way to the vertical pipe.

 

[Sponsor]

 

[wwhitney]

Yep, definitely an elbow then straight down into the slab.

Ah, you can open up the wall and bend the galvanized riser between the slab and the elbow, so the elbow entry is at the correct slope. : - )

Cheers, Wayne

 

[gwills]

I have worked on the remodel of this bathroom for a year. The walls are covered with T&G nickle gap reclaimed oak fence boards. The 2" galvanized pipe does not have any flex since it is set in concrete. I know because I tried to move it when the wall was open. Cutting open the wall is not a palatable option. The room will be done after I get this drain working and the toilet set.

 

[gwills]

I guess that even 2" pipe can be bent with a big enough lever! Firing up my heat gun....

 

[Reach4]

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.

So you have an elbow making the transition from horizontal to vertical? Any chance of changing that angle a degree or two? Most elegant.

If the elbow is fixed, bending the pipe near the elbow seems next-most elegant and functional.

Pulling that pipe out of the hole would make it easy to raise the top of the hole. You could probably use a hand rasp quicker than you could assemble the power tools, and make up guides to position a hole saw.

 

[wwhitney]

The 2" galvanized pipe does not have any flex since it is set in concrete.

To be clear, the : - ) meant I was joking. At this point, I like putting a male adapter on a piece of pipe that already has a small bend in it.

Cheers, Wayne

 

[gwills]

Reach4,

Yes. No.
On my way to Lowes to get 1.25" pipe and fittings. Since the hole is sized for 1.5", I should have enough room for the slope if I use 1.25" pipe.
My plan is to heat up the pipe and give it a little bend. Not too much that I can't screw it into the elbow inside of the wall. Then attach a T about 4" from the inside of the cabinet then another piece of 1.25" PVC will connect the T to the P Trap.

Wayne,

I am glad that you were joking! I will put a bucket under the sink before I cut open the wall. I will make sure that I get a DWV T this time!!

Gene

 

[Reach4]

To be clear, the : - ) meant I was joking. At this point, I like putting a male adapter on a piece of pipe that already has a small bend in it.

Clearly that requires a bigger hole, and special attention to install. I would fear crossthreading. If you tried that, you would use the hole saw, and first saw a hole in another piece that will serve as a guide to keep the hole saw in place.

 

[wwhitney]

On my way to Lowes to get 1.25" pipe and fittings. Since the hole is sized for 1.5", I should have enough room for the slope if I use 1.25" pipe.
My plan is to heat up the pipe and give it a little bend. Not too much that I can't screw it into the elbow inside of the wall.

Right, if the elbow face is 6" from the inside vanity face (you didn't specify the setback from elbow face to stud face), then you want 1/8" of rise over 6". So by reducing your pipe size by 1/4" (0.24" in OD), if you bend 1/8" over 6" into the pipe, as you rotate the male adapter into the elbow, the pipe should orbit around your existing hole at the same hole edge clearance as the 1-1/2" pipe in your OP.

Cheers, Wayne

 

[gwills]

Wayne,

Agreed. I have to order the 1.25" fittings from SupplyHouse because none of the DIY stores have the fittings.
I feel good that this approach will work.
Thanks for helping me work through the options.

Gene

 

[James Henry]

I wouldn't change that pipe size to 1-1/4". If you can get 1/8" per foot fall by strapping the pipe to the underside of the cabinet that should work fine. The only thing going down that drain is soapy water. Your choking off the drain when you down size.

 

[Reach4]

On my way to Lowes to get 1.25" pipe and fittings. Since the hole is sized for 1.5", I should have enough room for the slope if I use 1.25" pipe.

That hole is in wood, and not porcelain tile, right?

 

[gwills]

Reach4,

Correct. There is 2.75" between the inside face of the cabinet and the face of the elbow.

James,

I could probably get 3/8" over the 36" span but I would have to put the pipe under tension with a pipe strap. There isn't much flex in 36" of sch 40 PVC. Do you really think that I am going to cause a problem if I use 1.25" pipe which is standard for bathroom sinks?

I could heat and bend the 1.5" PVC pipe about 4" out from the face of the drain elbow but that would leave 4" of pipe with no slope. By using 1.25" pipe, I have room to slope the pipe all the way to the elbow in the wall. Am I splitting hairs?

Gene

 

[wwhitney]

I could heat and bend the 1.5" PVC pipe about 4" out from the face of the drain elbow but that would leave 4" of pipe with no slope. By using 1.25" pipe, I have room to slope the pipe all the way to the elbow in the wall. Am I splitting hairs?

Your plan for 1-1/4" pipe, you can do the same thing with 1-1/2" pipe, you just have to enlarge your holes by 1/4" in diameter.

Cheers, Wayne

 

[gwills]

True but I would have to enlarge the hole.

Finding all of the 1.25" parts was a challenge but I was able to locate them at Ferguson's.

 

[James Henry]

1-1/2", 1/8" per foot. Fast draining with no clogs.

 

[Reach4]

Correct. There is 2.75" between the inside face of the cabinet and the face of the elbow.

Holes in thin wood are easy to enlarge.

Before deciding to go 1-1/4, select the fittings to match-- including a trap adapter.

 

[gwills]

True and I have a complete woodworking shop but I also know that things can go wrong when drilling a big hole with a hole saw. Why take a chance of messing up custom cabinets.

Would 4" of 1.5" pipe with no slope be better or worse than using 1.25" pipe with a continuous slope?

 

[Reach4]

True and I have a complete woodworking shop but I also know that things can go wrong when drilling a big hole with a hole saw. Why take a chance of messing up custom cabinets.

A hand rasp can elongate that hole upward in two minutes. An escutcheon can hide the hole. A power tool can mess things up in 3 seconds.