View Full Version : 3" copper - Moving toilet

10-07-2009, 06:34 PM
House built in 1972. Concrete throughout - walls and all floors. Owner/builder was in the military. Wanted to be safe I guess.
Copper throughout; drain and vent lines.
Bottom pic: is the overall project area. Toilet A is area in question.
Upper left pic: Proposal - right red box is coupling, left red box is DWV Y, black box is ABS line for new toilet location
Upper right pic: Toilet A, to be moved and capped

Question one:
Is it worth it to remove a 15' 3" copper vent, scrap it and replace with ABS? I have complete access to the vent line right now. What about replacing the rest of the copper with ABS and scraping the copper? Is there a chart as to how much elbows, unions, etc weigh?

Question two:
I am moving a toilet line 6 feet. Do I need to add a vent? What is the best way of joining the new 3" toilet line? I was thinking of using:

a) 3" Cast Copper DWV Y, attach a small section of 3" copper pipe and then add a rubber boot to attach to ABS

b) 3" Cast Copper DWV Y, attach a small section of 3" copper pipe, attach
3" Copper DWV Male Adapter, screw on Female ABS adapter

I understand that "b" will be more expensive, but I do not want any leaks as there will be computers (home office) below all that plumbing.

Question 3:
How do I physically add the 3" Cast Copper DWV Y into the main line. I do not have any way of moving the main line left or right. Would I cut out the existing line a little longer and add a coupling to the setup?

Question 4:
Should I prepare to use an oxy/acetylene setup as apposed to the standard propane torch? Lotta copper there..

Thank you all for the help!

10-07-2009, 11:21 PM
The existing plumbing looks a little sketchy. Looks like the sinks and tub/showers drain into the trap arms of the toilets? Anyways, Here's some ideas:
1) Venting: The closet flange needs to be within 6' (developed length) of the vent. I would put a 3"x2" combo on your new branch, before the closet bend, and go up into the wall upstairs and tie it into the existing vent.

2) For joining the copper to the ABS, use the no hub shielded coupling (mission band ck33?). They are reliable enough to be used in all cast iron systems. If you use the ABS male adaptor, the threads on the adaptor will be you weak spot and will tend to crack if there's movement or stress put on the pipe.

3) As for cutting in a copper wye, you may want to use two couplings. One at each end. Prefab your wye with the pipe coming out of each end then put your couplings on the existing pipe and push them all the way on past the stops ( you can flatten the stops with a hammer or use repair couplings). Then simply put your prefabbed wye in place and slide the couplings over you r pipe. You may want to mark the pipe so you know when the coupling is equally over each side.

4) Propane is o.k. although you can use MAPP gas which burns hotter and comes in the same small cannisters as propane.


10-08-2009, 06:06 AM
Without going through each of your proposed options, let's cut to the chase and say you cannot do ANY of them without major revision to the existing piping.
1. A "Y" or "combo" will NOT take the place of the elbow, so it will not be a simple replacement.
2. IF you extend the pipe to the new location, you disrupt the existing venting for toilet "A" and therefore it will need a NEW vent.
3. You may be able to unsolder the pieces, but unless you have room to move them they will not come apart.
4. If you use a MAPP gas torch you will probably need two of them to keep the entire joint hot while you take it apart. I have a "staghorn" multiburner tip for my acetylene torch to heat the entire joint at one time, instead of trying to move it around and get everything hot.

10-08-2009, 07:23 AM
I added an updated pic with the 3" vent noted. The vent is in between the toilet A and B lines. The copper cast has 4-3" and 1-1.5" lines.

What is a 3"x2" combo?

When you say "before the closet bend" do you mean the side further from the closet flange?

Is the "no hub shielded coupling" the one with a metal band around the entire rubber section?

Your #3 That's exactly what I was going to do minus the second coupling. I wanted to minimize the amount of solder connections. Now that I think about it, I will have to add the second coupling. Good catch!

I was planning on do all the work with the elbow in place. I know that would be near impossible to get it out and add the wye

Thank you both for your assistance as well as your time and knowledge!

10-08-2009, 08:48 AM
What is a 3"x2" combo?
It, or a Y and 1/8 bend, are the only fittings which would replace that elbow

When you say "before the closet bend" do you mean the side further from the closet flange?

Between the toilet and the new Y.

Is the "no hub shielded coupling" the one with a metal band around the entire rubber section?

A "No-Hub" coupling will NOT work with copper tubing. It would have to be a "BandSeal", or a similar transition coupling, sized for copper tubing and/or whatever the other material would be.

I was planning on do all the work with the elbow in place. I know that would be near impossible to get it out and add the wye

That only changes using a combo in place of the elbow. The new toilet "A" would still be unvented and need its own vent.

The only other undesirable thing about your project is that, because you have a cross, rather than a figure 5 back to back fitting, between the two toilets, debris from toilet "B" is going to splash into the abandoned branch for toilet "A", and since there will no longer be periodic flushing to clear it out, it will tend to accumulate in the dead pipe. That material could eventually cause corrosion of the copper as it deterioriates.

10-08-2009, 09:15 AM

Old location of toliet "A":
I can get a 3" to 1 1/2" adapter and put a sink line there. I was planning on adding a double sink (currently there is one sink). That will address the issue of the stagnant waste that might come from toilet "B". Once again great catch on your part!

Is there a difference in sizing on a standard 3" line/couplings and Copper Drain-Waste-Vent Fittings (DWV)?

10-08-2009, 09:18 AM
Could I tie the new toilet vent with a sink vent line? 1.5 "

10-08-2009, 09:09 PM
1) The toilet vent must be two inch diameter. That's why you'll use the 3"x2" combo and run your vent off the 2" branch. The combo is just a 3x3x2 wye with a 1/8 bend (45 degree) included on the 2" side. Combo is short for "wye combination". It looks like a tee with a long sweeping 2" branch.

2) Pipe sizes: The pipe sizes are called for their inside diameters which are equal. The different sizes you need to worry about for your transition band is the outside diameter... Copper has a very thin wall and the abs has a thick (1/4") wall. So the coupling will be thicker on one end (for copper) and thinner on the other end (for ABS).

3) HJ is right about that double san tee between the two existing toilets. That existing plumbing was obviously not inspected.

Good Luck.


10-08-2009, 09:36 PM

Thank you for your knowledge. I will be getting all my information together to pull a permit. Do you see me having an issue with the original plumbing as far as passing inspection?

10-09-2009, 11:40 AM
whatever is existing, should have nothing to do with whatever you add. DWV copper fittings are much thinner than pressure ones, and the "socket" is much shallower, so it does not take as much solder or heat to make the joint. You can also "bend" the joint slightly for alignment purposes.