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Discussion Starter · #1 ·
Go easy on me, this is my first plumbing project.

My house is a tri-level, and both bathrooms are on the top floor. The laundry room is on the lowest floor (garage level) and i am going to add a utility sink in the garage. The plumbing for the laundry is inside the wall opposite where the sink will go, so this should not be very difficult.

My first question is regarding this pic: This will be the drain for the sink. It will drop into the 3" horizontal main that slopes to the street.
 

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Discussion Starter · #3 ·
I actually have 3 initial questions:
The 3" horizontal pipe is the "stink pipe" and it takes waste from the upstairs 2 toilets. The point where i would like to cut in and have the drain for the new utility sink is just a few inches downhill and so close to the toilet junctions.

As it is my first time cutting into the 3" pipe (1) i want to be sure this location looks ok, and (2) with a vent going above the utility sink, i will not have sewage comping up into the new fixture. And (3) what can i expect when i start cutting into the 3" pipe? What is best saw for this?
 

· Doing it myself
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Location is fine.

Do you have a sawzall? I like a sawzall with a bi-metal blade, it makes a cleaner cut than a regular wood blade, but you still need to deburr the pipe before gluing. If not any kind of handsaw you have will work. Hacksaw is a little too fine of teeth. Need something coarser than that.

There shouldn't be anything really nasty in that pipe. It looks like it has nice grade. If there is, then you have discovered a problem.

My question : How are you going to get that fitting on there? You have to have some flexibility in the pipe. If you don't have enough, you might have to get a no-hub coupling to make it work.

You could eliminate a fitting there as well if you used a wye instead of a combo, and use one of your 1/8 bends to change to vertical. It's not illegal the way you're doing it, but a bit more expensive.
 

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Discussion Starter · #5 ·
Location is fine.

Do you have a sawzall? I like a sawzall with a bi-metal blade.

There shouldn't be anything really nasty in that pipe. It looks like it has nice grade. If there is, then you have discovered a problem.

My question : How are you going to get that fitting on there? You have to have some flexibility in the pipe. If you don't have enough, you might have to get a no-hub coupling to make it work.

You could eliminate a fitting there as well if you used a wye instead of a combo, and use one of your 1/8 bends to change to vertical. It's not illegal the way you're doing it, but a bit more expensive.
Thanks for the reply!

I will have to get a sawzall, and just manually saw away. I really like the cutoff blade i have in my circular saw for the 1.5" tubes. Too bad i can't use it on the 3".

You asked How am i going to get he fitting on there? Well, if i cut the 3" pipe in the right place, everything appears to line-up. If i did a no-hub coupling, i think it would be best to go with a 1.5" no-hub, and not the 3" ??
 

· Household Handyman
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Unless you will have further need of a Saw-Zall, that's a lot of money spent for just a few cuts on this pipe. They do sell a sort of "hand-saw" for PVC piping, a thin, round blade with handles on both ends. This does work rather well and especially in tight spaces. Actually I've seen one plumber cut 4" PVC with a piece of nylon cord from his plumb bob, using two screwdrivers as handles.
 

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Discussion Starter · #8 ·
Unless you will have further need of a Saw-Zall, that's a lot of money spent for just a few cuts on this pipe. They do sell a sort of "hand-saw" for PVC piping, a thin, round blade with handles on both ends. This does work rather well and especially in tight spaces. Actually I've seen one plumber cut 4" PVC with a piece of nylon cord from his plumb bob, using two screwdrivers as handles.
I've got a half-bath to install too! So i could probably use a sawzall on several other cuts too.

I practiced with a standard hack-saw on 1.5" PVC, and the cut was never straight. It kept walking at an angle, even when i was trying to go slow and follow a line. I think the blase is just to thin and flexible. I think the cut would never be straight on a 3" pvc with the hacksaw.
 

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Discussion Starter · #10 ·
My question : How are you going to get that fitting on there? You have to have some flexibility in the pipe. If you don't have enough, you might have to get a no-hub coupling to make it work.

Alan! I have everything ready to begin cutting the long horizontal 3" pipe. Before cutting, i run through it in my head again. And your comment finally hits me. How much movement can i get out of the big drain pipe, once it's cut, to slip the reducing wye in?

I can remove enough of the hanging support straps to allow movement, but this raises two questions:

1) how much flex in 3" pvc is there in a 10' span? I just need 2 to 3 inches of opposing movement.
2) what is weakest link if i try to flex the pipe too much? a fitting at the end, where it is glued, probably.


So, now as a DIYer, I don't feel very confident about cutting into my house plumbing. I have no idea how much i can move the pipe until i have it cut. Maybe the thing to do is have a coupler ready in-case i can't get the movement and just stop work for the day.
 

· Doing it myself
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Alan! I have everything ready to begin cutting the long horizontal 3" pipe. Before cutting, i run through it in my head again. And your comment finally hits me. How much movement can i get out of the big drain pipe, once it's cut, to slip the reducing wye in?

I can remove enough of the hanging support straps to allow movement, but this raises two questions:

1) how much flex in 3" pvc is there in a 10' span? I just need 2 to 3 inches of opposing movement.
2) what is weakest link if i try to flex the pipe too much? a fitting at the end, where it is glued, probably.


So, now as a DIYer, I don't feel very confident about cutting into my house plumbing. I have no idea how much i can move the pipe until i have it cut. Maybe the thing to do is have a coupler ready in-case i can't get the movement and just stop work for the day.
There you have it! Yes, grab a No-Hub coupling and just plan on using it. It will save you 20 minutes of fight and frustration. You probably won't get enough flex out of PVC. ABS is a bit more forgiving, but I'd normally still use a No-Hub on ABS. :yes:

You need a minimum of 1" sticking out of the fitting for the No-Hub to attach to. Glue your piece into your new fitting, take a measurement, make the cut, put the no-hub on the existing piping, slide the band off the rubber part, further down the existing piping, FOLD THE RUBBER BACK onto itself, Glue, level, fold no-hub back down, tighten the band. Finish plumbing the rest.

:thumbup:
 

· You talking to me?
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I have found that a lot of time rather than separating the cut pipe longitudinally, I lift one of the cut ends and push down on the other, or move them side to side (each one opposite from the other). The side to side often works better. Move them far enough so the opening gains enough length to be able to put the fitting in there at an angle and then push the two cut pipes back into line with each other which shoves them into the fitting at the same time.
 

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Discussion Starter · #15 ·
Well, i decided to go for it... and there was just enough movement in the main tube to allow the combo T to fit.

Here are the completed pics (minus putting the wall back together with screws and spackling). I am also thinking about a plastic back splash to cover the wall area.
 

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· You talking to me?
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I noticed something in your pics. In your 3" line, to the right of where you were working (in the picture perspective), it looks like there is a street 45º (I'm not a plumber so please excuse the possible mistaken name) with some black something where it fits into the Y. Is that a leak?
 

· Just call me Andrew
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I have a similar project coming up in my parents' basement. Just for argument's sake, would it be OK to use the cleanout on the right side of the pic above as the feed for the new drain?

The situation in my parents' house makes it VERY difficult to cut into the 3" PVC, but they do have a cleanout. Could I get a 3x3x1.5" tee, and connect it to the existing female threads (which used to have the cleanout plug) with a 3" male fitting adapter? The other 3" of the tee would have a new cleanout, and the 1.5" would be for the sink.

See terribly drawn pic below:
 

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Discussion Starter · #20 ·
I noticed something in your pics. In your 3" line, to the right of where you were working (in the picture perspective), it looks like there is a street 45º (I'm not a plumber so please excuse the possible mistaken name) with some black something where it fits into the Y. Is that a leak?

Do you mean the red circled pipe in this picture? I think the original plumber touched the pvc with his torch. I wiped some of the black off, its not a leak, and its not melted.
 

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