Removing cast iron bathtub trap

[Ralph Vart]

I am installing a new bathtub. I don't think the existing cast iron trap is set right to fit the tub drain, so I want to remove it and put in an ABS trap with a flexible couple. The 1 1/2 inch cast iron trap is attached to a horizontal cast iron pipe. It looks like it has lead in the joint. I have read in a few places that a map gas torch will not get hot enough to melt the lead, but I don't understand that. The lead melts around 600 degrees and the torch is a few thousand degrees. Can I just heat up the hub on the trap for 15 minutes until the lead runs out into the pit under where the tub will go and hammer the trap out? Thanks very much for any advice you have.
Ralph

 

[Terry]

The lead is removed by using several drill bits, bits you don't mind breaking, and a flat blade screwdriver that can pry the rest of the lead out. Sometimes with 1.5" going into the 2" hub you can almost wiggle it out anyway.

Yes we have tried torches. I'm not recommending you do. Kind of a waste of time to try melting the lead. But then sometimes the best lessons in life are the mistakes we make. I think every plumber has tried using a torch at some point.

The lead and the oakum pulled out of the hub.
A new Fernco insert that took 2" pipe.

 

[Sponsor]

 

[Ralph Vart]

The lead is removed by using several drill bits, bits you don't mind breaking, and a flat blade screwdriver that can pry the rest of the lead out. Sometimes with 1.5" going into the 2" hub you can almost wiggle it out anyway.

Yes we have tried torches. I'm not recommending you do. Kind of a waste of time to try melting the lead. But then sometimes the best lessons in life are the mistakes we make. I think every plumber has tried using a torch at some point.

The lead and the oakum pulled out of the hub.
A new Fernco insert that took 2" pipe.

Thanks very much for the reply Terry. My setup is a little bit different. I posted a photo. I could cut the pipe right at the trap hub, but I though it might be useful to preserve as much of the pipe as possible so that we have flexibility to make the new connection.

 

[Terry]

I normally cut the pipe leading to the p-trap, using a shielded coupling, which comes in various sizing for the different pipes. Pipes from different years can be sized differently.
Diablo makes a nice sawzall blade for cutting cast.
No plumber is a fan of the flex that is showing up in home centers. I've never even thought about showing an inspector something like that. Solid piping is the way to go, especially when snaking.

 

[Ralph Vart]

I normally cut the pipe leading to the p-trap, using a shielded coupling, which comes in various sizing for the different pipes. Pipes from different years can be sized differently.
Diablo makes a nice sawzall blade for cutting cast.
No plumber is a fan of the flex that is showing up in home centers. I've never even thought about showing an inspector something like that. Solid piping is the way to go, especially when snaking.

Terry,
Again thanks. I misspoke about using flexible connection. I meant a shielded coupling that would connect the 1.5" cast iron pipe to a 1.5" ABS pipe that would then go into an ABS trap.

 

[Ralph Vart]

Can I ask one follow up question. I am going to have the tub installed before I build the back wall of the alcove. I figure it will be easier to handle the tub from two sides than one. When I build the back stud wall, should I set the studs directly against the tub or leave a bit of play, like an eighth or a quarter inch? The tub must expand and contract, right?

 

[Terry]

I normally have the tub tight against the back wall and use a stringer on the back wall for support that the lip rests on. The front apron gets shimmed if needed and there are some tubs that need some support underneath. What tub are you installing?

 

[Ralph Vart]

I am installing a Kohler Seaforth cast iron tub, which is a 54" wide tub. The instruction don't include a ledger, so I may not use one. It's supposed to be shimmed so all four legs sit solidly. I am going to build the wall opposite the drain after the tub is installed, which I think should make it a lot easier to install and level it. My question was about free play between the walls. Should the lip be tight against those studs (the ones on the side of the drain and the opposite side) or is it best to allow a bit of play?

 

[Terry]

I would have the tub tight, but the small gap you mentioned would work too. I have always installed them tight and with the stringer on the back wall. Do does hj.
Often floors in older homes are a little out of level. The shims would be nice if you have access to all of the sides, which never happens on a remodel for me.

https://terrylove.com/forums/index.php?threads/installing-a-kohler-villager-cast-iron-tub.33212/

 

[Sylvan]

I totally agree with all you said Terry I never would dare use a non shielded coupling even for vent

We used to use a steel wedge for levinging tubs sort of like a doorstop and a stringer and tight as possible to the studs YES

 

[Cacher_Chick]

Floors move up and down a bit with seasonal humidity changes and the ledger works to keep the tub and surround all tied together. With a big cast iron tub, it's best to not depend entirely on those narrow feet. Use some steel plates under the feet to keep them from sinking into the subfloor too.

 

[Sylvan]

Wow after installing thousands of CI tubs in high rise buildings I am glad to know the tubs I installed over 51 yrs ago may now shift do to the coefficient of expansion per deg of temperature change.

Live and learn everyday

By the way it is common practice to place cement under the tubs to prevent shifting

 

[Cacher_Chick]

Wow after installing thousands of CI tubs in high rise buildings I am glad to know the tubs I installed over 51 yrs ago may now shift do to the coefficient of expansion per deg of temperature change.

Live and learn everyday

By the way it is common practice to place cement under the tubs to prevent shifting

I don't think anyone was questioning your experience Sylvan. All my work is in stick-framed houses with crawl spaces or basements. I cannot imagine a reason to bed a cast-iron tub in mortar, and if the ledger is supporting the back of it, I don't see what the purpose of mortar would be under a tub that has no inherent flex.

 

[Sylvan]

The mortar just add extra support. It is like the plumbers who use Rector seal on top of teflon tape

 

[Ralph Vart]

I don't know if anybody will see this follow up, but my crew installed my CI Kohler tub and I've got some worries. I'll just ask about one. Kohler's instructions make no mention of a ledger and I called their customer service. They don't recommend a ledger. Anyway, the plumber put in a ledger and the tub is supported on the ledger. The back side cast iron leg on the ledger side is just a bit (may an eighth of an inch" above the floor. I don't like it. Now I see why Kohler recommends against the ledger. How can you possibly get the ledger exactly the height where it would allow the legs to sit on the floor at the same time the ledger is supporting the tub lip? The only way is to position the ledger an eighth below the lip and try to shim it with wooden wedges. The other problem is that he used a 2x4 for the ledger and I think that is too thick and not letting the tub butt against the studs. If I had been there, I would have trimmed down the 2x4 to maybe an inch thick along its length. Should I pull the tub out and get rid of the ledger? By the way, I have a concrete slab floor. The level seems fine in both directions. Ralph
PS: He had a real problem getting the tub drain to stop leaking, he left a half inch circular nick on the enamel on the flange, though it hopefully will be covered by tile. Bad job all the way around.

 

[Cacher_Chick]

If you have access, you can slide a couple 5x8 FHA plates under the high foot or feet to help distribute the weight. If the tub is within 1/8th inch of the studs and is straight, it would not be worth the risk to pull it out again to rip the ledger board.

 

[hj]

The ledger guarantees that the up and down contractions of the wall and tile will NOT cause a separation from the tub's rim. The legs are NOT necessary when you use a ledger.

 

[Terry]

The legs don't touch the floor, that's why the instructions from Kohler say to shim the legs.
hj and I use a 2x4 stringer to support the back of the tub and shim the apron if needed.
Sylvan mentions cement under the tub can also be used, which I often do on fiberglass tubs if needed for support. If cement or mortar is ever used, I drop piles down with space between so that the tub can squish them out. Too much and the tub won't drop down far enough.

A cast iron tub can weight 300 pounds. It's never an easy installation.
This my page explaining how it's done.

How it's done

 

[Cacher_Chick]

Some of the Kohler tubs now have protrusions in the casting under the flange that will prevent using a full-width 2x4. A good quality 1x4 or 1x6 will work fine.

 

[Ralph Vart]

The 2x4 stringer prevented the tub from getting close to the studs, so I pulled it off and cut it down to a net 1x3.5. I then screwed it back into the studs 1/4 in below the lip of the tub flange, which by the way has a v shape edge underneath. Then I shimmed the gap with wood wedges that I made so the ledger supports the tub but doesn't lift it.
SECOND PROBLEM....the Gerber drain is driving me nuts. It is an all brass turn and lift type, which should be a top end drain. First, it requires the drain shoe to be perfectly aligned over the hole in the cast iron tub or you can't thread the shoe plug into the shoe without forcing it. After two tries, I got it aligned perfectly and it threaded in without any difficulty. I filled up the tub and let it drain. I notice some water on the horizontal pipe that goes from the drain shoe to the brass tee. I am pretty sure the leak is not from the drain shoe plug but from where the horizontal brass pipe feeds into the tee. I know for sure before I installed this unit that I inspected the rubber slip nut washer and tightened the slip nut into the tee pretty tight. It seems this thing is designed to swivel even once it is assembled tight. The Gerber instructions didn't mention anything about additional sealing for this connection, but I am wondering if I should have put some teflon tape on the threads where the nut screws into the tee???? I have a small access door on the back side of the installation but it is too small to do much work and I don't want to pull the whole assembly apart. So at this point, I am thinking a tiny bit of wetness on the under side of the pipe is something I will have to live with. It isn't even a drip. It is over a small pit in the concrete slab. I have done a lot of plumbing and never seen something so fussy. Maybe a much cheaper PVC drain would have worked better than this alleged high end 17 gauge brass Cadillac.