Vented cast iron closet bend?

[treebark]

I removed a lead closet bend which was all rotted and leaking. It had a 2 inch vent outlet just below the flange. I'm planning to replace everything with cast iron cause that's code where I'm at (NYC) and I'd rather not deal with another lead bend. At Home Depot I've found a 4" cast iron quarter bend which has a 2 inch side outlet right at the bend. Can this be used as a closet bend which appears to need a vent (base on the lead bend which I removed)? Do they make cast iron closet bends with a vent? Do I even need a vent? Do they make cast iron closet bends or does one just use a regular short or long sweep?

It seems like it would work but I'm concerned about the vent being lower on the cast iron then it is on the lead. Would this make any difference?

My next questions will have to do with connecting 4 inch no hub cast iron to the 4 inch cast iron hub which currently has a 3-3.5 inch? lead covered brass ferule sticking out of it.

Thanks.

Here's a picture of what was and a picture of what I'm thinking of doing.

[LazyPup]

Wow.. a number of interesting and rather difficult to answer questions here.

Lead pipe and flanges were code approved when first installed in your structure therefore you may continue to use them as long as they remain in servicable condition but lead is no longer listed as an approved material when the lead flanges or pipes fail we are required to replace them with materials that are code approved. Under most circumstances that would include ABS, PVC and Cast Iron but, as you stated, your local code restricts it to cast iron only.

Whether or not you require a vent is again determined by your local code. The International Residential Code does not require a vent if the line only serves a water closet. Under the Uniform Plumbing Code a waste arm serving only a water closet may run up to 6' developed length from the closet flange to the vent opening or to a vented horizontal branch line.

You may use a common cast iron 1/4 bend or a long radius 1/4 bend.

The important question here is the 2" vent pipe. Code prohibits any horizontal dry venting until the vent is 6" above the flood level rim of the highest fixture served. In this case it would mean you cannot have a horizontal dry vent until the vent is 6" above the rim of the toilet.

Code does permit a low heel inlet 1/4bend or in some instances a side inlet 1/4 bend if the line connected to the side inlet is washed by another fixture, by example, if the 2" line were turn vertical to the roof and have a Tee on the riser for a waste arm to a lavatory the portion of the line from the lavatory Tee down to the closet bend is then classified as a Wet vent, and would be premitted.

That 3-1/2" brass ferrule presents a problem because you may not reduce the size of a waste line in the direction of flow. The solution would be to rent a "Cast Iron Snap Cutter" and cut the cast iron pipe just below the ferrule to creat a cast iron raw end. You could then join your new cast to that existing cast with a No-Hub connector or a Fernco Connector.

[treebark]

Yes, I more or less managed to come to similar conclusions via more research as well as running into a local plumber who said that if it was a REPAIR and it was him, he would use the side vented bend even thought it's not to code - unless I wanted to start busting into walls and running a whole new vent. One thing he did say was that I could have run three inch pipe from the ferrule as three inch for a single closet is code here. Not sure I would have done this though just because even though I'd thought about it, when I looked at the 3" fittings they just seemed so narrow. So I went ahead and drilled and chipped out the lead and ferrule, then used the plumber's epoxy method you've described in other posts. I'd also thought about cutting off the hub but behind that wall is a shaft which drops about 100ft. I was going to use my grinder. Anyway, the oakum and epoxy seem to work great. I'm very impressed with the epoxy. There's about an inch and a quarter packed in there on top of about an inch of compressed oakum. I ran water down it for an hour and there were no leaks. Behind the wall, that hub is a long sweep quarter bend which goes directly into the stack so I think the entire run is less then 5 feet at most.

Below is a picture of where I'm at now. I decided to keep the vent cause that's how it was done originally and it seemed to work for 70 plus years (although the vent did have a whole bunch of wet dirt in it which I cleaned out. Not sure if that collected from stuff falling down the vent or diverted from the toilet or a combo.)

So what do you think? I figure if the vent gets blocked up again it would be the same as if I had just put in a regular quarter bend with no vent as per the International Residential Code and if it doesn't, well then I"ll continue to have a vent (which can only be a good thing, right?) even though it isn't required by the IRC.

[LazyPup]

I am in full agreement with the local plumber you discussed this problem with.

The key word in the statement is "repair".

Whenever we are working on an existing system if we are making repairs that maintain the origiinal design and layout the work is classified as "Repair" or "maintenance work". As such we may opt to use a modern material providing it still maintains the original design and layout.

If we alter the layout in any manner or add any additional fixtures or load to the system it is then classified as "New Work" and as such it would be required to meet all current code specifications.

In your case the original closet bend was lead but lead is no longer available so you should be okay with that cast iron bend because it still maintains the original design and layout.

When I made my previous post I started to mention the option for a 3" closet flange and 3" closet bend but you stated you had already obtained the 4". In fact, my first choice for water closet would be 3" because 3" is less likely to cause clog problems in future, especially on longer runs, but in this case the run is very short so you should have no problems with the 4".

[treebark]

Wow! How counter intuitive. Why is 3" pipe less likely to clog then 4"? Also, all the closet flanges I've come across in my neck of the woods are 4" which is what made me think that 4" was the standard. Is there an approved way to go from a 4" flange to a 3" pipe? Or does one just hunt down a three inch flange?

[LazyPup]

The Plumbing Codes define a rather complex method for sizing all DWV(Drain,Waste &Vent) Lines.

In the code books we have a table that lists every type of fixture that is intended to be attached to the drainage system. The table then lists the minimum size of drain and trap for that type of fixture as well as assigning a DFU(Drainage Fixture Unit) load value for the fixture.

Once we know the DFU load value for each fixture attached to a line we can then add the values together to determine the total DFU load at any given point in the system.

Once we know the DFU load value we then consult another chart that tells us the maximum permissible DFU load for each size of pipe.

Most people look at a drain line and they only think of it in terms of conveying the waste but in fact we must design the system to perform 3 functions in harmony. 1. Maintain a sufficient velocity of flow to insure all waste will discharge completely 2. Maintain a sufficient level of liquid in the waste line to insure it can suspend and convey any solid particulates that may be present 3. Permit the proper transfer of vent air to insure that there is no negative pressure condition that would suck the water out of the fixture traps.

If a line is too small the volume of liquid flowing in the line will completely fill the line and it pushes the air in the pipe ahead of the water flow. The causes two problems. 1. The additional resistance of pushing the air reduces the velocity of flow and 2. The volume of liquid fills the pipe like a piston and as it pushes the air ahead it then leaves a negative air pressure in the void behind the moving water. This results in the water being sucked out of the traps and once the liquid has passed the traps are left open and sewer gasses could then enter the structure.

When a line is properly sized the level of liquid in the line under full flow conditions should fill a horizontal line 1/2 full. This insures enough liquid to suspend & convey any solids that might be present while still keeping the upper half of the pipe open for the transfer of vent air to maintain equilibrium with atmospheric pressure.

If a line is too big the level of liquid in the line is then substantially lower and in many cases there is not enough liquid to suspend the solids in motion. The end result is the solids will then drag along the bottom of the pipe and the liquids flows around the solids until there is no longer enough liquid to suspend the solids which are then left in the line as the liquid flows away. After the liquid is gone the solids are then exposed to the air in the line and the solid particutates will dry and form a partial clog. As this cycle is repeated the solids continue building up until the line is completely clogged.

As you can see we must size all drain lines very carefully because an oversized line will clog much faster than an undersized line while on the other hand a line that is too small results in dangerous sewer gasses entering the structure.

A watercloset presents another unique problem. The actual DFU load of a 1.6GPF watercloset is only 3DFU which according to the line sizing charts could be conveyed by an 1-1/2" diameter line, however the code also takes into consideration the physical dimension of solid particulate fecal matter and requires the line to be a 3" or 4" line. Years ago when waterclosets discharged 3.5 to 5GPF the 4" line was considered the standard but with the advent of 1.6GPF watersaver toilets we find the 3" line to be the preferred size.

If you cannot find a 3" closet flange in your local home supply center contact a local plumbing supply house and they will surely have them.

One word of caution here. There is a 4x3 reducing flange on the market. Years ago they were commonly used but they are now specifically prohibited by most plumbing codes.

[treebark]

Wow! I love learning and for that reason I particularly love great teachers and you are certainly one.
So I guess that means I love you.

I am oh so gratefull for your methodically clear and oh so helpful answers here and elsewhere on this forum. I guess if I had waited a few more days I could have saved myself some work - but no harm done - I think (as long as that plumbers epoxy holds up).

For the edification of other intrepid souls who have decided to tackle their toilet, here's some more info:

Before I drilled out the lead and ferrule I cleaned the ferrule using a blow torch and dry towel, heating and wiping as described in another post. I did this 'cause I was just curious if it would work as described in that post. And it did! Very easy to do. I also tried melting the lead out of the hub to get the ferrule out and, with a propane torch anyway, that was completely hopeless.

Here's some more pictures - one of the cleaned brass ferrule and a few of getting the lead and ferrule out and one of the packing tools I used. After everything was out I wire brushed the inside of the hub with the wire brush attachment for my drill, getting all the flaky rust out. Then I cleaned it with a wet rag and finally, as recommended in the Plumbers Epoxy instructions, with mineral spirits.

Packing the oakum was very straight forward and after three layers held the 4" cast iron stub quite securely. The epoxy (Oatey brand) dries very quickly so you've got to be sure to have your hammer and packing tool at the ready and to only mix about half the epoxy stick at a time. Be sure that your packing tool fits the smallest gap between the hub and the stub (depending on how well you pack the oakum, your stub may be a little off center making the gap a little smaller on one side then the other). I actually made a curved oak packing tool that exactly fit the curve and size of the gap but my stubout ended up being a little off center so I had to use a thinner straight piece of wood as well which seemed to work fine. The epoxy I rolled between my hands to make a rope, then wrapped it around the stub and squeezed it into the gap with my fingers and then started packing. I did this several times till the gap was full up.

Peace