I posted this to the plumbing and heating group as well:

I'm rehabbing a bathroom in my old victorian rowhouse in Philly, and I
have a question about routing the drains for the tub and sink.
Currently they drain into the cast-iron toilet bend which has two
inlets on one side of it. The bathroom is on the second floor (of
three) over the top of another apartment. I would like to change the
configuration of things in the bathroom and route the drain pipes for
the sink and tub down an existing chase in the wall directly to the
basement where they would enter the main stack where it has been
replaced with PVC. I don't have an easy way to route a vent for those
two drains, however, so I'm wondering if I can drain to the stack in
the basement but vent through the inlets to the toilet bend. Is this a
totally non-compliant configuration? What sort of trouble would I have
doing this? Any advice would be appreciated.

Also, I would like to move the toilet 90 degrees. Since the current
cast iron ring has just two notches for mounting bolts, I want to
replace it. But I don't have any experience working with cast iron.
Is it just soldered on there? Can I heat it up, pop it off and stick
another one on there? Thanks,

Andrew

Andrew wrote:

I posted this to the plumbing and heating group as well:

I'm rehabbing a bathroom in my old victorian rowhouse in Philly, and I
have a question about routing the drains for the tub and sink.
Currently they drain into the cast-iron toilet bend which has two
inlets on one side of it. The bathroom is on the second floor (of
three) over the top of another apartment. I would like to change the
configuration of things in the bathroom and route the drain pipes for
the sink and tub down an existing chase in the wall directly to the
basement where they would enter the main stack where it has been
replaced with PVC. I don't have an easy way to route a vent for those
two drains, however, so I'm wondering if I can drain to the stack in
the basement but vent through the inlets to the toilet bend. Is this a
totally non-compliant configuration? What sort of trouble would I have
doing this? Any advice would be appreciated.

Also, I would like to move the toilet 90 degrees. Since the current
cast iron ring has just two notches for mounting bolts, I want to
replace it. But I don't have any experience working with cast iron.
Is it just soldered on there? Can I heat it up, pop it off and stick
another one on there? Thanks,

Andrew


I can only imagine the response from the "other" group!

No, you can't use the closet bend side inlets as venting.

Working with cast iron is *very* difficult. It's not
soldered. Molten lead is poured into the joints and
then tamped in place (calked).

You can use a PVC "expansion flange" which is designed to
fit *inside* 4" CI. GOOGLE around.

Personally, I think you're asking for a lot of trouble
re-working the whole design of the bath plumbing.

Hop down to the Philly library and dig out some old books
on cast iron DWV practice. I'm sure they have something.

Jim

the pvc drain pipe would be much noisier than the present system. find
a venting diagram such as at fernco [rubber adapter] at:
http://www.fernco.com/specialty.asp
http://www.fernco.com/home.asp


Andrew wrote:
I posted this to the plumbing and heating group as well:

I'm rehabbing a bathroom in my old victorian rowhouse in Philly, and I
have a question about routing the drains for the tub and sink.
Currently they drain into the cast-iron toilet bend which has two
inlets on one side of it. The bathroom is on the second floor (of
three) over the top of another apartment. I would like to change the
configuration of things in the bathroom and route the drain pipes for
the sink and tub down an existing chase in the wall directly to the
basement where they would enter the main stack where it has been
replaced with PVC. I don't have an easy way to route a vent for those
two drains, however, so I'm wondering if I can drain to the stack in
the basement but vent through the inlets to the toilet bend. Is this a
totally non-compliant configuration? What sort of trouble would I have
doing this? Any advice would be appreciated.

Also, I would like to move the toilet 90 degrees. Since the current
cast iron ring has just two notches for mounting bolts, I want to
replace it. But I don't have any experience working with cast iron.
Is it just soldered on there? Can I heat it up, pop it off and stick
another one on there? Thanks,

Andrew

No, you can't use the closet bend side inlets as venting.

....
Personally, I think you're asking for a lot of trouble
re-working the whole design of the bath plumbing.

Hop down to the Philly library and dig out some old books
on cast iron DWV practice. I'm sure they have something.


I'm curious why I couldn't use the side inlets for venting. The house
was designed to have a single vent at the top of the main stack, and
everything--the kitchen and three baths--all drain into and vent from
that stack. So, when the sink and tub were originally plugged into
those side inlets they both drained and vented there. I'm proposing to
just vent there and drain lower in the stack (in the basement).

I would much rather avoid reconfiguring the bathroom plumbing, but the
current design is awful. When it was rehabbed in the 80s, someone
sledgehammered a canyon into the original wet bed tile floor and ran a
cobbled-together mixture of copper and PVC drain pipes through that
canyon to the tub, and it actually *rises* between the tub and closet
bend. No wonder I was always showering in a pool of water. To make
matters worse, after backfilling the canyon, they drilled anchors into
the floor so they could put down plywood and linoleum, puncturing the
drain pipe in 4 separate locations...I know everyone's got a hard luck
DIY story, but thanks for letting me 'vent'. Andrew