bathroom water supply and drainage Q's

I am re-doing my upstairs bathroom and have 2 questions.

#1

The drain for the tub is a 10' run to the main stack through the floor cavity only - with a finished ceiling below and no vertical walls to go down, so it is a "low sloping drain" (but is still layed at a 1/4" per foot)
it runs straight for 8' then hangs a 90 degree right and runs 2' to the main stack. It is vented at the tub and at the 90 degree bend (and the main stack as well). The sink is completely separate with its own vent and runs direct to the main stack as does the toilet.

QUESTION

Do I need a 3" or 2" ABS drain pipe for that distance. I initially ran 1.5" but it's draining slow. I see by code it should be a 3" due to the critical distance length between the trap and the vents but since it all has to fit in the floor cavity, the bigger the pipe, the lower the slope as i only have so much space in the cavity between the bathroom floor and the living room ceiling below.

--Can I get away with a 2" one?


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#2

The water for the tub, toilet and sink all pull off the same 1/2" copper lines coming up through the wall from the basement (house is from 1950). All the plumbing in my house including the main line in from the city is 1/2" copper

QUESTION

I see by code if more than one fixture is run off a supply line it should be 3/4". If the whole house including the main in is 1/2" is there a point in adding a section of 3/4"? If so how far back do I need to go?

--is there a point in running 3/4 if the main line in is only 1/2" ?

thanks

You could always add an expansion tank, and then plumb back to it.

Or you could continue sipping a pineapple shake through a small straw.

what about the drainage?

plaza500 said:

what about the drainage?

Click to expand...

If your tub is vented at the tub you are fine, doesn't matter how far it is to the stack. I personally like to see 2" but 1-1/2" is code compliant.
I usually design for larger pipes on long runs to keep the slope down, but that's at 20-25'+ length runs.

okay so i get you - but i have no clue as to why my tub takes so friggin long to drain. you can hear the water gurgle and fill up the long sloping pipe

here's the thing thbough - the long 8' pipe is ABS but at the elbow/90 degree it turns into 1.5" cast iron, which runs the 2' to the main cast iron stack.

could that pipe be completely clogged? i can snake it, but i wonder whether the elbow is causing the problem. should it be two 45's instead? its a pretty sharp 90 - what bo9ut a sweeping 90?



also what is the best way to vent the tub at the source?

On a flat runout you should use (2) 45's. The cast, if it is old, could be corroded.

I don't understand why you would have 2 vents on that line either.

To add about the water, if you are willing to replace 1/2" with 3/4" can you replace it all the way to the meter?

DWV

well, i had this initally. the P trap off the tub ran staight into the sloping drain. the vent was T'd off the sloping drain it ran up. if you search my older posts you can see i have ben having drainiage issues with this tub for a while.

the drain runs 8' to the 90 where there was a cleanout located for the cast iron piping. i just added a vent to it and ran it up as it was easy and required little work (hidden in a closet)

so you mean my INITIAL system should have worked? sheeeet i thought i was retarded.

AND 1.5" pipe should work even over a 10' run? i think i will upgrade it to 2" just to be safe.

so i should put two 45's instead of a 90 at the cast iron.

what type of fitting should i use to T a 2" ABS pipe into a 4" main vertical cast stack? a sweeping T? does the fitting need to be a cats iron one if it is vertical (thinking the weight of the pipe itself above)

WATER

yeah i couold go all the way back to the meter but it would involve probably 15 large holes in the wall and a divorce. so not really...

the water line i can live with, the pressure drops i nthe shower when someone turrns on the tap downstair but whatever its a small house and just my wife and I.



the drainage i need fixed......
\


thanks for the help, BTW.

a few more questions:

-if my bathtub drain pipe is 2" does the p trap off the tub need to be 2" or can it be 1.5". the vent is 1.5" does this matter?

- can a toilet 4" waste pipe have a 90 degree bend in it laying horizontal and if so does it need to be a long sweeping one

- when cutting a wye or T into a cast iron main stack, what fitting is required if the line coming in is ABS 2 or 3". do i need a cast iron fitting?

- does a vent care if it has a 90 degree bend in it versus two 45's

- can i use flexible water supply hoses (typical for sinks) to supply a shower? thinking from the shutoff to the actual shower control so a run of 10" or so - otherwise i have to reroute the existing copper

thanks

...anyone?