Plumbing layout check

[bhfs100]

I am remodelling my Kitchen and am proposing the attached plumbing layout. I would appreciate any comments that forum members may have. All the pipe & fixtures will be 2" no-hub cast iron.
Thanks in advance,
Ben

[Peter Griffin]

you can't loop vent the washer
You can't wet vent the kitchen sink through the loop vent for the washer
You can't put a combo horizontally (the one that drains the washer)
You can't pipe the dishwasher without an air gap.
The washer has to drain into a 3" main.
in short you can't do much of anything there, and why 2" no hub?

I think it may be a good idea to call in a pro. Had you actually gone through with all that it never would have passed inspection and you would have to pay to do it all over again.

[seaofnames]

I guess you want cast because of fire code? Thats the only reason I'd use cast in residential.

In addition to Peter's reply.

That dishwasher and washing machine is considered an 's trap'. Those have been illegal pretty much everywhere for a long time.

That main waste line should be 3" due to the fixtures being drained into it, on top of the fact the washer requires one in a lot of places.

If you want some advice outside this forum, show that diagram to your local plumbing inspector or a plumber.

I know I'm basically repeating what Peter said, but it should be reinforced that the layout you have might have worked 50 years ago, but from what we know now, its not good enough to ensure a healthy piping system.

[gardner]

That dishwasher and washing machine is considered an 's trap'.

I'm not an expert, but I don't see that. The DW vent comes in above the trap weir. Were the loop vent okay (and you say it isn't) it also meets the WM trap arm above the weir. Can you explain where the S-trap comes from?

[seaofnames]

Here are my suggestions....

[gardner]

1/8th bend and the drop make it an s trap

Huh? I'm missing something. This is below where the vent meets the trap arm.

I always understood an S-trap was where the drain dropped below the level of the trap before the vent joins.

Here the vent is above the trap weir, so all should be well WRT S-trap. What kind of weird-ass bends the drain makes this way and that after the vent shouldn't affect whether there's an S-trap. Dropping on a 45 is fine. Pitching at 1/4 per foot is also fine.

[Peter Griffin]

I don't see the s trap either because the dw trap is vented before it drops but it makes no difference anyway cause the whole thing is a mess.

[hj]

Why is the vent making an "U"? If it has to be that way, and the inspector does not mind it, then it MUST have a connection to the horizontal drain line to eliminate any water that enters it. The dishwasher connecting directly to the drain line creates its own set of problems which will have to be addressed before the DW is installed.

Sea: the vent between the trap and the 1/8 bend keep it from being an "S" trap.

[bhfs100]

Thank you all for your very useful feedback. As you can tell I am new to plumbing and posted my diagram prematurely before researching the relevent plumbing codes. My intention is to develop a workable plumbing diagram before I submit it to my building management and for permit. Since my first post I realise that the DW is close enough to the sink for me to hook up the DW in a conventional manner to the sink waste tailpipe. Also I have decided to eliminate the plumbing for the Washing Machine.
So that just leaves the waste and vent for the sink. I would ideally like the vent to make a "U" to bypass an existing recessed cabinet. If the plumbing inspector allows me to do this, should I propose going under the cabinet (diagram A) or over (diagram B). If diagram A is preferable where is the best place to locate the combo wye connecting the vent back to the waste (A, B or C)?
Oh, and yes, I'm using cast iron because I'm in NYC in a building over 5 stories.
Thanks again,
Ben

[hj]

Plan B would seldom pass inspection because the vent drops down and most inspectors do not like that, even though it would work. The connection should be a point "A", but you will probably have to install a cleanout at point "C" in case backed up material accumulates in the horizontal line over time.