Legal Kitchen Sink Drain?

Gentlemen,

I recently re-plumbed a neighbor's kitchen sink drain (dual sink-disposal) and am now wondering if the layout constitutes an S-TRAP?

And can the S-TRAP be explained as I cannot pull it out (understand) from tech materials?

Again,

Thanx For Sharing Your Knowledge

Yes, it is an S trap. If you look at it sideways, you see the shape of the letter 's'. The problem with that is that the trap will siphon dry. There is not entry for the vent air . A p trap...shaped like the letter P on its side....as soon as the sink is drained, the vent air enters at a level above the water level in the U part of the trap. This level is called the weir of the trap, and the siphon is broken.

jimbo said:

Yes, it is an S trap. If you look at it sideways, you see the shape of the letter 's'.

The problem with that is that the trap will siphon dry. There is not entry for the vent air . A p trap...shaped like the letter P on its side....as soon as the sink is drained, the vent air enters at a level above the water level in the U part of the trap. This level is called the weir of the trap, and the siphon is broken.

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I see said the blind man.

Because the outlet was placed so low at the rear of the sink cabinet (P-TRAP will be on cabinet floor), will a AAV alleviate this and where exactly does it need to be placed?

Thanx for the quick and informative reply...

Below Is Text From Another Thread With A Similar Problem-

Patcs2 said:

Just bought this house and want to add a disposer under the double kitchen sink. The "flipper" we're buying from moved the sink from across the kitchen and the new one isn't tied into the vent stack. Our home inspector said the nearest vent is seven or eight feet away...inaccessible and too far from the fixture to satisfy code anyway. He suggested we have a air admittance valve put in when we have the disposer installed. The under-the-sink drain plumbing doesn't seem to be well done and needs a makeover when a disposer's installed. I think that's an S trap they created in there.


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jadnashua said:

If you did use an AAV, it would be as high as possible under the counter where you could still unscrew it to replace. There a lots of diagrams of other projects where this has been done to go by.

Yes, that does look like an s-trap. Even if it had a loop vent (which would pass code most places), it's still not installed properly.

The disposal will have a DW inlet port, you can use that. You need a baffle T on the part connecting the two sinks to prevent the outlet of one from flowing to the other sink. The disposal acts like a pump, and without that, you'll have problems.

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Is a sanitary tee (PVC SCH 40) available with an internal baffle?

There is no reason to think about using an AAV.
Cut off all that junk you have in there and install a P-trap.
It looks to me there is room room to do this, despite that it will take away from the storage space in the cabinet.
The proper thing to do it open the wall and raise the level of the tee in the wall.

You connected the drain system the "hard" way by using glued sch. 40 PVC. You also made it difficult to revise it because the tee at the wall may not have enough pipe available to cut the tee off and install a different fitting. Your real problem is that you believe the guys at Home Depot when they tell you all you need is " a few fittings and our advice". As an aside, plastic threads do NOT like metal slip nuts.

cacher_chick said:

There is no reason to think about using an AAV.

Cut off all that junk you have in there and install a P-trap.

It looks to me there is room room to do this, despite that it will take away from the storage space in the cabinet.

The proper thing to do it open the wall and raise the level of the tee in the wall.

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Is this I WANT-TO-BE-A-PLUMBER TOUGH LOVE SESSION?

hj said:

You connected the drain system the "hard" way by using glued sch. 40 PVC.

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You should have seen what I cut out. I reasoned the SCH 40 would be a better system than the thin wall tubing used previously (it even sported two separate traps).

You also made it difficult to revise it because the tee at the wall may not have enough pipe available to cut the tee off and install a different fitting.

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Actually, there is a PVC adapter at the wall that screws into a CI 90 degree bend so tear out is no problem.

Your real problem is that you believe the guys at Home Depot when they tell you all you need is " a few fittings and our advice".

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There are no sales people at my area box stores that actually speak English so I buy @ a plumbing supply store. Much easier and cheaper. I actually draw what little knowledge I have from HARRY HOME OWNER TEXTS.

As an aside, plastic threads do NOT like metal slip nuts.

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I had no idea. That will be remedied. I just didn't like the look of the plastic slip nut. CHARLOTTE actually sold this setup so I ass-u-med it was OK.

cacher_chick found my actual flaw, I was concerned about taking up storage space. I certainly do not wish to remove the counter top to slide the cabinet out. I will re-plumb with a P.

I just hate the look of that thin gauge tubing and am actually concerned it could become damaged with storage under the sink. He doesn't want to go the cost of metal tubing.

Now that I have been corrected, is there available a sanitary tee (SCH 40) with a diverter inside or should the GD discharge (right hand sink) be lower on the left sink drain (now do-able as replacing with a P-TRAP and lowering assembly)?

Again, Many Thanx!

Once the existing drain piping is out of the way it would be a simple matter of cutting out an access panel in the back of the cabinet and then removing a 1x2 piece of wallboard to cut out and replace the tee. If it's an old house, it might not even have a vent and the riser may be accessible from below.

You might want to check your local codes, as some places require a separate P-trap for each sink basin.

cacher_chick said:

Once the existing drain piping is out of the way it would be a simple matter of cutting out an access panel in the back of the cabinet and then removing a 1x2 piece of wallboard to cut out and replace the tee. If it's an old house, it might not even have a vent and the riser may be accessible from below.

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You must read minds. This house (circa late forties) has block walls with a brick face. The drywall is against the block (maybe with furring strips as an electrician had trouble pulling a line for the GD).

The drain pipe this is on (dedicated) runs along the block wall below (basement laundry room). There is major blockage and leakage on this line. It runs downwards parallel to the vent. The kitchen sink line is on the right (painted ABS) and the vent on the left (painted galvanized) both going into a hubbed CI pipe @ the slab. The galvanized tees are leaking (corrosion) and I was going to tear both out to the hub in the slab and replace with NO HUB CI and PVC.

Now, can the drain line and vent be combined (wet vent) or must they stay separate?

You might want to check your local codes, as some places require a separate P-trap for each sink basin.

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I will first thing MON morning.

Thank You for your time and knowledge...

The vent must remain a vent.
You cannot wet vent an upstairs kitchen over a laundry tray.

What you can do is remove the pipe going into the 2" cast iron hub, and pipe with 2" from that point.
The vent to the left, is reventing upstairs above the hight of the kitchen counter.

For every pipe going down, there is a pipe going up through the roof. That has never changed.

Thank You Terry...

So the laundry tub is plumbed correctly by going directly to the vent base (sanitary tee) and not into the actual kitchen drain pipe?

Yes,
What you have is done correctly, but to the old sizing.
In the current code, it would look the same, but use 2" for the kitchen sink drain, 2" for the L/T and 1.5" for then vent. But the layout is correct.

The trap arm and the p-trap for both sinks will remain 1.5"

I have been using tubular for the sink drains for over 60 years and have SELDOM, if ever, had them "come apart" when people put stuff in the cabinet, AS LONG as it is assembled properly. What you have as far as the drain and vent piping was, and still is, proper, because while you cannot undersize drain and vent pipes there is nothing to prevent you from oversizing them. We did that in the "old days" so we did not have to keep changing our threading dies for the different size piping.

quote; There are no sales people at my area box stores that actually speak English so I buy @ a plumbing supply store.

In that case there is a quotation and a paraphrase which fits your situation.
the quote; "If the blind lead the blind, will they both not fall into a ditch?"
and the paraphrase; "There is a way that seemeth right to a man, but the end thereof is a bad system"

Again Gentlemen, Thanx...

One last question-

Would it be permissible to empty the LT drain into the kitchen sink down pipe (sanitary tee) as to permit easier wall finish (framing) (moving the drain pipe closer to the wall) at a later date?



Thanks to all who have replied.

If that were allowed, that is how it would have been installed originally. You cannot do it now, either.

hj said:

If that were allowed, that is how it would have been installed originally. You cannot do it now, either.

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Maybe they were not concerned about how far the plumbing rough-in stood out as there were no plans to finish the wall?

Shown is a somewhat similar application (I believe) I came across where both a vertical and horizontal drain are included into one main drain, the PVC on the right (vertical) being a dry vent.

A tee cannot be used on its back as a vent connection.
The tee must be horizontal and the waste connected to waste stack with a wye.
It can be done but you have to revent the L/T properly.
As per IPC code.

Trap arms always extend through the wall to a sink drain.
Are you also going to frame in the sink so that it doesn't protrude into the room.
Perhaps you can install the sink outside in the back forty, and that way you won't hear water running from the faucet.

cwhyu2 said:

A tee cannot be used on its back as a vent connection.

The tee must be horizontal and the waste connected to waste stack with a wye.

It can be done but you have to revent the L/T properly. As per IPC code.

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It seems I threw confusion into the discussion by the showing of the kitchen sink drain (2nd photo). That tee (vent) (I ass-u-me) this is what is under discussion here) is lying on it's back but is rotated approx thirty degrees and I am ass-u-meing that this is correct as this was how it was built originally.