Kitchen sink plumbing question

mf915 · Dec 31, 2006

Hi,
Everything is PVC. Here is the current setup. The drain pipe coming out of the wall is 2 1/2". Then a reducer coupling to a 2" pipe. Then a 2" J-bend, and finally an adapter that connects the 1 1/2" tail piece.

I'm about to install a new double-bowl sink. I got two 1 1/2" tail pieces, a center outlet kit (1 1/2"), a p-trap kit (1 1/2").

Because of spacing issue, I don't think I can use any part of the 2" pipe. I'll need to connect the 1 1/2" wall tube (from the p-trap kit) directly to the 2 1/2" pipe.

Questions:
1) is there any problem to go from 1 1/2" (p-trap kit) to 2 1/2" ??
2) Are there slip-joint adapter out there ? will I need some kind of reducer coupling before the slip-joint ?

3) i have a dishwasher and air trap. Is it okay to use clear vinyl tubing (5/8") between air trap and the tailpiece ? Is this material strong enough ?

Please be specific what parts I need... I'm a newbie

thanks !!!

Randyj · Dec 31, 2006

You can cut the 2 1/2" back to just enough to get a 2" coupler on, insert a 1 1 1/2" x 2 1/2" bushing then insert a male trap adapter into it...then the p-trap. Size it up to make sure you have the proper distance before you start cutting so you will know where to cut.

Sponsor · 2022-01-29T12:20:58-0800

mf915 · Dec 31, 2006

Thanks Randy.

One more question I forgot to ask

4) because the bowl is 9" deep. I have to shorten the two tailpieces in the attempt to get the center outlet piece slightly higher than the wall pipe going into the wall. Is there any minimum requirement on a) the length of the tailpiece b) how much center outlet is above the wall pipe

hj · Dec 31, 2006

pipe

You are measuring the pipe incorrectly. There is NO 2 1/2" pipe. The outside of 2" pipe is 2 3/8" and for 1 1/2" pipe it is 1 7/8". Without seeing a picture of what you have and the space available we cannot tell you which fittings you need, but a good guess would be a 2 X 1 1/2" reducer and a 1 1/2" X 1 1/2" spigot slip joint adapter glued into it.

Randyj · Dec 31, 2006

hj... I was wondering about that too but assumed he knew what he had. I've just seen so many strange things (including radiator hoses for drain pipes) that I expect about anything.

hj · Jan 1, 2007

ppipe sizes

I have seen a lot of blueprints where the "engineer" who designed the plumbing system has 2 1/2" and 3 1/2" pipes specified.

Kordts · Jan 1, 2007

I have 2-1/2" pvc pipe and fittings in my shop.

Randyj · Jan 1, 2007

That's something you don't see much of in the real world.

Cass · Jan 1, 2007

kordts said:
I have 2-1/2" pvc pipe and fittings in my shop.

I'll trade you for some of my 5" PVC.

Randyj · Jan 1, 2007

not sure if I'm supposed to be snickering or just be dumbfounded.....

Kordts · Jan 1, 2007

I have got one cut piece of 5" pvc in my shop, no fittings. My shop came with a bunch of oddball stuff.

Phil H2 · Jan 1, 2007

kordts said:
I have 2-1/2" pvc pipe and fittings in my shop.

Yeah, but are they are they DWV fittings?

mf915 · Jan 1, 2007

it is actually 2" and 1 1/2".... As a newbie, i eyeballed the OD and thought that was a 2 1/2" and 2"

Anyway, i got the the installation completed. Here are some pics... See how much I have shortened the tailpieces and and the tee connecting the J-bend.

Do you guys see any issue ? What would be a better approach ?

Dunbar Plumbing · Jan 1, 2007

Looks fine to me with the exception of that direct connection of the dishwasher to the waste line.

When your sink clogs and you plunge it in your first attempt to get it clear you'll wander where that wastewater goes when it drops a little. You'll be forcing it back into the dishwasher where it was never intended to be.

Codes to prevent such a issue are strictly enforced in Kentucky, parts of Ohio now and soon it is going to spread.

Don't know your location so I can't tell you other than it's a safety call on judgement.

mf915 · Jan 1, 2007

I thought having the dishwasher connecting to the 5/8" opening of the special tailpiece is the typical way.... What's the other alternative ?

BTW, i'll be using an air trap. So the vinyl tube coming out of the tailpiece goes to the airtrap....

Thanks

Randyj · Jan 1, 2007

That's very typical around here... Tho' I see Rugged's point and would like to see a better method myself.

Cass · Jan 1, 2007

kordts said:
I have got one cut piece of 5" pvc in my shop, no fittings. My shop came with a bunch of oddball stuff.

I did a line replacement from house to tap and had 4" ready until we dug it up. I glanced at it and thought it was 6" so I went and got every thing for 6" Thats when I realized it was 5". I called a local supply house and they had the 5" PVC and the ferncos to go from 4-5".

Randyj · Jan 2, 2007

Don'tcha just luv it when a job goes weird on you?... sounds like the time I dug up a sewer pipe to repair and was told that it went to the city sewer. It was going to a septic tank buried in the middle of an acre of asphalt. Septic tank top was broken in. Had to replace the septic tank lid and have the tank pumped.... crappy job.

hj · Jan 2, 2007

kordts

I also have a 3 1/2" X 2" bushing, but you will not find any 2 1/2" or 3 1/2" drain pipe or fittings. And I also doubt you will find any normal residence with 2 1/2" water lines, and if you do, and they are inside the house, they will not be PVC.

Kitchen sink plumbing question

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