Basement kitchen drain install

[G3d13]

I have started basement kitchen project. Per main designer/architect (my wife) request is to install kitchen sink at about 112" away from sewer main drain line on the left side of the picture.



I need 1/4" of slope per 1 foot; since I am at about 9 1/2 feet away - I need it to be at around 2 1/2 drop. There are couple of concerns:

1. Longer wall (left side) is the outside underground concrete wall (there is a window in the middle). There is 4" between the inner stud and concrete. Winters can be cold, but basement is heated - do I need to add additional insulation around pipes? This is not a load bearing wall.
2. Starting with 17 1/2" off the floor to middle of 2" pipe (34 1/2" counter high - 8" deep sink - 7" disposal) - 10ft long pipe - 2 1/2" drop - leaves about 2" to connect to 3" house main drain as clean out fitting is at 12" off the ground. What low clearance fittings/options are available to connect 2" to 3" pipe? I am not sure about durability of rubber couplers as you can see in one of the pictures - this same main drain is connected to 2 bathrooms + 3 sinks from above; any leak can be 'messy'.
3. Do I must ditch the disposal - that would give another 7" to work with - I could then raise the drain to almost 22" off the floor.
4. Would it make a difference going to 1 1/2" pipe - plan is to have kitchen sink with disposal, dishwasher and RO system for drinking water and fridge.
5. Does this additional sink connection require an air vent; or a p-trap is what all it takes?
6. I know it would be easier to move the sink closer to clean out; but wife wants to have kitchen sink below the window.

Looking for an advise and recommendations; thank you very much in advance.

 

[G3d13]

Another change that can give me another 1" is by going to a different garbage disposal - I found out that InSinkerator Evolution Compact is a 6" bottom of sink to disposer drain - https://insinkerator.emerson.com/do...nstallation-care-use-manual-en-us-6867438.pdf

 

[CT18]

I am not sure of your code but mine would not allow that line to be unvented. I could add a AAV under the sink.

 

[MicEd69]

It's pretty tight, but I think I would cut the existing 3" cleanout off at the hub and add a coupling and pipe to moving the cleanout higher for easy access. I would use a reducing wye into the stack for the drain from the kitchen sink. You will need to vent the kitchen P-trap within 5 feet of the P-trap (UPC) or 8 feet (IPC) or whatever the AHJ dictates. That can probably be done with an AAV as CT18 said, but you need to check as some AHJ don't like those.

As there is a window, I assume this must be a walkout basement. You will want to be sure insulation is behind the drain lines, but not on the drywall side. Your water lines are a larger concern. Running them behind the cabinets on the inner surface of the wall rather than inside the wall would be a good move if you are in a very cold climate.

 

[G3d13]

Thank you for great info CT18 and MicEd69.

What is AHJ?

I can’t find any wye that could connect 3” to 2” with non moving 3” pipe.

Would something like this work? Oatey® Saddle Tee Kits | Oatey

I know it is PVC and I would have to go with PVC pipe all the way to sink sink, but would it
be even be recommended or work PVC to ABS?

 

[G3d13]

Due to height constraints, what could work -
1. sanitary tee. Can a sanitary tee be used 2” horizontal to 3” vertical main drain? What about water from 1 jet tub, double shower, 1 bathtubs, 2 toilets and 3 sinks from upstairs draining into same pipe? Would it run down or it can fill up the horizontal pipe?
2. wye
3. combo wye 1/8 bend

 

[CT18]

AAV is an air admittance valve, also called studor vent. In my area we can use it in place of running a vent line up into the attic. It is not allowed in all areas.

 

[G3d13]

I know what is AAV, I am still not sure what is AHJ.

 

[Twowaxhack]

I know what is AAV, I am still not sure what is AHJ.

Authority having jurisdiction

Or

Asshat Having Jurisdiction


Depends who comes out.

 

[MicEd69]

As Twowaxhack said, AHJ is the Authority Having Jurisdiction. If you live in a city, they are it. They can impose rules that are over and above the plumbing codes they follow., like CT18 said.

I'm out of town so I answered quickly and mentioned adding a coupling to move the cleanout higher, but I meant your 2" connection fitting. A sanitary tee is allowed to connect a horizontal run to a vertical stack, but it is better to use a wye and 45 or a combo wye 1/8 bend. The combo is what I would recommend that you install after cutting off the existing cleanout. If you don't have enough pipe left sticking out from the concrete to install the hub of the combo, then you will need to peel the hub of the cleanout off the pipe.

Then install this fitting or a comparable combo from another manufacturer.



I'm thinking you should be able to obtain the proper slope to this fitting from your disposal elevation if it is installed basically with hub of the combo sitting on the floor.

And that saddle connection is totally inappropriate for this connection, and much worse than a sanitary tee.

So, your only issue is the venting of the sink's P-trap. If an AAV is not allowed, you can vent through the wall and up the outside of you house. There are rules as far as distances to windows and eaves and the like, but that is possible. The vent needs to be vertical or at a minimum of 45 off vertical until it is 6" above the top of the sink. then it can run horizontal with the same 1/4" per foot slope towards the drain.

An AAV would be obviously easier, but it is a mechanical device and does need periodic checking and replacement if necessary.

Check if the AAV is allowed, and if not, get back with this forum and we'll look into the parameters of venting through the wall.

 

[Twowaxhack]

I was surprised to read that technically a AAV that uses a diaphragm isn’t considered a mechanical vent by some.

The explanation given was that it’s a diaphragm that’s acted upon by changes in air pressure.

Sounds like BS to me but that’s what was said. Gotta love the code thumpers and their definitions and attempts to change definitions. The guy who said it was the President of Studor.

https://www.pmmag.com/articles/102128-aavs-in-the-upc

 

[arctic bill]

Thank you for great info CT18 and MicEd69.

What is AHJ?

I can’t find any wye that could connect 3” to 2” with non moving 3” pipe.

Would something like this work? Oatey® Saddle Tee Kits | Oatey

I know it is PVC and I would have to go with PVC pipe all the way to sink sink, but would it
be even be recommended or work PVC to ABS?

saddle tees are not allowed ,The local authority has determined that the proposed subject mechanical tee is a saddle hub or fitting and therefore is not permitted in the

 

[MicEd69]

saddle tees are not allowed ,The local authority has determined that the proposed subject mechanical tee is a saddle hub or fitting and therefore is not permitted in the

Yes, I've only used them as a vent connection to the vent stack where no drains flow by the connection.