Inspector discouraged AAV, which option works better?

[wwhitney]

He can't get it that short; he is routing the trap arm under a window, behind a dishwasher, to a side wall. 5 ft could be a challenge.l

Certainly it's possible if you're willing to take the vent horizontal below the window rough sill.

If you want to avoid that, I agree it may not be possible, but we don't have any precise info on the horizontal distance from the sidewall to the sink drain. We know it's at least 36", as I assume it's at least 6" off the dishwasher, then a 24" dishwasher, then a 6" cabinet. But it may be more like 48".

Cheers, Wayne

 

[Reach4]

We know it's at least 36", as I assume it's at least 6" off the dishwasher, then a 24" dishwasher, then a 6" cabinet.

plus another distance to the U of the trap.

 

[Sponsor]

 

[wwhitney]

plus another distance to the U of the trap.

Say the trap arm emerges from the right back corner of the sink base, and that point is 32" off the sidewall (6" cabinet plus 24" dishwasher plus 2" for cabinet sidewall clearance). It can emerge at a 45 degree angle, and say the trap outlet is about 15" off the drywall and not more than 47" from the sidewall. Call that angled run 17" * sqrt(2) = 24" to get behind the drywall before hitting a 45 degree bend within the wall.

Then the trap arm can run another 18" from left to right within the wall, to a san-tee that is around 14" off the sidewall. That san-tee can be 12" AFF, with a street 45 at the top for the vent, which adds less than 2" of vertical rise before turning. The vent can then rise 12" while moving 12" towards the sidewall. At that point the vent could emerge from the framing at about 26" AFF (below the rough window sill at around 30" AFF) and 2" off the sidewall. That lets it get around the jackstud and the 4x6, while staying under the bottom of the counter at 34-1/2" AFF, to enter the sidewall.

So under those assumptions, it's doable but just on the margin. If everything is 6" farther from the sidewall, I agree it's not possible.

Cheers, Wayne

 

[puyehue]

You guys are relentless.... it's great!
Ok, here is the sink:
https://www.us.kohler.com/webassets/kpna/catalog/pdf/en/086563_4.pdf
We have the R - drain board on right side.

There is a 6" cabinet, like that for cookie sheets, pizza stone, etc that goes between this sink, and wall.
I'll hide the 45 degree angle behind that.
So, what do you think? I see 30" + 6" cabinet. That goes to the center sink. (so far, so good?)
Can I come up there with the trap drain, then lateral over to the larger sink, (Tee slip fitting?)
And stay in the 1 1/2" pipe size?

 

[Reach4]

Can I come up there with the trap drain, then lateral over to the larger sink, (Tee slip fitting?)
And stay in the 1 1/2" pipe size?

You are going to get from the U in the trap, around the dishwasher, thru the small cabinet, and to the santee in the side wall in 3.5 ft? Not as the crow flies, but the whole path.

A dimensioned plan view drawing showing the 4x4s and the 4x6, the sink base and drain, the dishwasher, and any other cabinets would be helpful.

Yes. That.

 

[puyehue]

Ah, right....
I'll get some better dimensions.

This just in:
We can use a shallow cabinet for the 6" side, which would allow the drain to go in the floor, 45 over to wall for vent, reducing trap arm length a bit. let me sketch a drawing.

 

[wwhitney]

the santee in the side wall in 3.5 ft?

But the san-tee doesn't have to be in the side wall. It can be behind the dishwasher, with the vent wrapping around the corner below counter height, as I explained.

Cheers, Wayne

 

[puyehue]

But the san-tee doesn't have to be in the side wall. It can be behind the dishwasher, with the vent wrapping around the corner below counter height, as I explained.

Cheers, Wayne

Thanks Wayne! That helps....

best I can do below:

Putting drain pipe into floor behind cabinet ok? Would have to angle over and up...
Studs behind DW are non load bearing, so can notch, reducing distance.
And I think DW is 21 1/4" deep. If 1 1/2, maybe run it along wall?
Lastly, can I bring trap up to middle 30" drain, and tee over to left sink basin?

Might be the last one here....
Best Regards.

 

[wwhitney]

Thanks Wayne! That helps....

Looks like post 43 would work fine for you. Let me know if any part of it needs further explanation.

Directly under the sink you'd use a SJ 1-1/2" 90 under one sink drain, with a (pitched) horizontal line going to the side inlet on vertical SJ tee directly under the other drain. Then the bottom tee outlet goes into the trap.

Cheers, Wayne

 

[Reach4]

I was not aware of such narrow dishwashers. Bosch 300 Series 18 in. See https://images.homedepot-static.com/catalog/pdfImages/c5/c58adfb1-39d5-44c7-8035-1042aa28e92a.pdf page 6.

 

[puyehue]

Looks like post 43 would work fine for you. Let me know if any part of it needs further explanation.

Directly under the sink you'd use a SJ 1-1/2" 90 under one sink drain, with a (pitched) horizontal line going to the side inlet on vertical SJ tee directly under the other drain. Then the bottom tee outlet goes into the trap.

Cheers, Wayne

After re- reading 43, it's becoming clearer. I might draw it in, and send it to you, to confirm my understanding.
Probably tomorrow.
Thanks a lot.

 

[wwhitney]

I was not aware of such narrow dishwashers. Bosch 300 Series 18 in. See https://images.homedepot-static.com/catalog/pdfImages/c5/c58adfb1-39d5-44c7-8035-1042aa28e92a.pdf page 6.

The instruction manual for that sink (which the manufacturer shows as discontinued, FWIW) show details for installing it with a 24" dishwasher under the drainboard. Looks pretty tight, the middle bowl is called out at 11" wide, centered on the 60" assembly, so there is less than 24.5" under the drain board.

Cheers, Wayne

 

[puyehue]

The instruction manual for that sink (which the manufacturer shows as discontinued, FWIW) show details for installing it with a 24" dishwasher under the drainboard. Looks pretty tight, the middle bowl is called out at 11" wide, centered on the 60" assembly, so there is less than 24.5" under the drain board.

Cheers, Wayne

Hi Wayne. We have had the sink and DW for about 10 years. They were installed in our manufactured home, which we sold (driven to another location). So, we know they work together.

Post 43: when you emerge from the rough framing, ~26" AFF, under sill framing, what fittings are you using to come around the 2 2x6s and that 4x6 corner? Still needs to be rising at a 45 degree until 6" above flood rim, correct?

 

[Reach4]

Orange line path doesn't work?

 

[wwhitney]

Still needs to be rising at a 45 degree until 6" above flood rim, correct?

That's open to interpretation, as it is allowed to go below 45 degrees above horizontal if necessary due to structural conditions. Since you can avoid it if you're careful, you might as well stay above 45 degrees off horizontal.

Post 43: when you emerge from the rough framing, ~26" AFF, under sill framing, what fittings are you using to come around the 2 2x6s and that 4x6 corner?

Reach4 drew a path (projected in plan) that I take to be a 45 degree turn (after projecting), and that's a good choice (but could be changed if needed for some reason). So if your vent were flat, you'd just use a 45 degree elbow, but it is rising at 45 degrees above flat, and you want to keep it that way. It turns out that you want a 31.4 degree bend (see below for the math).

A 30 degree bend would be close enough, but that's not a common DWV fitting. So I suggest you use a 22.5 and a street 22.5. Putting them together and rotating the joint can give you anything from 0 degrees of bend (with an in plane offset) to 45 degrees of bend (and the intermediate positions have some out of plane offset). That gives you some flexibility if one of your runs isn't at exactly 45 degrees above horizontal, you can dry fit it and get the exact bend you need.

Cheers, Wayne

Math: Call the postive x-axis to the right, the positive y-axis towards the window, and the positive z-axis up. Coming into the turning point your vent is parallel to the vector (1,0,1). To turn 45 degrees in plan while still rising at a 45 above horizontal means you want to follow the vector (1, -1, sqrt(2)). The angle between them is arccos(dot product / product of lengths) = arccos( (1+sqrt(2))/(2 * sqrt(2))) = 31.4 degrees.

 

[Reach4]

Reach4 drew a path (projected in plan) that I take to be a 45 degree turn (after projecting), and that's a good choice (but could be changed if needed for some reason). So if your vent were flat, you'd just use a 45 degree elbow, but it is rising at 45 degrees above flat, and you want to keep it that way. It turns out that you want a 31.4 degree bend (see below for the math).

I don't follow why a street 45 over the santee and a 45 in the wall wouldn't get him vertical toward the attic. Rotation in the plan view can be anything.

Not commented on that I noticed, but under the santee should be a 45 or long sweep. If a long sweep 90 under the santee, the bend in the wall could be a short 90 turning horizontal to vertical for the drainage.

 

[wwhitney]

I don't follow why a street 45 over the santee and a 45 in the wall wouldn't get him vertical toward the attic. Rotation in the plan view can be anything.

That would work if the san-tee is right next to the double jack stud, so that starting vertical at the top of the san-tee, the street 45 would point into the sidewall, and another 45 would go back to vertical.

However, putting the san-tee there would mean the trap arm would probably be over 42" (edit: maybe not, in which case your suggestion is definitely simpler), so it would need to be a 2" trap arm. To keep the trap arm under 42", I instead propose to put the san-tee ~12" to the left, and the street 45 at the top of the san-tee will point up and to the right within the wall under the window. Once the vent is now near the double jack stud (and has also risen ~12"), it needs to exit the wall to enter the sidewall next to the 4x6.

To do that along a path that is a 45 degree bend when projected into plan view, starting from 45 degrees off vertical and remaining at 45 degrees off vertical, requires the 31.4 degree bend.

Hope that helps.

Cheers, Wayne

P.S. As to the outlet side of the san-tee, I'm assuming that will be straightforward to get into the crawl space below, somewhere under the right hand window.

 

[puyehue]

Reach4 - thanks for asking. Wayne - good, that clears that up. Two slightly different paths. For me, I'll try to do the 45 - 45 from jack stud for simplicity, after confirming I'm under 42". 45 or long sweep going out, good.

I appreciate the discussion. Sorry, I was a little slow on getting dimensions over, but we got there, and avoided the AAV and island vent, which is big.
"A fool who persists in his folly will become wise."
Thanks a lot.

 

[wwhitney]

For me, I'll try to do the 45 - 45 from jack stud for simplicity, after confirming I'm under 42".

Since it may be close, you can draw your layout on the subfloor, showing the drywall thickness, the exact cabinet dimensions, the drain location, the dishwasher footprint, etc. That will let you figure out your exact san-tee location and your trap arm length. You'll want to have a trap on hand, since it has two degree of freedom, so your trap arm doesn't have to point directly to the drain.

I think you'll find that you need a 6" x 6" void behind the 6" filler cabinet for your vent to clear the 4x6. And that your san-tee can be 1" - 2" off the double jack stud while still avoiding the dishwasher footprint.

Also, just to be sure, cabinet layouts often include a scribe or filler of 1" or more to allow for reality diverging from the plans, particularly when cabinets go from wall to wall. So you want to be sure that your cabinet layout isn't going to shift over 1" to the left, causing the dishwasher to hit your trap arm emerging from the wall into the sink base. Or leave an extra 1" of clearance if that is a possibility.

Good luck,
Wayne