Venting with AAVs

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We have a new house under construction, small project for my retirement. I made a short video of the layout, I would greatly appreciate anyone telling me what part of the venting system would violate code:

Small change to the video - the inspector said that I needed at least 3" of natural ventilation, so I plan to change the kitchen sink from an AAV to a natural ventilation.

Original WDV system proposal

The house has open ceilings so venting through the attic is not ideal, so I'm trying to design a system that leverages AAVs. The system must meet code. I've explained to the county inspector what I want to do, but I'm a bit confused about his responses that I cannot "wet vent". Anyway, now he is away on personal business for the next two months so I can't get clarification from him and he is the only inspector that understands plumbing. This is Washington state, UPC. I'm using the Studor vents. Natural ventilation to the kitchen sink + dishwasher, master shower, water closet and lavatory. The guest lavotory is vented by a Studor AAV and leads into the guest water closer. The clothes washer uses a Studor AAV and also serves the guest bathtub and shower.
 

Twowaxhack

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Technically only one open air vent is required on an AAV system.

Your inspector will need to approve the system.

Of he won’t.......Check with a certified engineer and see if he will draw and sign off on a AAV plumbing system with one open air vent.,

In my state if an engineer puts his stamp on it, I can tell the inspector to pound sand.

That said, I do not like AAV systems. And I realize no one cares. 😬
 

Twowaxhack

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Your showers are not vented. The tub is not vented. You can’t wet vent a tub and a separate shower downstream of the washing machine. You’ve also said the inspector will not allow wet venting.

Your other shower on the outside wall has the kitchen and a whole bathroom group flushing past it, you can’t do that without risk......

The double vent going up really doesn’t serve a purpose. You could combine them in the wall above the fixture., If the inspector would allow wet venting on the open air vent then you only need one vent. Not sure why you have two going up.

the drains near the washing machine may get soap suds backing up into them.

Everything on an outside wall should be vented outside.
 
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Thanks @Twowaxhack . I'm reaching out to local engineers, but in my experience they are always booked for months in advance. I'll find a way to eliminate the AAVs, and I'll combine the double vents in the wall above the fixture. My attempt at a "combination waste and vent system" appears not to work and I've also just learned that it violates UPC 2021 910.1 so I will add revents to the remaining fixtures.

This is the section I had missed ...
910.1 Where Permitted. Combination waste and vent systems shall be permitted where structural conditions preclude the installation of conventional systems as otherwise prescribed by this code.
 

Twowaxhack

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When you’re designing a system like this (alternate system combination waste and vent) it can be very important how certain high flow and sudsing fixtures or appliances connect to the drainage.

The soap bubbles can close off your free flow of air across the water flowing below. This closes your vent.

Increase the pipes in the ground to 4”. Increase the washing machine drain to 3” then install a 2” trap. You could even go all 4” then a 2” trap fir the washer. This will help with the suds.

Get an engineer or a good plumber to design it for you that has experience with these systems.

With these systems bigger is better. Large pipe and plenty of cleanouts.
 
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PerplexedPlumber

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Hello.

This may be apparent to other members of the forum, but why does an open floor plan impair venting? We were able to use 6" walls where vent pipe was run, with an open floor plan. Black pipe on the roof makes the vents less noticeable.

If you use an air admittance valve, I presume that would be installed so that it would be accessible, to replace when there is a failure?
 
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Thanks @PerplexedPlumber. Good point and we are redesigning to eliminate all AAVs plus implement @Twowaxhack recommendations. I will post a link to an update when it is ready. The reason I was leaning towards using AAVs: The space above the wet wall is open, and the wall does not connect directly to an exterior wall that reaches the roof so that vent must run horizontally between the open ceiling joists. Not impossible, just not ideal. Since wet venting is prohibited (UPC 910.1) then using AAVs is an even bigger headache.

Yes, AAVs must be installed in an accessible location.

If ignorance is a defense, I asked the inspector months ago if I could wet vent as shown on the AAV vendor's installation instructions (Studor) and they told me it was fine. It was only after we showed them a dry-fit layout that they said wet venting was not allowed ("it will probably work but it will not pass code").
 
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I'm still waiting for a callback from an engineer, in the meantime I updated the design based on feedback from @Twowaxhack and @PerplexedPlumber. I'm sure it has problems, but I am hoping it is closer to code. We eliminated all AAVs and wet vents. Moved the washing machine tie-in further down the line (not sure if this was required with the standard venting?). A couple of items stand out to me:

1. The shower in the main bath bothers me since the p-trap is lower than the drain. It seems like waste from the main drain could find a way into the p-trap.
2. We cannot fit a 2" vent into the wall behind the guest lavatory, so I added a 2" vent downstream of the water closet.

Anyway, comments and insults are appreciated :)

Here's the video:Updated proposed fully vented DWV system
 

Twowaxhack

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I would ask if I could eliminate the dry vent by the toilet. If you do keep it, install a cleanout in it above the level of the toilet bowl.

I’d use all 2” pipe for my vent take offs under the floor. Reduce to 1.5” up higher in the wall.

I’d also use one vent ( common vent ) for the two lavatories if they’re within about 6’ on center with each other or less....
Use what’s called a “ double fixture fitting “ to connect the two lavatories to the vent/drain. It’s in between a double combination and a cross. It still protects your trap seals.

I’d use a 2” trap on the Ksink.

I’d put cleanouts under the lavatories or use slip joint traps.

I’d definitely put a cleanout for the kitchen sink. Either on the side of the house or underneath the sink.
 

Twowaxhack

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I liked that you moved the washing machine to connect downstream of the other fixtures. Not that it wouldn’t work the other way, I just like this way better.
 

ohh sheet

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Can anyone help me out with a kitchen vent problem? I want to remove the through roof 4inch vent completely. Can I use one aav under the roof deck instead?
 

JG plumbing

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Upc doesn't allow aav's at all. I'm late to this thread. Just forget them in my opinion. You can to crawl up under your roof deck and change an aav? I thought you were retiring, that sounds like unnecessary maintenance.
 
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