Ok to Use Double Elbow Vertically?

[Edward Louie]

Hello. I am planning out the DWV for a tiny house on wheels. As a result, I don't have a crawlspace or a below grade in the slab space to work with. To keep the DWV from freezing I'm routing the horizontal runs just under the subfloor. I plan on cutting and sloping a channel in the rigid foam floor insulation to fit the horizontal runs and locking everything in place by spray foaming the gaps then putting in the OSB subfloor. My question to you is my use of a double elbow to join the flow from the two horizontal directions OK? Will it work well? OR do I need to consider an alternate design? If so please suggest.

Any other issues you see in my DWV design?

Thank you.

 

[Terry]

Plumbers don't like the double wye fitting as the snake passes through instead of following the line downward.
You need at least one vent to the air in the system for an AAV to work.

Can you use a wye with a medium street 90 on top and a 45 on the outlet to the other side?

 

[Sponsor]

 

[Reach4]

Can you use a wye with a medium street 90 on top and a 45 on the outlet to the other side?

Illustrating:

Another possibility is a double fixture fitting

or even a double santee, and run the top port to a flush cleanout on the floor above. That solves any snaking problem, but most people won't want a cleanout in the bathroom floor.

Just ideas.

 

[Edward Louie]

Illustrating:
View attachment 58344

Another possibility is a double fixture fitting

or even a double santee, and run the top port to a flush cleanout on the floor above. That solves any snaking problem, but most people won't want a cleanout in the bathroom floor.

Just ideas.

Thanks for the reply. I have the vertical space for a double fixture tee and even a double santee with a clean out on top but not a wye with a 90 and a 45 on top. The place above where the double elbow is located at is where a kitchen drawer will be located. So I can have a cleanout in the floor and have it be hidden. Just would need to pull out and remove the drawer to access the cleanout.

 

[Edward Louie]

Plumbers don't like the double wye fitting as the snake passes through instead of following the line downward.
You need at least one vent to the air in the system for an AAV to work.

Can you use a wye with a medium street 90 on top and a 45 on the outlet to the other side?

Thanks for the reply Terry. Love your website. Why would I need at least one vent to the outside in the system for an AAV to work?

The Studor literature made it seem like I could completely eliminate exterior penetrations to the outside for drain venting. The tiny house will have a balanced pressure heat recovery ventilation system and a recirculating kitchen exhaust hood so no strong negative pressures will be present to mess wit the AAVs.

 

[Terry]

Installation:
A. The valve should be connected to the piping in accordance with the manufacturer’s installation instructions.

B. The valve should be installed in the vertical, upright position after rough-in and pressure testing of the DWV system.

C. A minimum of one vent shall extend to the open atmosphere for every building drainage system.

D. The valve should not be installed in non-neutralized special (chemical) waste system or in supply and return air plenums.

E. The valve may be installed on sewer ejectors, if installed according to engineer design and prior local code approval.

F. For installation in areas with temperature range between –40 and 150° F.