Tapping into 3" PVC drain line
- Thread starter salimajmeri
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salimajmeri
Member
Also, is there another way to do this that doesn't necessarily meet code, but wouldn't cause any problems?
wpns
Well-Known Member
/* complete venting solution for any Multi-storey building over 10 storeys high.*/ for $1,036.90
I’m also interested in why a “studor” or Air Admittance Valve isn’t applicable.
turdchaser2000
Well-Known Member
The aav would pass in my jurisdiction. Two wax is right there’s a possibility of positive pressure causing an issue but you won’t know for sure until it’s in use. I expect it would work fine.
If that’s the last outlet on the system and if they’re on a septic system, there may very well be positive pressure.
Water displaces air. That air has to go somewhere.
There are a lot of “ if’s and but’s “ in plumbing. The rules are in play to make systems work 100% of the time.
It may work perfect 99% of the time and then one day Mrs Jones is doing laundry in the basement and both toilets get flushed upstairs and Mrs Jones gets covered in 3 day old trap water sprayed all over the room.
There was a multi story building I worked in and it had water cooler fountains in the lobby. Everyday between 11:30 and about 1pm every few minutes water would shoot out of the drain and spray water all over the lobby if the trap was full and fill the lobby with sewer gas.
God help you if we’re about to get a drink of water……
Renovations upstairs sealed the vent. So the system was venting through the water cooler.
Water displaces air. That air has to go somewhere.
There are a lot of “ if’s and but’s “ in plumbing. The rules are in play to make systems work 100% of the time.
It may work perfect 99% of the time and then one day Mrs Jones is doing laundry in the basement and both toilets get flushed upstairs and Mrs Jones gets covered in 3 day old trap water sprayed all over the room.
There was a multi story building I worked in and it had water cooler fountains in the lobby. Everyday between 11:30 and about 1pm every few minutes water would shoot out of the drain and spray water all over the lobby if the trap was full and fill the lobby with sewer gas.
God help you if we’re about to get a drink of water……
Renovations upstairs sealed the vent. So the system was venting through the water cooler.
salimajmeri
Member
Thanks. I'm on a public sewer system, not septic, so at least I have that going for me. I'll still try to find a way to connect to the dry went, but it looks like it will require drywall demolition on the first and/or second floor.
The basement bathroom I mentioned must also be connected to that dry vent somehow. It was part of the house during initial construction and the house is a 2015 build. I'm assuming I should be able to connect through there somehow.
The basement bathroom I mentioned must also be connected to that dry vent somehow. It was part of the house during initial construction and the house is a 2015 build. I'm assuming I should be able to connect through there somehow.
I might would try a studor but if the studor didn’t work I’d try to find one of those pipes that didn’t have a toilet flushing through it and use it as a vent. But it wouldn’t pass code.
turdchaser2000
Well-Known Member
If you’re correct and the basement bathroom is vented through the roof, you should be able to connect to that vent assuming it’s in proximity to the new laundry.
Some codes prevent a washing machine, a sudsing fixture to be installed at the base of a stack.
It also prohibits went venting fixtures on different floor levels.
Don’t shoot the messenger
This is ‘Merica, you do you
It also prohibits went venting fixtures on different floor levels.
Don’t shoot the messenger
This is ‘Merica, you do you
salimajmeri
Member
Thank you both for your input.
salimajmeri
Member
@Twowaxhack What if I moved my cleanout lower and then lowered the other two branches and tapped into that line above the other 3" branch? Wouldn't this significantly mitigate my positive pressure risk? Something like the attached?
Yes it would. Those branches wouldn’t be flushing past your washing machine trap.
But it would be easier to vent the trap into the pvc that got hot when you ran hot water. Just install the vent connection on the top of the pipe so water doesn’t run down your vent.
Make sure a toilet doesn’t flush down the pipe you marked in red.
You can try whatever then test it. If it causes a problem then you’ll have to take a step back and reconfigure.
Many things can work but I just can guarantee it.
salimajmeri
Member
Okay, that makes sense. I'll try to figure out if there is a toilet connected to that pipe in red first.
As others have said, an AAV is allowed in their jurisdictions. Twowaxhack brings up the real issue of where an AAV has its problem and some jurisdictions do not address. The AAV is a one-way valve, whereas an atmospheric vent allows air flow both ways. So, if any positive pressure develops in the plumbing system, especially like in multi-story buildings, the pressure has to find its way out from the downstream plumbing.
So, if AAVs are allowed in your jurisdiction and they do not have any asterisks by their allowance, and if they do not restrict washing machines to be installed at the base of a stack, here is an idea that would resolve the positive pressure issue and I believe would be acceptable per code.
Install a 2" reducing wye below the AAV and run a 1 1/2" or even 1 1/4" line to the vertical line you said had hot water flowing in it from a sink. Install it as high as practical. Use a Sanitary tee for that connection. That vent line would likely provide the venting of any positive pressure that may occur.
You asked earlier if you could vent through a wall instead of through the roof. Yes, you can with the following restrictions. These are IPC, but UPC is pretty close as well.
An open vent terminal from a drainage system shall not be located directly beneath any door, openable window, or other air intake opening of the building or of an adjacent building, and any such vent terminal shall not be within 10 feet (3048 mm) horizontally of such an opening unless it is 3 feet (914 mm) or more above the top of such opening.
903.6 Extension through the wall.
Vent terminals extending through the wall shall terminate at a point not less than 10 feet (3048 mm) from a lot line and not less than 10 feet (3048 mm) above average ground level. Vent terminals shall not terminate under the overhang of a structure with soffit vents. Side wall vent terminals shall be protected to prevent birds or rodents from entering or blocking the vent opening.
So, if AAVs are allowed in your jurisdiction and they do not have any asterisks by their allowance, and if they do not restrict washing machines to be installed at the base of a stack, here is an idea that would resolve the positive pressure issue and I believe would be acceptable per code.
Install a 2" reducing wye below the AAV and run a 1 1/2" or even 1 1/4" line to the vertical line you said had hot water flowing in it from a sink. Install it as high as practical. Use a Sanitary tee for that connection. That vent line would likely provide the venting of any positive pressure that may occur.
You asked earlier if you could vent through a wall instead of through the roof. Yes, you can with the following restrictions. These are IPC, but UPC is pretty close as well.
Section 903 Vent Terminals
903.5 Location of vent terminal.An open vent terminal from a drainage system shall not be located directly beneath any door, openable window, or other air intake opening of the building or of an adjacent building, and any such vent terminal shall not be within 10 feet (3048 mm) horizontally of such an opening unless it is 3 feet (914 mm) or more above the top of such opening.
903.6 Extension through the wall.
Vent terminals extending through the wall shall terminate at a point not less than 10 feet (3048 mm) from a lot line and not less than 10 feet (3048 mm) above average ground level. Vent terminals shall not terminate under the overhang of a structure with soffit vents. Side wall vent terminals shall be protected to prevent birds or rodents from entering or blocking the vent opening.
salimajmeri
Member
Wow, this is amazing. Thank you for the insight. I will report back!
salimajmeri
Member
Seems like that Red Pipe is actually serving 2 Full Bathrooms from the second floor. So two toilets are flushing down that pipe.
1. Given there are two full bathrooms flushing and draining to that red pipe, is that still a good option to use for the positive pressure vent? Or should I use one of the other 3" pipes that have less load (maybe the half bath one in green).
2. Since this is an exterior wall, wouldn't adding a new vent directly to the outside be easier by going through the wall. My house does have soffit vents. The code says it can't terminate under the overhang of a structure with soffit vents. Does that mean it can't terminate anywhere underneath it even if that soffit is 30 ft high? There are no openable windows or doors on this side of the house and the roof is at least 30-40 ft off the ground.
I would first try an AAV between my trap and main connection.
I’d test everything. Made sure it worked. If it doesn’t then I would cut this 90 out and install a tee. At the top of the tee I would install a 180 degree bend or equivalent, remove the AAV and pipe it together.
Test every thing. If it doesn’t work, cap the top of the tee. Run the vent above the roof the best way you see fit.
I’d test everything. Made sure it worked. If it doesn’t then I would cut this 90 out and install a tee. At the top of the tee I would install a 180 degree bend or equivalent, remove the AAV and pipe it together.
Test every thing. If it doesn’t work, cap the top of the tee. Run the vent above the roof the best way you see fit.
salimajmeri
Member
Ok great, thank you for the input.
I'll answer #2 first.
#2 - Yes, it would be easier to go through the sidewall for an atmospheric sewer vent here than running up an interior wall to the attic to the main vent stack or through the roof. But as you indicated, the codes do not allow vents to terminate beneath soffits with vents, and there is no "exception" that says, "unless the soffit is 20 feet above the vent opening". However, you could possibly obtain a variance from your AHJ if the geometry is as you indicate, but that is no guarantee. But you could also run the vent up and around the soffit terminating it at least 12" above the roof line.
#1 - The purpose of my suggested tie-in to the drain line was solely to relieve any positive pressure that Twowaxhack was concerned about which could possibly occur if slug flow happened in the sewer line above the tie-in point. However, after looking at the way your drainage and vent piping is laid out, it seems that there is no reasonable way that you can develop any positive pressure in your drainpipes, assuming each of those red, green and blue lines are vented to the atmosphere as they surely must be. Any positive pressure from slug flow in any of those 3 lines would be vented up through the other two lines. And it would be close to impossible to come up with a scenario where slug flow would simultaneously occur in all three of those lines at the same time.
As such, if your AHJ allows AAVs, that would appear to be the easiest way to proceed for a code installation.
Twowaxhack's idea of, "At the top of the tee I would install a 180 degree bend or equivalent, remove the AAV and pipe it together" would actually work, however it would be way against any plumbing code.
salimajmeri
Member
Thank you! I appreciate you both taking the time to read my posts, look at the pictures, and provide this advice.
