Adding Vents

[Bird Doo Head]

Hi
I have a situation of a house with improper vents (I think, anyway). Everything seems to work OK and I don't hear or see or smell any traps being pulled dry. I do notice, that if the toilet is flushed on the second floor, the first floor toilet water bounces. It does that if it is windy out as well. But, I'd prefer the system was as close to proper as possible. Now's a good time, since the areas I'd need to access are open-wall for other work.

I'd like to ask if you all don't mind looking at the drawing I've attached and offer your suggestions or comments. The black is what is there now and the red is what I can do to vent some of the items. For the record, there is no permit on the job, I'd just like to "repair" it to make sure it won't become a problem for us or for a future owner (if I ever sell the place).

Thank you all very much!

[phishfood]

I am assuming that on the upper bathroom, that the tub and lav are draining into the side of a side inlet tee that the toilet is attached to?

Also, I had to zoom in a lot to make out the drawing (my eyes aren't the best), and that makes the numbers and letters fuzzy, what is the size of the main stack?

[Bird Doo Head]

Thank you for your fast reply. Sorry about the drawing, I had problems getting the file size small enough to post. I chopped part of it off to make it larger. It is attached. i hope it is more legible.

However- I made a mistake on it. The 2nd floor lav vent is actually in place, but not as drawn- wrong stack.

The 2nd fl lav vent tees into a separate 2" that starts at the 3x3x3x2x2 in the basement (Tee is in drawing, but missing this vent). It goes up and crosses to the opposite side of the 2nd floor bathroom, where it increases to 3" about 18" below the roof before it exits. The lav vent hits this pipe, the drain goes to the other stack, as shown in the picture. Nothing else is in this pipe.

The biggest uncertainly I have is that the proposed vent for the 1st floor tub/shower & floor drain has to go horizontally before it goes vertical. I drew in a cleanout. Don't know if that's OK or not.

The stack in the photo is 3" until about 18" below the roof, where it changes to 4" (Frost closure prevention??) Below the basement tee, it is 3" until it goes into the floor. There, it hits the building's 4".

Thank You again for helping me with this!
Paul

[phishfood]

OK, that makes things much clearer.

I think that the biggest problem your system has is that the main stack is venting the first floor bathroom and is draining the second floor bathroom, but is only 3" in size. As the water from the 2nd flr water closet falls down the stack, it builds up a slight increase in air pressure below it, causing the bouncing in the traps on the first floor. I would be willing to bet that the other fixtures are doing the same thing, but obviously you can't see that. If the main stack were 4", you probably wouldn't experience this.

The vent that you propose on the first floor should fix the most of that, as it will relieve the pressure buildup until the water passes the tee for the first floor bath. According to most codes, you shouldn't run a vent flat until it is 6" higher than the rim of the highest fixture it serves. This is in case the drain backs up and fills up the vent as well, you don't want any solids settling in the vent and clogging it off. The cleanout that you have drawn would allow to fix this, but wouldn't prevent it. I would prefer a flat vent here to no vent at all. Does the 2 inch to the floor drain or tub not run underneath a wall anywhere in it path?

As far as the added vent stopping the toilet water from bouncing when the wind blows, I don't think that will be of much help. As you probably have guessed, the wind blowing across the vent pipe is creating a pressure differential, and since your new vent would be tied back into the same vent stack, it won't relieve that differential. Now, IF the other vent that you mentioned is on a different plane of your roof, and if you could tie into that, it might be better in that respect.

And yes, the increase in pipe size just underneath the roof is to prevent frost closure.

[Bird Doo Head]

Thank You Very Much!
It all makes sense to me now.

The floor drain doesn't pass under a wall. But, if it is OK to use a tee right after the marvel for the trap, (or a few inches away) I could go straight up the wall with the faucet supply pipes to almost the bathroom ceiling, then jog out and put a soffit within the tub space to reach the 2" vent to the other stack. It passes perpendicularly above the tub.

If it helps the situation, I can easily change the stack to 4" starting just above the 1st floor tee until it taps into the 4" below the slab. Above that point, it would be an outrageous project. The basement is very accessible. Do you think this would be worthwhile?

As far as the water bouncing when it is windy: Stopping the bounce would be unfair to my dog buddy. Last night she was staring at it like a TV. Does it often on windy days. Totally fascinated!

Thanks again for your help un-confusing me. Since most of the project is open, including the 1st floor bathroom ceiling, this will be a great time to try to make things correct. (Or as close as possible!)
Paul

[phishfood]

Originally Posted by Bird Doo Head

Thank You Very Much!
It all makes sense to me now.

The floor drain doesn't pass under a wall. But, if it is OK to use a tee right after the marvel for the trap, (or a few inches away) I could go straight up the wall with the faucet supply pipes to almost the bathroom ceiling, then jog out and put a soffit within the tub space to reach the 2" vent to the other stack. It passes perpendicularly above the tub.

OK, now this might work out well. IF you have enough distance between the drain piping to the tub and the floor above, you might be able to do this within code. You need 2 pipe diameters pipe diameters or more between the trap and where you attach the vent pipe to the tub drain. So, in your case, you want at least 4 inches between the point that the trap turns horizontal out of the U portion of the trap and the wye fitting that you will use to add the new vent in. Turn the branch of the wye so that it faces straight up toward the floor above. Remember, use a wye here, not a tee. Add as long a piece of pipe in as you can, than a 45 degree fitting to turn the vent pipe straight up, and through the floor. If this will get you into the wall that the tub valve piping is in, great. If not, hopefully this will get you into the open space underneath the tub, where you can use 2 45 degree fittings to offset into the wall. Above that, do as you described. The use of the wye will eliminate the flat vent, as the code considers any pipe 45 degrees or more from horizontal to be vertical.

If it helps the situation, I can easily change the stack to 4" starting just above the 1st floor tee until it taps into the 4" below the slab. Above that point, it would be an outrageous project. The basement is very accessible. Do you think this would be worthwhile?

No, as the problem is the pipe between the first and second floor bathrooms. I think that you are best to try to add a vent to the first floor bath.

As far as the water bouncing when it is windy: Stopping the bounce would be unfair to my dog buddy. Last night she was staring at it like a TV. Does it often on windy days. Totally fascinated!

Thanks again for your help un-confusing me. Since most of the project is open, including the 1st floor bathroom ceiling, this will be a great time to try to make things correct. (Or as close as possible!)
Paul

LOL, dogs are amused by the strangest things. Of course, they think the same of us.

[Bird Doo Head]

On The Way To Success!
After reading your latest reply, I believe I can, indeed, vent the tub vertically. Using a wye, instead of a tee, I can aim toward the open space on the side of the tub and 45 my way up that wall cavity instead. (I have to learn tothink outside-the-box)
I didn't really want to put a soffit above the tub (for the vent), but what the heck. I'll call it an 'Architectural Accent' & charge more for it if I ever sell the house.

I still can't vent the floor drain this way. It would go horizontally. But, better than nothing! (Unless it is Ok as it is. The floor drain shares the same pipe to the stack as the soon to be vented tub.)

Thanks Again. Should be an interesting project.
Paul

[phishfood]

The vent you will add for the tub will serve for the floor drain as well.

Much luck with the project, and let me know if you need more input.

[Bird Doo Head]

Thanks Again Phishfood!
Glad the hear the tub vent will serve both. It just got way easier and will be a cleaner looking installation!

Now, time to get my hand busy on it!
Paul