Vent issue new basement bathroom

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TIBO, Jul 23, 2014.

  1. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Hi,

    I recently did a complete remodel of our basement and we decided to install a small bathroom (toilet,

    shower and sink).

    I think the plumber did a good job. Here's what he did (see underground work photo):
    - far left is the sink drain
    - top/left is the shower drain (with the white plastic around it)
    - middle is the toilet drain (with the lead on top of it)

    All those drains go to a check/non-return valve (under the staircase) then to the main drain that goes

    to city drain.

    On the other photo (vent placement photo), you can see that the vent is installed starting from the sink.

    The original installation from the plumber was
    - a long ABS pipe going from the roof of the basement (where the photo stops),
    - then outside the bathroom in the basement hall's roof (about 20 feet)
    - then in the basement bedroom's roof (another 15 feet)
    - then upright to the main vent

    Now, the problem...

    Because of clearance for the staircase with the roof, and esthetic reasons, and advice from another plumber we had to decide to let go of all the vent part that was outside the bathroom (so about 35 feet + the upright part of the main vent that goes to the house's roof, 2 stories above) and replace with a mechanical vent. I don't recall the brand but it's the costly white one that is rated for in-wall installation.

    So I Installed it at about 6 feet up in the wall, just before where the ABS was turning outside the bathroom in the first installation (so about where the photo stops in vent placement photo.

    Some time after I've installed my toilet (luna double flush TB351) and my sink.

    My toilet doesn't flush (well, after an hour, the bowl is now to a normal level...) and when I fill my sink (with the drain closed) the minute I open the drain to let go of all the water in the sink, it's slow and I see/hear little bubbles in the toilet bowl...

    My plumbing supplier told me that since I see bubble in the toilet it was 100% sure a vent problem. So I think I shouldn't cut the big vent to install my mechanical vent but:
    - How can I be 100% sure that by redoing the but vent to the main house vent I'll resolve my problem (you know all the hassle of reopenning walls...).
    - If any, how come 6 feet of open vent will not do the same than a much longer one?
    - Can I troubleshoot anything to find another solution before redoing all my vent?
    - Is there any other solution (a big vent loop in the wall behind the sink...)
    - Do you see any problem with this installation after seeing the photos (can it be a drain installation problem)?
    - Could it be because the check valves are improperly installed (is there any thing I can do to test the check valves function)?

    I'm lost and I want to troubleshoot anything before redoing a vent in my newlly finished basement. Even if it takes time.

    Thanks a lot guys,
    - Eric Thibeault[​IMG] [​IMG]
  2. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    I presume the second photo is the vent photo. Suppose you remove that orange cap or open whatever is now there. That vents the vent pipe to the room. Then flush your toilet. Does the toilet flush well then? If not, you have a problem other than venting.

    If it flushes well, does air come out of the now-open pipe? If so, remember that an AAV can admit air, but it cannot relieve a pressure. You would need a real vent for that.

    I am not a pro.
  3. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    The orange cap is not the vent, this is the roughing for the sink drain, which is now properly connected to a p-trap and the sink drain. The vent is the upright part you see on the left. The AAV is connected about where the photo top stops (about 6 feet high).
  4. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    I had figured that. Can you open that drain that connects to the vent pipe to the air for testing, or is it all glued? It seems to me that you could at least drop the trap. to provide an air path for testing. Do you have an easier way of testing? Is there a cleanout that you could open? It seems to me that there should be a cleanout.

    I don't know if your toilet flushing problem is caused by lack of venting or not.
  5. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    I'll try to understand what you said by asking you some questions.
    "Can you open the drain...", "...at least drop the trap"
    - Do you mean that for testing purpose, I should "unscrew" the lavatory p-trap?

    "Cleanout"
    - I have one cleanout on the main drain. You're telling me to open it while I flush to see if it would take it's air from there (4-5 inches wide pipe)?

    If it flushes well with those two open, what will that prove in the troubleshooting process?
    Thanks
  6. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    >I'll try to understand what you said by asking you some questions.
    >"Can you open the drain...", "...at least drop the trap"
    >- Do you mean that for testing purpose, I should "unscrew" the lavatory p-trap

    Yes. If you want to see what happens if a vent can relieve pressure and make the toilet work, you would want to open something up.

    >
    >"Cleanout"
    >- I have one cleanout on the main drain. You're telling me to open
    > it while I flush to see if it would take it's air from there (4-5 inches wide pipe)?

    If that cleanout is on the toilet side of your new check valve, then, it seems to me, that it would be good to open that cleanout instead of the P-trap.

    >
    >If it flushes well with those two open, what will that prove in the
    > troubleshooting process?

    If it flushes well with either of those open, that would point to a venting problem. If it does not, then expect that something else is the problem. A workman or a child could have disposed of something in a pipe, for example. Do you know if that toilet worked well before you removed the vent, or did removing the vent precede the installation of the toilet? From what I understand, bad flushing is seldom caused by bad venting. Yours could be the exception.
  7. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,236
    Location:
    Maine
    It's not a vent issue. Unless you are draining into a closed container such as a tank and pump. I would be looking at the check valve that shouldn't be there.
  8. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    I've got to check valve:
    - one for the basement bathroom
    - one for the city

    "I would be looking a the check valve that shou.dn't be there"... what are you saying: I should have check valves? Yet it is mandatory from code.
  9. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Thanks, I'll try all that.

    Also, being that
    - I have a hole in the wall behind the sink (it's my workshop) where I can see my AAV
    and
    - I have access to where I've cut the first big vent the plumber installed (in the bedroom suspended ceiling)

    Could I try reconnecting them in a MacGyver way - temporarily - just to see if the "option" of redoing the whole vent. Like, reconnecting some pipes - below ceiling (remember: temporarily) between those two ABS.

    Do you know what kind of material could do the trick? Something flexible would be good and no ABS. If it's absolutely ABS, does it have to be air-tight (glued) or it could only be press fit for the test. I need about 30 feet of piping so if it's not the problem, I don't want to be stuck with this piping.

    I'm thinking of a 1-hour installation: connect it, flush, see if it works. If it works, redo all of that in ABS in the ceilings.

    Thanks for your advice.
  10. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    I did not suggest much. I mainly suggested opening something in the vent system before the checkvalve for testing, then flush the toilet. An open pipe for purposes of the test are as good as a pipe that goes through the roof. A real vent will prevent smells and gasses. But the symptom you are pursuing right now is the toilet flushing. Put up with any smells. Does your AAV unscrew, or is it glued too?

    If you have a check valve to prevent sewage from backing up into the basement, those flapper valves are notoriously not effective after a few years; stuff holds the flapper open. Normally-open backwater valves are much more effective for that.

    Tom Sawyer is very experienced. I am not. I am just proposing what I thought would be an easy test/demonstration to try before you tear into things. Your sewer flapper valve with no real vent upstream is unusual .
  11. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,236
    Location:
    Maine
    Toilets are a full siphoning fixture and do not require a vent. They get all the vent they need from the water surface area in the bowl. If it won't flush it's because there is either an obstruction or a sag in its drain line.
  12. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Hi,

    My AAV is a Oatey, it can be unscrewed. In fact, the first time I flushed the toilet, the AAV wasn't screwed to the pipe yet. My vent was free of it. Afterward I screwed the AAV but it was neither better nor worst.

    As for the check valves, I don't have the brand right now and I don't know if it's really a check valve or a normally-open backwater valve, I just googled the translation for that word from french! ;) I'll check the brand latter.

    "An open pipe for purposes of the test are as good as a pipe that goes through the roof. "
    - Apart from the smell, Is that real? You told earlier: "remember that an AAV can admit air, but it cannot relieve a pressure. You would need a real vent for that." My understanding of that (and correct me if I'm wrong) is that the longer the pipe, the better the pressure relief. So a ±50 feet that goes to the roof could be better than my ±6 feet to an open pipe (unscrewed AAV).
  13. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    You have confirmed what Tom Sawyer has been saying.

    Your longer-is-better-performing story for vents sounds outlandish to me.
  14. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,882
    Location:
    Cave Creek, Arizona
    The check/backwater valve is acting just like a second trap and locking the air in the system. When you run ANY water there is not enough pressure to open the valve and the AAV CANNOT relieve positive pressure, so nothing drains until some air is forced through the valve. You either have to disable the valve or connect to the vent out the roof. Unscrew the AAV and everything will drain properly.
  15. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    As said earlier, the AAV have been unscrewed and the toilet didn't work much more.

    How can I "test" the check/backwater valve (how can I force open it, while someone flushes the toilet, if it's what I need for testing purpose)? Could the valve being installed on the wrong side? How to verify that?
  16. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Last edited: Jul 24, 2014
  17. Reach4

    Reach4 Well-Known Member

    Messages:
    2,496
    Location:
    IL
    While that sheet did not have a picture, I found a picture elsewhere. That flapper type is what I had been presuming.

    There is a better type to do the job that your flapper valve was intended to perform. The backwater valves which are normally open to pass effluent cost more, but they will perform better when the water rises.

    You could clean yours periodically, but I don't know how often cleaning would be needed. Let's hope your sewers in your neighborhood don't back up.
  18. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Thanks, I've changed my link in the #16 post.
  19. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,882
    Location:
    Cave Creek, Arizona
    Just unscrew the cover on the BWV and flush the toilet to see if it flows through it.
  20. TIBO

    TIBO New Member

    Messages:
    19
    Location:
    Quebec
    Well, found it. It was the BWV. I don't know why but the rubber o-ring on the valve was kind of sealed. I had to pry it with a flathead screwdriver. Afterward, I cleaned it, I flushed the toilet (and pulled some sink water in the same time) and everything worked as intended.

    I also found why I have two BWV.
    - 1 coming from the basement bathroom main drain
    - 1 coming from the basement floor drain (near my water heater)

    The bathroom BWV that was stuck also have some notches at the bottom of it. I think that It will not seal properly because of that. I will post two photos this evening (one of the valve and one of the pipe where the valve goes) and I would appreciate your thoughts about if it is necessary to change the whole BWV because of that little "notch".

    Thanks again for your help guys.
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