Sewer gas after bathroom remodel - replace cast iron??

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by walkman, Jan 7, 2014.

  1. walkman

    walkman New Member

    Messages:
    26
    Location:
    San Diego
    Update: Thanks for responses below getting me off the idea of cast iron leaks -- turns out the wax ring wasn't big enough because it's on an oval shape offset flange. I didn't realize it when I followed the toilet instructions to mount their wax ring to the toilet. I'm trying a sani-seal now which is larger. If that doesn't work I'll kludge together a couple of wax rings mounted on the flange.

    --- Original Post ---------------------------
    I remodeled a bathroom putting in a new tile floor and replacing the toilet. Now I'm getting a lot of sewer gas smell in the bathroom and basement. I don't think it's just a wax ring problem as I was getting a sewer smell during construction even though I had a towel stuffed in the pipe. I suspect some of the joints in the 50 year old cast iron pipe may have shaken loose or it was damaged in an area I can't see.

    1) Is there a way to see/test if the wax ring was installed correctly if I pull the toilet?

    2) Do you think I should go ahead and swap the toilet section of cast iron in the picture below? If so should I switch from 4" waste pipe to 3" pipe (bath has a shower and sink).

    cast_iron_1.jpg
    Last edited: Jan 12, 2014
  2. Smooky

    Smooky Member

    Messages:
    653
    Location:
    NC
  3. bluebinky

    bluebinky Member

    Messages:
    408
    Location:
    Santa Clara, CA
    Is that the shower trap on the right side? Is is full? To me, it looks like a vent is missing or has been removed.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    I doubt that ANY cast iron leaded joint would EVER leak sewer gas. If your diagnosis, that it IS sewer gas, is correct, it is coming from somewhere else.
  5. walkman

    walkman New Member

    Messages:
    26
    Location:
    San Diego
    That's good news. I thought the joint might have been weakened with age and vibration during the rehab. The smell is coming from the toilet area as the smell stopped in the bathroom when I caulked around the toilet (made it stronger in the basement). The sink and shower traps are okay and the vent goes through the roof.

    I'll pull the toilet and try to inspect the flange & pipe and install an oversize wax ring before I mess with the cast iron.



    p.s. There's no doubt that it's sewer gas.
    Last edited: Jan 8, 2014
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    quote; There's no doubt that it's sewer gas.

    I once had a customer who was a professional building maintenance supervisor tell me HE had a sewer gas leak in his bathroom. I, and my helper, spend HOURS checking everything, even doing peppermint and smoke tests, with no results. It was in the wintertime so it got dark early therefore, I turned on the bathroom light, but then left to get some more peppermint oil. When I returned he told me, "the smell has come back while you were gone". I went into the bathroom and smelled the odor. I told him, "That is NOT sewer gas, it is scorched plastic". He had put a 100 watt bulb in the fixture at one time which scorched the socket, and EVERY time it got hot it exuded the odor, even with a smaller bulb.. If I had not turned the light on and left it for a while, I would never have found the source of his odor.
  7. jm66208

    jm66208 Member

    Messages:
    99
    Location:
    KC
    HJ has the BEST stories! I like the one about the drain snake coming out of the roof at a supermarket or something like that :D
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    Stay in the business long enough and you will have your own stories to tell.
  9. Soapm

    Soapm New Member

    Messages:
    50
    Location:
    Aurora, CO

    Love it, I was looking for the source of the oder when the light came on...
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,263
    Location:
    Cave Creek, Arizona
    I'll give you a couple of others.

    We had replaced a coal stoker with a gas burner in an "octopus" gravity furnace. I connected the stoker wire to the gas burner and checked it out and it was working perfectly. I got a call at 9:00 p.m. that the customer was freezing. I went over there and went right to the basement, because he had left the light on. The burner was "roaring" just like it should have and when I went upstairs hot air was flowing out of the floor register. I called the next day and they said the house was toasty warm. The next night I got a call from them because they were freezing, so went over, and in a repeat of the night before the burner was working and hot air was coming from the register. The next morning, same thing, the house was toasty warm. I had just made arrangements to borrow a recording pyrometer so I could tell when the burner was going on and off, when the electrician called and said not to worry about it. He was rewiring and as a temporary feed to the basement, he had accidentally tied into the traveler wires between the switch in the basement and the second floor where the owners lived. When he went down to the basement he would turn the basement light on from the upstairs switch, but when he came upstairs, being frugal, he turned the light off and came up the stairs in the dark, but that also turned off power to the basement and the gas burner. When he knew I was coming, he turned the light on from upstairs and that let the burner start working.

    We installed the waste treatment plumbing for a dog food plant, The main part consisted of 4 large holding tanks which had 12' diameter agitators and air injectors to act as a sort of high speed septic tank. The water level in each tank was 6" lower than the previous one and the water flowed from one tank to the other. The agitator "propellers" were 24" under the surface to roil the water. I asked the job superintendent "what keeps the water in each tank 6" above the next one, because they are all tied together?" He told me not to worry about it, that is why they have engineers who know their business. We finished the job on a Friday afternoon, and they were going to make their initial test run on Saturday. When I came in on Monday, I asked how it went, and one of the construction crew told me, "You should have been here. All the "suits" were on the catwalk above the first tank when they turned the agitators on. The water level was 18" too low, (because all the tanks were connected together and that was the level in the last one), so the agitator was only 6" below the surface. When it came on it threw a 12' wide column of the worst smelling water you can imagine 15' straight up in the air, and the suits had nowhere to go to get away from it". Think about it and have a good laugh, I did.
    Last edited: Jan 10, 2014
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