Toilet venting

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    • #277782
      Greg Apple

      We are looking at converting a 1st floor under-the-stairs pantry into a half bath. Because of the location and construction, it will be impossible to put in a through the roof vent. The plan is to use a Studor type air admittance valve for venting. My questions are what size the valve should be, and how high the air admittance valve should be?

    • #297110
      Retired plbg1
      Participant

      Those are ok for awhile but later on they stick open and you start to smell sewer gas, you have to put access panel in wall to get to them if you have to change them. I would out in loop vent if i were you, if you need drawing for one I have them send yor e-mail add. and i will send you one, let me know.



      Art retired plbg

    • #297111
      Zandoz
      Participant

      I understand that the air admittance valves are less than ideal, but in this location they are the only solution.

      The area only has 2 walls. The sloping underside of the overhead stairs make the 3rd wall. The exterior wall in this location is solid brick with plaster over. The only interior wall for the area only rises as far a the overhead stairs. There is only one interior wall in the entire house that runs all the way from the first floor to attic…it is over 20 feet away…and would require cutting into 100+ year old plaster walls on 2 floors.

      The intent is to mount the vent in that under the stairs interior wall, in one of the ventilated access panels designed for that purpose.

    • #297112
      Robert Stephen Morton
      Participant

      zandos. Air admittance valves are purely that, they admit air to stop siphonage.
      They are not a vent to vent air from a system.
      It is normally written into regulations that they are NOT a replacement for a vent, however in some situations they may in conjunction with other means provide a relief vent.
      Consider that these contraptions were never invented & work on that premise & the half bath option may be a non event if you are not prepared to vent the half bathroom properly.
      Bob

    • #297113
      nicktheplumber
      Participant


      In reply to message posted by Robert Stephen Morton:
      zandos. Air admittance valves are purely that, they admit air to stop siphonage.
      They are not a vent to vent air from a system.


      Great point by Robert, and one which so far as I recall has not been made by anyone else. Of course ONE purpose, and a major one, of venting is to prevent siphonage. The OTHER purpose is to vent sewer gases safely outside the building. AIVs work (so long as they are working) to admit air to prevent siphonage of traps. Unfortunately AIVs can create a closed (from the atmosphere) drain system and it’s possible that sewer gases can build up pressure in that system with possible bad consequences. An open vent wouldn’t allow that.

      NtP

    • #297114
      Retired plbg1
      Participant

      I still think you can geta loop vent in there, if you can get a pipe up for a drain then you can get pipe up for loop vent. let me know.



      Art retired plbg

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