In conjunction with a new bathroom I'm installing in my basement, I'll be cutting into a 4" cast iron stack/drain just after it enters the slab and makes a sweep from vertical to horizontal where it turns towards the front of the house and eventually the sewer. I plan on combining the bathroom's 2 small lavs, a toilet, and a tub/shower into a 3" line that feeds a 4-3-4 wye in that drain from one side. I would like to put a floor drain on other side of the drain (in a utility area behind the bathroom) on its own wye to provide a proper drain for my furnace condensate and the pressure-release/condensate on my WH. They are currently going into a sump pit (with pump). Here's the questions:
1) I gather the drain/stack functions as a vent for the floor drain as long as I do the following (please confirm):
- Don't go below 18" on my floor drain trap leg
- Don't plumb it with a diameter less than 3" including the trap.
- Keep the wye at the drain close to flat and pitch the 3" section so the top of the drain is over the drain's trap wier.
2) My state requires "Where a trap seal is subject to loss by evaporation, the trap seal shall be protected by a trap seal primer or other approved method. A trap seal primer valve shall conform to ASSE 1018 or ASSE 1044." My water heater produces a small amount of condensate nearly constantly while operating, but can the operation of a permanently installed appliance be considered an "approved method" or do I need a dedicated priming valve or grey water tap from a lav, etc?
3) The previous owners of the home had a sewer backup that flooded the basement to several inches. While the blockage was in the front yard, I believe the "source" of the flooding in the interior was a cleanout on this very stack being improperly tapped and used for a sump pump outlet. Are there any specific precautions I should take to prevent backup via the floor drain or is that what the 18" min and required diameters are intended to do?
4) Any other common gotchas installing drains where there were none previously?
Dan
1) I gather the drain/stack functions as a vent for the floor drain as long as I do the following (please confirm):
- Don't go below 18" on my floor drain trap leg
- Don't plumb it with a diameter less than 3" including the trap.
- Keep the wye at the drain close to flat and pitch the 3" section so the top of the drain is over the drain's trap wier.
2) My state requires "Where a trap seal is subject to loss by evaporation, the trap seal shall be protected by a trap seal primer or other approved method. A trap seal primer valve shall conform to ASSE 1018 or ASSE 1044." My water heater produces a small amount of condensate nearly constantly while operating, but can the operation of a permanently installed appliance be considered an "approved method" or do I need a dedicated priming valve or grey water tap from a lav, etc?
3) The previous owners of the home had a sewer backup that flooded the basement to several inches. While the blockage was in the front yard, I believe the "source" of the flooding in the interior was a cleanout on this very stack being improperly tapped and used for a sump pump outlet. Are there any specific precautions I should take to prevent backup via the floor drain or is that what the 18" min and required diameters are intended to do?
4) Any other common gotchas installing drains where there were none previously?
Dan
