Originally Posted by pistolkell
Thanks for the reply. know there is a trap on one maybe both. So should I add water to the drain where there is no water visible? Can that cause a back up or overflow? And how much do I add?
I would add a couple of glasses of water to the one on the right. More would be fine but you said you've had leaks on the 1st floor ceiling. a couple glasses should be enough to create a trap seal.
On a side note, a lot of plumbers in my area do this same set up- using flanges with 3 x 2 reducers. When the equipment is in the garage, they are pipe directly out the joist bay to the exterior. No trap is then needed since it is not connected to the sanitary drain system.