Hi, I have a sewer smell coming from our floor drain in the furnace room.I had the sewer main cleaned by a professional.THe weeping tile is tied into the floor drain and the smell seems to be coming from there.Also there is a backflow valve about 6 feet from the floor drain a it was wet around the soil.I tried flushing the weeping tile and noticed no water was running back to the floor drain so I pulled the hose out and about 2 feet in I heard a splashing noise so I moved the hose around and heard water splashing.Is there a void there and why are we smelling sewer gas?

You should have a trap at the floor drain. If you do, put water in it.