Back to Back American Standard toilets..I installed back to back toilets and of course they started reverse siphoning from each other. I ordered a

[sgennaro]

.I installed back to back toilets and of course they started reverse siphoning from each other. I ordered a Totem Toilet Safety Valve, had it installed into one toilet and the siphoning stopped. However, now the floor drain in a hall closet which houses a Navien tankless water heater and water softener stinks of sewage anytime hot water is introduced, especially from the washing machine and bathtub or shower. Would a double wye resolve this sewer smell issue ??