RonMar
Elite Member
As mentioned, if your house ventilation is not balanced IE, your house pressure is negative, or under a slight vacume with respect to the outside atmosphere, you will draw air down the plumbing vents, thru the "P" traps and into the house. This airflow would lead to rapid evaporation of the water in the "P" trap... You can usually detect this by placing an ear beside a door or window seal. As you slowly open the door or window, you will hear the movement of air as the pressure equalizes. What causes this? A furnace, wood or pellet stove heater with a clogged or inadaquate air supply duct which draws air from the space and sends it up the chimney when it is running. Clogged outside air supply filters on homes with forced air supply/exchange systems(required by code in most homes these days). I have been in structures so pressurized that your ears pop when the door opens