Black tank odor

[IC2]

If we have a power vent on, we will occasionally get an odor in our 5er. Also, for whatever reason and one I am working on, our black tank from new, day one, is a much slower drainer then any other trailer we have had necessitating a through the toilet fairly high pressure clean out after each stay. You may have an accumulation of solids that need to be broken up and dumped and a legacy from the previous owner (been there - had that).

That tank vent may also be near the 'attic' vent which is what it says and vents the area between the ceiling and the roof. If there is a second vent in that attic area, the air flow may be such that it draw black tank fumes into the attic, hence the smell. To find which is the tank or 'attic' vent, you do the sniff test with the caps off

[CarlGeo]

From your description it seems you may have a problem with your vent stack as others have stated.
However, if you have an on-board washer, that could be the source of the odor. When the washer is not used often, the trap will become dry and thus create a direct path for sewer odors into the coach.

[david jewitt]

I had the same problem on my rig, and went for the 360 siphon vent elimanater, from Amazon .com
Works perfect and no more smells.

[mgscott4]

Mine would start smelling after 3-5 days of use after dumping. I would get a whiff every time I flushed. I installed this fan and have never had a problem with odors since. I don't use chemicals, just water. This keeps a negative pressure even with no breeze.

Lil' Stanker™ In-Line Deodorizer Fans