Humidity activates old creosote
Creosote and soot are dormant when dry. When San Antonio humidity climbs, those deposits absorb moisture and release a sharp, smoky, campfire-ashtray smell. The deposits do not have to be thick — a season of fires is enough.
Air conditioning makes it worse
A tightly sealed, air-conditioned house runs at slightly negative pressure. Instead of air rising up the chimney, outside air is pulled down it and into the room, carrying the odor with it. That is why the smell appears exactly when the AC runs hardest.
What actually removes the smell
Deodorizers and baking soda mask it for a day. The permanent fix is removing the fuel and reversing the airflow.
- A full professional sweep of the flue, smoke shelf and firebox
- A top-sealing damper that closes the flue airtight at the top
- A rain cap so water stops washing odor down the walls
- Checking for animal nests or debris on the smoke shelf