One hot mother!!! Be careful in your garage!!!!!!!!!!!

The pellet stove doesn't build up much of any soot. Ash for sure. But not much of that is in the vent pipe. I pulled the vent pipe down before winter and cleaned it. I'm at a loss. Left it running today.

I do think I'll add a fresh air intake. Seems like it would just make the stove more efficient.

The detector upstairs didn't go off. I was surprised. Wife keeps a ceiling fan on and I'm wondering if it was pushing the smoke away. The detector down stairs was disconnected at some point. That one's on me and has been rectified.
Just a thought: There's only two ways that smoke could get into the house from the heater/stove. Air blowing down the vent or blockage of the vent. Could something have temporarily blocked the vent from the outside??