The pipe and cat have shipped. I ran up a top down start tonight letting the flue probe get around 400F before I closed the bypass. I went outside quickly with the door cracked and bypass open to check the stack. Completely clean burn, but I saw a few occasional red embers fly out of the cap. They seemed to go out quickly but was still a little unnerving. I closed the door and latched the bypass. I got a plume if gray smoke for a few minutes before things cleared up. The flue probe never went over 500F so I’m thinking no chimney fire but the strong updraft pulled the embers up. That’s the first time I’ve noticed anything like that.