About 1.5 hours after a small reload of 3 smaller splits before I load it up before nighttime. It's about 10 degrees outside and. the wood is 6+ years dry, and I have a small rolling flame. I never know if it's a big deal if I can see smoke from the stack. It seems like it quits smoking once the wood it basically coaled up and not much before. The cat temps are always up throughout the burn cycle.