Confessions of an early air cutter, flue smoke

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Oct 25, 2023
Cady, WI
After a month of burning in my Kuma Aspen LE I have made a few observations and learned a few things. I figured I would share one of my early problems and how I dealt with it.

On startup I would have smoke for the first hour of burning, sometimes even longer. Nothing excessive but more than I would like to see from a catalyst stove. I was initially suspicious of my wood so we checked and found sub 18% on average for room temp fresh split face. I came to realize I was cutting my air way to early on startup and reloads due to fear of overfiring (Cutting air down to 50-75% within 5-10 minutes). Now I burn full air on start up and 75% for 15-20 mins or so after engaging the catalyst on cold starts and reloads and making the adjustments down to a low burn more gradually. I monitor my catalyst and have not had it further than the 2/3 mark.

After making these adjustments I find I still get a bit of smoke on startup and reloads for the first 15-20 mins but it is greatly reduced and is almost gone within 25 mins.

Long story longer, keep a close eye on your cat probe but don't be so afraid of a runaway that you don't get your fire established.
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I had the same issue when I first started. Now I keep the door cracked for 15 min until there is a char on all of the wood, then I latch the door wait another 10 min or so and begin to close the damper. Also started to do Top Down starts on new startups. That really reduces the smoke on startup. On Reloads, if my coal bed is not large I pull them forward/center and then crack to door until they are glowing hot, then throw in some small kindling. When that gets going I then add my bigger splits.
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I had a similar issue, and used a similar solution. My procedure had been: (1) hot reload, wait 5 min, close bypass, (2) wait 10, reduce air to 50%, (3) wait 5, reduce air to final, usually minimal. Occasionally still had a small amount of visible smoke 45 min. after the reload. Increasing (2) from 10 min. to 15 has mostly fixed it. At the moment, all of my wood has been stored under cover for at least 4 years; I haven't seen MC over 15%. Mostly hemlock and alder with rare splits of cherry or fir.
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