Well, tonight was full of new experiences, and that new cat probe came in mighty handy. Being already tired of the two-load process to get the stove up to temp and then loaded for an overnight run, and getting home to start the stove much later than usual, I tried building my first top-down fire. Bottom up, I had four big splits (6" x 6" x 20"), fire starter, kindling, and then two small splits. I should have had three small splits on the top, but more on that later.
I got things warmed up and the cat engaged, before heading up to put the kid to bed. I set the primary air to 50%, leaving the wife with instructions to go to 25% then 0% over the next 15 minutes. Apparently she forgot, and when I came down to check things 30 minutes later, the stove was a very warm 575*F with the cat at 1170*F. Not crazy hot, by any means, but the big load was just starting to really take off, more than I'd like to see. I figured another 20 minutes in that mode, and we could have had a glowing stove.
I started to throttle down from 50% air to 0%, and quickly became aware of how useful a cat probe is. I was able to play the game between lowering the air and watching the cat probe temp shoot up with each change, keeping the cat probe temp below 1400*F while still slowing the fire as quickly as possible.
We're now cruising at 0% primary air control, stove top at 500*F and falling, and cat holding roughly 1000*F. Room temp came up from 67*F to 72*F very quickly with this monster stove at 575*F. Now we're holding steady.
Lessons learned:
1. Put more small splits on top of the kindling when starting a top-down fire. While my stove top got quickly up to 450*F, because the fire was started literally right under the top, I did not have enough small ammo loaded to get things going to the point where I could engage my cat. Throwing in a third, medium-size split, got things going better.
2. When your stove is going way stronger than you'd like, perhaps on the verge of a run-away, resist the urge to shut down the air too quickly, lest your secondary system go completely nuclear. Work it down in very small increments. (Actually, I already knew that, but this reinforced the concept)
3. If you're not running with a cat temp probe, for goodness sake... get one! If nothing else, it will make you understand how your stove works so much better.