Oh man,, don't get me started on reliving my learning experiences with my AA260.. OUCH,, what a frustration for about a month.. Suffice to say,, the directions for starting a fire in the AA boilers is too simple.. the directions work fine for a AA 130 because of the much smaller firepot.. But in the AA 260, the firepot is huge,, and it is possible to get a fire burning in only part of the firepot. And there is NO WAY to see this, or know that it is a partial fire,, except to see lots of unburnt and partially-burnt coal in the ashpan..
So the experiment was an attempt to drop the firebox or fire tube level lower into the ashpan, making for a deeper fire,, in an attempt to burn the coal better... But it was a failure because even after several experiments I still was getting only a partial fire in my firebox...
ONce I discovered the partial fire situation, by digging out the unburnt and partially burnt coal from around the central column of burning coal in the firebox,[by reaching in from below and over the ashgrate and ashpan], I had one of those head-slapping moments,, AH-HA !! and knew then what to do, and that I needed to assure I had the ENTIRE firebox burning.. ONce burning completely,, the AA has run flawlessly for 5-6 months..
My above problems seem to only exist in the bigger AA260, not in the 130 size boilers.. the difference is the size of the firebox and the amount of coal burning in it.. There are numerous 130 boilers, both AA and AHS on the forum with ZERO issues mine was the only one with this problem... mostly created by myself, and by my instalation in my odd-ball setup.
Read my story in the 'Axeman Anderson 260 Disection' thread... do a search for the topic,, it is about 15 pages long,, from this time last year..