About the 'tater chips. BIL stated they were from the refractory. I am wondering if the chips could be some mineral from the ash that was vaporized then condensed back there to flake off in chips. We opened up a large water tube type boiler at work for refractory repair. I pointed out some chip like materiel scattered about downwind of the burn chamber that had peeled from the refractory. The explanation was that in our location, the natural gas has some small amount of mineral in it. Since the unit had run 24/7 burning about 700 CFM for two years, the mineral had collected and flaked off over time. I asked why it stuck to the refractory and not the iron piping and the answer was electrical charge. At those temps the mineral has the same electrical charge as the piping does, causing the mineral to pick other areas to stick to while it is repelled from the piping. We know that wood ash is various mineral. Do you think the chips you observed could be something similar to what I observed in the boiler? On a side note. The chips were not the reason the refractory was being repaired.