We have started having a severe smokeback issue.
I don't know what's relevant, but on wednesday, we went to 12 hr intervals between loads instead of 2 hrs, and also added the last of the insulated pipe and cap outside. On friday we started having more smoke push out the pipe joints. This continued through the weekend but the stove was useable. Sunday night, we primed as usual with small pieces of paper and cardboard in the riser, then let a few pieces of kindling burn down, then kindling and two pieces of wood, then a full load (leaving three inches at the front and top.) This burned cleanly for ten minutes with all the wood in the box ignited. Suddenly the p channel started belching smoke, followed by every possible gap. We pulled the caps and inspected for blockages, and removed a wad of paper. Waited until the next night and got the same behavior.
Yesterday i piped up a bypass to omit the ground loop and the stove ran with no major issues, although it seemed cooler and dirtier than i expected. No temps, sorry.
Last night we tried the same startup with a cleanout outside on the last vertical uncapped, and got the same behavior, except that during failure mode, smoke poured heavily out the open cleanout.
At paul's suggestion, this morning we tried opening the building door as soon as it started smoking, and it was no better.
Would appreciate any suggestions. I'm just learning about these beasts and I'm not sure what to try next.