whistlenut wrote:Your 'slag' dam sounds very strange. Is it possible that there is a fused piece of coal causing that back-up. That problem is unheard of, so when you can, shut it down briefly and clean off the grate, remove it if necessary and make sure the holes are all free, and keep a few small drill sizes handy to drill out anything plated with slag. Keep us posted, your situation is unique.
That may be the case, as I had a restart once I had the pipe work finally installed. It was running without an issue up to then, and I've pulled half the coal pile (coals and unburnt) into the ash pan to try to fix the problem, but I have not checked the holes with the unit off.
Saturday is coming, so I guess a full cleanout is in order.