franco b wrote:
McGiever wrote:Volatiles must be consumed at a timely rate or...boom!
Exactly. Those volatiles might very well be CO as well. When troubleshooting any mechanism it is often helpful to ask, how could I deliberately make this happen. There is a flaw in the basic theory of operation of this machine that is unable to cope with conditions existing at shut down. Supply proper air and heat at that point and there will be no boom.
Did I mention somewhere within this long thread that Jeff Gingerich of AHS (former owner of the company) told me that puff-backs are always due to poor anthracite coal (I'm assuming here that he means lots of volatiles and perhaps lots of dust, or poor grade as to size) and insufficient draft? I contend that if the sight tube door does not spring open properly and immediately and sufficiently when the fan shuts off there is a condition of poor draft across the top of the super hot coals at the immediate juncture where the unburned coal is riding atop them, regardless of how well the chimney is drafting.
When I asked Jeff about opening the small rotating window port on the sight tube cover he told me to close it all the way if my coal was good and my draft was also good. He said they only added it for bad draft and bad coal.
Perhaps also as the mines have over the years "highgraded" their mining, thereby mining the very best and easiest anthracite coal to get to first and therefore long ago, the remaining coal itself is slowly getting to the point where even the best of it remaining is quite often no longer as good as it was when this boiler design originated?