So I went to load the P&M 250 this morning and as I approached the boiler shed I could smell that it had just shut down. I knew that I was in for a backdraft or fireball as I had loaded it with more big ash the night before than I usually did. So I cracked the door and let it bleed off the gasses for a bit, then slowly opened the door.
I know what you're thinking... Whoosh and no more hair. Nope. The rest of the gasses flowed out of the door and everything seemed fine (although very smoky in the shed!).
I began loading for the day and everything seemed fine. Then as I was throwing a piece in, there was a loud CRACK like a gunshot. Scared me and I jumped back. Some gasses had been sucked into the reaction chamber, mixed with the fresh air and exploded with the sound of a gunshot. I've had huffs and whooshes many times, but never a sharp snap/crack explosion. Those fresh gasses are VERY explosive!
Life is full of surprises.