That is a fascinating and very educational story for me. Thank you for sharing it with us.
You cannot be careful enough running these furnaces, boilers and stoves, and by telling your story you probably have saved a few people out there perhaps, a very dangerous fire that will not now happen.
In summertime when I shut down my VA-600 Van Wert coal stoker, late June to late August, I keep coal stoker warm and dry by letting a little warm water
feed back into the stoker unit when I am using the oil burner for summer domestic water...
....in winter time it is the reverse and warm water from the
stoker feeds back into the oil burner. seems to keep everything dried out.