Yup, some fire dept. work via the stove, especially with tough, snow covered roofs. These are experienced firefighters in full protective gear( or should be) that have the training and proper equipement, fight chimney fires every year, have the ability to chase fires in walls etc. and of course it's not their home so they stay calm and do a great job. But even then I've seen some ffs open the stove, hit the fire and send sparks all over a nearby rug. Never good to play surgeon, pilot or firefighter. Back to chimex, if it works do you wait to see if the fire has migrated to the attic or walls or just hope. We could beat this topic to death, theories are fun, but clean chimneys save lives and homes. Be safe.
Ed
Ed