I have a Woodgun E180 and have learned to live with the chugging or huffing whatever you call it when burning very dry wood. It is a normal part of my burning now, I dont pay any attention to it anymore. I was just thinking why not have a large diameter short stroke piston of sorts in a wall of the firebox connected to a crankshaft and flywheel and take advantage of these "explosions". I would guess frequency at approx 3 per second. my boiler weighs 2700lb and shakes (slightly) to this so there must be some significant energy there. It has been doing this since day 1 and I tried everthing to stop it but at the end of the day it doesnt hurt anything and heats the house perfectly so I just let it do it's thing.