i posted last feb. about a boiler i was looking at made by wasser. after some research it is identicle to a harman sf 360 and was made in manitoba. i bought it and recently hooked it up to 500 gallons of storage. after looking at it and watching/reading about secondary air for more effecient burns, im thinking it could be modded to have pipes come in from the bottom up the back and run parallel to the water pipes in the boiler, with the holes aimed at them. a sliding shelf could be installed below the pipes to force the smoke to the front and pass these pipes instead of heading strait up the flue. when loading it could be moved towards the door to allow smoke a path strait up and out. secondary air intake could be controlled by a normally closed valve powered by the damper door circut. i wont be doing any mods this heating season as its up and running now. has anyone done this in a boiler? ive seen the youtube vids where its done on stoves and it seems to work well. i know im not going to turn this into a full on gassifier, but i think i can increase its effeciency quite a bit. thoughts ans ideas are welcome.