While I believe a baro damper is not 100% necessary in MY APPLICATION, I do understand there are some finer points of draft control I just do not understand. Outside temperature change, atmospheric barometric pressure, height/length of flue & wind are just 4 variables one must consider for most efficent operation. How much these 4 variables effect a coal burn surely is different in every application since no two are exactly the same. I do not know if a properly installed and tweaked baro control would really help my system as I believe it works really well once the temps fall into the 30's and below. But having said that, I found a web site today which explains and offers a baro controller for solid and or gas fuel burns. They also sell models different than the one piece Tee you often see in the coal stove stores.