BIG BEAM wrote:Or is the baro needed so that the fire stays the same.I mean if it gets cold at night and the chimney starts to draft better and the furnace starts to make more heat isn't that a good thing because if it's getting colder you would want more heat.
Yes, you need it so the fire stays the same, that is, so you can predict how fast the burn will be based on how much you open the air inlet. Without the baro, it's true that colder = more draft = more heat, but the "more heat" you get may be less than or greater than the "more heat" you need. Without the baro, it's also true with many chimneys that more wind = more draft = more heat, again not necessarily in direct proportion to how much more heat you need due to the wind. There is potentially the effect, also, of sucking the combustion gases through the stove and up the chimney faster than they can release heat to the stove, so you have a nice high stack temperature (i.e. wasted heat) but not enough heat in the room.
As a born-again baro user, who originally was as skeptical as you, I highly recommend the baro.