I know that talk of a barometric damper comes up from time to time. Those of us who have wood furnaces, most companies require them. I've also seen Blaze King recommending them in cases of overdrafts. I just got done relining my chimney which was too big. When I would go to the top of the chimney, the temps would be maybe 90 degrees causing alot of condensation. I always knew that the baro was allowing cool air into the flue which that on top of a 11x7 external chimney was a recipe for disaster. I capped my baro towards the end of the season and I still achieved overnight burns, better performance but lost burn times by a little.
Being concerned I contacted the manufacturer of the furnace and questioned them about the use of a manual damper instead. Their reply was they are meant for old fashioned burners, not epa burners. They are dangerous and should not be used. Well there are a few things that I question now. One is with the old chimney that was too big...When the fire was burning full bore with the damper open, the chimney would overdraft without the use of a baro. But when the damper would close when demand was met, the flue being too big the draft would drop too low and the furnace wouldn't perform like it should. Now with a liner being 5.5" when the damper closes, the draft will be much greater than before the liner right? With the damper open how will the liner be different as far as draft is concerned then with the old chimney? What I am worried about is now that the chimney will stay much hotter with the liner and insulation, with a baro open leveling draft will it cool the gasses below the point of condensation? I know that barometric dampers get a bad wrap. Alot of times when they are installed on a smoke dragon they plug, produce nasty creosote levels, etc. But with units that burn cleanly buildup is minimal. Draft is even through out the burn and more heat is extracted from the unit as well as better combustion. I guess I don't know what to expect having the liner. Theres nothing I can find online about studies showing the effects of a baro on wood flue temperatures. I've heard the velocity can increase after the baro sending gasses out much quicker with air entering the baro. If thats the case then there is little that can accumulate on the chimney walls. Any thoughts? Wood is actually seasoned this year and the chimney is fixed so I am sure things will be better.
Being concerned I contacted the manufacturer of the furnace and questioned them about the use of a manual damper instead. Their reply was they are meant for old fashioned burners, not epa burners. They are dangerous and should not be used. Well there are a few things that I question now. One is with the old chimney that was too big...When the fire was burning full bore with the damper open, the chimney would overdraft without the use of a baro. But when the damper would close when demand was met, the flue being too big the draft would drop too low and the furnace wouldn't perform like it should. Now with a liner being 5.5" when the damper closes, the draft will be much greater than before the liner right? With the damper open how will the liner be different as far as draft is concerned then with the old chimney? What I am worried about is now that the chimney will stay much hotter with the liner and insulation, with a baro open leveling draft will it cool the gasses below the point of condensation? I know that barometric dampers get a bad wrap. Alot of times when they are installed on a smoke dragon they plug, produce nasty creosote levels, etc. But with units that burn cleanly buildup is minimal. Draft is even through out the burn and more heat is extracted from the unit as well as better combustion. I guess I don't know what to expect having the liner. Theres nothing I can find online about studies showing the effects of a baro on wood flue temperatures. I've heard the velocity can increase after the baro sending gasses out much quicker with air entering the baro. If thats the case then there is little that can accumulate on the chimney walls. Any thoughts? Wood is actually seasoned this year and the chimney is fixed so I am sure things will be better.
