Yanche wrote:I'd be interested in learning members experience with the depositing of fly ash vs. the location of the barometric damper.
It also seems to me that you want to use flue pipe velocity to your advantage and help deposit fly ash where you want it. Ideally the fly ash would make it all the way to your chimney and then fall to the bottom clean out. This would require damper placement close to the chimney, since it is what causes a change in flue gas velocity, and the resultant dropping of fly ash. For those of you that have a damper close to your coal stove does the fly ash collect in the stove pipe between the damper and the stove? Or does it make it past the baro.
I have about a 25' clay line brick chimney, 8x8. My boiler has a 9" stack outlet. Nine inch pipe goes horizontal out the rear for about 12" and then an elbow. Pipe then goes 4' at about 60 degrees up to the next elbow then reduced to 8" to go into an 8" piece of cast iron pipe that someone used to go through the stone foundation wall and into the chimney. Keystoker recommends the damper in the "first full section of stove pipe" I put mine in the four foot section running up at about 60 degrees. My first attempt was to go cheep and use an 8" damper (which I had) on the 9" pipe. Field controls says it can be put on 7,8,&9 inch stove pipes. During the heating season the 8" damper was not able to consistently keep the draft low enough in my boiler so I had to spring for the 9" damper which works fine.
Fly ash is distributed throughout the stack and accumulates in the horizontal pipe out the back of the boiler and in the horizontal pipe going through the wall and in the chimney sump. Cleaning these areas twice a year is sufficient for me. Once in October/November before heating season and then again April/May at the end of heating season. The boiler has fire year round.
I clean my mothers coal boiler also. It has a pipe layout much like mine but has about a 6' run at about 45 degrees between the elbows. It is a 7" pipe and the damper is about 12-16 inches behind the boiler in the horizontal pipe. This boiler runs year round also and we clean it only in the fall. Again the fly ash deposits in the horizontal runs of pipe and in the base of the chimney.
That is what I experience FYI. I have never contemplated what moving the location of the damper would do. As long as things are working I won't be fixing it. Other folks experiences would be interesting too. If there is a proven "better way" I would look into it down the road when my pipes need replaced.