location of baro damper

I've cleaned out my little coal system for the upcoming season and purchased a barometric damper.

Instructions for installation show the baro damper should install between the stove and the solid damper I already have installed.

One good reason given is that this would allow vent cutoff in event of a chimney fire... but I burn coal.

Also, in this position it can closeoff the flue when not in use.

it seems to me that the solid damper should go between stove and the baro damper to regulate outflow to the flue.

Can anyone give some reasoning here? Thanks.

Someone correct me if I am wrong...I don;t think you have to worry about a chimney fire with coal, the fly ash doesn't burn....That reasoning was probably for the old Wood stove reasoning, creosote build up could ignite.

I would think the manual damper should be between the Stove and the Baro Damper, if the other way, if you close off the manula damper, the fumes back up and can leak out the baro into the house!!
You really do NOT need a manual damper for most stoker stoves.

That is how mine is, I would not want the plate after the baro for the reason you describe.

I guess, maybe I can hijack this thread, but keep on topic.

Please explain to me how the baro and manual dampers play in this modern age. Before the baro, the only thing used was the manual pipe draft.

My installation doesn't have a manual pipe draft, but I'm wondering if it wouldn't help? And just when/how/why?

The manual is found on a lot of hand fired units, not to often with stokers.

On my stoker, I only have the auto baro damper to automatically control the draft in the stove along with a draft gauge (Dwyer MkII) to monitor it. Makes it much easier to adjust and calibrate. I never really knew what my chimney was doing.

You don't want it to reduce the draft too much from the stove so that the heat/exhaust builds up in the stove and starts backing up thru your hopper.

Thanks for the reasoned comments.

I've installed the baro as shown by WNY's diagram, which is what I think is best also. Firing it tonight has worked well.

I've set the draft to 0.02"WC to 0.04"WC as described.

I'll let you know how it works.

If you are using the Baro Damper why would you need the manual one? I'd be inclined to just eliminate it completely. If you already have the pipes installed, then I would say leave it, though.

I'd be interested in learning members experience with the depositing of fly ash vs. the location of the barometric damper. As I see it many of the recommended locations for barometric dampers are based on fuels other than coal or are just wrong in my way of thinking. As I see it a barometric damper should be located at the chimney thimble and should be sized based on the chimney stack size and height. Think of it this way, the damper is a flow control device, it needs to operate ideally in center point range. That means it need to be sized on chimney size not on the connecting stove pipe size. For example if I had an industrial size monster of a chimney and I wanted to vent a little coal stove, its small 4,5 or 6 inch barometric damper would always be open. No regulation at all.

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.

Yanche wrote:As I see it a barometric damper should be located at the chimney thimble and should be sized based on the chimney stack size and height.

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.

I would have to concur.

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.

I have read much on the topic of manual and baro. dampers and manometers on this and other threads. Right now I don't have any damper. Most of the time the flue temp (based on a magnetic thermometer about 1 foot above the stove) is about 150*. I get a lot of wind, and when the wind gets blowing hard, the flue temp goes up to as much as 300*.

I understand that a properly set baro damper will open and pull room air to reduce the negative pressure of pull on the stove, and thereby not pull stove hot flue gasses up the chimney and waste fuel. However, then the baro is alowing heated room air to be pulled up the chimney. That may be more cost effective than loosing the very hot stove air, but I want the best of all worlds.

Would adding a manual damper before the baro damper allow me to reduce the heat loss from the stove with that, in high winds, and manually close the baro damper to prevent loss of room air. Under normal wind velocities I would open the manual all the way and allow the baro to take over regulation of the draft I do plan to buy a manometer.

grizzly2 wrote:Would adding a manual damper before the baro damper allow me to reduce the heat loss from the stove with that, in high winds, and manually close the baro damper to prevent loss of room air.

Don't worry about the room air (everyone seems to in the beginning), its sacrifice is well worth the fuel savings.

You can't be there everytime the wind picks up or when the wind dies down.. The automatic action of the barometric damper is it's best feature... It will safely keep your chimney draft under control, whether you are sleeping, away at work, or watching it...

The amount of heat from the room is a small loss, the heat from the coal, is a large amount of wasted heat and fuel.. If you are seeing 300* on the outside of the flue pipe, the inside temps are around 450-550* That's a lot of lost heat and wasted coal.

I think once you get a baro installed, and a manometer I think you will see a reduction in coal burnt.

Greg L

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Thanks Coal and Greg, That is what I needed to know. When I clean out the pipes, in goes the baro and manometer.