Key Damper experience so far

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weee123

Feeling the Heat
Oct 19, 2022
452
NJ
Well so far I am now a strong proponent in installing a key damper whether draft requires one or not. The fine tuning ability it provides you over just the stove damper is huge.

For example, say slightly open is too much, but all the way shut is too little, you can set it slightly open and then start to close the key damper until it starts to slow the fire down to a nice happy burn.
 
I think I installed mine summer 2016, along the magnehelic to monitor flue pressure, and honestly can't imagine operating a stove on this tall pipe without a damper. I'm even thinking of installing one on my shorter stack, as even 15 or 18 feet can rage pretty good in bypass mode, or during the initial 20 minute high burn that BK prescribes for each load through these stoves.

Put otherwise, my 30 foot pipe with a damper is more tame and well-behaved than 15 or 18 feet without.

Did you install some sort of magnehelic to monitor flue pressure? You can get by without, but it's sort of like trying to drive a car by the rearview mirror, as your only evidence of its effect would be the behavior of the burn several minutes after making an adjustment.
 
I actually just picked up a magnehelic from work and will be installing it soon. Just need to get a piece of steel tubing to hook into the flue pipe. How far up the pipe did you install yours?
 
I have an in-line flue damper (key damper) and a manometer (measures draft). I use the manometer and the flue temperature to run my stove. I could not run the stove without these. I adjust the damper as needed. Without the damper I was getting very excessive draft (.18) and flue temperatures (1200 F). And I only have 14.5 feet stove top to top of chimney!! My target draft reading is .04 or .05.
I place my manometer probe 4" above the stove top. Used copper tubing similar to an ice maker water line.
 
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I put one in this year just for testing. Our flue system is 20' tall and in the previous 14 yrs of service the stove has performed well without it but in the name of science and hearth.com the damper was worth a try.

For the most part, I find the damper still unnecessary. We are having an unusually warm start to winter. With temps in the low 40s the damper is more of annoyance if someone forgets to open it before reloading. This has happened twice to me and once to my wife. With this 43º morning's load I have full control of the fire with the flue damper open. That said, this year we have unusually dry firewood. When the temps drop into the 30s, with some full loadings, the fire really takes off. Without the damper, the flue temperature would peak in the 800º range. With the damper I am able to keep it from going above 700º. The wood this year is crackling crisp. No need for kindling to get a full load fire in about 10 minutes.

So far, the damper's best use had been as an emergency brake. It's still early and maybe we'll see some below freezing temps eventually. If so, I may be using it more.
 
I installed one at the beginning of this heating season to slow down a very strong draft.

Prior to that, I would have a fan on the double wall to keep temps under control early in the burn... it was a problem even with closing the air intake to the minimum and as early as possible.

It certainly is easier now to prevent excessive draft; however, I'm limited on how far I can close that damper. At times I cannot close it far enough to keep flue temps centered in the normal range without getting a bit of smoke leakage into the room, about a 45 degree angle max.

Also, even with the key damper fully open it takes longer now to achieve operating temp. On reloads it allows a bit of fine ash to exit the loading door. It is surprising how much resistance it introduces even when fully open.

fluedamper.jpg
 
I installed one at the beginning of this heating season to slow down a very strong draft.

Prior to that, I would have a fan on the double wall to keep temps under control early in the burn... it was a problem even with closing the air intake to the minimum and as early as possible.

It certainly is easier now to prevent excessive draft; however, I'm limited on how far I can close that damper. At times I cannot close it far enough to keep flue temps centered in the normal range without getting a bit of smoke leakage into the room, about a 45 degree angle max.

Also, even with the key damper fully open it takes longer now to achieve operating temp. On reloads it allows a bit of fine ash to exit the loading door. It is surprising how much resistance it introduces even when fully open.

View attachment 321205
Couple of comments: I do not see how a fan blowing air on the outside of a double wall stove pipe will influence the temperature of the air inside the stove pipe.
I suggest that you get a probe thermometer for measuring the temperature of the air inside the stove pipe. It looks to me like you have a magnetic thermometer attached to the stove pipe. If you have smoke leaking into your room, you are not re-burning it with secondary combustion. Flue temperature in the normal range as displayed on your thermometer will be well under the actual temperature inside the stove pipe.
I also suggest that you get manometer or magnehelic to measure draft. Knowing the draft will help you set the damper.
I understand every situation is different. In my set up I have added metal inside my damper to cut off more of the air flow; and yet I do not get much effect until the damper is almost 45 degrees closed.
 
I agree there are installs where it is needed but it adds another variable and I’m still learning mine. It complicates control and I don’t like that aspect.
 
I'm finding I rely more heavily on my flue damper as time goes on. Its almost my primary method of control now, when lighting I start closing it down before I close down the stove damper.

I should get a magnehelic, but I'm not sure exactly where I'd put it. Ideally I'd drill and tap a pressure port on the rear of the stove, but I'm not sure if this is as accurate, and install the magnehelic under the ash lip.

What I'd really like is a set of automotive analog style gauges with a digital flue probe (pyrometer from a diesel truck) and a vacuum gauge, issue is none of them accurately read vacuum down to hundredths (or even tenths) of an inch of water column.
 
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I also use one, before installing I was operating at .18"wc thats over 3x draft of what the stove was calling for, before installing I was literally blowing threw loads of wood, had excessive coaling and not enough heat, the heat was literally being sucked through the chimney like a blow torch, since installing the damper, things are much slower and way nicer.
 
I have one, I have used it a couple times, as in 2x.
I’m glad I have the option.
 
Got the magnehelic installed. Looks like im cruising around .12 WC

Also, since I have the new Iphone it seems the pics I take are too large to upload now. So that’s cool.
 
Got the magnehelic installed. Looks like im cruising around .12 WC

Also, since I have the new Iphone it seems the pics I take are too large to upload now. So that’s cool.
That's damper open, or closed?
Just crop the pics a bit, that will do the trick
 
That's damper open, or closed?
Just crop the pics a bit, that will do the trick

That’s damper full open. I dampered it back to below .10
 
Couple of comments: I do not see how a fan blowing air on the outside of a double wall stove pipe will influence the temperature of the air inside the stove pipe.
I suggest that you get a probe thermometer for measuring the temperature of the air inside the stove pipe. It looks to me like you have a magnetic thermometer attached to the stove pipe. If you have smoke leaking into your room, you are not re-burning it with secondary combustion. Flue temperature in the normal range as displayed on your thermometer will be well under the actual temperature inside the stove pipe.
I also suggest that you get manometer or magnehelic to measure draft. Knowing the draft will help you set the damper.
I understand every situation is different. In my set up I have added metal inside my damper to cut off more of the air flow; and yet I do not get much effect until the damper is almost 45 degrees closed.
Hi Tom, I am indeed using a probe type thermometer, a Condar Fluegard. It does use a magnet to help keep the probe positioned. It's difficult to see in the photo.

A fan moving air across the DW stovepipe certainly does lower the internal temp substantially, according to this thermometer.

Regarding secondary combustion; that is without a doubt working as intended, very intensely. A sniff test reveals the leakage is between the key damper section and the stovetop collar. That tells me the flue gasses are not flowing past the damper with sufficient ease and so some is being forced out below the damper, presumably due to 'combustion pressure', for lack of a more precise term. Not billowing smoke by any means, just a hint of smoke scent.

Tonight was a much different burn experience: I was able to close the key damper completely with no evidence of leakage. The secondary burn was less intense than usual as a result, nice and leisurely. It appears that I am getting a longer, more even burn time as well. I didn't do anything differently.

Perhaps I'm behind on the learning curve... maybe I'll get the hang of it with more practice!

The suggestion for a manometer is a good one... I should consider it.
 
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That’s damper full open. I dampered it back to below .10
You could go down more, -0.04 to -0.06 is a common spec for draft on modern stoves.
 
Hi Tom, I am indeed using a probe type thermometer, a Condar Fluegard. It does use a magnet to help keep the probe positioned. It's difficult to see in the photo.
Goat, Thanks for the update and info.
I think these stoves are a learning curve that never ends. Every fire is different to some degree.
As I stated in post #4, I could not run my stove without the temperature probe, the manometer, and the damper.
Good luck with all future burns.
 
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You could go down more, -0.04 to -0.06 is a common spec for draft on modern stoves.
Didn't realize the spec was that low. So far I've been dampering to about .08 and it seems to be running much better
 
Got the magnehelic installed. Looks like im cruising around .12 WC

Also, since I have the new Iphone it seems the pics I take are too large to upload now. So that’s cool.
I got a 15 a while back, and most pictures I take now, I have to screenshot, crop, then post. It’s a pain. I’ve changed the resolution settings in the phone to worst, and it still didn’t help.
 
Screenshot_20231223_145123_Samsung Notes.jpg


I was just looking into this. I'm having smoke issues due to what in sure is a mis-balanced outside air system and am getting ready to dig into it.
 
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