Installing butterfly damper in stove outlet

[Explorer2402]

I have a 8020 Hearthstone Heritage wood stove. I have been having symptoms of too much draft and I'm thinking that a flue damper could help regulate air flow better. Unfortunately I don't have much space to work with. The outlet from the stove goes directly to an elbow (angled at about 15 degrees) which connects to the flue liner. The only part of the flue that is actually exposed is the elbow and a small amount of the liner (picture 1).

What if I installed the butterfly damper in the actual outlet of the stove, like in picture 2? Would this function as well as if it were installed higher in the flue? I would appreciate any advice!

More background info:
- Stove is about 10 years old bought used
- Chimney is in center of house
- Chimney liner is 6" stainless new 9 months ago, professionally installed
- Flue length is about 30 feet
- Fireplace blockoff plate installed around flue with roxul insulation above
- Metal panels fastened to fireplace behind stove with 1" offset to help reflect heat
- Brand new ceramic insulating blanket in stove
- Has been shopvac'd to remove all ash before season start
- I removed the secondary air pipes to verify they were clear, cleaned and reinstalled
- Door seals checked with dollar bill test and they are tight

Why do I think I have too much draft:
- stove never smokes during a cold start, and you can feel a little draft in the cold stove with your hand
- stovetop never gets over 375 degrees
- it is hard to get stovetop over 300 degrees
- usual starting procedure is a few pieces of fatwood and a lot of small dry kindling pieces interlaced, get flue temp to 600 degrees and then gradually reduce air over next 30 minutes (following Browning's thread)
- I have tried well seasoned wood from my neighbor as well as biobricks, and cannot get this stove to 500 degrees after trying about 20 times. The hottest part of the top surface is the back right and the front left is about 100 degrees cooler
- I have had wood stoves before in other houses, and I believe that for the size of the firebox the wood is burning at an OK rate. If I fill the firebox before going to bed it will be fine ash by morning, only a few small embers left.

 

[Batman]

I can't see a downside to it. It looks like that would be the easiest place to put one. Shouldn't matter where in the flue the damper is placed. Bear in mind that most modern stove makers recommend against using them, but to my mind, its worth the ten dollar gamble.

I installed one in my rangeley, even though jotul says that they are not needed. I don't use it much, but its nice to have it when the stove goes nuclear, and to just plain play with.

In short, why the hell not? I say go for it.

 

[MountainStoveGuy]

30' is allot. All your points are correct with overdraft symptoms. Personally I like to run soapstone in the 400-450* range. Squeeze a damper in there wherever you can! My burn times are similar to yours using local pine on a 24' chimney @ 9000'

 

[Grisu]

- usual starting procedure is a few pieces of fatwood and a lot of small dry kindling pieces interlaced, get flue temp to 600 degrees and then gradually reduce air over next 30 minutes (following Browning's thread)
- I have tried well seasoned wood from my neighbor as well as biobricks, and cannot get this stove to 500 degrees after trying about 20 times. The hottest part of the top surface is the back right and the front left is about 100 degrees cooler

Once warm, are you then loading the stove full with the dry wood? Or do you try to get the stove to 500 F just with the kindling? How are the secondaries looking?

 

[Explorer2402]

So an update. I installed a 6" flue damper right in the outlet like shown in the picture. This seemed to help control the draft. I have done about 10-12 burns since installing and stovetop temps are getting up to 350 routinely, but still not past 375.

@Grisu generally I will use a full box of kindling, then when there's room I add small splits until the stove top gets to 300, at which point there are some good coals and I load in dry logs. This will take about an hour, sometimes more.

Before installing the flue damper, the only way I could get secondary burn (flames shooting from holes in overhead rods) was by opening the ash door and letting it roar for a couple of minutes, then closing the ash door and closing down the air control. Then I would get secondary burn for about 1-2 minutes and then nothing from the secondaries.

Now, I am getting secondary burn with the air control in almost any position when the stove top is at 350 degrees. However, most of the holes are not lighting up at the same time. The best way to describe it is that the flames coming up from the logs are bluish and wispy, and when they rise to the level of the burn tubes, then I will get ignition from a few holes.

Also, now that I have the flue damper in, I find it's effective to close it when the stove gets to about 200. Even with the side door cracked and the damper closed, I don't get smoke in the room. I only close the side door when there's a sustainable burn.

Ideas? I may end up giving up on this stove and buying a new one, but I don't want to have the same problem with an expensive new stove.

 

[begreen]

It sounds like a great improvement. You don't necessarily want a fountain of fire coming out of the secondary tubes. A wispy, wraith-like bluish flame is good. If you want more activity and heat open the flue damper a little bit to increase draft a bit more, but not wide open. Maybe try it at a 45 deg angle for a day or two.

 

[Grisu]

BeGreen is right, you don't need gasburners shooting from the baffle tubes. Wispy blue flames are the sign of an efficient, clean and sustained burn. However, your description so far fit more with wet wood than overdraft. Since you don't see an improvement when burning Eco bricks that does not seem to be the issue here either. Do you have the baffle plate and a ceramic blanket on top of the burn tubes? Somehow I am wondering whether your baffle area just does not get hot enough for a longer secondary burn.

 

[fitter9]

Correct me if I'm wrong, but wouldn't overdraft cause the stove to go nuclear with stove top temps that are over 700 and uncontrollable ? The op said he can't get his stovetop over375????

 

[Explorer2402]

@Grisu My model is the 8020, which is the older Heritage. So I have firebricks on top and a (brand new) ceramic blanket on top of those. When I went to install the new ceramic blanket, I actually took out the secondary burn tubes, cleaned them, then removed the firebricks, cleaned them, and re-set tightly, then smoothed the new ceramic blanket on top of them. I am going to get some more ecobricks for a couple days and try to burn those exclusively to see if I can completely rule out wet wood.

So while the symptoms make it plausible that the baffle area is not getting hot enough for a sustained burn, I don't see anything out of place that could cause that to happen.

@fitter9 I have tried to push the stove to "nuclear" by opening the ash door. If I have a good burn going (stovetop 300) with plenty of coals and some burning logs, and then I open the ash door and open the flue damper, there is a huge surge of flames. But, there is only minimal secondary burn (at least what I can observe - no flames shooting from burn tubes and flames in firebox are very yellow). All those yellow flames look like they're shooting right up top through the baffle at great speed, and there isn't an appreciable gain in stove temperature even when I leave it like this for 20-30 minutes.

 

[begreen]

@fitter9 I have tried to push the stove to "nuclear" by opening the ash door. If I have a good burn going (stovetop 300) with plenty of coals and some burning logs, and then I open the ash door and open the flue damper, there is a huge surge of flames. But, there is only minimal secondary burn (at least what I can observe - no flames shooting from burn tubes and flames in firebox are very yellow). All those yellow flames look like they're shooting right up top through the baffle at great speed, and there isn't an appreciable gain in stove temperature even when I leave it like this for 20-30 minutes.

Don't do this unless you like expensive repairs in short order. With good dry kindling and seasoned wood it's completely unnecessary.

 

[fitter9]

there are a lot more "seasoned" people on this board than me, but the problem to me seems to be lack of draft, or not so dry wood. a damper is going to slow the air thats going threw the stove even more. I'm not familiar with your stove but did you reinstall the baffles,firebrick or blanket correctly after cleaning or replacing them?

 

[Explorer2402]

I had this problem before I touched the firebrick and blanket. After reading different posts on Hearth.com I thought that maybe the blanket was the problem. I'm 99% sure I replaced everything correctly. The firebricks seat very tightly and I had the stovepipe off so I could reach down into the stove and smooth the blanket over the firebricks evenly.