Too much draft?

[wondermic23]

I recently installed a Sierra 2100HS in the fireplace of my new home. I'm used to burning with a smaller non catalytic stove (Englander) similar in style to the Sierra but smaller. I ran a SS liner up the chimney and mounted the stove on my hearth. I think I have too much draft since I can hear a good amount of air coming down the chimney before it's lit. Once lit it will burn up around 800 degree with the damper fully closed until it burns down a bit then will run at about 600 for a few hours. Additionally, I don't feel like it is heating as well as it should for the size of the stove. I have not installed a damper block off plate but I did seal the top of the fireplace chimney (probably not air tight). My questions are: Should i do something to reduce draft? I.E. flue damper or reduce liner size to 5". Will the damper block off help with heat loss?

Here is the link to the stove I'm using:

(broken link removed to http://sierraproductsinc.net/woodstoves.htm)

 

[Grisu]

How tall is the chimney? Where do you take your temp readings? Were there problems with the Englander before this one?

I think I have too much draft since I can hear a good amount of air coming down the chimney before it's lit.

That would be a downdraft which would make lighting a fire more difficult, not causing excessive updraft. Do you have problems with smoke spilling into the room at start-up?

Once lit it will burn up around 800 degree with the damper fully closed until it burns down a bit then will run at about 600 for a few hours.

That sounds like it is cruising along nicely once it settles in. I would first try to change a bit your operating procedure to not have those high peak temps. Are you raking the coals forward before loading the wood or do you put it right on the hot coals? By how much and when do you adjust the air?

Additionally, I don't feel like it is heating as well as it should for the size of the stove. I have not installed a damper block off plate

Do the block-off plate and you should see an immediate improvement in the heating performance.

 

[wondermic23]

How tall is the chimney? Where do you take your temp readings? Were there problems with the Englander before this one?


That would be a downdraft which would make lighting a fire more difficult, not causing excessive updraft. Do you have problems with smoke spilling into the room at start-up?


That sounds like it is cruising along nicely once it settles in. I would first try to change a bit your operating procedure to not have those high peak temps. Are you raking the coals forward before loading the wood or do you put it right on the hot coals? By how much and when do you adjust the air?


Do the block-off plate and you should see an immediate improvement in the heating performance.

The Englander is on a different chimney at my old house. This chimney is 22 ft tall. I'm taking temp readings on the surface of the stove. The fire lights and gets going normally with no smoke spilling back usually. I did have that problem once when it was overcast and the house was cold. . I've been reading that these newer non catalytics can burn pretty hot on the surface due to the air injection tubes. The tubes have never been red which I read is a common occurrence, but I haven't burned the stove longer than about 8 hours at a time before letting it go out. (We haven't moved into the house yet, I have been lighting the stove when I go up there to work). I'm working on the block off plate today so hopefully we can get the place cooking. Thanks for the feedback!

 

[jatoxico]

Hi Wonder,
Just as I had to be corrected I wanted to get some of your terminology right so there's no confusion. I think by damper you mean primary air or just air control on the unit itself? Also need more info on the install. Is the stove installed with a liner in a masonry chimney or would you be able to add a key damper in the chimney?

Hitting 800, although fine may not be desirable all the time. Once you start a fire you might want to start closing the air when the temp reaches say 400. Close it a bit (maybe a 1/4) then let the fire recover then close a bit more until you reach your final setting which would be the lowest setting you can use while still getting a clean burn (no smoke). That way you're more likely to hit a lower peak temp while still having a nice hot cruising temp.

When you say you hear air coming down do you mean through the liner into the stove or outside air coming around the liner outside the stove? A block off plate will help in all likelihood to help heat better but isn't going to stop any over drafting if that is really an issue. For a temporary fix can you access the old damper area and stuff some Roxul in there?

 

[wondermic23]

Hi Wonder,
Just as I had to be corrected I wanted to get some of your terminology right so there's no confusion. I think by damper you mean primary air or just air control on the unit itself? Also need more info on the install. Is the stove installed with a liner in a masonry chimney or would you be able to add a key damper in the chimney?

Hitting 800, although fine may not be desirable all the time. Once you start a fire you might want to start closing the air when the temp reaches say 400. Close it a bit (maybe a 1/4) then let the fire recover then close a bit more until you reach your final setting which would be the lowest setting you can use while still getting a clean burn (no smoke). That way you're more likely to hit a lower peak temp while still having a nice hot cruising temp.

When you say you hear air coming down do you mean through the liner into the stove or outside air coming around the liner outside the stove? A block off plate will help in all likelihood to help heat better but isn't going to stop any over drafting if that is really an issue. For a temporary fix can you access the old damper area and stuff some Roxul in there?

Yes i mean the air control on the stove. I have a SS liner installed in a masonry chimney and like you said I cant really use a key damper since the exaust is connected to the liner with an elbow. By air i mean i can open the stove door and hear some air coming down the chimney and i can hear pretty clearly noises from outside the house.

I light the stove with the air control (what i referred to as damper) all the way open and get the fire going pretty good. Then i close it about halfway and let it go for a little. Once i have a nice bed of coals i will add some more wood and when that goes i will shut the air control down some more. After about 20 minutes it will be really rolling so i close it all the way and it continues to go pretty good. Is that normal? Compared with my Englander it seems like i have much less control over the burn. My assertion is that this is the case because the chimney is much taller on my Sierra (the stove we are talking about). Is that more clear?

 

[jatoxico]

I thought I understood correctly just wanted to make sure. You may have more draft than you are used to and it's a different stove so hopefully a few adjustments and you'll get what you want. If the house is unoccupied and it's cold it will take a long time to get the temp up. That said a block plate will make a big difference, did for me. Like I said just in the short term you could stuff Roxul up there if you can access it.

Also based on what you're doing and describing it sounds like you could shut down more air and or more often. I have a similar setup to you I think. 26-27' 6" liner in outside wall masonry chimney. Sometimes I have cold air rushing down into the stove on a cold start and I have to hold a burning piece of newspaper up near the flue to clear the cold slug of air. Once the system is warm I get good draft.

Cold starts vs hot loads are different but I pretty much start shutting down air at least a little around 400-450 depending on how fast the fire is building in intensity. If I just let it roll I will get hotter max temps especially when loading on hot coals. Sometimes I want that but shutting air along the way is how you prevent runaway stove and excessive peak temps. I usually run stove to 600-650 and cruise at 500-600.

 

[Grisu]

I light the stove with the air control (what i referred to as damper) all the way open and get the fire going pretty good. Then i close it about halfway and let it go for a little. Once i have a nice bed of coals i will add some more wood and when that goes i will shut the air control down some more. After about 20 minutes it will be really rolling so i close it all the way and it continues to go pretty good. Is that normal?

Rake the coals forward and place some splits behind it and only a few should be on top of the coals. Putting lots of dry wood on a layer of hot coals will lead to rapid outgassing of the wood and can indeed lead to an overfire. Adjust the air in stages, when your draft is good there is no harm in closing it already some (1/4 to maybe 1/2) after a few minutes. As long as you have good flames coming from the baffle tubes you will be fine. Given that the stove settles in at 600 F suggests you are just a bit late in turning down the air, especially when the stove is already hot.