Secondary Burn Problems

[FireBall]

Have been a reader for some time, but this is my first post. Must say I am impressed with the knowledge of members on this forum and their willingness to share this knowledge. Now about my problem- I have a Buck Model 81 insert (non-cat). Stove heats up quickly, however, I am unable to get the sustained secondary burn others on this board achieve. I can fill the stove full, get temp up to 500-550 and then cut back the air. However, if I cut it back to half or less, the temp begins dropping and within a couple of hours is back down to 300. Also, secondary burn appears minor. I get the best secondary burn when stove is fully loaded and the air is wide open. However, this uses up a lot of wood and requires a lot of tending.

I burn good quality wood- hickory, oak, etc. (try to let it dry for a year before using). I have an insulated liner. Little or no smoke ever noticed coming from chimney, except when starting a fire. Should also add that neither the stove or chimney has a damper. Could a poor draft be the cause of this problem? Appreciate any suggestions!

 

[gpcollen1]

Try cutting back on the air a bit less. Once up to temp, my stove really cooks with the air damped down by 1/3. If I cut it down to 1/2 or 2/3 closed, that is more for an extended burn that will result in a cooler stove, eventually, but not in only an hour or so.

Have you tried just cutting the air back a bit? Bit by bit...

 

[babalu87]

The temps will drop and then rise again as all the wood is in a state of combustion and you are getting the most heat out of the firebox at that time.
Stoves just dont hold high temps over the entire secondary burn cycle.

 

[begreen]

Welcome Fireball! How dry is the wood you're burning? Has it been well seasoned?

Can you describe the flue on this stove? How tall? How many 90 deg. elbows in the installation, interior or exterior chimney?

 

[ansehnlich1]

My Jotul is on an exterior masonry 7x7 inside diameter chimney, and if I put a load of small, dry splits in there it'll go to 700 degrees, but it'll normally get up to only 600 or 650 as measured on the back right corner of the stovetop........and takes it time getting there I might add, like, 20 minutes or so, sometimes sooner, sometimes longer, depending on conditions.

ANYWAY, I have no fear of overfirin' the stove, guess it would be possible, but the draft just ain't there to do it, unless I'd load it with kiln dried stuff.

Once I get 'er up to 500 or 600 degrees I can cut 'er back to half air, and it'll secondary there, and then I can cut er back to about a third open and it'll still cruise along secondarying (new word, haha).

I've read where guys shut the air off the whole way and the stove continues to secondary, mine won't, she'd go out and smolder for sure.

I'm convinced my Jotul would run much improved with a 6 inch liner in my chimney, which I may install sometime, but for now it's doing just fine!

My bet on this buck insert is poor draft?

 

[begreen]

We need to be able to visualize the whole chimney system. How tall is the chimney, how many elbows between the stove and the chimney? How long is the horizontal connecting run to the chimney?

 

[FireBall]

In response to BeGreen's post- my chimney is an internal masonry chimney, 18.5 ft., high including 5 ft. that extends above the roof. The flue is 13 X 13 inch tiles, but again I had an insulated stainless steel liner installed. There is one 90 degree angle. Couple of other things I have noticed which may give you additional info on what I am experiencing-

Like I said, no smoke from chimney, except when first starting a fire, however, I do notice a lot of heat coming from chimney (by seeing refraction of air above chimney). Is this normal with the newer high efficiency non-cats? If not, am I losing heat which should have been captured in secondary burn? May need blocker plate near the base of the chimney?

When I burn real dense, hardwood like hickory, I get a lot of coal build-up, takes a big effort to burn them down before reloading. Problem may be poor draft, wood not fully cured, or just a result of my having to use a lot of wood to maintain good burning temps on stove. Again deeply appreciate all responses!

 

[begreen]

Hmm, maybe not draft FireBall. It sounds like a decent chimney setup. Though check the horizontal run to be sure it is pitched uphill at least 1/4" per foot. Next would be the wood. Do the splits sizzle at all on the ends when heating up?

ansehnlich1, what is your chimney setup?

 

[FireBall]

BeGreen- no, have never had any sizzle from my splits, so that leads me to think the wood is relatively dry. Not sure about the roof pitch, as soon as the snow on roof melts (based on weather forecast should be gone later this week) I will get on roof and check. Thanks again.

 

[ansehnlich1]

ansehnlich1, what is your chimney setup?

The Jotul sits on a brick hearth, 6 inch double wall out the top of stove 2 feet up to a 90 degree elbow and 8 inches or so to the thimble through the wall to exterior 2 foot square brick chimney that has an 8x8 (7x7 interior) square clay flue tile. From thimble to top of chimney is 20 feet.

Draft is good, no odor or smoke spillage into home, ever. No complaints about my setup, after spending countless hours here I'm convinced a 6 inch liner would improve draft and allow me to bank the stove down a bit more while maintaining secondary burn.

Had sweep with 20+ years check the chimney after 2 cord burned and he said it looked good, some glaze right at the top flue tile, otherwise grey/white ash. I think the air pocket that surrounds the flue tile provides decent insulation value between flue tile and brick chase. Top of chimney is capped, and bottom is sealed tight, including ash cleanout.

Total chimney height is about 24 feet from base to top.

 

[begreen]

I'm beginning to think exterior chimneys are evil.

 

[BrotherBart]

I'm beginning to think exterior chimneys are evil.

I am beginning to wonder why mine work so well. Bof'em.

 

[begreen]

Liners and they never cool down after October?

 

[ansehnlich1]

Hey, my chimney ain't evil, sheesh, it might not be perfect, but I got no problem seeing 90 degrees on the living room thermometer if I want