How do you heat up a stove when all the flames goes up flue and the flue goes nuclear?

This has happened to us twice now. We need to heat up our stove so the top is approx 400-500 degrees before trying to engage AB. Last night, no matter what air setting we used, the flames flew up the open damper, heating the flue to super high temps (and the stove top was not even 300 degrees). We have double insulated stove pipe and it started to smoke (just paint fumes but stinky nonetheless). No matter what we did, the flames/heat went up the chimney and wouldn't heat the stove. I tried to rearrange the wood, thinking that was the problem, but it didn't do any good. I tried the low air setting with no luck. We simply could not get the stove hot enough to engage AB. This morning, no issues whatsoever.

Are there any "tricks" to getting the wood to burn more evenly, without all the flames shooting up the flue, while AB is not engaged? Is there something we might be doing wrong to cause this kind of problem?

WoodpileOCD said:

What is the "AB" that you are trying to engage? Not familiar with that acronym.

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Sorry... "after burn". The stove has a combustion chamber. The manual says to add wood, get it up to temp and then close the bypass damper.

branchburner said:

Don't worry so much about the stove top. Sometimes the AB will kick in even before it's at the "right temp" and sometimes the AB WON'T kick in even though the stove seems above the "right temp." As suggested, close the bypass when the flue is getting too hot, just to slow things down - if the AB stalls, you can always open the damper back up again.

I spent my whole first season obsessing about the stove top temp, and I think I was needlessly letting the wood burn too much (as you may be). I now watch only the flue temp and the temp of the rear burn chamber (I make sure to put the fan on when it pushes 800F). If I close the bypass too soon, the AB usually kicks in anyway, after a bit. The main exception is if a log is blocking the airflow at the back of the firebox, in which case I need to move it.

At some point you will be able to do it by feel, at least most of the time. The key to getting there is to use dry wood, without exception. Nothing will mess with that AB like unseasoned wood - everything I use now is at least a year cut and split.

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We've never been able to get the AB to kick in after the bypass has been closed for any lengthy period of time (it seems to either kick in almost immediately or not at all). As far as a log blocking the airflow, wouldn't that have to be a tight fitting log to block air? Or is "disruption" in the airflow enough of a problem to cause the AB not to kick in? I've noticed sometimes moving the wood around will make a huge difference.

We were told that closing the bypass with no AB could eventually damage the burn chamber and we shouldn't burn the stove that way. I understand that creosote could muck things up really badly; but if we're using good, seasoned wood and the AB doesn't engage, will leaving the bypass closed do any damage to the firedome?

I tend to listen for the rumble and look for high temps on the back of the stove to indicate AB. But several times we've had the rumble and good hots temps on the rear guard and there is still smoke (not steam) coming from the chimney. What flue temp do you use a guide to shut the bypass? What temp in the back of the stove typically indicates AB? (Where do you have your thermometer in the back of the stove? We typically check it on the back guard.)

I'm sure we will eventually be able to tell "by feel" when the stove is in AB. But now, we're still running out to check the chimney...

BeGreen said:

mishmouse mentioned in another thread that it is critical to have the small holes in the rear shoe clear. You might want to check them.

https://www.hearth.com/econtent/index.php/forums/viewthread/71940/

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I've been checking/cleaning them once/week -- definintely something to keep an eye on.

branchburner said:

There is a huge difference in the ease of getting the AB to work depending on whether you start with a cold stove, and no coals, or you are reloading a half-full stove that is loaded with a days worth of coals. The former can take as much as a few hours, the latter as little as a few minutes. Without the deep coals of a long-burning fire, I find it helpful to use a lot of smaller splits or branchwood, 1-3"", to get the process accelerated.

As for leaving the bypass closed if the AB is not working, I try to do that only for a matter of minutes. I agree, you do not want to make a habit of it or do it for any extended time period. Keep playing around with different loading technique, air settings, wood size, etc.

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I agree with the coals/no coals. It seems to take us a long time to get a good bed of coals. We use kindling (as yous aid, 1-3") but sometimes, it just seems to burn and not leave any real coals. I'm wondering if wood type makes a big difference in whether or not you get a good bed of coals or not...

branchburner said:

What kinds of wood are you using?

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Our last load was mostly hickory (shagbark) and walnut, with some oak and locust. We try to use the hickory and oak for kindling.