How do you guys get "runaway" stoves? Max heat NOT at max air?

[avc8130]

I think I am noticing with my Jotul Oslo that max stove top temps do NOT occur when the air is opened all of the way. Is this normal?

I seem to be able to hit a max temp with the damper all of the way open, and then if I knock it closed about 1/4 of the way temps will usually rise another ~50 degrees at the stove top.

ac

 

[Fsappo]

How old is the stove? Maybe something with the gaskets..maybe the ashpan gasket?

 

[avc8130]

How old is the stove? Maybe something with the gaskets..maybe the ashpan gasket?

Brand new. Less than a month with maybe a dozen fires.
ac

 

[Fsappo]

Id check the gaskets on the front, side and ashpan door anyhow with the dollar bill test. That would take the gaskets out of the equation. I know that depending on a lot of factors, some stoves will for a while jump up the surface temps when those secondaries start taking off. I look at it this way. You get a full load of wood on a good bed of coals and that stove should cruise at 500-600 surface temp with the air closed down for a good part of the burn cycle. What are your temps at when you say "Max"?

 

[avc8130]

Id check the gaskets on the front, side and ashpan door anyhow with the dollar bill test. That would take the gaskets out of the equation. I know that depending on a lot of factors, some stoves will for a while jump up the surface temps when those secondaries start taking off. I look at it this way. You get a full load of wood on a good bed of coals and that stove should cruise at 500-600 surface temp with the air closed down for a good part of the burn cycle. What are your temps at when you say "Max"?

With the air wide open I usually hit around 450-500. Close the air down a bit and I can usually grab 500-550.

I don't understand how the gaskets could be the issue. Wouldn't bad gaskets let MORE air in? I thought more air ALWAYS meant more heat?

My observation is that LESS air is making more heat with my stove.
ac

 

[Fsappo]

The stove may not be noticing the extra air with the primary open. It all depends on where they air is coming in from, and a million other stupid things that make diagnosing biomass combustion a challenge. So I just look for the easiest stuff and eliminate them first. Always shell the calvary before sending in the infantry.

 

[avc8130]

The stove may not be noticing the extra air with the primary open. It all depends on where they air is coming in from, and a million other stupid things that make diagnosing biomass combustion a challenge. So I just look for the easiest stuff and eliminate them first. Always shell the calvary before sending in the infantry.

I can support that. Dollar bill testing this evening when I get home.
ac

 

[Fsappo]

Keep in mind..you can go crazy micro managing a stove. If the end results are nice long burns on a full load of wood, with 500 degree surface temp (providing the gaskets are in good shape) dont sweat the small stuff too much. I burned an Oslo for about 5 years in the showroom. A full load at 9am and at 5pm we were still a few hundred degrees furface temp with a bed of coals. Was like clockwork.

 

[firefighterjake]

I think I am noticing with my Jotul Oslo that max stove top temps do NOT occur when the air is opened all of the way. Is this normal?

I seem to be able to hit a max temp with the damper all of the way open, and then if I knock it closed about 1/4 of the way temps will usually rise another ~50 degrees at the stove top.

ac

You would be correct . . . with the air control open all the way you will get lots of flames, but the majority of the heat is being sent up your stack . . . what you want to do is bring the stove up to temp and then start cutting back on the air which you are doing . . . this will result in a secondary burn and the stove will start to warm up. This is how you want to run your stove . . . since the goal is to heat your house . . . not the outdoors.

Many newbies have a common misconception that more air = more heat and less air = less heat . . . however running a woodstove is not like driving a car in the way you want to go faster you "open up" the throttle . . . it's actually just the opposite . . . the key however is to get things warmed up and brought up to temp first and then start slowly dialing things down.

Sounds like you're doing things right . . . secondary burns will almost always result in more heat in the stove and in the home . . . in my own case with good wood and my chimney . . . I can dial things down to the quarter mark . . . and even all the way "closed."

 

[avc8130]

I think I am noticing with my Jotul Oslo that max stove top temps do NOT occur when the air is opened all of the way. Is this normal?

I seem to be able to hit a max temp with the damper all of the way open, and then if I knock it closed about 1/4 of the way temps will usually rise another ~50 degrees at the stove top.

ac

You would be correct . . . with the air control open all the way you will get lots of flames, but the majority of the heat is being sent up your stack . . . what you want to do is bring the stove up to temp and then start cutting back on the air which you are doing . . . this will result in a secondary burn and the stove will start to warm up. This is how you want to run your stove . . . since the goal is to heat your house . . . not the outdoors.

Many newbies have a common misconception that more air = more heat and less air = less heat . . . however running a woodstove is not like driving a car in the way you want to go faster you "open up" the throttle . . . it's actually just the opposite . . . the key however is to get things warmed up and brought up to temp first and then start slowly dialing things down.

Sounds like you're doing things right . . . secondary burns will almost always result in more heat in the stove and in the home . . . in my own case with good wood and my chimney . . . I can dial things down to the quarter mark . . . and even all the way "closed."

Excellent. This is good to hear. I was thinking everything you posted, but just wanted the confirmation.

I just read about all of these guys who claim 700+ runaways when they leave the air wide open too long during start up and I just don't think that would happen to my setup. I guess that is a good thing.
ac

 

[firefighterjake]

I think I am noticing with my Jotul Oslo that max stove top temps do NOT occur when the air is opened all of the way. Is this normal?

I seem to be able to hit a max temp with the damper all of the way open, and then if I knock it closed about 1/4 of the way temps will usually rise another ~50 degrees at the stove top.

ac

You would be correct . . . with the air control open all the way you will get lots of flames, but the majority of the heat is being sent up your stack . . . what you want to do is bring the stove up to temp and then start cutting back on the air which you are doing . . . this will result in a secondary burn and the stove will start to warm up. This is how you want to run your stove . . . since the goal is to heat your house . . . not the outdoors.

Many newbies have a common misconception that more air = more heat and less air = less heat . . . however running a woodstove is not like driving a car in the way you want to go faster you "open up" the throttle . . . it's actually just the opposite . . . the key however is to get things warmed up and brought up to temp first and then start slowly dialing things down.

Sounds like you're doing things right . . . secondary burns will almost always result in more heat in the stove and in the home . . . in my own case with good wood and my chimney . . . I can dial things down to the quarter mark . . . and even all the way "closed."

Excellent. This is good to hear. I was thinking everything you posted, but just wanted the confirmation.

I just read about all of these guys who claim 700+ runaways when they leave the air wide open too long during start up and I just don't think that would happen to my setup. I guess that is a good thing.
ac

Oh it's possible . . . trust me . . . FYI: Don't leave the air control all the way open and take a long shower expecting the fire will take awhile to build up . . . trust me on this . . . it took me two times and two showers to learn this fact. The stove will not heat up that hot . . . but you can easily get above 1,000 degrees F (as measured by a probe style thermo in a doublewall pipe) in short order . . . and this can be a problem . . . a lot depends on your chimney and your wood.

 

[avc8130]

So you are saying that stove top temp may not be above 500, but fire temp would be soaring over 1k? I think I need to change my morning habits:
1. Wake up and gain some conscienceness. Observe stove top temp ~200.
2. Open air and rake coals to spread nicely from night before.
3. Add 3 smaller pieces on coals. Leave air wide open and take shower.
4. Adjust air down to 1/2-3/4.
5. Wife breaks these splits down and loads full about an hour later.
6. Burn wide open 30 minutes.
7. Wife chokes to minimum and heads off to work.
ac

 

[firefighterjake]

So you are saying that stove top temp may not be above 500, but fire temp would be soaring over 1k? I think I need to change my morning habits:
1. Wake up and gain some conscienceness. Observe stove top temp ~200.
2. Open air and rake coals to spread nicely from night before.
3. Add 3 smaller pieces on coals. Leave air wide open and take shower.
4. Adjust air down to 1/2-3/4.
5. Wife breaks these splits down and loads full about an hour later.
6. Burn wide open 30 minutes.
7. Wife chokes to minimum and heads off to work.
ac

No . . . I am saying that it is possible to get your flue way too hot by leaving the air control open all the way for too long.

I suspect you would not see such a wide discrepancy in temps between the flue and stove top during normal operation.

Your morning routine isn't bad . . . I do pretty much the same thing only I am less patient and sometimes add kindling . . . or keep the side door open ajar to bring up the flue temp . . . and as mentioned I try not to take the long showers with the air control open all the way . . . I also tend to do a full load . . . even when I do just add some small splits on the coals . . . I put larger splits on top . . . and it is pretty rare that I would have the air open all the way for as long as half a hour . . . maybe if I was starting up the stove from a cold start . . . but never that long with a good bed of coals and the stove already warmed up to 200-300 degrees.

 

[avc8130]

No . . . I am saying that it is possible to get your flue way too hot by leaving the air control open all the way for too long.

I suspect you would not see such a wide discrepancy in temps between the flue and stove top during normal operation.

Your morning routine isn't bad . . . I do pretty much the same thing only I am less patient and sometimes add kindling . . . or keep the side door open ajar to bring up the flue temp . . . and as mentioned I try not to take the long showers with the air control open all the way . . . I also tend to do a full load . . . even when I do just add some small splits on the coals . . . I put larger splits on top . . . and it is pretty rare that I would have the air open all the way for as long as half a hour . . . maybe if I was starting up the stove from a cold start . . . but never that long with a good bed of coals and the stove already warmed up to 200-300 degrees.

3 small splits seem to start nicely. I could add some larger wood on top, but the firebox fills pretty quickly with the ash/coals from the night before still in there. Plus this gets me an extra hour of burn time between when I leave and she leaves that I assume is being added on at the end of the daily burn. She leaves at 8:30 and I get home at 5:30 with a ~200 stove top and enough coals to get going with small splits again.

The reason I advised her to leave the air open 30 minutes was to make sure everything was caught and a good clean burn would maintain while we are gone. I will have her try 20 minutes next week.
ac

 

[Backwoods Savage]

avc8138, Jake is correct! Except for one tiny detail. I say nobody should ever leave the stove room while the draft is set full open! I also say to never time it to figure when you start closing the draft. Too many variables there but for sure it is a rare case when we could leave our draft open full for 20 minutes. More like 5 or less here!

Also on the stove temperature vs. the flue temperature. On our stove once we start closing the draft the stove top can soar quite fast and going up 300 degrees can happen really fast....after we close the draft partially. This morning we got the stove top to 650 degrees from 200 in a very short time. I wish I'd have checked the time but did not. In addition to that, after I put the wood in and had the draft set full open, it was just a couple of minutes when my wife rushed over to the stove to turn the draft down....because the flue temperature was as high as we want it to be. Things can happen pretty darned fast.

 

[branchburner]

Burn wide open 30 minutes... chokes to minimum and heads off to work.

With many stoves (like mine) it works well to cut back the air in increments. My usual reload is only 5-10 min wide open, then 5-10 at 1/2 open and set to cruise at about 1/4 air (depending on the wood, time of day, and indoor/outdoor temps).

 

[Battenkiller]

avc8138, Jake is correct! Except for one tiny detail. I say nobody should ever leave the stove room while the draft is set full open!

Gotta agree with Sav on this one. Many stoves (mine included) will take off like a jet engine if you have a good load of nice, dry wood in the box and leave the air open all the way. "OK.... OK..... OK......... Guess I can leave it for a little while." Then within a minute's time the flue temps are off to the races. I can watch mine rise 100º easily inside a minute, and it won't stop until the magnetic flue pipe thermometer is sliding down the pipe because it got so hot it lost its magnetism. 800-900º. That's over 1500ºF gas temp inside the pipe! If you have a creosote buildup down low, this is a sure way to clean the entire stack in a hurry, and not the way you're supposed to clean it.

Even if you use a timer, things have a way of distracting us in this modern world. Jake is slow like me and it took two times to make a believer out of him. Even with my three minute shower, things can get out of control in a hurry. That's why I'm not a huge fan of the spring-controlled air intake stoves like the Quads. I think it shuts down over like 15 minutes or something. What if because of any number of variables the stove only needs 5 minutes today?

Stay with the stove until things are stabilized is my rule - no matter how inconvenient.

 

[firefighterjake]

No . . . I am saying that it is possible to get your flue way too hot by leaving the air control open all the way for too long.

I suspect you would not see such a wide discrepancy in temps between the flue and stove top during normal operation.

Your morning routine isn't bad . . . I do pretty much the same thing only I am less patient and sometimes add kindling . . . or keep the side door open ajar to bring up the flue temp . . . and as mentioned I try not to take the long showers with the air control open all the way . . . I also tend to do a full load . . . even when I do just add some small splits on the coals . . . I put larger splits on top . . . and it is pretty rare that I would have the air open all the way for as long as half a hour . . . maybe if I was starting up the stove from a cold start . . . but never that long with a good bed of coals and the stove already warmed up to 200-300 degrees.

3 small splits seem to start nicely. I could add some larger wood on top, but the firebox fills pretty quickly with the ash/coals from the night before still in there. Which is why one of my first things that I do is stir the ashes/coals so the ash drops down into the ash pan and then I can level out the coals to an inch or two depth. Plus this gets me an extra hour of burn time between when I leave and she leaves that I assume is being added on at the end of the daily burn. She leaves at 8:30 and I get home at 5:30 with a ~200 stove top and enough coals to get going with small splits again. Which is good . . . so again . . . you're doing OK.

The reason I advised her to leave the air open 30 minutes was to make sure everything was caught and a good clean burn would maintain while we are gone. I will have her try 20 minutes next week. What I do is not go so much by the time as by the temp . . . monitoring my probe temp . . . when the needle is in the "green" so to speak I'll then start dialing things down . . . typically in 10-15 minutes after reloading the stove.
ac

 

[Adios Pantalones]

In some stoves- more air than is needed acts as a coolant I would guess. In my little "outdoor burner"- I get to 2375F by controlling the air in. Plus a lot of time. And some elven magic.

 

[avc8130]

Should I be adjusting by flue temp or stove top temp? Maybe THAT is part of my procedure that needs to change. I have been only monitoring stove top temp because that is what the manual said.

Should I be adjusting the air to keep the flue temp in a "sweet zone"? What zone would that be? 300-500?
ac

 

[branchburner]

And some elven magic.

You baking Keebler cookies in the thing?

 

[Battenkiller]

And some elven magic.

You baking Keebler cookies in the thing?

You haven't see Adios' weenie roaster?


http://www.youtube.com/watch?v=xezw6p8Qcsw&feature=player

 

[Fsappo]

Im pretty sure I did NOT just see someone disrespect the Elven Nation

 

[Adios Pantalones]

Im pretty sure I did NOT just see someone disrespect the Elven Nation

No way- they are a major trade partner (I'm part leprechaun)

 

[Battenkiller]

Should I be adjusting the air to keep the flue temp in a "sweet zone"? What zone would that be? 300-500?

That's all I care about, but I don't know your stove. Perfect flue temp for me before closing the bypass is 550ºF. After closing the bypass, I like to see temps drop close to 300º on my magnetic thermometer set 20" up from the stove collar on my single-wall pipe. That's the sweet spot for my setup. My stove top can vary over about a 200º span (550-750º) over the course of a few hours, all at around 300º on the flue.