Non-Cat Secondary Burn Questions

[Highbeam]

A runaway stove is just a stove that is getting hotter than you want it to despite all normal efforts to cool it down. The stoves are designed to prevent the uncontrolled temp from climbing too high. It is possible, though unlikely, for a stove to runwaway beyond a safe temp. This can lead to a chimney fire, it can lead to stove damage, it can lead to burning your house down. Way to hot runaway stoves can happen for a variety of reason including poor stove design, high energy fuel load, leaky gaskets, other air leaks, plus maybe more. All EPA non-cat stoves are runaways to some extent. You can not close the throttle off so you can not prevent these stoves from getting hotter than your predetermined desired temp unless the temp you want is hot.

So you don't have full control but with experience you can know what to expect. Might as well get used to it, this operational limitation leads to lower emissions since a hot stove is a clean stove. Clean stoves are here to stay.

 

[grommal]

--snip-- On some stoves, like my Hearthstone, all combustion air comes through a single air intake port which is conveniently the shape of a 3" pipe to allow outside air to be ducted and supply 100% of combustion air. Also allows me to block it off if I ever need to. The rest of the stoves have sneaky secondary inlet(s) that can be hard to find and harder to throttle.

The Jotul Oslo (and at least some of the other Jotuls, I think) is one that's like yours in this regard. Not sure about other stoves. Indeed, this kind of design makes it easy to duct outside air to both primary and secondary if desired, as well as block it all off in an emergency.

 

[certified106]

--snip-- On some stoves, like my Hearthstone, all combustion air comes through a single air intake port which is conveniently the shape of a 3" pipe to allow outside air to be ducted and supply 100% of combustion air. Also allows me to block it off if I ever need to. The rest of the stoves have sneaky secondary inlet(s) that can be hard to find and harder to throttle.

The Jotul Oslo (and at least some of the other Jotuls, I think) is one that's like yours in this regard. Not sure about other stoves. Indeed, this kind of design makes it easy to duct outside air to both primary and secondary if desired, as well as block it all off in an emergency.

My PE has a round hole you can hook duct right up to also and It look like it's around 3".

 

[wkpoor]

A runaway stove is just a stove that is getting hotter than you want it to despite all normal efforts to cool it down. The stoves are designed to prevent the uncontrolled temp from climbing too high. It is possible, though unlikely, for a stove to runwaway beyond a safe temp. This can lead to a chimney fire, it can lead to stove damage, it can lead to burning your house down. Way to hot runaway stoves can happen for a variety of reason including poor stove design, high energy fuel load, leaky gaskets, other air leaks, plus maybe more. All EPA non-cat stoves are runaways to some extent. You can not close the throttle off so you can not prevent these stoves from getting hotter than your predetermined desired temp unless the temp you want is hot.

So you don't have full control but with experience you can know what to expect. Might as well get used to it, this operational limitation leads to lower emissions since a hot stove is a clean stove. Clean stoves are here to stay.

I agree with your statements. Problem is most stoves on the market today aren't designed to withstand daily abuse from hot fires. Case in point was my Mag. More than likely the front end warped from the heat. You just can't expect a flat piece of 1/8" steel to stay straight with frequent 800 degree stove temps. I was resorting to small fuel loads to limit stove temps which in turn cuts down on burn times.

 

[leeave96]

On my install of the Englander 30, I'll probably put in a stove pipe damper as a means to shut things down in the event of an overfire - but even those things are not air tight.

Bill

 

[Highbeam]

The flue dampers don't need to completely close off the flue or be air tight, you wouldn't want that anyway. All the flue damper needs to do is ruin the draft sufficiently to slow down the air moving through the stove with more control than the stove's control allows. I think that a flue damper is a great idea and even tried to install one but they don't play nice with double wall pipe. What a flue damper will do is give you back some control that the EPA took away. If you use that new control poorly you could create a creosote monster and pollute the air too. So be sure to use the flue damper wisely.

 

[certified106]

The flue dampers don't need to completely close off the flue or be air tight, you wouldn't want that anyway. All the flue damper needs to do is ruin the draft sufficiently to slow down the air moving through the stove with more control than the stove's control allows. I think that a flue damper is a great idea and even tried to install one but they don't play nice with double wall pipe. What a flue damper will do is give you back some control that the EPA took away. If you use that new control poorly you could create a creosote monster and pollute the air too. So be sure to use the flue damper wisely.

Highbeam, I agree that if you install a damper you need to be extremely careful as to how you use other wise you risk creating a creosote mess. For most brands of stove pipe you can just order a double wall damper as I have looked them up before. A couple of the ones i distinctly remember were Selkirk and Duravent and they were around $60-$100.

Here is a link for the Duravent (Click Here)

Edit: I was being slightly serious in asking if anyone with secondary combustion has had their stoves completely run away from them and if so what happened

 

[pen]

Edit: I was being slightly serious in asking if anyone with secondary combustion has had their stoves completely run away from them and if so what happened

Almost all cases I've seen of this were eventually linked to a leaking gasket or a cracked stove.

Once stove I hear alot of seeing the 800+ range while in good operating order is the Castine.

Another factor is when and how the stove was loaded as well as w/ what. Load the stove up on hot coals w/ good fuel and almost every stove will go nuclear.

pen

 

[wkpoor]

Edit: I was being slightly serious in asking if anyone with secondary combustion has had their stoves completely run away from them and if so what happened

Almost all cases I've seen of this were eventually linked to a leaking gasket or a cracked stove.

Once stove I hear alot of seeing the 800+ range while in good operating order is the Castine.

Another factor is when and how the stove was loaded as well as w/ what. Load the stove up on hot coals w/ good fuel and almost every stove will go nuclear.

pen

I'm not the only one on this forum that has posted on the magnolia doing the same thing so add it to your list.
Got cool here last night. Had to fire up the stove again. In morn I added some wood, let get to about 400 and completely shut down the primary. Little while later I checked on the stove (The Elm) and it was 750 degrees. I actually like a stove that can do that.

 

[gyrfalcon]

OK, I'm confused (it takes so little). I thought we were talking about runaway stoves (stoves getting to too high temps due to the inability to control the secondary combustion). Chimney fires are different, aren't they, in that they happen in the chimney, not the stove? I feel like I'm missing something here, forgive my ignorance.

comment deleted. Never mind!

 

[oldspark]

The T5 uses a super secret mechanism to simultaneously close the primary and secondary air inlets with a single lever. There is some effort made to conceal this secret for some reason. I can assure you that the secondary air inlet, or the primary inlet, is never totally closed. This stove is the closest thing you can get to a cat stove in performance.

.

It is so secret that no one will answer any questions about it or post any pictures, it would be nice to confirm this.

 

[Adabiviak]

Edit: I was being slightly serious in asking if anyone with secondary combustion has had their stoves completely run away from them and if so what happened

Almost all cases I've seen of this were eventually linked to a leaking gasket or a cracked stove.

Once stove I hear alot of seeing the 800+ range while in good operating order is the Castine.

Another factor is when and how the stove was loaded as well as w/ what. Load the stove up on hot coals w/ good fuel and almost every stove will go nuclear.

pen

I haven't had my stove (non-cat secondaries) get out of control (yet?). Is it bad form to put good fuel on hot coals? That's usually how I run the fire - once there are coals left, before they get "cold", I'll put the next batch of wood on, and it'll take right off. Plus the stove is pretty close to operating temperature for secondaries to fire up during the outgassing phase of the new fuel, so it's a cleaner burn right off the bat.

What's the official thing to do if a stove gets out of control? I have a fire extinguisher available, but I'm interested in a more elegant approach.

 

[certified106]

The T5 uses a super secret mechanism to simultaneously close the primary and secondary air inlets with a single lever. There is some effort made to conceal this secret for some reason. I can assure you that the secondary air inlet, or the primary inlet, is never totally closed. This stove is the closest thing you can get to a cat stove in performance.

.

It is so secret that no one will answer any questions about it or post any pictures, it would be nice to confirm this.

I agree oldspark I think we need some pictures or evidence of this mystery. Maybe its just an urban legend hahaha