Overfired Ideal Steel, What damage to expect?

Yep I agree with that, doubt if you hurt anything to speak of.

 

I dont have a stovr like this but those metal flakes remind me a lot of the ones that flaked off the kerosene barrels i made into a charcoal retort. I burned this out in my pit and put a mix of apple, cherry and plum wood in. You can bet it was hot. The exhaust hole was like a jet. That was INTERESTING to say the least. Upon checking the outer sides, it was more than apparent bubbling had occurred. Didnt warp but at that heat must find spmething else.

 

Hey everyone,

Went searching threads, and I’ll post here, as it seems most appropriate.

This is my 4th season with the IS, and we love it. It has operated just as designed, with only regular matainence and care. I cleaned the flue in October.

Last night, I loaded up as usual, with the same wood species, moisture content I’ve always used, got it all set, and went to bed. Woke up 2 hrs later to the smoke alarms. House was full of smoke. The stove had no flame (pyrolizng), but it was overfiring. The condor flue therm. wasn’t pegged, about 3/4 of the way there. The stove had never been this hot in 4 years. The smoke was the paint re-curing to the high temps. I had to open the air to make it “flame on”, and the temp came down. Also, when bringing the stove to temp, I had a full-flamed firebox. I engaged the cat, turned it down to notch 2, and the flame went out very quickly and it went to a very fast cat burn. Does this factor in somehow?

Any IS owners ever experience this? It has me thinking now about not leaving the house with it running, and I can’t really have that.

 

Check the ash pan and door gasket. Also the plate above the cat for enough warpage that it lifts off the gasket. But check the ash pan gasket first (if you have one).

 

Brad38 After gaskets check to make sure your cat is not clogged. Then clean it. In my experience, when your cat starts to slow down it doesn't burn all the smoke completely until you get a great build-up and then like kicks off because you have too much smoke in the Firebox and you're basically giving it too much fuel. Think of it like an old carburetor, it won't idle well so you give it gas and race the motor.

This is probably more likely then a loose gasket as too much air would give you more flames and less smoke.

 

What you experienced only happens with cat. stoves (and hybrids act as cat. stoves for this example): the wood is very dry, perhaps small splits and pyrolyses very quickly but does not have enough airbox air to actually burn. So all the smoke, and there is a huge quantity of it, goes to the combustor where it is 'fuel' and causes the catalyst to crank out tremendous heat and extremely high temperatures. In addition, with that smoke (fuel) rich airbox getting too little air, occasionally it will get just enough to make an burnable ration and the firebox gasses will ignite, which is why the house was full of smoke. I have not had this happen on the IS but I have on other cat. stoves, with bright yellow- to- white cats. actually turning the steel around the cat. a dull red, the classic cat. stove over- firing yet with a black firebox which is putting out relatively little heat. This is exactly where 'smoke dragons' waste tremendous amounts of fuel energy by putting smoke and creosote into the chimney and yet run very low and slow. The correction is exactly what you did- feed the airbox more air so some of the smoke (fuel) is burned in the firebox itself. This will yield less fuel to the cat. and in turn slow it down both in heat as well as direct temperature.

To eliminate this from happening, do not set the stove quite as low on the draft as you did last night- keep the draft open to a minimum of [some number of notches] and it will not happen again. On my IS, the lowest setting that works well is about 4 lines although I can use 3 lines if the splits are quite large. Also, large splits reduce or eliminate the possibility of over- firing the cat., as does increasing the water content of the wood. If your wood is very, very dry, try mixing in 1 or 2 splits that are not as dry; say mixing 90% very dry wood with 10% splits in their first year of seasoning. Place the higher water content randomly around in the fuel load and they will serve as 'brakes' to prevent as much smoke from being generated due to generating a bit more steam instead.

The upside to all this is it serves as a perfect example of just how much potential wood heat cat. stoves really do recover. Too much in your very specific case but I find that perhaps something like 50% of the fuel energy is liberated by the cat. while most manufacturers claim something like up to 30%.

BTW- this also happens in gasoline cars that are not running correctly due to misfiring, a cylinder not firing, a clogged injector(s) and similar: raw fuel goes out the exhaust where it is mixed with O2 (air) and burns inside the catalytic converter. They overheat and get tremendously hot, sometimes actually causing things such as leaves to catch fire under the car as well as scorching / burning carpet inside vehicle. Same cure works for them, produce fewer HC (hydrocarbon) in the first place and there is less fuel for the cat.

Brian

 

BDF,
Would this also be a case where a person could get by entirely by putting less wood into the stove to begin with...if indeed the wood is that dry and burning that hot/that well?

This is exactly what scares me about these stove manufacturers of CAT stoves, hybrids, and even VC tube stoves...the dealers tell me to load them full. If everything is going well and working as it should, then I can see this, but a person never knows when an ash pan gasket or door gasket will begin to leak...and it seems more frequent loading...as bad as that seems...with smaller and/or less wood each time...is the more simple solution...at least to my simple way of thinking. I mean, I could see loading up the stove for an all day burn if I was going to be home all day where I can monitor things, but I'll be danged if I'd feel comfortable leaving the house with the stove that full...let alone going to bed with it that full.

I'm just glad it ended well.

 

Bearing in mind that we are just chatting here (and not arguing.....): I think using less than 100% of any machine is wasteful and if it is required to correct something else, it indicates some error in the design and / or use of the device. Think about, say, a washing machine rated for 20 lb. of clothes, if you could only put in 8 lbs. of clothes before something went wrong, such as a slipping belt, leaking, stalling, etc., would you not think something wrong with the machine or usage? I would expect a 20 lb. rated washer to wash.... well, 20 lb. of clothes continuously for the life of the machine.

So it goes with a woodstove. In the end, the only reason to use a larger size is really to get extended burn times out of it. If a larger stove cannot be filled without some flaw showing up, I would consider that a poor wood stove or one that was being used incorrectly. An example of being used incorrectly would be filling a wood stove with lumber scraps which are extremely dry and fast- burning wood; the stove would overheat but it would be the user's fault IMO. On the other hand, if a wood stove could not be filled completely in an effort to get the longest possible burn out of it using proper firewood (hardwood, more moisture then lumber and larger pieces than typical lumber sizes) then I would say the stove is flawed in design or its build.

For my own opinion, I am comfortable leaving a house with a wood stove full of fuel if I am comfortable sleeping in that same house under the same conditions, so I would not use a wood stove in any manner if leaving the building than when I am present in the building. Bearing in mind that I sleep in this building with a running wood stove.

In a better world, a wood stove would only need attention once in a 24 hour period IMO.

As to finding a flaw in a stove such as a leaking gasket, a warped part or anything else, I would rather lean toward fixing the flaw instead of 'under- loading' the stove to compensate for said flaw. Put another way, maintain the machine properly, perform checks for proper operation as needed, and then use the machine to its full capacity.

Wood that is too dry for a wood stove is not 'better' wood, it is simply a bad fuel for a wood stove. So again, in my own opinion, I would tend towards the usually accepted range of around 20% or a little less water content, reasonably sized splits (between 3" and 5" on any side of a split, with some larger mixed in but none smaller, and never filling a stove with 3" splits exclusively) hardwood as a viable fuel to fill a wood stove to its capacity, meaning as much fire wood as one can fit into the stove. After a reasonable period of a 'full load start' (meaning adjusting draft to catch the new fuel load if needed) of not more than 30 minutes, then setting the stove for the 'long burn', I would expect any wood stove to consume that entire load of fuel without over- or- under firing appreciably.

When I was a pup, I had a great- uncle who heated a large garage with a pot belly, wood burning stove. He locked the door draft to "the right" setting and never adjusted it. The stove was regulated by how much wood was put in it and how often. A great heater but not efficient in the modern term in my opinion and that stove never went more than 20 minutes without being fed during the winter. State of the art for 1875 but not nearly as well as we can do today.

Again, just my opinions based on usage, experience, a little bit of study and a lot of 'paying attention'. Your mileage will vary. <friendly smile>

Brian

 

I've learned that that the best method for me (ymmv, etc) to avoid the above scenario where the stove goes crazy after setting it for a long burn is to leave it with active secondaries - even if just a little action is present.

This seems to avoid the runaway cat situation by making sure that some of the gases the cat would consume instead are burned in the firebox. To my line of thinking, this is probably also the most efficient way to extract heat from the wood, as it won't overwhelm the cat's capacity, and avoids sending those nice volatile gases up the stack at the beginning of the burn when they're still available. Sacrificing a little burn time for maximum heat extraction is ok for us, because someone is always around at least every eight hours to tend the stove.

For a long LOW burn, I'll just set it a little lower than I think I need to, and let the cat clean up the smoldering mess. This is during "black glass season" as I like to call it.

-edit- I think I just have a fifth grade rendition of exactly what BDF said.

 

That's pretty much exactly how I run the IS. I'll leave more secondaries as the temps dip below zero.

 

Brian,

Thank you for the very detailed explanation. It pretty much mirrors what Woodstock stated when I called earlier. I learned about cat overfiring the hard way last night. I’ll be more mindful when choosing my splits and stove setting. Thank you and everyone for taking the time to respond. -Brad

 

Glad to help if I can and the best of luck to you going forward.

This is a great forum, very pleasant and there is a huge base of knowledge here that everyone is willing to share. I have learned a lot browsing through this 'place'- hey, one gentleman even finally got me on the 'three year plan'.

Brian

 

The way I solved this problem is with a flue damper. The stove itself does not give you manual control of the CAT air, so if loaded up and the wood is out gassing, the cat can really take off.

With the flue damper, I can clamp down the draft which reduces the air pulled into the CAT and it also allows me to keep the main control open more to give it more primary/secondary air.

I can load the IS to the gills, even with compressed wood blocks and it will run steady and much cooler this way. Without the damper the cat would run up to 1600+ with a full load and the main air control at one or two notches. Now I see the cat probe peaking in the 800-1000 range with the air control at 4-5 notches. I am getting longer burns with more even output which is in the end what I really want to see.

 

Runaway cat? Anybody ever try restricting the secondary air supply in this situation? Is secondary air unregulated on the IS like many standard tube stoves?

 

The IS used a mechanical linkage to control both primary and secondary air with a single control lever. The ratio of the two changes through the travel so as you go lower, the primary is cut more first and then the secondary air dials back. At the lowest setting the air is not cut off but it is very restricted to just a trickle.

The third air supply in the IS that feeds the catalyst is auto controlled and opens with heat, so when the stove is getting away from you, the cat air supply is wide open and feeding all the air the draft can suck through. This is where you can get in trouble because once it starts to run away, the operator has no control. I think the best and easiest way to control this is with a flue damper. Restricting the draft cuts back on the air sucked through the stove and slows the burn down very effectively.

 

On cold days like today <10 degrees my damper gets shut pretty near closed. Damper plate has holes in the center and air gap on outer edge. It dials the stove in very nicely!! I also like using the damper to adjust draft and leave the air lever more open, it seems to get a more complete burn and keep the coaling issues down. I dial it into a slow dancing flame from the secondaries a half hour in and let it ride from there.

 

Been awhile! So nice to see your still giving great advice Brian