Over firing

[wg_bent]

Over in the "nails in wood" thread, Dylan postulated that the issue of overfiring a stove is WAY over stated.

Well, I figured I'd open that one up.

The other night I definitely got concerned that I was possibly overfiring my stove when I put a fairly large block (no other term really works for that hunk of wood) of pine in the stove. The stove was nicely hot with good bed of coals, and almost instantly, the stove was FULL of fire, even before the wood caught fire. It was like putting a rag full of kerosene in the stove. The sap on the surface of the pine boiled instantly and produced so much combustible fuel that I got very concerned. I put the blower on high, damped down as much as possible, but the secondary burn would not quit.

The stove was as hotter than I've ever seen it. Temp in the room was near 85 very quickly.

I was not comfortable at all.

So was I unnecessarily concerned? In the end the stove seems no worse for wear. I cleaned the glass with some water the next day, and there is no visible damage.

Was I actually overfiring? The manual states that a sign of overfireing is that the door handle is too hot to touch, but that never happened. The air control was too hot to keep my hand on, but not too hot to touch. The surround pannel was pretty hot though.

 

[Corey]

IMHO, there is 'overfiring' and there is 'overfiring'

The difference being that in 'overfiring' - a stack of scrap wood will put out lots of big yellow flames that aren't relatively that hot, and only last for several minutes so they don't contain a lot of energy either. The flames roaring up the chimney can get any creosote build-up good and hot, then light that off and lead to a great conflagration, though.

But in true 'overfiring' you may have a stack of oak, hedge or locust in the stove burning with hot blue flames, over a bed of orange-hot coals which are generating their own heat as well. The whole stack is generating a large amount of heat and a fair amount of energy content as well. This is what seems to actually get the stove hot and lead to 'classic' overfiring where the stove can actually turn red, metal parts warp, etc.

As always, there is 'way more to it than that' - but just to kick off the discussion.

Corey

 

[elkimmeg]

Well you have not need for super starters split up that pine and there you go. I always believed that it was ok to mix in 15% pine with hardwood. So if you are trying to get rid of some use smaller splits and not big chunks

 

[Roospike]

I have seen many warped wood stoves over the years. Many have been brought in to be fixed. Seems like a break down i have see is 40% just being over fired with wood logs and 60% being over fired from lumber and mill ends / scraps. Out of the 40% over fired stoves i have seen the biggest problem was too small of wood stove to start with and running max btu for too long and or trying to get more heat out of the stove size it was designed to do .

 

[MountainStoveGuy]

pine doenst over fire stoves, unless its a fatwood split. Dont forget most of the west half of the US uses pine everyday.

 

[velvetfoot]

As I recall, the manual that came with my Quadrafire 2700i said to avoid making your stove glow red, or something like that, LOL.

Turning 'off' the air supply did no good? Your door gasket is in good shape?

 

[wg_bent]

As I recall, the manual that came with my Quadrafire 2700i said to avoid making your stove glow red, or something like that, LOL.

Turning 'off' the air supply did no good? Your door gasket is in good shape?

Yes. I'm sure if I opened the air supply it would have been even hotter. The stove was purchased new last year, so it's in good shape. I did the dollar test before firing it this year and it passed just fine. What I had in the stove was a large ball of secondary combustion from a very large chunk of pine. The flames were very yellow, and were wrapping around the baffle and well up past where I could see.

It's entirely possible that this was not an over fire condition at all, and I've just never gotten my stove that hot before using hardwoods. I don't tend to keep much past a very low setting until wood has really burned down quite a bit.

The glass got very sooty...I've never seen my stove do that before with any hardwoods. Possible the wood needs more seasoning? It seems dry and lit within 10 seconds after putting it in the stove.

 

[MountainStoveGuy]

was this chunk of pine heavy? sounds like it was full of pitch. Typical pine firewood doesnt burn any different then your hardwood. Just not as long, and less BTU's per pound.

 

[BrotherBart]

I burn pine this time of year when I am around to feed the stove and also when I know that the morning warm-up fire isn't going to need to run all day. Same with the late evening one to keep the chill off. Will use it for fast starts for most of the winter for the little stove that won't hold coals overnight.

It is at 14 to 16 percent moisture and behaves itself fine. I have to cut up some of the pine trees that are downed to get to the hardwoods so on the pile and in the stove it goes.

We named the cord and a half of pine this year the Ryan stack in honor of MSG da Wild West Pine Burner.

 

[wg_bent]

It had a big knot in it and there was a lot of sap (Pitch?) leaking from the knot. As soon as I put the peice in the stove, the sap started boiling. Also, after it chared up, there kept being a huge amount of secondary burn that seemed incomplete. It was like there was more fuel than the oxygen could even keep up with. Lots of soot on the glass. VERY yellow flames.

 

[MountainStoveGuy]

your burned a fatwood log Next time you get one of those slice it in slivers and use it as firestarter. I had one of those one time, in my old house. My wife threw it inthe fire and WOOOOOOOOOSH. crazy fire, set of one of my 2 chimney fires i had in that place. (unlined masonory chimney 16x16 with a epa stove).

 

[iburnpine]

Warren,

You didn't mention the temperature of the stove or pipe? How hot was it? Over 700, 800, 900 degrees? That would've freaked me out too man.

 

[wg_bent]

My stove is an insert, so I have no way of measuring the stove pipe temp. It's buried behind the surround. It's one of the big drawbacks of inserts. Also, the front of the Osburn has a shrowd over it so the actual front top of the stove is not visible. It's easy to remove it and it's not essential to the operation of the stove, so in theory I could have measured a stove top temp there...if I had a thermometer....Maybe I'll get one and put it on that surface to see what temps I'm running at.

 

[RoosterBoy]

i hope i did not over fire my stove i have a rutland thermometer on my stack about 15 inches above the stove top and it was between 400 450F but when i read the manual they said to put a thermometer on the front left beside the door. witch would mean the stove must have been real hot if the stack was 400-450F so this weekend i am going to buy one for the stack and have to thermometers
none of the stove was glowing except in the dark the air tubs in the front looked red hot but i think that's normal. my old stove never had glass doors or air tubes so Ive never seen how it fires

thanks
Jason

 

[JMF1]

Maybe Bart remembers Saturday nite I had the same secondary burn going on...............My Rutland thermometer was pinned! I still cannot figure out why, but the guy at the stove shop said not to worry, just turn it down sooner. It was both amazing and scarey to watch all of that secondary going!

 

[BrotherBart]

As Craig said one time, those stoves are tested with firebrands a lot hotter than you will ever get the stove.

Overfiring should not be done for sure. But I sinned against the Sierra, often in thousand degree territory, for 20 years before it got fed up with it and developed a crack in the firebox.
And where the crack developed I am convinced that banging those big spilts against the back of the box tossing them in lengthwise for years did it more than the overfiring.

 

[Sandor]

Overfired my Regency with pine years ago.

The whole top and about the first 18 inches of stovepipe was cherry red. Scary sight. No long term effects.

I looked in the manual, and it just said "If the stove is red, you are overfiring, turn it down"..... or something like that.

 

[brian_in_idaho]

As I recall, the manual that came with my Quadrafire 2700i said to avoid making your stove glow red, or something like that, LOL.

Turning 'off' the air supply did no good? Your door gasket is in good shape?

Yes. I'm sure if I opened the air supply it would have been even hotter. The stove was purchased new last year, so it's in good shape. I did the dollar test before firing it this year and it passed just fine. What I had in the stove was a large ball of secondary combustion from a very large chunk of pine. The flames were very yellow, and were wrapping around the baffle and well up past where I could see.

It's entirely possible that this was not an over fire condition at all, and I've just never gotten my stove that hot before using hardwoods. I don't tend to keep much past a very low setting until wood has really burned down quite a bit.

The glass got very sooty...I've never seen my stove do that before with any hardwoods. Possible the wood needs more seasoning? It seems dry and lit within 10 seconds after putting it in the stove.

A few things make me think that you were probably fine, just excess pitch burning off. First, you said it was a large block, not a bunch of small pieces, I don't think the surface area would promote an overfire condition. While pitch burns fast, it doesn't seem to put out the heat that a bunch of small splits does, and it doesn't tend to burn for all that long. Second, you mentioned that even with the secondary air control closed as far as it would go, that you were still getting good, and orange, secondary combustion. IMO, this is normal, even fully shut down you may still see secondary burn with a full load of wood, in fact, you should, it tells you its burning clean and operating properly. I'd argue that no secondary burn means that the fuel load is too small and/or the control is damped too much. Third, you mentioned the soot buildup, I think if you were even near overfiring you would be too hot for soot buildup on the glass.

Just my humble opinion...

Bri

 

[Martin Strand III]

It's doubtful one can overfire a non-cat stove enough to cause structural damage on a single overly hot burn regardless of the fuel unless you're intentionally trying to wreck something or burn down your house. Cat stoves may be different and coal stoves probably aren't.

In a pre-Phase II steel Timberline fireplace insert years ago, when I was on the learning curve and when it was sub-zero outside, I'd routinely get the top steel plate and collar of the flue cherry red, sit back in the dark with a sundowner and marvel at the effect thinking of all that money the big gas conglomerant wasn't getting. I quit it after a while when I saw the 1/4" steel baffle inside begin to sag. Well, I'm here now to tell you I've done some foolish things and that one was probably near the top of the list.

As has been brought out before, metal begins to glow red at about 900* F, which most responsible companies making wood burning stoves recommend you avoid to save harm to their mfg'd product and, possibly, save you an emergency call to your local FD. And I have to believe that most companies wouldn't make a metal stove now 'a days so fragile it would be damaged severely by the limited exposure to higher than recommended heat from an overexuberant new customer finding his wood burning bearings.

'Bout the only red metal I see now 'a days is the red hot metal paper clip tip I use to push through my fingernail, occasionally, to relieve the pressure of a painful blood blister underneath.

Aye,
Marty

 

[Martin Strand III]

Dylan:

I started calling my evening "prescription" a "sundowner" some time back when I was on the ole salty and it was time to relax and enjoy the sunset.

Could be a G & T, a brewskie, glass of vino or whatever makes the taste buds happy and the soul glow. There's no wrong choice as long as you have a choice.

Aye,
Marty

Grandpa used to say, "A gentleman never has more than three martinis before dinner". And, I now agree.