Coal stove, burning wood, and chimney fire(s)

I'm new to the forum and burning. I have a coal stove, Baker Fireside Insert, so no secondary burn, no cat, no damper, do have somewhat of a baffle and air/air box/pipes within the stove near the top that a fan blows room air thru to extract heat. It's an insert, T and ~8" to 10" snout, rear exit, 6" SS corrugated liner ~23' high and a chimney cap. The chimney is masonry and has a terracotta liner.

I had the opportunity to get firewood for next to nothing and my labor last season. I cut and split the wood and let is season ~6-8mos. Wood is mostly oak, splits were on the large size, needless to say the wood was not ideal for burning. After ~1.5 to 2 cords I had a small chimney fire, glowing cap and maybe 1' flames out the top. I closed off the knobs and it settled quick. I had a sweep clean and check the liner, he said it was all good and did not see much of a reason for the fire in the first place. That was at the end of last years season. I burned one more time using small splits to start my coal going.

This year, after re splitting some of the larger splits and checking the moisture, 8-15% taken in the middle of a split after splitting it again to get to the middle, I burned ~1/4 cord. Well, the chimney cap started getting flashes of red during my last fill, another minor fire. That's fire #2 in a very short and low volume of burning. After the first fire I started burning very hot to cut down on the creosote production, 450-550F and no less than 3 fills of the box.

Did I wreck my liner with 3rd degree creosote or is this something inherent to this stove as in maybe I can't burn wood in it? The company used to advertise it as a dual burner before the EPA had their say. I figured it was like an old smoke dragon and no big deal, I would just have to be careful and clean it once a month. I have about 3 years worth of wood and I love burning wood, any thoughts on how to do this safe in my existing stove?

 

Hey tungsten , welcome aboard.
First off, I'm not sure there are many burners here that would consider 450-550 to be "very hot". It's about 40 here, and my stove is running at 500 right now. Is your home on the smallish side? Very well insulated?
Although your sweep said he didn't see any real reason for a fire, you still had one. Clue # one that something's wrong.
Sounds to me as though prior to your "very hot" fires, you were burning lower temps than that, and with less than ideal wood, you got some creosote in the flue.
I'm having some doubts about your MM readings on 1-1.5 year "seasoned" Oak. Consensus among most Oak burners around here is that it takes at least 2 years to get down below 20% MC, and sometimes longer. There are circumstances, such as climate, and processing dead trees, that might allow quicker drying times, but it's fairly unusual for most of us.
After reading again, there's a good possibility the flue is too cool. Is the chimney on an outside wall or in the middle of the house?
Although it's lined, if it's not insulated, the liner could be losing enough heat to the chimney to cool things enough to cause the creosote.
Just some thoughts.
I'll bet some others will chime in soon enough. Could be tomorrow though, as it's getting a bit late (not for everyone).
Hang around, we'll get this figured out.

 

I snapped some pictures today of the set up. It is hard to see details on the chimney cap; it has a mesh screen around it.

I borrowed the MM, maybe I'll get my own. Last year after ~6-8 mos I was getting a lot of mud, drippy mud on the fire brick and glass, this is why I think I killed the liner. It's my own fault I knew I shouldn't have been burning it but thought I could get away with it. This year, the initial kindling produces a film on the brick, minimal on the glass, after load 3 it burns off, however with each load I will see the brick fog up and the air box exchanger fog up until the wood chars. I do have some ash that is reading 13% after ~7mos of seasoning. I try and burn wood in the shoulder season when coal is way too over powering. Once temps are a steady <40 daytime I typically switch over; however with all the wood I have I may not. I play the market price game, when oil is near or at 1.55 I don't burn coal, that's the break even point, and dealing with the ash needs to be worth my while, PIA that coal ash.
I use the top down method to start the fire, I grab 1 or 2 splits and make kindling out of it, use about 5 to 6 pieces of news paper and have 2 to 3 med size splits under it and have the kindling ~ in the middle to get heat on the larger splits. Seems to work ok. By the middle of the 2nd load I'm running about 450, 3rd load I'm at 550, the time form initial to 3rd load is a about 2 hrs, the thing eats wood like it's a job. I'm mainly using the bottom knobs and have the top knobs open to air wash the glass. The system drafts pretty well, maybe too well especially when the wind blows, I get a vacuum effect.
The chimney is a masonry and is outside the house. The SS liner is insulated, Fireside Chimney Supply FireFlex Insulation Wrap 1/2in - 3in to 6in liners (25ft), liner is Fireside Chimney Supply FireFlex 316Ti Basic Flexible Chimney Liner Kit - 6in x 25ft.

BTW, I had no idea you guys existed, I googled burning wood in a smoke dragon and the smoke dragon thread came up.

 

I've heard Ash is quick to dry, but now that I'm burning some from last year, it still sizzles a little bit, so it's not dry.
Again, I'm doubting your firewood is dry.
Even with my older stove and dry wood, I had a stove temp of 500 within 15-20 minutes.
After seeing those tubes, I'm now wondering if they aren't robbing the whole system of heat. It's not going to be a real efficient stove anyway, which means a lot of particulates going up the flue, then add in the heat robbing tube deal and possibly not ready for prime time wood, you get creosote.
Nice to see the insulated liner,.........that helps.

Burning too low, and/or wet wood......that's not mud, it's creosote. In the firebox, not so much a problem, but it's a good indication that the flue is in a similar condition. That's a problem.
Still waiting for the smart guys/gals to show up.

 

Papadave, I was thinking the tubes may be hurting my flue temps, but wasn't sure it's blowing enough air. If I wasn't so lazy I would run some arbitrary numbers and determine a rough % drop in temp. I basically researched the hell out of everything, I paid to have the liner and stove installed, I did everything else, wrapped it, uncoiled it. I new I would never be efficient burning wood, I bought the stove knowing I could go 12 to 18hrs on coal without touching it; however I thought I'd be able to burn wood in it. I also under estimated the coal ash.

 

IDK if this would have anything to do with your creosote problem but I wonder if you should feed the wood fire with air from the bottom. I always thought that was just for coal, have a manual w/ this stove?

 

Welcome tungsten.
I agree with these guys, if it is creosoting up that bad I guarantee your wood is not as dry as that meter says...those things only give a ballpark # at best anyways, but yours may be faulty. Try burning a little kiln dried lumber...construction cut offs, pallets, etc, see what happens. (but only after a chimney cleaning...if you burn good dry stuff after the chimney is crapped up...well, you know..."self cleaning chimney" Oh, and your chimney sweep must be brand new...because they teach you, pretty much first day on the job, that after a chimney fire, (which is caused by creosote buildup) the chimney will be squeaky clean. Bet you're glad you sprung for an insulated stainless liner now after having a chimney fire or three!

And yeah, try slowly closing those bottom air controls after the fire is established and cruising...wood fire needs top air so try using the top knobs to control the fire more so. Speaking of top air, you mentioned air wash...I don't think your stove has it...unless there is passages internal to the door that comes out above the glass. an actual factory "air wash" puts air in right above the glass (the "cool" incoming air falls in the hot firebox, making an air curtain that keeps the smoke from condensing on the glass)

 

welcome tungsten I have no more help for ya... but what others said ....seems odd!

 

tungsten , have you tried a fire without using the blower that pushes air through the tubes?

 

Ok, so the consensus is, wood is not ready and I'm burning too cool and too slow to get up to temp. I haven't tried burning without the tubes/blower running, I'm afraid of damaging the unit. If I mess up the tubes I have lots of welding/grinding to do as they run thru the fire box. I have a manual, but it covers burning coal, and the only mention of wood is kindling for a coal fire. they are not allowed, EPA, to advertise wood burning. The top knobs, for coal anyway, when open cool down the fire box, I'm not sure much of this air makes it to the fire or creates a vacuum to allow heat to go up the flue versus hang around to create actual heat in the stove/room. When burning wood, it creates a turbulent burn and flare up/die out cycle with puff back, sounds nasty, and like a chimney fire is starting...which in my experience is terrifying.

 

The tubes can not extract enough heat to cause your issue, moisture in your wood is #1 problem. Now, I haven't burned splits in decades but I remember my father's advice burn only well seasoned wood three year split and on the stacks. In other word cut, split, and stack for 3 year from now. I seem to recall 15% to be he ash weight for a good hard coal, used to burn a lot of that stuff years ago, like 26 years ago or so.

 

Probably a combo of all the above, but I'll go back to what I said earlier and what Smokey said too, mostly I think it's the wood.
Add in the burning low and slow, and ............
I'm not sure if you'd get any more heat from those tubes than I do pulling heat off the outside of the stove with a blower and deck, so ............?

 

Disclaimer, I now burn wood pellets so what the hey do I remember.

 

Coal stoves do not burn wood well! Add to that wet wood and you get flue fires.

I have a French trash burner. In France it is certified to burn almost any fuel, there is even an oil adaptor. It burns coal very well. It also does small hot wood fires pretty good. If I load it with a large load of wood for an over night burn it smokes like crazy. Since I have an insulated internal flue and dry wood I get away with it, warm flues do not condense a lot of creosote before the smoke gets out the top!

I normally use it for long coal fires, I've gotten 48 hours out of it easily. I also use it for quick hot wood fires to quickly warm up the house.

First make sure your wood is dry, less than 2 year oak is probably not. Then get used to your stove. When I burn wood in mine I open the bottom to get the fire to the level I want then open the top a little to help burn off the smoke before it enteres the flue. If you have smoke coming out the flue then adjust the air until it is minimized. The more moistue & smoke in the flue the bigger the chance of a flue fire...

KaptJaq

 

KaptJaq,

once your burning at the level you want, what are you targeting, do you close the bottom knobs?

to the rest of you guys, thanks for the replies. I'll probably pick up another moisture meter, see what I'm getting.

 

No, I adjust them to keep the stove at the heat level I want. If they are closed then the fire does not get enough air and smoulders/smokes.

The important thing to watch is how much smoke comes out the flue. Try to minimize it as much as possible. Small, hot wood fires work best in this stove...

KaptJaq