Creosote

[Corley5]

I just came in from filling up the outdoor stove and once again noticed how much more creosote this well seasoned wood has in it.  I've been burning hard maple and beech that was cut green and has been stacked inside, some of it since the woodshed was built in the fall of 97.  It's got way more of the stuff in it than the green maple I started burning in December.  It will actually drip from the heat exchanger tubes and run down the sides of the firebox and pool in places.  The ash pan even got semi stuck because of it.  Never seen anything like it.  The green wood never did that.  It had creosote in it but not of this consistency or magnitude.  It really doesn't matter because it's an outdoor stove without much a chimney.  The cap caught fire last night and burned for 20 mins or so.  Nice pretty blue and orange flames 8).  I wouldn't want to burn this stuff in an indoor furnace.  Shoots down the seasoned wood theory as far I'm concerned.  This new heating system takes more wood and that's why I'm into this extra dry wood.  I figure I'm burning about 25% more wood this winter but it's OK with me.  The house is 80 degrees in the living area and 77 in the sleeping areas.  Dee complains about being cold if it gets below 78 in the living room :.  My electric bill is about $40.00 less a month with the wood heated hot water, I've only got to fill the stove once a day and the fire and mess is outside, so it's good 8) 8) but I still can't believe the creosote in this extra dry wood .   

[WH_Conley]

I burned an outside stove about ten years before we moved, never had cresote problem, green wood, fan worked a little harder, my daughter uses it now, lots of cresote. Their wood is inside no less than a year before it is burned, I might be wrong but I think the wood is too "good".

[beenthere]

Corley5
That is certainly a mystery. Hope you find the cause.

[old3dogg]

I read somewhere that cresote is not caused by how dry the wood is but is caused by a lack of air to the fire?
I used to "bank" off my wood burner at night and had a lot of trouble with cresote. Had to clean the flue every few weeks. I let the fire go out at night now and have not had any trouble at all this winter.

[SwampDonkey]

I'm at a loss Corley. Anyone burning green wood here has bad creasote and the neighor has a flu fire annually. He never cuts the wood untill a week or two before he burns it. Green as can be. My wood is well seasoned and I don't have creasote problems at all in the flu. My cousin got green wood two years ago and it was a horrible mess, she was about to throttle the cutters at one point.

I'm wondering if the green wood you burned first was building up creasote deposits and the hotter dry wood was causing it to work out of the unit.

[sprucebunny]

If you let the fire get ripping with alot of air once a day it will reduce the creosote.

Adding a half cup of deisel fuel will help, too.

Burning coal once a week or maybe adding a few lumps will reverse the build up. But BEWARE because I've had the whole winters build up fall down the pipe into the stove when I switched to coal one spring.
Things were a little out of control...... had to mist the stove to keep it from melting 

[devo]

I think theres something to what Old3dogg said. I'm sure I read somewhere that creosote can be caused by too little air. In an outdoor type stove this fits since you can have long smolder times before the thermostat calls for more heat. Since you are useing very dry wood that might make your smolder times even longer since your efficency is higher. Just a theory though. You might try burning some green wood once in a while to get a longer burn time and see if that burns up the excess creosote.

[redpowerd]

i wonder how soon the 'sote would burn out keeping her good and hot with some nice dry wood for a while

[Ron Wenrich]

I don't know how the outdoor furnaces work, but for my inside stove, I keep my stack temperature at about 300.  I don't ever have creosote problems.

Green wood can be burnt, but the first thing your fire has to do is burn off the excess moisture so it can ignite the wood.  That lowers your stack temperature, and creosote forms.

Creosote forms with temperatures under about 240.  If your getting a big problem, I would suspect that your burning at too low of a temperature.

[chet]

    Great explaination Ron.   

This is used as a handout from our fire department. We make sure all folks that call us for a chimney fire get this.  http://www.cnr.uidaho.edu/extforest/WFS6.pdf

[Mark M]

I agree with Ron. When I first started mine this fall I had a bad problem with creosote collecting in the firebox. At the time I didn't have an aquastat on the circulator so when there was a demand for heat the water temp could be drawn down to as low as 100 degrees. Now the circulator cuts out if it is less than 160 so that is as low as it gets and it can recover much quicker. The main aquastat is set at 200 so it runs pretty warm. The design of the boiler can be a factor so if you have a lot of "water cooled" surface area inside the firebox then condensation will be more of a problem.

[SwampDonkey]

Thanks Chet for the link, I've downloaded and printed a couple copies for family members.

[Corley5]

The circulator pump on mine runs all the time.  I've got the draft blower set to come on at 170 and go off at 180.  The water temp will usually climb to 187 or so after the blower shuts off.  The walls of the forebox never get real hot and would explain the condensation of creosote but not why the dry wood forms more than the green did.  Cycle times for the draft blower are about the same for both woods depending on outside temp etc.  It kicks on every 2 or 3 hours, more if we are using a lot of water.  The creosote that forms in chimney is miniscule when compared to that in the firebox.  This dry wood does burn with MUCH less smoke.  Only a wisp of white smoke comes out at an idle and just slightly more when the blower is running.  Once this winter I let it burn down and took a round point shovel which fits the round firebox just about right and scraped the deposits off and put them on the bed of coals to burn.  That was after a couple months of burning green wood.  It needs it again after a couple weeks of dry wood.  One thing that probably would do more to relieve the condition than anything else would be firing twice a day to keep a smaller hotter fire instead of filling it to capacity once a day and having a larger cooler fire.  But it sure is more convenient to only do it once ;) 

[MemphisLogger]

What Ron says 

I dry my split Oak at least a full summer, Cherry and Walnut for at least 3 months and Elm or Gum as much as 2 years.

I leave the air all the way open on my stove all the time and regulate it's output by load size, piece size and species. My kids tell me first thing in the morning just what flavor of fire to start  ;)

Lately, all they want to burn is Cedar--a sure sign of spring.

Almost all the smoking/creosoted stoves I know of are oversized for the space they serve and the operators always have the air way down to moderate their output.  :(

Since I run a small, highly efficient stove with a catalyzed secondary burn, hot primary combustion is essential for performance. I'm sure the second burn helps reduce creosote too.

I have a brush and check it several times a season but I've never had any build up--the insides of my chimney are still so shiny that the light that comes in through the glass doors is enough to inspect it clearly from the roof.

That brings up another thing--straight-up chimneys are the bees knees for efficient burning. 

[Corley5]

That brings up another thing--straight-up chimneys are the bees knees for efficient burning. 

That's for sure.  I had an 8" chimney in the house that went straight and it never needed cleaning.  I'd run it hot now and then and what was in it would dry out, fall back into the stove and burn up.  Elbows in chimneys are a pain in the butt 

[chet]

Corley,
I know what you mean with your outdoor boiler. I think what happens when you burn green wood, the burn cycle is much longer so as to burn off the moisture content of the wood. This brings in fresh air and sends combustion products up the chimney. With dry wood the cycle time that the fire is actually free burning is much shorter, thus the smolder stage is longer. This leaves the combustion products just sitting in the stove and thus collecting.

[Corley5]

Good theory Chet and I think you're probably right .  I like green wood better ;)

[farmerdoug]

I have to agree with Chet on that point.  I only have problems with the Central Boiler I have when I burn mostly dry wood.  I even had a problems with the damper sticking this year for the first time as i was burning alot of pallets I received last year.  When I finially run out of dry wood and switched to green wood no more problems.  I guess I will have to mix dry and green together in the stove next year.  I think Chet is right about the fire burning hotter and the reaching top temp faster and then sitting longer to restart burning again.

[Bro. Noble]

When they make charcoal,  they get the wood burning well and then shut off the air.  This creasote and acetone are produced as by-products.  This is called distructive distillation. 

I usually fill our furnace each morning when I come in from milking,  and again before dark if the weather is especially cold.  Lately it has been frosty at night and up to 60 during the day.  When I start to fill it of an evening,  :)there is a deep bed of charcoal,  creasote is running down the stack,  and I bet a bunch of acetone went up it.

It has been mentioned to let the fire burn hot and not to let the fire smolder.  This is so you avoid destructive distillation.  We need to change how we charge the furnace when it's warm during the day to avoid creasote production.