February 01, 2003

Hope Runs Eternal ~ Part Six

or, Uncle Fred's Recipe for Creosote

1) Start with wood that has a lot of moisture.

Fresh green wood has up to 90% moisture, depending on tree species. Air dried wood that has seasoned for a year has about only 20 percent moisture and will not be a good source of creosote. Green wood not only contains lots of water but it will make your fire slow to reach ignition temperatures and will cool down the temperature in the firebox nicely for our purposes. Green pine is absolutely the best, especially if you follow direction #2.

2) To make the best creosote, starve the fire for air.

Woodstoves are excellent in this regard. Fireplaces draw vast volumes of air from the room, making them as worthless at producing creosote as they are at efficiently warming the air inside the house. Woodstoves, on the other hand, reduce O2 intake to only the total cross section of the draft openings... maybe 4-5 sq inches tops. Combine with this the tendency for stove operators to want to 'save' their load of wood overnight by shutting the draft way, way down. Green wood and restricted oxygen: now you're on your way to producing amazing volumes of gummy distilled wood liquor called creosote.

3) The final condition that must prevail if we are to produce the sought-after end product of combustion is cool stack temperatures.

Given that you have met conditions 1) and 2), you have only to cool the rising smoke and it's heavy load of contained moisture and unburned organics sufficiently while it remains in the chimney flue. This is easily accomplished when you slow cook your wet wood in a woodstove in an unimproved chimney designed for fireplace use! Warning: Do not add a ceramic liner to improve the draft; and whatever you do, don't use insulated double or triple wall pipe. This will keep flue gasses hotter than the distillation temperature and you will produce a disappointing amount of creosote. Let's review:

High fuel moisture + low stove temperature/reduced oxygen + cool gasses inside the chimney = copious high-quality creosote!

Congratulations! With these three basic principles under your belt, or rather, inside your heating system, you and your family are well on your way to having that certain air about you that says "We heat with wood, but mostly, we distill creosote!"

I apologize for that little tongue-in-cheek reverse lesson. Let me briefly recap the practical implications of my having learned these basic principles in the hardest of schools...

We moved from the house with the hot-fudge fireplace after six years in the house. (Yes, we did manage to clean the oily, smelly creosote off the hearth and mantle, and we redeemed the ESPERANZA so that hope ran again in our lives, but not with that awful black bile we had lived with there for an awful while.) We moved to a smaller house out in the country. The Fisher Stove went with us and lived happily there, fed by wood I cut off our twenty acres, but burned only after those couple of cords sat stacked and drying for a full year. I found a draft cap replacement that had a bimetallic coil that would open up the stove if it cooled off too much. A stove themometer on the smoke pipe helped me keep the stack temp over 250 degrees. The chimney was not great and we still had some creosote that had the good manners to stay inside the chimney. I climbed on the roof five or six times every season with a 4' length of heavy chain on a piece of rope; I jangled this all around to break off the dry flaky creosote, and then cleaned ashes from the cleanout in the basement. And we never had a flue fire.

After that, we have enjoyed (to various degrees...ask me if you have specific questions) Vermont Castings, Jotul, and Hearthstone woodstoves prior to our current stove. By far, I am happiest with our present stove and woodstove setup (which I will tell you about in some detail) and offer the final installment as an summary of 'what I have learned about wood heat'. I know I've already lost you city types, so Country Mice, stay with me just one more posting.

Posted by fred1st at February 1, 2003 06:45 AM | TrackBack

There's just nothing like wood heat. I've so enjoyed reading about your experience - not only has it filled me with memories of my first home, first fireplace and first husband (lol) - but it's reminding me again of how much I adore central heat & air ;)

Posted by: deb at February 1, 2003 08:15 AM

I once heated a two story 10 room house with wood. I don't remember now how many cords of wood it took to heat from Setember to April or May, but I spent four months cutting and spliting maple for heat. This was in Vermont. State motto, "Nine Months of Winter and Three Months of Poor Skiing". They way my son and I would clean the chimney was (With me in the celler and him on the roof) to pull a ball of chicken wire up and down the chimney. This was done in June and during the "December Thaw"

Posted by: Don at February 2, 2003 05:09 PM

'Sorry it took so long for me to comment on this series, but I was just SPEECHLESS and in awe that you could write an entire series on creosote! That's probably why there have been so few comments. Everyone was impressed.

Besides, when I type the word, "creosote", I can actually conjure up the smell and choking feeling I get when near the stuff. We opted for a propane fed gas fireplace this time.


Posted by: Red at February 3, 2003 07:06 AM

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