Wood seasoning question

[Cal-MI]

Nope, burning green wood produces creosote.

That is a half truth, which is a lie. Burning green OR dry wood can produce creosote. What is required for creosote formation is that the temperature of the flue be below the dew point of the fumes. Whether the wood is green or dry is irrelevant. Then it condenses on the inside of the flue.

In an ordinary stove, green wood produces more heat per cord, and less creosote than dry wood, according to the USDA FS wood laboratory, under their test conditions with a wood furnace. But apparently the Forest Service wood laboratories has not done any tests in the last 20 years to confirm this. The latest FS literature I could find on it is quite old. Since airtight stoves have come into wide use more recently, YMMV.

Probably some new stoves heat up the flue more quickly than others. For example, 30 years ago an eight inch or larger flue was standard. Now apparently it is 6 inches.

 

[BrotherBart]

In an ordinary stove, green wood produces more heat per cord, and less creosote than dry wood, according to the USDA FS wood laboratory, under their test conditions with a wood furnace. But apparently the Forest Service wood laboratories has not done any tests in the last 20 years to confirm this. The latest FS literature I could find on it is quite old. Since airtight stoves have come into wide use more recently, YMMV.

Probably some new stoves heat up the flue more quickly than others. For example, 30 years ago an eight inch or larger flue was standard. Now apparently it is 6 inches.

I have been toasting trees to heat the house since 1977 Cal and me and every wood burner I have ever known knows that the water you are cooking out of that green wood not only cools the stove but the flue on its way up the pipe.

Show me something that proves me wrong.

 

[Cal-MI]

???? Partly true, but it condenses on the flue if the flue is too cool, to put it more simply. As I, and the USDA FS, said. It is produced, or condenses out, whichever terminology you prefer.

 

[Cal-MI]

In an ordinary stove, green wood produces more heat per cord, and less creosote than dry wood, according to the USDA FS wood laboratory, under their test conditions with a wood furnace. But apparently the Forest Service wood laboratories has not done any tests in the last 20 years to confirm this. The latest FS literature I could find on it is quite old. Since airtight stoves have come into wide use more recently, YMMV.

Probably some new stoves heat up the flue more quickly than others. For example, 30 years ago an eight inch or larger flue was standard. Now apparently it is 6 inches.

I have been toasting trees to heat the house since 1977 Cal and me and every wood burner I have ever known knows that the water you are cooking out of that green wood not only cools the stove but the flue on its way up the pipe.

Show me something that proves me wrong.

Theoretically true, some species of green wood MIGHT cool the stove and flue more than dry. But USDA lab tests show that green wood produces more BTUs. I have been unsuccessful in finding the data on the USDA web site this year. It is old data. I have been heating with wood since before 1970 and I know that green oak is much easier to use to heat the house than dry oak. As I said, some modern stoves might behave differently, IOW YMMV.

 

[rdust]

Theoretically true, some species of green wood MIGHT cool the stove and flue more than dry. But USDA lab tests show that green wood produces more BTUs. I have been unsuccessful in finding the data on the USDA web site this year. It is old data. I have been heating with wood since before 1970 and I know that green oak is much easier to use to heat the house than dry oak. As I said, some modern stoves might behave differently, IOW YMMV.

I don't think you're going to have luck finding data to support this anymore. Even if you can dig up the old data I'd like to read through it.

In the 70's it was ok for me to ride on my parents lap in the front seat of their car, things change.

 

[branchburner]

Cal, I'm curious: how many sq ft are you heating and how much green oak do you go through in a season?

 

[madrone]

I'm having a real hard time understanding how this result could even be achieved in that study. How could wood with more water in it burn hotter than a similar piece of wood with less water? It simply cannot have any more btu's than it has, since water doesn't burn. In an old leaky smoke dragon, I can see maybe that green wood slows things down enough to produce some heat longer, since the dry stuff will indeed just burn up quickly with so much available air. You won't lose as much heat up the flue. I don't see how you could get more BTU's out though, since you're losing some of that heat to water vapor. I guess the difference here is that in a new stove, you're restricting air and increasing temperature to burn almost all the available BTU's, whereas in the "green wood" leaky stove theory, you're using water to combat the massive draft. You're simply going to extract more of the available energy in a new stove, since I can't imagine much reburn occurs with green wood. Could it?
I'd bet you'd still use less wood in a new stove with dry wood than an old one with wet wood. You seem like a candidate for a catalytic stove.

 

[madrone]

Quick googling produced this:

http://www.sredmond.com/vthr_index.htm

Interesting project. Page 2 has the good stuff. Seems to offer some insight to how a USDA study could show furnaces running on green wood, especially the part about CO and Hydrogen from moisture. Ultimately, they admit to an 11% loss in heat from using green vs. dry wood. Wood stoves seem like a different story anyway.

 

[branchburner]

Thanks, Madrone... really good stuff. I noticed Cal originally said "stove", and later said "furnace", so I was wondering if that USDA study was for some larger-scale OWB or industrial furnace. (Even then it might have gotten those results only under certain conditions.) I'm sure it wasn't for a household woodstove.

Page 2 also had an interesting observation about the performance of "green" oak chips vs. "wet" oak chips in that experimental burner. It got me wondering how "green" vs. "wet" plays out in different wood stoves, EPA or not. But I'll leave that experiment to someone else.

A guy who sells firewood and heats with an old Allnighter or Fisher was just telling me how he throws a few green splits on to slow it down for the night. And he won't burn dry softwood, it goes too hot, too fast. The times are changing, but changing slowly, at least around here. Cast iron just lasts too damn long, even if it leaks a bit.

 

[Cal-MI]

Cal, I'm curious: how many sq ft are you heating and how much green oak do you go through in a season?

When we bought the house (1964) we were told that if we but bales of straw around the foundation it would take 10 cords. We insulated the foundation by stopping up all cracks. We poured cellulose into the attic and walls and installed inside storm windows and ended using about 5 cords. About 1600 sq ft as I recall. Had the thermostat on the oil, later gas, furnace set at 55F and it took over after the fire died.

 

[Cal-MI]

???? Partly true, but it condenses on the flue if the flue is too cool, to put it more simply. As I, and the USDA FS, said. It is produced, or condenses out, whichever terminology you prefer.

blue smoke out hte chimnitop is unburnt/wasted fuel...& CO invisible produces 2.5x the heat as carbon
c- co = 1
c-co-co2 = 3.5

I agree with both statements. But how does one burn CO? Add a catylist afterburner? If you only restrict the input air in order to gain effeciency, you could produce lots of CO.

 

[branchburner]

Cal, I'm curious: how many sq ft are you heating and how much green oak do you go through in a season?

When we bought the house (1964) we were told that if we but bales of straw around the foundation it would take 10 cords. We insulated the foundation by stopping up all cracks. We poured cellulose into the attic and walls and installed inside storm windows and ended using about 5 cords. About 1600 sq ft as I recall. Had the thermostat on the oil, later gas, furnace set at 55F and it took over after the fire died.

With a new EPA stove and 5 cords dry wood, the fire won't die and maybe you can retire the furnace.

 

[Cal-MI]

Well, I have finally installed a Jotul C 450 certified effecient fireplace insert. It is a whole 'nother way of burning wood from my old almost airtight stove. I am burning quarter split red pine that has stood so long that the bark had fallen off before it fell over. It is a little damp from being out in the rain for years. The air restriction on the stove's input controls the burn quite well.

I do occasionaly have to open a door a bit and/or use a bellows to get a fire started. I have never seen a wad of newspaper refuse to burn before.

I am quite disappointed that I cannot put in one 10" diameter round section, but have to only load 1 or two quarter splits. No room for any more. What a tiny firebox! I could not install the larger model Jotul without cutting some brick from the fireplace. But the air control does make the burn last a long time. And the fan keeps circulating hot air for an hour or two after the fire has died.