"Hardwoods create more creasote than softwoods"

[croghanite]

Back in the early 1980's, tests were conducted to discover which kind of wood created the most creosote in a regular "open" fireplace. The results were surprising. Contrary to popular opinion, the hardwood's, like oak and madrone, created MORE creosote than the softwoods, like fir and pine. The reason for this, is that if the softwoods are dry, they create a hotter, more intense fire. The draft created by the hotter fire moves the air up the chimney faster! Because it is moving faster, the flue gas does not have as much time to condense as creosote inside the chimney. Also, because the flue gas is hotter: it does not cool down to the condensation point as quickly. On the contrary, the dense hardwood's tend to smolder more, so their flue gas temperature is cooler. Thus, more creosote is able to condense on the surface of the flue. So, saying that "fir builds up more creosote than oak" just isn't true! It is a misunderstanding to think that it's the pitch in wood which causes creosote. It's not the pitch that is the problem, it's the water IN the pitch. Once the water in the wood has evaporated, that pitch becomes high octane fuel! When dry, softwoods burn extremely hot!

What do y'all think about the bolded quote? True or false?
quote taken from :http://www.mastersweep.com/wood.htm

 

[BrowningBAR]

Going with 'false'. If your wood is dry it shouldn't matter if you are using hard or soft wood (creosote wise, that is).

Oddly enough this is the exact opposite that is usually mentioned (but still wrong) about pine wood.

 

[Lumber-Jack]

Actually there is a correlation between the precceding logic and how the myth that Pine causes chimney fires probably got started.
You take your typical Easterner who burns predominantly unseasoned Oak for a few years, blissfully developing a good thick coating of creosote in his chimney. He finds, or someone offers him, some nice dry Pine. He then proceeds to burn a load of this nice dry Pine in the same manner as he usually burns the wet Oak expecting much the same sort of results, but instead the fire burns much hotter (the way it is suppose to) than it has ever done in the past, thus igniting the creosote, that has been developing in the chimney for years, and he has a huge chimney fire. The fire department comes and puts out the fire (hopefully saving his house and family), later the fire chief asks the homeowner how the fire started? And the homeowner says, “all I did was burn a load of Pine.” Thus perpetuating the myth that the Pine was the “cause” of the chimney fire.

 

[northwinds]

Seems like they're comparing dry softwood with smoldering (wet) hardwood.

 

[NH_Wood]

Interesting. I'm from the northeast and one of the things I remember my Dad saying about wood burning was to NEVER burn pine. I've been burning all my pine in my outdoor pit - and saying to friends around the fire 'what a shame I can burn all this wood in the stove'. Even with all the information I've read on this site about burning pine (e.g. it's safe, burns fast and hot, etc.), I can feel myself wincing from the thought of putting some in my stove. I guess I'll make use of all the pine and experiment with mixed loads - using the pine to burn down coals, etc. (in other words, taking the advice from all you pros!).

 

[Lumber-Jack]

Seems like they're comparing dry softwood with smoldering (wet) hardwood.

Yes they probably are, but because of the relative ease and short time that it takes to dry softwood and the years that it takes to properly dry hardwood, it is what most people burn. Very few people will actually store their hardwood for the 2-3 year that is required for it to be properly seasoned, and even less people sell properly seasoned hardwood. That's just the way it is, and probably always will be.

 

[fossil]

Doesn't matter what kind of wood...burn it before it's properly seasoned, and you get crappy fires and run the risk of a lot of creosote buildup. Burn it only after it's properly seasoned, and you get good fires and little creosote. I burn almost nothing but softwoods in two stoves every season, and I sweep my flues once/year after the burning season's over. Yes, I have creosote...maybe ¼" buildup on the inside walls of the pipes...less down low, more up high. Black, fluffy stuff that brushes off very easily. We burn a lot of wood (~7 cords/year), always stay warm, never had a chimney fire. Sometimes I come across some Oak or Madrone. Nice wood to burn when seasoned. I save it for special occasions, or mix it in during particularly cold weather. Rick

 

[hareball]

I'd say the seasoned softwoods would have the advantage in a basic fireplace. A stove is a different story yeah?

 

[fossil]

I'd say the seasoned softwoods would have the advantage in a basic fireplace. A stove is a different story yeah?

Not sure I understand your question, in the context of the OP. I burn softwoods because that's what's available where I live. I burn them in 2 steel plate EPA certified free-standing woodstoves. If I had hardwoods available to me, the advantage over what I typically burn would be longer burntimes, and burning a smaller quantity of denser fuel for the same heat output. Personally, I think burning anything at all in a "basic fireplace" is just a waste of time and fuel. Rick

 

[hareball]

What I mean is a fireplace only has as much draw up the pipe as a natural fire will create. A seasoned softwood is gonna burn hot and exit the chimney quicker th a hardwood of similiar size in the same fireplace.

In a stove air becomes more like a real fuel and this test is not valid in a woo dstove. Am I on the right track here lol?

 

[Valhalla]

Properly seasoned wood will never cause a
problem when burned safely.

Seasoned wood fuel always levels the playing field.
I have to say that having a large wood shed helps
me out so many times. I'll put all sort of wood in it,
at all stages of the process. I can then work
it up in most any weather. Leaving less excuses
for me to be stupid, be it hardwood or soft.

Lastly, a clean chimney flue is the final assurance of
success.

Always burn safely!

 

[Pagey]

I think part of the problem is that people think creosote is this substance that's already contained in various woods in varying degrees. Meaning it's something solid, already in the wood. Something you could touch and measure if only you could open up the wood somehow and get to it. Perhaps they think that natural wood resins are creosote in its "natural" wood state before being released by burning. So, they think since softwoods have a lot visible, natural resin "omg, teh creosote machine!"

But my understanding is that creosote is simply a byproduct of combustion - i.e., it's "in" EVERY wood species. You burn wood, you release, among other things, tar, organic particles, and water vapor. In the flue, as the exiting gases slow and cool, the water vapor (even seasoned wood is 20% water) and these organic particles/tars combine and collect on the relatively cool surface of the flue. If not cleaned regularly, they build up over time, decrease the surface area of the flue (thus further slowing the gases' exit), and pose a fire hazard.

It's not like creosote is in some "pre-packaged" form that you can pick up two pieces of wood and say "oh, this one has more creosote". You can, however, pick up a green, wet piece and be assured that when you burn it, you will release MORE water vapor which will combine with tars/organic particles, slow secondary combustion, and cool your flue gases.

 

[savageactor7]

Well the tests were conducted in an open fireplace. Since softer woods burn *hotter* it seems reasonable to me that the hardwoods would produce incrementally more creosote.

So What? Another million dollar govt boondoggle expenditure that proves the obvious but creates confusion.

 

[Lumber-Jack]

The conclusion reached from this test had nothing to do with it being conducted in a fireplace,,, the same results would very likely have been reached if it were conducted in a wood stove, in fact it happens every day in a wood stove and you can read about it here in this forum daily too. The single biggest, most common problem posted about in this forum is that of people dealing with trying to burn unseasoned hardwood. The stuff just takes to dang long to dry, and most people aren't prepared or willing to store 2-3 years of wood ahead of time, and the availability of properly seasoned hardwood is practically nonexistent or too cost prohibitive. Nobody I know buys or stockpiles their fuel oil or the LPG 3 years in advance, but that is pretty much what you have to do with hardwood to be able to have it burn properly, or else pay a premium from some outfit that sells kiln dried wood, and if you do that any savings from burning wood to heat your house are out the window.
So, the end results are that most people, who live in areas where hardwoods are the norm, end up burning hardwood that is not seasoned properly and of course it burns poorly and produces a heck of a lot of creosote, or at least more so than softwood that dries much quicker and is more likely to be seasoned properly.

 

[billb3]

I think someone at mastersweep .com burns whacky tobacky.

 

[rphurley]

Every year I'm amazed at how many of my neighbors buy their wood supply in the fall to burn in the wintertime. There is a lot of unseasoned hardwood being burned on my street!

 

[Battenkiller]

Every year I'm amazed at how many of my neighbors buy their wood supply in the fall to burn in the wintertime. There is a lot of unseasoned hardwood being burned on my street!

I buy almost all of my wood in the fall. I just pulled my flue pipe out yesterday and took a look up the flue with a flashlight and mirror. There was a little creosote right by the bend from the thimble into the main flue from the night before that I probably burned off in the first half hour of the burn following my inspection. There were patches of very dry and dusty looking flaky stuff a ways up and some deposits in the corners way up high. Nothing to annoy the sweep about after well over 1 1/2 cord burned, and my stove is what you all consider to be a "smoke dragon". I know what I'm doing, but I can see that a new stove owner and a big pile of green oak is not a good match.

Personally, I believe that the hotter wood burns, the more complete the combustion, and the faster it will exit the flue regardless of wood type. My smoky burns (yes, they do happen on occasion) have always been from a slow burning fire no matter what kind of fuel. Big chunks of 3 year old dry oak will produce a slow burning fire if thrown in a warm stove. Toss them into a roaring bed of coals and you won't have a problem (except with the production of too many coals). The cleanest burns for me are the ones where there are about three fair sized splits on top of a really hot, relatively small coal bed. If the coal bed is too deep, you won't be able to get it really hot because you can't get the air through the coal bed as easily. CFM of air in equals CFM of air out. Since flue size is constant, faster burns that consume more air necessarily increase the velocity inside the flue and speed the exit of gases from the top of the stack.

Pressed for an opinion based on my limited experience with burning pine in a stove, I would guess that dry pine will burn hotter and faster than dry oak cut the same way, and therefore will produce less creosote.