Hardwood vs. softwood burn times

[branchburner]

For the first time ever I have a lot of pine in my stacks this year, so I'm going to get the answer myself anyway, but I'm wondering what difference in burn times people get with softwood vs. hardwood?
I know a lot of folks burn just one or the other, so this question is directed more to those who burn both. Just curious for a given stove under similar weather conditions what has been observed. Obviously a full load of fuel with half the BTUs is going to give less heat, but I'm wondering how much of that difference will be in lower stove temps and how much in shorter burns.

 

[Backwoods Savage]

You won't necessarily have lower stove temperatures but will have shorter burning times.

 

[gzecc]

Depending on the species and dryness anywhere from 50-20% less heat and more wood. Higher stove temps for shorter times in general. Very relative question.

 

[firefighterjake]

Uh . . . yeah . . . what Savage and Gzecc said . . . shorter burn times, not much difference in stove top temps except perhaps for a short time when it may increase a bit.

Personally I like burning pine during this time of year . . . good for getting the place warm without having a long-burning fire which would over heat the house. I also like pine for use in starting the first fire from a cold start. Pine may not be so useful if you're looking at doing an overnight fire and want coals in the morning.

Oh yeah, I forgot to mention . . . you do know that burning pine will cause chimney fires and baldness in males and a propensity to think you are the best and smartest wood burner anywhere right . . . wait a minute . . . forgot that last part . . . that only occurs if you've been drinking too much tequilla.

 

[branchburner]

So do guys who burn only pine not get overnight fires? I understand the general idea of shorter burns. My experience with pine is pretty limited (scared of losing all my hair). I seem to get a hotter fire at first, as I'd expect, but then my cruising temp seems lower for the duration of the burn. I don't know if that was just the condition of the wood, or what.

The big problem for me seems to be the lack of coaling with pine. My stove likes a good coal bed to engage secondary burning (and maybe that's why my temps were lower). I don't know if downdraft stoves are more fussy about what they eat in this respect.

Pine has about half the BTU per volume of hickory. So I realize my two cords of pine is worth a cord of hickory in heat value, but I'm thinking the shorter burns mean less efficient BTU conversion. Maybe the pine is best used in shoulder season as you say, or mixed in instead of burnt alone.

To be more specific with my original question, if I get a 10-hour burn from a full load of hickory in the dead of winter, should I expect a 5-hour burn with all pine and expect the same stove temps?

 

[stockcarver]

'I know a lot of folks burn just one or the other, so this question is directed more to those who burn both. Just curious for a given stove under similar weather conditions what has been observed. Obviously a full load of fuel with half the BTUs is going to give less heat, but I’m wondering how much of that difference will be in lower stove temps and how much in shorter burns.'

I could be wrong on this, so no hurt feelings if someone can set me straight. I seem to recall hearing it stated that 40 pounds of bone dry wood will give off a certain amount of BTU's, regardless whether it is pine or oak. If you think about that for a moment, it makes sense. If a full cubic cord of bone dry oak weighs, say, 3500 pounds, how much cubic measure would the 3500 pounds of bone dry pine be? Probably 1-3/4 or more full cubic cords? Just imagine how many cords you would get if you had 3500 pounds of balsa wood?

The key here is BONE DRY, to eliminate the weight of moisture for the comparison. Stands to reason that if you loaded the stove full with oak, you might have 40 pounds of fuel, the same stove would only hold 20 or 25 pounds of pine.
I have no problem heating my house with pine, and overnight fires of 12 hours are easy, keep in mind this is with a blaze king princess which has a nice size box. I have also done the same with our local oak, which is more of a bush than a tree, not the same quality as the real oak species, it does last better than pine, but only because there are more pounds of wood in the firebox, at more cost I might add. I think we would have different opinions on firewood if we compared weight of dry wood rather than measuring by cubic size.
Just an opinion, nothing more...

 

[Vic99]

I plan to do an experiment this season to test burn times.

My plan is to pick a stovetop temp., probably around 200F. and load the stove to a repeatable level (maybe 1/2, 3/4 or full, not sure yet) with all of one species that is <20%. I'll probably do lumber scraps, white pine, sugar maple and whatever else is suitable. I'll time it until that temp is again reached. I'll try to do it with similar outside conditions on each test run so that draft is not a factor.

Stovetop temp, level filled, and all that don't really matter as long as I am consistent and careful each time. I have a woodstock fireview.

When it gets colder I'll run it and post my results.

 

[branchburner]

Stands to reason that if you loaded the stove full with oak, you might have 40 pounds of fuel, the same stove would only hold 20 or 25 pounds of pine.
I have no problem heating my house with pine, and overnight fires of 12 hours are easy, keep in mind this is with a blaze king princess which has a nice size box.

Understood as to the point about weight vs. volume (figuring oak at 25 btu/cord, pine at 15 btu/cord ballpark) - that's what I'm looking for, an apples to apples comparison for a full firebox, not on which wood is better. It's funny around here, though... people pay you to take away pine!

I would figure a cat stove like BK is the way to go for long burns with pine at best efficiency.

So my question is this: if you get 12 hours with a load of pine, can you get around 20 with the same size load of oak?

 

[Highbeam]

I burn a lot of cottonwood which is as low or even lower than pine in btu and I can easily get an overnight burn. True, there are half as many btus in my full firebox but the burn time isn't half what it would be with hickory. I mean, I am getting more than 8 hours on the junk wood but I wouldn't expect a 16 hour fire from this stove with anything but coal. This tells me that I must actually be making less btus per hour at low burn when burning softwood.

 

[Wet1]

So my question is this: if you get 12 hours with a load of pine, can you get around 20 with the same size load of oak?

Sounds pretty close to me, all things being equal.

 

[Wet1]

I burn a lot of cottonwood which is as low or even lower than pine in btu and I can easily get an overnight burn. True, there are half as many btus in my full firebox but the burn time isn't half what it would be with hickory. I mean, I am getting more than 8 hours on the junk wood but I wouldn't expect a 16 hour fire from this stove with anything but coal. This tells me that I must actually be making less btus per hour at low burn when burning softwood.

Have you compared the btus of coal and hickory?

 

[stockcarver]

"I would figure a cat stove like BK is the way to go for long burns with pine at best efficiency.

So my question is this: if you get 12 hours with a load of pine, can you get around 20 with the same size load of oak?"

Absolutely yes, even longer, but there comes a point where I need more heat if I expect to maintain 70 in the house. We do not have choice oak in New Mexico, only oak brush, which is no comparison to the oaks and hickorys available back east. If fact, I think our pinon is just as good as oak brush, if not better.
I had a full size blaze king in No. Idaho, and burned only fir and larch (a very dense resinous fir) I loaded the stove as full as possible, even filling in gaps with small splits. I set the thermostat at the lowest setting and we left for the Christmas weekend. No other heat in the house (a converted pole building) at all, when we returned 47 hours later, the house temp was 50 degrees and there was a large glowing coal the size of my forearm remaining. It was bumping 15 below at night, I was just expecting to come home to frozen pipes, so 50 was amazing.
Had that load been oak or good hardwood, I'm sure it would have been warmer with wood remaining. Few stoves could hold a fire and radiate useful heat for that long. Most folks have a second source of heat to kick in, but we only had the woodstove and conifer wood. The ability of Blaze Kings to make long burns with marginal fuels is what makes them so popular in the north country. On the other hand, premium fuel can make a marginal stove quite suitable.
I am not saying there are not better stoves than the blaze king, but I am not aware of them, and have not seen any in action out here. I can only relate to my own experience. I will say this, I will NEVER buy another stove WITHOUT a thermostat to control the air intake.

 

[Highbeam]

"I will say this, I will NEVER buy another stove WITHOUT a thermostat to control the air intake."

And that means that you will ONLY buy a blaze king. Too bad the thermostat isn't more common on stoves, it is also a safety mechanism.

 

[EatenByLimestone]

I haven't seen any mention of surface area of the loads. Getting air in and around the fuel is what allows it to burn. If I throw a large block or two of pine in the stove it may take all day for it to burn. If I throw in an equal volume of oak splits I may have it go up in a few hours. The larger the surface area the quicker it will burn.

Matt

 

[Todd]

Pine around here is junk, it will burn but leaves no coals and doesn't burn long. I can get 6-8 hour burns with it, but would rather use it for a quick fire or kindling. But if that's all I had to burn it would have to do. I think the Pine out west or way up north is a little more dense and can burn as good as some medium BTU hardwoods.

 

[branchburner]

Mostly white pine around here, very low on the BTU chart. I think you are right, pine out west is a little more dense as a rule.

Another great plug for Blaze King here, huh? I'm starting to get BK envy!

 

[begreen]

"I will say this, I will NEVER buy another stove WITHOUT a thermostat to control the air intake."

And that means that you will ONLY buy a blaze king. Too bad the thermostat isn't more common on stoves, it is also a safety mechanism.

For the record, also on several VC stoves.

 

[SolarAndWood]

Another great plug for Blaze King here, huh? I'm starting to get BK envy!

From a cold start, a full load of pine went up in a BK King on high this evening in 4 hours. We'll see how the locust I just loaded does.