Burn Time assessment

[TonyP]

Almost every wood stove I see advertised describes it's 'burn time,' however, I just read on the Jotul site that very few stoves actually maintain a burning log for more than 3 hours. Makes sense, considering there's only so much burnable fuel inside a log to start with. Is the projected (read:mythical...) 'burn time' then generally how long the stove stays above 300 degrees? Or is there indeed a class of herculean stoves that, when fully loaded, will burn (produce flaming logs) for 6...8...10...+ hours?

 

[gzecc]

Its really a heat production length. Flames shouldn't be your goal. Its just part of the picture. There are many variables, fuel and stove design probably being the two most important.

 

[TonyP]

Its really a heat production length. Flames shouldn't be your goal. Its just part of the picture.

Thank you.

 

[BobUrban]

Or is there indeed a class of herculean stoves that, when fully loaded, will burn (produce flaming logs) for 6...8...10...+ hours?

Nope

 

[blueguy]

Is the projected (read:mythical...) 'burn time' then generally how long the stove stays above 300 degrees?

There is no real definition of burn time. It seems most manufacturers equate it to the time elapsed from the first match to the last ember going out. Very, very few actually equate it to the amount of time useable heat is being produced.

Or is there indeed a class of herculean stoves that, when fully loaded, will burn (produce flaming logs) for 6...8...10...+ hours?

There are lots of stoves that will produce useable heat for 6, 8, 10 or more hours, but the majority of heat is produced during the coaling stage after the flames die out. It all really comes down to firebox size, type of wood being burned and how the stove itself was designed. House type, construction, insulation and chimney draft play a role too. Judging by the majority of posts on here, most 3 cu ft. stoves will produce useable heat for about 8 hours or so, maybe a little more, but only a couple manufacturers' stoves seem to be able to consistently reach 16+ hours on a single load - namely Woodstock and Blaze King. I'm sure there are other manufacturers that can hit that timeframe, but these two are the ones most discussed and compared.

Personally, I have a BK Sirocco 30, and I have no problems getting 24 hours of useable heat from a full firebox in the shoulder seasons. To me, that's a stove top temp of between 250* and 350*. During the dead of winter, I'm able to achieve 12 hours of useable heat (350* - 400*) on an almost full firebox which is what I was looking for when I swapped out my Napoleon 1450 a couple years back.

Edit to add: I'm heating 2300 sq. ft. total from a finished basement on an exterior chimney. My house was built in 2010 and has 2X6 walls with R20 insulation and between R40 and R50 blown-in insulation in the attic. YMMV.

 

[TonyP]

There is no real definition of burn time. It seems most manufacturers equate it to the time elapsed from the first match to the last ember going out. Very, very few actually equate it to the amount of time useable heat is being produced.



There are lots of stoves that will produce useable heat for 6, 8, 10 or more hours, but the majority of heat is produced during the coaling stage after the flames die out. It all really comes down to firebox size, type of wood being burned and how the stove itself was designed. House type, construction, insulation and chimney draft play a role too. Judging by the majority of posts on here, most 3 cu ft. stoves will produce useable heat for about 8 hours or so, maybe a little more, but only a couple manufacturers' stoves seem to be able to consistently reach 16+ hours on a single load - namely Woodstock and Blaze King. I'm sure there are other manufacturers that can hit that timeframe, but these two are the ones most discussed and compared.

Personally, I have a BK Sirocco 30, and I have no problems getting 24 hours of useable heat from a full fireboxes the shoulder seasons. To me, that's a stove top temp of between 250* and 300*. During the dead of winter, I'm able to achieve 12 hours of useable heat on an almost full firebox which is what I was looking for when I swapped out my Napoleon 1450 a couple years back.

Thank you.

 

[firefighterjake]

BlueGuy's post pretty much said everything I would have . . . so no further comment needed from me.

 

[TonyP]

BlueGuy's post pretty much said everything I would have . . . so no further comment needed from me.

Thank you.

 

[Starstuff]

Even the term "usable heat" is dependent on context. In the shoulder season, heat from a 200F stovetop that has been burning for 10 hours is still very usable, but in the dead of winter, nothing less than 400 is going to maintain temperatures in my poorly insulated home, and the stove usually starts tapering below 400 at about 4-5 hours, dependent on the quality and species of the wood.

 

[Highbeam]

Or is there indeed a class of herculean stoves that, when fully loaded, will burn (produce flaming logs) for 6...8...10...+ hours?

Absolutely. Your demands of 6-10 hours are easily met by many stoves. All cat stoves from Woodstock and BK can accomplish this. Most large stoves (over 3 cubic feet) can do this too. Understanding of course that burn time means different things to different people, also that longer burn times come from lower burn rates, and finally that the quality of fuel you feed your stove can have an impact on burn times. A stove full of ironwood much more energy available than a stove full of poplar.

I happily get 24-30 hours from each load of wood in my 2.85 cubic foot blaze king using low btu PNW wood species to fully heat my 1700 SF in WA.

 

[TonyP]

Absolutely. Your demands of 6-10 hours are easily met by many stoves. All cat stoves from Woodstock and BK can accomplish this. Most large stoves (over 3 cubic feet) can do this too. Understanding of course that burn time means different things to different people, also that longer burn times come from lower burn rates, and finally that the quality of fuel you feed your stove can have an impact on burn times. A stove full of ironwood much more energy available than a stove full of poplar.

I happily get 24-30 hours from each load of wood in my 2.85 cubic foot blaze king using low btu PNW wood species to fully heat my 1700 SF in WA.

Thanks.

 

[LEGAL BEAGLE]

Almost every wood stove I see advertised describes it's 'burn time,' however, I just read on the Jotul site that very few stoves actually maintain a burning log for more than 3 hours. Makes sense, considering there's only so much burnable fuel inside a log to start with. Is the projected (read:mythical...) 'burn time' then generally how long the stove stays above 300 degrees? Or is there indeed a class of herculean stoves that, when fully loaded, will burn (produce flaming logs) for 6...8...10...+ hours?

I just purchased the Napoleon 1450 and the damper doesn't go in very far so the fire burns hot and is usually out within 4 hours. This means I have to start with a cold stove every morning. Have used a Blaze King and Lopi since 1979 to heat the house and never had this problem. Any suggestions would be greatly appreciated.

 

[xman23]

For my cabin, which is well insulated the need for a constant stove temperature output is normally not needed. Once I get the cabin mass and the wall insulation heated, The house cools rather slowly when the stove is dying out. Like all stoves I cycle up and back down in the burn cycle.

So the question. What is the stoves burn time? Depends on all the variables that day. Just thinking, if it has anything to do with temp output, maybe not. Anyway they are grossly overstated for marketing. Most of the time on single digit days I need two splits every 90 minutes. My wife told me 25 splits a day. But whatever you need to heat the house will be you burn time.

 

[TonyP]

I just purchased the Napoleon 1450 and the damper doesn't go in very far so the fire burns hot and is usually out within 4 hours. This means I have to start with a cold stove every morning. Have used a Blaze King and Lopi since 1979 to heat the house and never had this problem. Any suggestions would be greatly appreciated.

I find it curious that "the damper doesn't go in very far." I'd check the manual, or from whom you purchased it. Can you not nearly close, or fully close, the air supply? Burning hard wood or soft? Maybe a mid-flue damper, I think they're called barometric dampers, will help to dial back the blaze. Sorry I can't be more help.

 

[TonyP]

For my cabin, which is well insulated the need for a constant stove temperature output is normally not needed. Once I get the cabin mass and the wall insulation heated, The house cools rather slowly when the stove is dying out. Like all stoves I cycle up and back down in the burn cycle.

So the question. What is the stoves burn time? Depends on all the variables that day. Just thinking, if it has anything to do with temp output, maybe not. Anyway they are grossly overstated for marketing. Most of the time on single digit days I need two splits every 90 minutes. My wife told me 25 splits a day. But whatever you need to heat the house will be you burn time.

Thanks. Since I originally asked the question, other wood burners have told me the same thing about the overstatement of stove marketing. Shame on them since wood burners typically like the independence of burning wood, and wild marketing schemes counteract that, but shame on me for actually giving them the time of day.

This winter I practiced the ancient art of "Observing, Trial & Error", and I learned a lot. No real mystery.
Thanks for your response.

 

[begreen]

Burn time is a marketing term that is undefined. By any definition it is going to vary widely, just like the sq ft heated will. There are too many variables to assign one number to these attributes.

 

[Seasoned Oak]

Burn time is a marketing term that is undefined. By any definition it is going to vary widely, just like the sq ft heated will. There are too many variables to assign one number to these attributes.

True but, any one experience with a particular stove can usually be duplicated. In my experience i usually get about 50 to 60 % of the burn time rating to result in usable steady heat with a non cat stove. With dry wood.that is. I didnt believe harmans claim on my stove of 17 hours ,but i already went 27 hours,and still had enough hot coals in the stove for a reload. Usable high heat production is closer to 10 - 12 hours or like i said 50 -60%. Seems the same formula works for the englander 30 IMO.

 

[begreen]

Burn time can mean enough coals to restart no matter what the stove temp is or to some it means the period of meaningful heat, say from 300F start and back to that temp. There is no set definition. With either measure it totally depends on how hard the stove is being pushed to make up for the heat loss of the building. The wood species makes a big difference as does the way the stove is loaded and run.

example - I'm getting regular 12 hr reload cycles for the past couple months. But our house has a whole lot of glass and that changes the picture entirely when it gets below 20F outside. During a dip into the teens I might be reloading every 6 hrs. to compensate for the heat loss.

 

[BKVP]

In order to pass the EPA emissions test, you have two choices currently. Use a catalytic element and with COMBUSTOR temps of 550F and higher, you can get clean burning results.

Or, you can do so with high temps. 1176F is necessary to breakdown particulate and minimize particulate 2.5 microns and smaller.

If you think back to the 1970's, the amount of movement in the air control was usually quite a bit from low to high. That is before emissions standards were first introduced in Oregon in 1983.

As the standards have evolved (nice way of saying become more strict), the amount of latitude in air control movement has decreased. This is because on low, you have to allow sufficient air into the firebox in order to burn cleanly ...to pass the new standards.

If you think there is minimal or limited movement today....wait until 2020 when the standard drops to 2.0 on crib fuel and 2.5 on cordwood ( a test method yet to be finalized). There will be "High" and "Littele Less Than High".

 

[heavy hammer]

Everyone's heating situation, setup, size being heated, and fuel will vary. These can all change once again if temps are thirty five compared to zero. It all depends on what you are trying to accomplish with your heating goals. There are a lot of great products out there, what are you trying to heat? Size? Insulation? All questions that can be answered and a stove for those needs.

 

[Sprinter]

Of all the "features" listed in sales literature and sales talk, that one has to be the most meaningless.

Even using flames as a measure doesn't mean much. The flaming part of the burn cycle isn't even when most heat is being released. Cat stoves are a prime example of this, I believe.

 

[JA600L]

Heat loss is a better tool to determine your wood stove needs. If your in a situation where your furnace is constantly running, chances are you are going to need a big wood stove. Choose a big stove with a high efficiency number from the Epa's website then. Efficiency and firebox size usually gets you in the ballpark.

I witnessed first hand what happens when you lower your heat loss. I insulated, air sealed, and installed new windows. Suddenly I was getting much longer "burn times" out of the same stove.

 

[BKVP]

Heat loss is a better tool to determine your wood stove needs. If your in a situation where your furnace is constantly running, chances are you are going to need a big wood stove. Choose a big stove with a high efficiency number from the Epa's website then. Efficiency and firebox size usually gets you in the ballpark.

I witnessed first hand what happens when you lower your heat loss. I insulated, air sealed, and installed new windows. Suddenly I was getting much longer "burn times" out of the same stove.

Yup....reduce demand, get more!