Do any stoves last longer than 24 hours on a fill?

[windthrown]

I don't completely agree with your statement that "size doesn't equal longer burn times"
More wood will equal longer burns. That is a fact.

Sorry, that is not a fact. Size does not really matter in the case of burn times, otherwise OWBs would burn for a week, simply because the fireboxes are HUGE compared to wood stoves. I also had one of the largest wood stoves ever made which was an Earth Stove, and the firebox in that thing was also huge. The burn times on that and the Central Boiler OWB and this Englander stove I have now were and are all about the same. None of them can or could get a full 24 hour burn time, even stuffed full. Close, but not 24 hours. More typical is 12-18 hours for all of them, large or small splits, oak or locust or madrone or any other hardwood out here in the wild west. You might have some coals last that long, but not anything to heat much with.

What I have found burning in a lot of different stoves , inserts and boilers is that if you stuff them full and damp them way down, you just make a lot of charcoal. The wood gasses escape unburned and you get charcoal. That is how charcoal is made actually. Fill a steel box with wood, heat it up, and let it smolder by cutting off the air supply. Also by making charcoal the heating efficiency drastically drops and you do not get as much heat out of the wood compared to burning it. You may get heat for a longer period of time by damping your stove down, which is what most people do, but you are not going to get more total heat energy into your house. You get the most heat by burning dry wood hot and fast, like in a wood gassifier. Then the problem is what to do with all that heat energy released in a short period of time. The answer is to either build a large masonry fireplace with a long flue to capture the heat and radiate it slowly, or build a water jacket around the burn chamber and trap the heat in a large tank of water and run a hydronic loop to radiate it slowly.

From my experience, I have found that I get the most heat out of my wood by burning fewer splits in wood stoves at a time and feeding them a steady diet. I rarely stuff my stove here full of wood, and I keep a smaller, hotter fire going here. If it gets colder, I add more wood more often and open the damper more, if it is warmer I add less wood, less often and damp it down more. I also vary my wood species that I am burning; cold temps I burn oak and locust, warmer temps I burn cedar and pine. It varies as to what wood I have available. I also burn 20% moisture or less dry wood.

 

[NSMaple1]

I fill my boiler, it burns out in 4 hours.

I fill it half full, it burns out in 2 hours.

Everything else being equal, the more wood, the longer it takes to burn it all.

 

[Gypo Logger]

Don't give me that crap! 10 wooden matches keeps my place warm all night!
What's your problem???
John

 

[Whitespider]

I fill my boiler, it burns out in 4 hours.
I fill it half full, it burns out in 2 hours.
Everything else being equal, the more wood, the longer it takes to burn it all.

You're really missin' this ain't ya??
Your boiler heats water, and then maintains it at that temperature. It has some sort of active control, like an automatic damper or draft blower... correct?? So then... everything else ain't equal.

When you fill your boiler it has more sticks in it, which means more heat at any given moment, which means the boiler will spend less time in high firing rate and more time in standby or low firing rate. Everything else is not equal... the firing rate is not constant, and high firing rate times are shorter. Essentially, your boiler reduces the total amount of air fed to the fire because the fire is making more heat... and that's why your boiler runs longer on a full box... because the air has been reduced, not because the box is full.

The "result" end result of a full box may be a longer burn time... but the "reason" for the longer burn time is a choked-back fire because more individual burning pieces mean more heat. (I'm loosely using the term "choked-back")
A larger, thicker piece of wood will burn longer than a smaller one... but if all else (I'll say it again, all else... meaning everything except the number of pieces you shove in the box) remains equal a full box will not burn longer than a half-full box (but it will make more heat).

More sticks mean more heat, but more sticks cannot make any one stick burn longer... if anything the added heat (theoretically) should make any one stick burn slightly faster.
There ain't no friggin' magic...
*

 

[Jordan91]

I have a shelter wood stove and like it a lot if I put two 7 inch by 18 inches long logs in and three 2-4 inch by 18 of hedge which is the best wood to burn. It will last 24 hours with my draft motor 1/4 the way open and damper closed

 

[v8titan]

One thing that works for me is to use my larger splits of Oak or Hickory for overnight burns. I can't speak to the efficiency and how it relates to rate of burn, burn temps, etc. but I can tell you for my application, with a Jotul Oslo, if I load it at 11:00 PM before bed, the stove temp on the surface is still 500F in the morning at 5:30AM with a just a coal bed remaining. I use the larger splits because I can get more fuel in the box than using lots of smaller splits all else being equal. Maybe the efficiency is less cause I bank it down, and if that's the case, so be it....don't really care...the house stays warm enough and I don't need to get up in the middle of the night and refill.

 

[olyman]

Sorry, that is not a fact. Size does not really matter in the case of burn times, otherwise OWBs would burn for a week, simply because the fireboxes are HUGE compared to wood stoves. I also had one of the largest wood stoves ever made which was an Earth Stove, and the firebox in that thing was also huge. The burn times on that and the Central Boiler OWB and this Englander stove I have now were and are all about the same. None of them can or could get a full 24 hour burn time, even stuffed full. Close, but not 24 hours. More typical is 12-18 hours for all of them, large or small splits, oak or locust or madrone or any other hardwood out here in the wild west. You might have some coals last that long, but not anything to heat much with.

What I have found burning in a lot of different stoves , inserts and boilers is that if you stuff them full and damp them way down, you just make a lot of charcoal. The wood gasses escape unburned and you get charcoal. That is how charcoal is made actually. Fill a steel box with wood, heat it up, and let it smolder by cutting off the air supply. Also by making charcoal the heating efficiency drastically drops and you do not get as much heat out of the wood compared to burning it. You may get heat for a longer period of time by damping your stove down, which is what most people do, but you are not going to get more total heat energy into your house. You get the most heat by burning dry wood hot and fast, like in a wood gassifier. Then the problem is what to do with all that heat energy released in a short period of time. The answer is to either build a large masonry fireplace with a long flue to capture the heat and radiate it slowly, or build a water jacket around the burn chamber and trap the heat in a large tank of water and run a hydronic loop to radiate it slowly.

From my experience, I have found that I get the most heat out of my wood by burning fewer splits in wood stoves at a time and feeding them a steady diet. I rarely stuff my stove here full of wood, and I keep a smaller, hotter fire going here. If it gets colder, I add more wood more often and open the damper more, if it is warmer I add less wood, less often and damp it down more. I also vary my wood species that I am burning; cold temps I burn oak and locust, warmer temps I burn cedar and pine. It varies as to what wood I have available. I also burn 20% moisture or less dry wood.

thanks!!!!!

 

[olyman]

You're really missin' this ain't ya??
Your boiler heats water, and then maintains it at that temperature. It has some sort of active control, like an automatic damper or draft blower... correct?? So then... everything else ain't equal.

When you fill your boiler it has more sticks in it, which means more heat at any given moment, which means the boiler will spend less time in high firing rate and more time in standby or low firing rate. Everything else is not equal... the firing rate is not constant, and high firing rate times are shorter. Essentially, your boiler reduces the total amount of air fed to the fire because the fire is making more heat... and that's why your boiler runs longer on a full box... because the air has been reduced, not because the box is full.

The "result" end result of a full box may be a longer burn time... but the "reason" for the longer burn time is a choked-back fire because more individual burning pieces mean more heat. (I'm loosely using the term "choked-back")
A larger, thicker piece of wood will burn longer than a smaller one... but if all else (I'll say it again, all else... meaning everything except the number of pieces you shove in the box) remains equal a full box will not burn longer than a half-full box (but it will make more heat).

More sticks mean more heat, but more sticks cannot make any one stick burn longer... if anything the added heat (theoretically) should make any one stick burn slightly faster.
There ain't no friggin' magic...
*

yup...........

 

[NSMaple1]

You're really missin' this ain't ya??
Your boiler heats water, and then maintains it at that temperature. It has some sort of active control, like an automatic damper or draft blower... correct?? So then... everything else ain't equal.

When you fill your boiler it has more sticks in it, which means more heat at any given moment, which means the boiler will spend less time in high firing rate and more time in standby or low firing rate. Everything else is not equal... the firing rate is not constant, and high firing rate times are shorter. Essentially, your boiler reduces the total amount of air fed to the fire because the fire is making more heat... and that's why your boiler runs longer on a full box... because the air has been reduced, not because the box is full.

The "result" end result of a full box may be a longer burn time... but the "reason" for the longer burn time is a choked-back fire because more individual burning pieces mean more heat. (I'm loosely using the term "choked-back")
A larger, thicker piece of wood will burn longer than a smaller one... but if all else (I'll say it again, all else... meaning everything except the number of pieces you shove in the box) remains equal a full box will not burn longer than a half-full box (but it will make more heat).

More sticks mean more heat, but more sticks cannot make any one stick burn longer... if anything the added heat (theoretically) should make any one stick burn slightly faster.
There ain't no friggin' magic...
*

No, it does not have any active burn control. It burns wide open until the wood is all gone. Half a load takes half the time. Simple.

 

[Woody912]

I think I heard once of a stove that could run 42 hours off one fill of wood. Don't remember what it was. I want a stove that can last from around midnight to 7pm, that's nearly 20 hours. Any recommendations?

I burned an elm stump underground once, still burning a week after I set it. I am fairly certain if my Fisher was big enough to stack 4-5 18" rounds of red elm on top of a bed of coals and then shut the doors I would still have a fire 2-3 days later. The house might be insufficiently warm, the chimney might be clogged and the neighbors laundry might be dirty but I would still have enough coals to have a roaring fire going in about 3 minutes. Which is really all I want when I have to be away for 12-18 hrs

 

[AIM]

Yes spidey you are once again TECHNICALLY correct. The REALITY of the matter though is that more wood = more time. (because all things are not equal) If you have a big firebox you throw in various size pieces that will likely be larger than someone will put in a small firebox.
Yes I understand that TECHNICALLY wood of X size will burn at X rate.

 

[Whitespider]

No, it does not have any active burn control. It burns wide open until the wood is all gone.

Really?? What keeps it from overheating?? What keeps it from boiling over?? Building too much pressure?? Exploding??
Really?? A boiler that always runs wide friggin' open, full firing rate until all the fuel is exhausted??
You'll haft'a point to a link for that model where I can read how it works before I can believe that.

If you have a big firebox you throw in various size pieces that will likely be larger than someone will put in a small firebox.

All you've done is re-word what I've already said...
*

 

[v8titan]

A larger fire box, as compared to a smaller one, will in fact give a longer burn time at a given BTU/hr rate of heat output. It's pretty simple.....a given species of wood will have a certain number of BTU's/ volume. A larger fire box will hold more volume and therefor more total BTU's of fuel. Now if you run the small firebox stove and the large firebox stove at the same BTU/hr rate of output (assume a rate sufficient to keep the temp inside your room constant), the larger stove will deliver heat longer simply because there is more fuel to burn. Think of the fire box as a fuel tank....more fuel = more total BTU's. Granted the efficiency may not be optimal in the larger stove running at a lower BTU/hr rate. One thing is for sure more total wood, more potential energy in the form of heat. Most new stoves are designed to vary the burn rate.....within limits...I get it.

 

[Whitespider]

A larger fire box, as compared to a smaller one, will in fact give a longer burn time at a given BTU/hr rate of heat output.

That's also a re-wording of what I've already posted.
*

 

[NSMaple1]

Really?? What keeps it from overheating?? What keeps it from boiling over?? Building too much pressure?? Exploding??
Really?? A boiler that always runs wide friggin' open, full firing rate until all the fuel is exhausted??
You'll haft'a point to a link for that model where I can read how it works before I can believe that.


All you've done is re-word what I've already said...
*

Yessir, wouldn't lie to ya, not my angle. It's plumbed to 660 gallons of water. If by chance things do get on the hot side, it just dumps heat into my baseboards. But I usually only run things up to 180 or so. This winter the most I have burned in a day is 8 hours. The rest of the time the fire is out. Mine is natural draft, the air intake is stopped open with a bolt. Wide open all the time. Course that means I have to make a new fire every day, but doing that plus a reload only amounts to 15 minutes a day tending it, maybe. Wouldn't go back to the old 'one fire lasts all winter' way for anything. So burning like that is about the best way to get to 'all things being equal' that I can think of - and half a load burns out in half the time. Just saying what I'm living. Google smokeless heat, and you'll see my unit in there somewhere.

(And I never heard if it either, till about 4 years ago - then dropped about $15k on a heating system overhaul based on a boiler I only saw on the Internet's. Crazy or what? Happy as a clam though...)

 

[showrguy]

Yessir, wouldn't lie to ya, not my angle. It's plumbed to 660 gallons of water. If by chance things do get on the hot side, it just dumps heat into my baseboards. But I usually only run things up to 180 or so. This winter the most I have burned in a day is 8 hours. The rest of the time the fire is out. Mine is natural draft, the air intake is stopped open with a bolt. Wide open all the time. Course that means I have to make a new fire every day, but doing that plus a reload only amounts to 15 minutes a day tending it, maybe. Wouldn't go back to the old 'one fire lasts all winter' way for anything. So burning like that is about the best way to get to 'all things being equal' that I can think of - and half a load burns out in half the time. Just saying what I'm living. Google smokeless heat, and you'll see my unit in there somewhere.

(And I never heard if it either, till about 4 years ago - then dropped about $15k on a heating system overhaul based on a boiler I only saw on the Internet's. Crazy or what? Happy as a clam though...)

So you had an OWB an went to inside gassification ??
If so, how much less wood are you burning..
Reason I ask is, a few buddies of mine put in gassifiers, but they're burning just as much as I am with my OWB....

 

[v8titan]

If longer burn time is a major factor in your stove purchase decision, pick the larger stove within reason. You can realize longer burn times with the larger firebox.

 

[NSMaple1]

So you had an OWB an went to inside gassification ??
If so, how much less wood are you burning..
Reason I ask is, a few buddies of mine put in gassifiers, but they're burning just as much as I am with my OWB....

No, went from an indoor wood/oil combo boiler, to the gasifier. Not sure how much of a reduction yet - I think went from around 7.5 to 5 cords/yr? I haven't had a winter with all good wood yet with it, due to some other circumstances - burning quite a bit of windfall spruce. Next year should have more decent hardwood. But also the house is a lot warmer than it ever was with the old one.

 

[Whitespider]

NSMaple1,
I visited the smokeless heat website and all but the two cheapest units use a an electrically controlled suction fan in the flue to control combustion rate via flue gas temperature... the suction fan is also an accessory for the less expensive two.
But you said you dropped $15k?? Even figuring the extras needed for converting your previous boilers system...

Although, putting all of that aside, they are not conventional combustion systems, they use "reverse combustion"... meaning not all of the wood is burning at one time. The fuel burns from the bottom, and flue gas exits the fire from underneath, so as the lower burning fuel is consumed new fuel basically falls into it. That's not the same as filling a conventional combustion system full and having it all be burning at once, it's more like a hopper feeding system (of sorts)... fill the hopper with more fuel, and it takes longer to empty it.

I don't believe that's a relevant comparison to what we were talkin' 'bout...
It's sort'a like sayin' that dumping two bags of pellets (rather than one) into my pellet stove hopper doubles my burn time...
*

 

[NSMaple1]

They do have one model line that controls the induction fan to optimize the burn, based on O2 readings in the smoke pipe - yes. But it never shuts it down, it still burns till the fuel is gone. Just ramps up & down a bit during the burn. My $ figure included other stuff like a backup electric boiler & new water heater - plus freight, customs & exchange getting it here. Basically my whole heating system, except for the baseboards & zone valves (4 zones over 2 storeys). Might not be directly comparable, not sure, but it's not like dumping pellets in a hopper either - the whole load of wood is in the firebox, and the whole load is all doing it's pyrolizing or charcoaling thing and wood gas releasing or whatever it's called during the whole burn even though only the very bottom of the fire is actually burning flames. Which I think would also be the case for a load of wood in a lot of other burner types too - load it up & let it go without stopping down the air or shutting dampers down & a bigger load will take longer to burn out.

Also, any boiler can be made to operate like this, just by plumbing a bunch of storage to it, even old school ones. But if the old school one doesn't have good heat exchange (like via tubes), there wouldn't be much point to it cause you do need decent heat exchange efficiency, and a simple water jacket doesn't have that.