Burning characteristics

Easy Livin’ 3000 · Jan 11, 2016

I've been burning in my new stove insert now for three or four weeks, and have noticed that I am getting much more efficient heating by adding a few spits and letting them burn down, then adding more, as compared to stuffing it full. Stuffing it full certainly lasts longer, but not on a one to one basis. What I mean by this is, if I get an hour out of two splits, I don't get 5 good hours out of 10, and the amount of heat that I get by adding the splits two or three at a time is much more effective at keeping our space warm. Any thoughts about why this is, and any suggestions about how to get a more efficient burn out of a stuffed stove?

bholler · Jan 11, 2016

ED 3000 said:
I've been burning in my new stove insert now for three or four weeks, and have noticed that I am getting much more efficient heating by adding a few spits and letting them burn down, then adding more, as compared to stuffing it full. Stuffing it full certainly lasts longer, but not on a one to one basis. What I mean by this is, if I get an hour out of two splits, I don't get 5 good hours out of 10, and the amount of heat that I get by adding the splits two or three at a time is much more effective at keeping our space warm. Any thoughts about why this is, and any suggestions about how to get a more efficient burn out of a stuffed stove?

To give you any input we need to know about your fuel your setup and your burning procedure. But generally it works better to fill the stove unless that is to much heat for your space.

Easy Livin’ 3000 · Jan 11, 2016

bholler said:
To give you any input we need to know about your fuel your setup and your burning procedure. But generally it works better to fill the stove unless that is to much heat for your space.

Fuel- Fully seasoned ash, white birch, walnut. Setup- Non cat EPA SBI stove insert, 2.4 cubic firebox, 23 ft forever flex SS flexible insulated liner in old external masonry chimney with Roxul insulation stuffed around the top under the top plate and at the bottom in the flue, with a block-off plate at the lintel. Roxul behind the stove to insulate the back of the firebox in the fireplace. The space I am heating is a 30' long x 9' wide x 7 ' tall, open to the stairway and another room, and drafty. The walls are 18" thick field stone with mud mortar characteristic of 18th century mid-Atlantic farmhouses. Procedure- get the stove hot with a small load, then either add two or three splits, let them get charred, and when the temp reaches between 600- 650 ::F

, close the air intake, not 100% closed. In the alternative, after the small load to get the stove hot, stuff her full, let the entire load get charred and up to the same temp, then close the air intake about the same.

We have never been able to get the room overheated, but it is toasty on side closest to the stove, and provides nice supplemental heat for much of the house- the gas furnace hasn't been working much.

What did I miss?

bholler · Jan 11, 2016

ED 3000 said:
We have never been able to get the room overheated, but it is toasty on side closest to the stove, and provides nice supplemental heat for much of the house- the gas furnace hasn't been working much.

Sounds about right to me. How seasoned is you wood? What is the moisture content? Everything else sounds about right

Smoked · Jan 11, 2016

When I am home (and awake) I do not do big loads, I do what you do. I can put a couple of splits in a hot stove and continue an efficient burn without touching the air. If I do a big load, I have to open it up more to get it going so I wonder how much more heat is wasted trying to get the load heated up?

Easy Livin’ 3000 · Jan 11, 2016

bholler said:
Sounds about right to me. How seasoned is you wood? What is the moisture content? Everything else sounds about right

I don't have a moisture meter (yet), but the ash was a snag, dead for a years before it came down, the walnut was cut up in 16" long rounds stacked for three or four years (but more recently split), only one that is questionable seems to be the white birch. But the burn is very clean for all, and while I bet the burn would be hotter if the birch was drier, wouldn't it also be longer? Just seems like I am getting significantly more heat from multiple small loads than from one large one, and this seems odd to me. I will follow all the good advice here to get a moisture meter in the future, and hopefully a solar kiln! My hunch is that you are right, bholler, that it has something to do with the wood.

bholler · Jan 11, 2016

ED 3000 said:
My hunch is that you are right, bholler, that it has something to do with the wood.

That is my hunch mainly because it sounds like a decent setup and your burning procedure sounds ok so that is pretty much all that is left. Generally wood does not dry allot till it is split and i have found that walnut really does not put out that much heat when compared to allot of other hardwoods.

Easy Livin’ 3000 · Jan 11, 2016

Smoked said:
When I am home (and awake) I do not do big loads, I do what you do. I can put a couple of splits in a hot stove and continue an efficient burn without touching the air. If I do a big load, I have to open it up more to get it going so I wonder how much more heat is wasted trying to get the load heated up?

Thanks Smoked. I have had similar thoughts.

jatoxico · Jan 11, 2016

I'm not so convinced that running the stove on packed full loads is the most efficient way. Seems to me getting the stove to an efficient operating temp and then maintaining it is better. That's how all other fuels including pellets are burned.

I run my insert by feeding small amounts more often a lot. I can keep the temp of the stove in a narrow range that way. Full loads cause me to hit high peak temps that I can't take full advantage of.

Maybe with a freestanding stove I would think differently since it's easier to get the heat into the house with one but I think the insert has a more limited ability to transfer heat to the living space.

As far as burn time of loading (using OP's ex.) 10 sticks at once vs a couple at a time, I wonder if higher the firebox temps achieved by a full load would consume wood at a faster rate. Intuitively I would say yes but not 100% sure.

bholler · Jan 11, 2016

jatoxico said:
As far as burn time of loading (using OP's ex.) 10 sticks at once vs a couple at a time, I wonder if higher the firebox temps achieved by a full load would consume wood at a faster rate. Intuitively I would say yes but not 100% sure.

You should run the same temps regardless of load size. bigger load will just burn hotter longer

Easy Livin’ 3000 · Jan 11, 2016

jatoxico said:
I'm not so convinced that running the stove on packed full loads is the most efficient way. Seems to me getting the stove to an efficient operating temp and then maintaining it is better. That's how all other fuels including pellets are burned.

I run my insert by feeding small amounts more often a lot. I can keep the temp of the stove in a narrow range that way. Full loads cause me to hit high peak temps that I can't take full advantage of.

Maybe with a freestanding stove I would think differently since it's easier to get the heat into the house with one but I think the insert has a more limited ability to transfer heat to the living space.

As far as burn time of loading (using OP's ex.) 10 sticks at once vs a couple at a time, I wonder if higher the firebox temps achieved by a full load would consume wood at a faster rate. Intuitively I would say yes but not 100% sure.

Bingo! This makes the most intuitive sense to me. +1 for knowing how to run my stove and wood conservation, -1 for convenience and overnight burns. Thanks Jatoxico.

bholler · Jan 11, 2016

ED 3000 said:
Bingo! This makes the most intuitive sense to me. +1 for knowing how to run my stove and wood conservation, -1 for convenience and overnight burns. Thanks Jatoxico.

If it works for you there is nothing wrong with it. But it is not at all what i have found works for me on quite a few different stoves

jatoxico · Jan 11, 2016

bholler said:
You should run the same temps regardless of load size. bigger load will just burn hotter longer

Sounds good in theory, doesn't work for me (tube stove) in practice. I know I'm not the only one either. Plenty of posts here about people hitting high temps, many concerned about too high.

Don't get me wrong I do run full loads but I will get peak temps of 700+ then I have to ride out burning down the coals to 250 or so. With smaller loads I can keep it between 400-600 pretty easy.

Guess this where a good Cat stove can beat out a tube stove.

bholler · Jan 11, 2016

jatoxico said:
Sounds good in theory, doesn't work for me (tube stove) in practice. I know I'm not the only one either. Plenty of posts here about people hitting high temps, many concerned about too high.

Well then you need a damper or to restrict the air inlet. You should always be able to control your stove if you cant you need to change your setup. I have 35' of insulated liner on my tube stove and i control it just fine

jatoxico · Jan 11, 2016

bholler said:
Well then you need a damper or to restrict the air inlet. You should always be able to control your stove if you cant you need to change your setup. I have 35' of insulated liner on my tube stove and i control it just fine

Insert, no damper for me. It's controllable but full loads (more fuel) reach higher temps than small ones. From all I've read here this is not unusual for many setups.

Easy Livin’ 3000 · Jan 11, 2016

bholler said:
Well then you need a damper or to restrict the air inlet. You should always be able to control your stove if you cant you need to change your setup. I have 35' of insulated liner on my tube stove and i control it just fine

I'm not having issues with controlling the burn or the peak temp, and there has been plenty of variability in my wood. I'm not ruling out the wood being the issue, perhaps with the big load there is enough moisture all at once that it affects the heat output more than the small loads where the moisture is quickly driven out. Just a theory.

Smoked · Jan 11, 2016

For the record, if I do small loads all the time I do start to have a coal build up problem. M-f though, I have to do the longer burn larger loads so not often an issue! When I do bigger loads, it really does take a lot of air to get it to cruising point s that has to be a down side.

bholler · Jan 12, 2016

jatoxico said:
Insert, no damper for me. It's controllable but full loads (more fuel) reach higher temps than small ones. From all I've read here this is not unusual for many setups.

Yes i know it is an insert so no damper but you can restrict the air intake. And if you cant keep the temperatures down to where you want them it is not controllable.

RandyBoBandy · Jan 12, 2016

I'm with bholler. Large loads are very controllable. I prefer larger loads to small ones. Heat output is controlled by your primary.

Nick Mystic · Jan 12, 2016

I wonder if you burn as clean when burning multiple small loads as opposed to a larger, full cycle burn? I have a Jotul F600 and with the very warm temperatures we had earlier this winter I was burning some smaller loads and I noticed that I rarely got much secondary burn action out of my tubes with the small loads. I had to keep my primary air control much more open to keep the fire going and even then I would often see some smoke out of my stack. When I fill my fire box at least 75% full I get pretty quick secondary action going and my stove burns more consistently with no smoke out the chimney.

jatoxico · Jan 12, 2016

Nick Mystic said:
I wonder if you burn as clean when burning multiple small loads as opposed to a larger, full cycle burn?

Definitely able to keep secondaries going. In fact maybe more so since I can keep the temp in the range where the secondaries are active so any smoke from fresh splits is burned as opposed to smoking at start-up on a full re-load. *Not talking about a small load that is burned in a cycle due to low heat demand. Talking about getting the stove to operating temp then keeping it there by adding fuel as needed.

bholler said:
And if you cant keep the temperatures down to where you want them it is not controllable.

RandyBoBandy said:
Heat output is controlled by your primary.

You have no control of the doghouse or secondary air in an unmodified EPA stove. My stove could probably be better and I'm sure some. But it is controllable in that I have some control over the temperature and am not afraid of over-firing. But if the assertion is that you can load a tube stove chock full then select whatever temperature you want simply by adjusting the primary then I disagree and that is not how the burn cycle occurs in a tube stove. Low and slow is not their forte'.

There is a current thread about the IntensiFire. Apparently one current obstacle is that it gets too hot. While very high temps are great for reducing emissions and particulates it is negatively affecting the burn time. And this is where I agree with the OP. A full load burns longer because there's more fuel. But I believe it's possible to get longer burns from the same amount of wood and operating at an efficient temp by evening out the amount of fuel present at any given time just like a carburetor, oil burner, pellet stove etc.

Yes, there is an absolute BTU content in a given amount of wood but higher temps result in those BTU's being released in a shorter period of time. Some of that heat ends up going (at least in my case) unnecessarily out the stack while others may overheat the living space if they're getting good heat transfer.

To be clear, I do burn large loads when I have a high heat demand or want to let it go unattended.

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