Understanding heat output question

[48rob]

My new englander 50-tvl 17 is doing well.

I'm still trying to get the hang of it.
I was having a problem with too much creosote.
I believe I have solved that issue by running with the air open a little more.

I'm having trouble with understanding the formula for heat output.
Very simple I'm sure, but sometimes simple things are hard to grasp, and complex things easy...

I can build a small fire with kindling and a couple 2" splits (bigger kindling ) and warm up the room nicely.
As those splits burn down to coals and start looking pretty thin, I'll add a little larger splits, about 3-4".
I'll burn until they also turn to coals, then add more.

This process is giving me reasonably steady heat for the room, and the secondaries are burning nicely when the wood is gassing.
The stove window is staying clean, and there is only smoke from the chimney for a few minutes each time I put fresh wood in.
The stove temps are running 300-380 degrees.

So, all is well right?
Well no... it is working as it should I think, but the above process requires I load fresh wood every half hour to an hour.
This is okay in the shoulder season, and when I'm in the shop all day, but...

I need to get longer burns.
If I put more wood in the stove each time I load it, it will burn longer, right?
But if I put more wood in, will it just burn longer, or longer and a lot hotter?

What happens if I load the stove to full capacity?
Will it climb to a particular (reasonable) temperature, and stay there until the fuel runs out, or will it climb out of control?
Of course I can control the heat to some degree with the air, but is it enough to prevent overfiring?

Thanks.

By the way, I was walking by the shop the other morning and noticed an interesting view of my setup.

Rob

 

[begreen]

Rob, as the first official poster with this stove, you are going to have to tell us. Normally, yes, once the initial coal bed is established, you would fill it up for the longer burn. In this small space, that may overheat it. Hard to say without trying.

 

[My Oslo heats my home]

couple questions. 1. the wood, is it completely dry? and what types of hardwood/softwood are you using? and 2. when you add wood to a bed of coals how long will that load last? I'd be curious of your wood to air mixture and what temp that produces in longevity.

To compare, my Jotul will accept a 3/4 load of dry oak and maple and the air intake will run about half during a daytime burn. This load will brun at about 425 deg for almost 3 to 3.5 hours until it starts to break down into coals. When the coals burn alone the stove will heat at approx. 325 deg for another hour to 1.5 hr.
I'm not sure this helps

 

[48rob]

In this small space, that may overheat it.

The stove being contained in a small space may allow the "stove" to be overheated, or the space it occupies?

I realize the space may be overheated simply because it is small, though can vent it.
It should require less venting/forced heat loss as outdoor temperatures drop.

I guess the easy answer as you suggested is "try it".
My concern comes from having a very narrow band of "control" over the stove (coupled with inexperience).
There is only one air control on the stove.
It has a total travel of 1 and 1/8 inch.
No bypass, no way to completely shut off the air...unless one were to cover the outside air intake...if all the air is supplied through it...,but we won't go there, no mods, gotta learn how it works the right way!

Rob

 

[48rob]

couple questions. 1. the wood, is it completely dry? and what types of hardwood/softwood are you using? and 2. when you add wood to a bed of coals how long will that load last? I’d be curious of your wood to air mixture and what temp that produces in longevity.

Wood is 10-17 percent.

Softwood for now as it is not that cold; Willow, pine.
I'm using Cherry for longer burns/nightime.
When added to a bed of coals, the Pine/Willow last 30-60 minutes for 4" splits.
The air control is open about 1/8 of the way, temps around 300-380 degrees with air closed all the way, or very near it.

Rob

 

[Backwoods Savage]

Rob, adding more wood will hold the fire longer; just think about other folks and what they do for overnight fires. Also remember that wood heat is much different than heating with gas or oil because you will have a more even temperature with oil or gas. With wood, the temperature will go up to the maximum and then gradually taper down until ready for a new load.

Last night should give you a good example. Our low expected to be 32-34 so we did not want much wood in the stove. I selected 4 small splits of 1 maple, 1 cherry and 2 ash. That sitting atop a coal bed got the temperature up around 400-425. This morning the stove was at 240 and we were comfortable all night. Well, with the exception that at first we were a bit too warm.

Compare that with a normal overnight which would consist of 1 or 2 soft maple and the rest filled with ash. Some larger splits would be used along with whatever was needed to fill in. With that, the stove would normally peak out around 650-670 and hold there for quite some time before gradually dropping and the stove might be a bit warmer when we get up. On some really cold nights it is not unreasonable for me to get up during the night and first open the draft more and then later add some splits to keep the house from cooling too much before morning. Besides, we prefer to not have big swings in temperature range in the house during winter.

With you burning the softer woods, you will find there is a big difference when you burn the harder woods. There is also a big difference between adding 1 split or 3 splits. 3 splits always will burn better than 1 or 2.

 

[begreen]

That is exactly right. To achieve a longer burn, select the hardest wood. Locust, cherry, hedge, osage orange are good choices. Once the stove is burning well, try closing the air control, in steps until all the way closed. Check the flue outside. If no smoke, it is burning well. Another thing you might try to extend the range of warmth is to put some soapstone of the top of the stove.