Smaller fires and burn times

[QuarryHouse]

We had a super dry fall here in NY and my ash is now 15% on a fresh split. The stove is burning really well - unlike last year, which was record wet, and my wood was around 20 to 21% on a fresh split. I'm getting loooong burn times in the active range - today I went 25 hours and still had a nice bed of coals. I'm wondering if I could burn a smaller load and still get a reasonable burn time? It's been fairly warm out (5C or so in the day) and with a full load after the charring stage the house is close to 80F. I don't particularly mind, but it feels less efficient to be over-heating the house with a large load.

Are others doing something like a half or three-quarters load and what impact do you see on burn times? I could .. you know... just try it but learning from others is always helpful!

 

[stoveliker]

No reason you can't do it as long as the cat gets up to temp.

Then burn times should just scale with the amount of wood you load.

With your current good wood, you may be able to decrease your initial charring time to help with the overheating.

 

[QuarryHouse]

Then burn times should just scale with the amount of wood you load.

Yeah that is my question - does all the wood "burn" (off-gas) at the same time, and so a larger load gives off more heat but burns the same amount of time, or does just the lower level of the wood burn at one time and a smaller load gives the same heat for a lesser length of time? I don't really understand the way these stoves work - the wood itself is kind of evaporating into wood gas which is burned at the cat (when running slow-n-low as I do 90% of the time)? I know I like the way they work though!

With your current good wood, you may be able to decrease your initial charring time to help with the overheating.

I'm definitely charring for less time than last year. And last year I had to keep the t-stat more open to keep the cat in the active zone, which led to shorter burn times. This also has a feedback to the charring stage - I think the stove is giving off more heat when charring since I'm not losing heat to moisture in the wood. I also de-barked a lot of pieces and I wonder if that affects charring.

 

[stoveliker]

Yeah that is my question - does all the wood "burn" (off-gas) at the same time, and so a larger load gives off more heat but burns the same amount of time, or does just the lower level of the wood burn at one time and a smaller load gives the same heat for a lesser length of time? I don't really understand the way these stoves work - the wood itself is kind of evaporating into wood gas which is burned at the cat (when running slow-n-low as I do 90% of the time)? I know I like the way they work though!

When burning low and slow,.most heat is provided by the hot cat. That can be a bit less (see the cat probe). And the firebox itself will give less heat when there's less glowing stuff.
The thermostat regulates heat output though, so it won't make a big difference, but my estimate is that it will make a small difference by using smaller loads.

Normally it works well to describe the firebox as a fuel tank that you drive a certain number of miles on. Put less in there, get less miles before a reload. This is also shown by the very similar minimum output numbers comparing the 20 and 30 models. The smaller firebox models have about the same low output limit as the bigger models. So it won't make a big difference.

You can always do what other stoves force one to do: intermittent fires, pulse a heat shot, glide down in temps until the next pulse.

Maybe others have more experience in this - I don't do half loads. (I only burn if it's below 40-45 for 24 hrs or more, because of the burn times.)

I'm definitely charring for less time than last year. And last year I had to keep the t-stat more open to keep the cat in the active zone, which led to shorter burn times. This also has a feedback to the charring stage - I think the stove is giving off more heat when charring since I'm not losing heat to moisture in the wood. I also de-barked a lot of pieces and I wonder if that affects charring.

Exactly, boiling water takes a lot of BTU!