Backwards burn

I have done it a few times now. On most attempts, I got to temp very nicely. Once that was not the case, the flame kept extinguishing and the wood smoldered. I think my loading that time impeded the airflow too much. Burning from the back does require airflow planning, it is not going to get there unless a channel is provided for it.

 

Yes, that is intentional, to get a more sustained burn.

Note, this is a 30-NC, a "tube stove." I suspect those with cats or hybrids would have little use for this method.

 

Yep, in a cat stove the wood is just smoldering and all the smoke ends up getting routed through the cat. In a secondary stove OTOH I would think wood positioning, tunnel of love trenching and so on, would have a larger effect on how air flows within the stove, and how the smoke is presented to the re-burn system. Of course, air flow will change as the load progresses and the splits break down. Still, the coals in the back will be more spent than the coals up front that are getting more air. I'd think this would give a hotter late burn, and less coals overall to deal with.

 

I'm diggin it! Choochin secondaries all over the top!

 

When it comes together, it is like magic!If you can, let us know how the burn progresses and finishes, it is not much help if one needs to fiddle with it all the time.

Tunnel of love

So far I have not noted that to be a problem. I am looking forward to hearing what DaveGunter or mike holton report from their testing.

That's the hoped-for result!

 

Looks like it's set on window cleaning mode.

 

double post

 

OK, so today I came home to cold stove. I took advantage of that to clean it, and did my first backwards burn cold stove light.

First I laid the two splits forming the v-shaped tunnel of love on the bottom. I tucked a wad of newspaper in the back behind the splits, and put a few small pieces of kindling there. I lit the newspaper, and waited a minute or two until I could see the kindling was catching.

Then I put a split as a cap over the tunnel, and one split alongside N-S. Then I put another row E-W on top of that. Then I took a photo.



I closed the door, and left the air on high, and exactly ten minutes later I had this. (You can see also that I added a stick in the tunnel to slow it a little, and another on the left side to prevent burning up through the gap on that side.)



For the sake of science, I closed the air about halfway at this point, and got a sustained clean-looking burn. I was not able to go out and look for smoke, as it was dark, but the flames looked good, and there was not a buildup of smoke in the firebox. The flue was less than 400 at this point, STT was still low, in the 300-350 range I would guess. I left the air there for a while to see what would happen, and the flue stayed at 400, and the STT came up slowly.

Then the missus came in, and asked me to "Quit fooling around and get some heat in the house!" So I opened it up again, and it came right up to where expected. It is now reaching the end of the active flame and it all looks equally well burnt. The glass remained spotless, which wouldbe expected for a hotter burn.

All in all, the behavoir seemed to be equivalent or better than a normal burn. A little awkward to light, but not as bad as I thought, but it was a stone cold stove.

 

Your flue temps are surface or probe?

 

I'd think you could get a lower, more controlled burn, starting it in the back, since the fire has to work it's way "upstream" against the air flow, which is pushing the heat and flame toward the back of the box.

 

Condar probe, doublewall pipe.

 

OK, I know this is getting a little redundant, but I am becoming convinced this is the best way to burn MY stove, and just want to share what I have tried and what I have learned.

Last night the house was 70 degrees, perfect for us. Bedtime, I pushed whatever I had burning in the stove to the back, and put in pine on the bottom, with the tunnel of love up the middle. I put another layer on top of that, one big chunk of tammarack (western larch) on top of the tunnel, and pine on the sides. It took about 15 minutes of tweaking it down to get it right where I wanted it, but when I went to bed the air was fully closed, and there was a good back burn going (glowing), with flame only on top. Flue was stable at 400 ish, and I forget STT, but it was higher than that.

I woke up this morning to good coals, and a 70 degree house. Outside it was 6 degrees, "feels like" minus 9. Glass was clean, except the bottom corners. This is the best overnight result I have ever gotten, on either this stove or the Allnighter I had previously.

 

I do the tunnel and always try for the back side to light up first, cut the splits at 17" to leave a gap at back wall, running about a 50/50 success at that. A lot depends on how big/deep a coal bed is there beforehand for me. If there are a lot then I rake forward and set a smaller split on top of them with the dog house wide open to burn the bed down some first. Been thinking about making an air redirect tube from the dog house to the backside. never ground off the ash dump lug so that would serve as a bit of an anchor. With the Nc and a big load on low air all day -tends to build up a fair amount of charcoal in the back when burning front to back. Another idea was a timed lever to open the air all the way say about 6 hours into a cycle ( which for me is around 12 hours or more between leaving and returning) Days that I need to plow snow get real long- 18-20 hrs- still have coals but no real additive heat to the house depending on the outside temps.

 

Interesting idea.

 

After a few days, and a few tries, I am not conviinced that lighting a cold stove "backwards" is all that great. It is unpredictable - sometimes it will light right up, and burn great. Other times it will smoke like there is no tomorrow, but not really get going for a long time.

For a relight of a warm stove with coals, I am getting consistent and great results using the backwards burn technique. This is where it shines for me. It is what I prefer to use for overnight burns.

If there are a lot of coals and a lot of heat in the stove, it seems just as well to go with a standard burn, as that is where it soon will be anyway, with all that heat.

YMMV