Backwards burn

Last night as I went to bed, I wondered whether starting a fire "backwards" would work, e.g. lighting in the back rather than the front. This would be with coals, as it would be a challenge lighting a cold stove that way.

My thinking was, pushing the coals to the back would get the heat immediately to the manifold that supplies the secondary burning, and result in quicker reburning. It would also heat the stove internals more quickly, with less heat going up the pipe.

This morning I tried it. There were a few coals left, and I pushed them to the back. Stacked the wood in NS with a gap for the doghouse air to go through to the back. It worked well. It lit quickly, and I had secondaries going in a minute or two, on a warm (not hot) stove, flue temp around 300. The primary burn did progress against the airflow (from the back of the stove to the door), although a little slower than usual. The secondary burning was a raging inferno, and started all the top surfaces burning, which burned down, like a top lit fire. Probably most ignition in the front was from the secondaries (top down), rather than bottom up.

I think it worked well, I will be trying it more.

 

Hmmm, hadn't thought of that.
Might be worth a shot on one of these daytime loads.

 

I've done that a few times myself. It seems to work about the same on my stove. Is it better heat than coals raked forward? Idk

 

I'm wondering if it might burn down the wood at the back of the stove better (on the 30) and if there's a difference in the elusive "burn time".

 

I load E.W. and on a cool stove with coals left from the night before that is how I usually start a fire with 1 difference. I put a small split against the back of the stove, push the coals against it and put a small amount of kindling on the coals and finish loading the stove.

 

Yeah, this is what I am wondering as well, both points. With the primary burn taking place contra-flow, it may result in a longer burn. And a buildup of coals at the back of the stove, if it doesn't decrease, becomes a feature, not a bug!

 

I enjoy reading about people coloring outside the lines to see what happens.

 

E-W loader here. Sometimes when it's cold out I will push the coals back if I want to get another load gassing and get STT back up. Another benefit I see is that with the fresh wood in front, it will burn faster and hotter as opposed to having a big chunk of wood low in the back of the box, where it can't get as much air and will burn slower. In this cold weather, I'm going more for a high-heat burn than a long burn.
As an aside, the Keystone does keep the coals in check pretty well; It has a hole in the ash pan housing that feeds some air to the bottom of the load through the grate.

 

Sounds like a good thing to try and see how it works.

 

Just started the 2nd load for the day, a small one of 2 splits. Pushed the coals back, put the 2 splits N-S, and bingo! I am liking this!

 

hmmmmm..... might have to try a test load on that when I can get my butt back down in the lab.

interesting thought

 

A little airspace behind the splits (between them and the vertical secondary air manifold) for the flame to come up through seems to help. Rather than pushing the splits hard against the manifold. Also, on one try yesterday, I put a small split (kindling size) E-W on top of the coals in the back, then the regular splits N-S on top.

My last load last night, I had a hard time getting a sustained flame over the top. I think I had it all pushed back too tight against the manifold. That load was one layer N-S, then a second layer E-W on top of that. I think I just blocked the air from the doghouse a bit too much with all that.

But for 2 of 3 tries so far, I got a good result. YMMV.

 

Tried another backwards burn tonight, and got a great result!



Sorry my photos are so poor, but there is just a little glow right in front of the doghouse, and very active secondaries. There is a sustained glow way in the back of the firebox, and the wood is just blackened at the front, with no sign of active burning other than the glow in front of the dogbone.

At the moment, STT is 550 (IR reading), flue temp is 450 (Condar probe), both steady for about 15 minutes now.

The wood for this load is 3 medium splits of pine. The coals were piled about 6 inches high, and pushed back against the rear wall, a little higher against the secondary manifold in the center than on the sides.

Air is set about 1/2 inch out from fully closed. I'm going to let this burn untouched and see what happens.

I think next time I might try a E-W split or a higher BTU wood in the front, on top of the N-S load, to see if I can get a longer sustained burn that way. The thinking is that it will take a while to coal so far from the intense heat in the back, and therefore will sustain the burn a long time.

Other ideas welcome.

 

May have just found that engineer you were looking for awhile back, huh???

 

So you load N/S and the splits are sitting on the coals pile in the back or just in front of the coal pile?

If on the coal pile then they are soaping down toward the front?...and you end up with a lot of space in the front below the baffle because the splits are higher in the back.

If just in front of the coal pile then you must be using short splits?

 

On top of the coals and sloped to the front. Yes there is space on top in the front, it is not the tightest way to pack a stove.

 

DaveGunter one could go with short splits on the bottom, butted up against the coals. Then regular length splits above, over the coals. This would result in a tighter packed stove. Thanks for adding to the idea, I may try this tonight.

But, I also think the upslope is part of the result I see. I need to experiment a little more.

BTW, last nights burn was good. The wood was all consumed, and no unburnt coals. There were a few small glowing coals, not enough to realistically do a relight. This is an expected result, remember all I had in there was three splits of pine. The glass was about the same as it was when I started, I had not cleaned it before, and this fire did not either clean it or dirty it.

 

Good Idea!, one thing to point out is putting all the coals to the side or to the back or too the front only part of your wood is on hot coals.

 

I tried the back to front burn before but it seemed to take about 3x the amount of time to get up to temp and a lot of smoldering during startup. Might give it a shot again maybe with hotter coals and smaller splits on em, but even once lit I didn't really see any advantage, at least with my stove.