Northern lights secondaries

[SculptureOfSound]

Has anyone ever had a burn happen in their tube stove/insert like the below video?

I've had these northern lights-ish secondaries before but typically only briefly and kind of sporadically...this time it lasted over 30 mins burning exactly as in the vid with NO primary flame visible.

Insert top (there's a spot on the Montpelier top that is exposed so can get real readings) held at about 650 during this time despite the very slow and very small amount of wood gas burning.

 

[kvesi122]

Yup! Only with properly dried oak or oak/maple mix. It's a beautiful thing to watch with the lights off.

 

[begreen]

Yes, the T6 tends to make billowy, wafting and sometimes wraithlike flames when turned down and the wood is offgassing. Some good hardwood will emit more bluish flames adding to the fun.

 

[Highbeam]

Yes, the T6 tends to make billowy, wafting and sometimes wraithlike flames when turned down and the wood is offgassing. Some good hardwood will emit more bluish flames adding to the fun.

Our local maple (not sure if its bigleaf or sugar) makes really nice blues and purples.

 

[SculptureOfSound]

Normally I get these up top but also have some primary flame, and they are rarely this completely blue/purple.

This was about an hour in to a load of Jack pine.

 

[SculptureOfSound]

So you guys have had it sustain like this for say 30 plus minutes of nothing but blue secondaries?

I virtually never saw that last year but have managed to slow down the internal airflow of the stove this year and am getting much better burns and secondaries.

 

[kvesi122]

What did you do to slow down the airflow?

 

[SculptureOfSound]

I added some steel foil "baffles" around the tubes. Sort of a soft "U" shaped piece of thin foil that sits between the tube and actual baffle and arcs down about 1.5 inches in front of the air holes.

On the rear tube the improvised baffle wraps from under the tube, this way all flame going up hits this thin piece of foil and it gets red hot almost instantly.
The air from the tube then washes over this red hot foil. Secondaries have much improved and it has helped curtail my high draft situation.

 

[kvesi122]

Do you mind uploading some pics? Very cool idea.

Was there any loss in radiant heat or did it improve the heat output as well?

 

[SculptureOfSound]

I will send you some pics when I get home. It is kind of Jerry rigged for now I was just testing a proof of concept, and also experimented with various depths and such and made some mods specific to the design of my insert.

It seems like overall heat output is up. Hard to say on the radiant heat as it is a flush insert but burn time is a bit better as I can turn down the air a little sooner (not a huge difference but maybe fully closed in 35-40 minutes rather than 45 on a cold start) and it seems like the retention time of the air has increased so more is transferred to the insert and less out the flue. My pipe temp dropped about 35 degrees for a given stove top temp (i.e pipe temp of 305 instead of 340 when top temp is 600).

Doesn't seem to have increased smoke rollout or anything either. Well it did when it was a bit warmer and the baffles were larger and more restrictive so I made them smaller and now it seems there are no negative consequences.

 

[Woody Stover]

Yeah, that can go on for a while. I've also gotten a "ribbon burn" at times, an undulating ribbon of flame created by air from the holes in the air wash igniting the smoke, but I don't think it lasted that long..maybe 10-15 minutes.