Secondary Burn??

ya ... sounds like a simple secondary burn wash/light show, but not so sure about the rumble part. is something loose in there?

I frequently get lots of nice looking washing afterburn when shutting down a hot stove's air fast, but never any rumbles, so far.

If you have single wall vent pipe - I'd suggest using a Thermometer on it regularly - it will give you some peace of mind knowing you are not over firing the stove.

Crank up the music, inhale, and watch the light show.

You have reduced air too much. At this point of the light show & rumble your secondary combustion is on the verge of either stalling (back-puffs) or taking off in the right direction....allowing a bit more air in the fire box will fix the issue.

Agree with Diabel completly! Add some throttle to it!
You should have a consistent secondary burn.
It is Everburn functioning. The rumble is normal
for an Encore NC. Like the sound of a glass pack
muffler!

Don't forget a stove top thermometer. See the many threads
on this subject. Enjoy your Encore!

Valhalla,

Congrats on the f500! Is it installed yet? I am trying to pick one of these up (used f600 firelight cat) & moving my encore to the basement. The encore does a fine job from Oct-Dec. & Mar-Apr. but when it gets really cold in Jan-Feb it need help from NG.

What Diabel said. I get the exact same thing in my downdraft stove when I have shut the primary too far/too quickly on a fire that has gotten too hot. Someone explained it very well here once - in essence each rumbling roll of flame is a sort of mini-backdraft explosion. Shutting the primary air leaves only the secondary inlets to feed the firebox. When you close the bypass, the secondary air is channeled through the afterburner instead of through the firebox. The firebox is looking for that air and it periodically gulps some back in, giving the quick, whooshing roll of flame.

Diabel said:

Valhalla,

Congrats on the f500! Is it installed yet? I am trying to pick one of these up (used f600 firelight cat) & moving my encore to the basement. The encore does a fine job from Oct-Dec. & Mar-Apr. but when it gets really cold in Jan-Feb it need help from NG.

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Thanks my friend Diabel! The Encore gets moved to a large fireplace
hearth on the other side of the house. Your move also sounds great!
Agreed, as it is a super stove, but more BTUs are needed.
The oil man will no longer know our greener house. Arabs too!

Thanks again and stay warm.

Valhalla said:

Diabel said:

Valhalla,

Congrats on the f500! Is it installed yet? I am trying to pick one of these up (used f600 firelight cat) & moving my encore to the basement. The encore does a fine job from Oct-Dec. & Mar-Apr. but when it gets really cold in Jan-Feb it need help from NG.

Click to expand...

Thanks my friend Diabel! The Encore gets moved to a large fireplace
hearth on the other side of the house. Your move also sounds great!
Agreed, as it is a super stove, but more BTUs are needed.
The oil man will no longer know our greener house. Arabs too!

Thanks again and stay warm.

Click to expand...

It is still too warm for my liking ....one fire per day & I'm running short on kindling! It has bee a long shoulder season here in Ontario.

I fee like I am hijacking this thread but all this information will benefit someone out there at some point....Anyhow, Valhalla I am sure you are aware that these VCs need the perfect flue set up & you have it now (as your stove works great as for your comments) Make sure your new location resembles the old set up....

In my case, I would be moving my VC to the basement...which means 30' flue & below grade (negative pressure) both work against what this VC wants!!

I will go with a 21 foot tall, 6 inch SS in a masonry chimney,
then also insulated. Complete with an easy midwinter cleanout tee.

Yes, this still concerns important secondary (Everburn) info
on an Encore NC. Thanks!

We have the cat Encore, so this is all a wild guess.
Once your fuel gets hot enough, it outgasses them volatile burnable lignites into the firebox for awhile. If the primary air is down too low - "I shut down the air completely" - the gas builds up and suddenly ignites. It aint secondary burn, just built-up delayed primary.
Yer lucky it doesn't cause backpuffing. Tweek up the primary intake until you get SOME flame going in the firebox. The rumble must be all that gas shooting into the refractory secondary and lighting up in there. Turning down your primary intake slowly (3 or 4 minutes) may help. The rolling blue light show is mesmerizing but our 2550 CAT back-puffs then unless it's COLD outside.

Northern NH Mike said:

This question will likely reveal how green I am going into my second year of burning.

Tonight I have a pretty hot fire going, actually hotter than I typically am comfortable with. I shut down the air completely, the bypass is closed and the flue damper is open as I try to slow things down. Every 20 to 30 second I get a wash of orange flame coming from the top of the box that rolls through the box with a rumble. The wash lasts less than a second. I've seen it before under these conditions and typically stops after the stove cools down. I suspect it is some type of secondary burning of gases given off by the wood combustion before the draft pulls them up the flue. Thoughts would be appreciated.

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I used to get the same thing with my old VC. Though it was a cat, it had a rear chamber similar to the everburn stoves like yours. For me, this phenomenon was a very bad thing. It would start gently, just as you describe, but then get more severe with each iteration. Each one would get less like a rumble, and more like a "whump" sound. Soon, instead of a rolling wash of flame it would be more of a sudden burst of flame, accompanied by smoke burping from the top loading door. Folks called this "backpuffing", but it was not caused by pressure in the flue as is the typical reason for that phenomenon. Our VC used to puff even when the draft was very strong.

Our VC was so difficult to control that this phenomenon could often not be avoided without either overfiring the stove or running it in bypass mode with the primary air choked all the way down. I hope yours continues to be a gentle roll of flame.

BeGreen said:

Mike, this stove can run hotter on the stove top without discomfort. I wouldn't worry too much until it gets above 650-700. In cold weather, I suspect you'll be pushing towards this territory.

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Agree with BeGreen here. My stove performs best when running at 550-650

Diabel said:

BeGreen said:

Mike, this stove can run hotter on the stove top without discomfort. I wouldn't worry too much until it gets above 650-700. In cold weather, I suspect you'll be pushing towards this territory.

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Agree with BeGreen here. My stove performs best when running at 550-650

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+2, my Vigilant was the same

yesterday it was very windy on long island 40mph+, when i closed the damper on my encore nc smoke came out of the damper handle on left side. i just reloaded the stove, i dont know if the stove was to full and a gust of wind cuased a backpuff. i had a good bed of coals and 650 griddle temp. it happend 3 times yesterday but never happened before, once the smoke kicked into secondary i did not happen again.

I had mine placed in a corner... any would work fine.

Northern NH Mike said:

mikepinto65 said:

Diabel said:

BeGreen said:

Mike, this stove can run hotter on the stove top without discomfort. I wouldn't worry too much until it gets above 650-700. In cold weather, I suspect you'll be pushing towards this territory.

Click to expand...

Agree with BeGreen here. My stove performs best when running at 550-650

Click to expand...

+2, my Vigilant was the same

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Thanks for the tip. Last year I kept it at or below 500 as that seemed to be where I got good clean burns and comfortable heat. My dealer even suggested that that was too hot. I keep my stovetop therm just to the right of the griddle on the cast iron. Just below that spot is open to the firebox (no component obstructions). Good spot for measuring temp or place it in the griddle?

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Beware, the stove-top thermometers can lose accuracy. The first year mine was accurate to within about 25 degrees. This year, my third its is almost 100 degrees off (to the cool side). Thankfully the infrared thermometer gun is pretty accurate.

I just experienced this "backdraft" combustion event writ large.

My VC Dutchwest was running hot in bypass mode with primary air wide open (starting from banked coals with dry wood).

I catalyzed it and slammed the primary shut. The flame went from roaring to out in about 4 seconds. I thought better of it, and popped the primary back wide open. I heard a sucking inhale, and then there was a bright flash and a BOOWWWOOOSH! Flames shot out of both the front primary air intakes, and rich, organic, fuelly smelling vapors hissed out of every crack for about the count of "son of a...!"

And so ends my cautionary tale.