Secondary Combustion

mjrotor

New Member
Oct 15, 2018
25
CT
Hi guys,

I am trying to learn more about the secondary combustion. Does the attached video show good secondary burn? It's set on medium air control. I am wondering if I should shut it down more. It's been like this for about an hour. I have a Lopi Freedom.

 

saydinli

Burning Hunk
Nov 6, 2016
233
Near Fergus Ontario
Looks pretty good to me. What happens when you shut it down all the way? Does it snuff out or continue burning up top? A good indicator of secondary burn is that there is slow dancing flames at the bottom and more lively flames up near the air tubes/baffle.
 

PaulOinMA

Feeling the Heat
Oct 20, 2018
369
MA
Wow. Another CT person. :)

Looks good, as mentioned. Looks like what I see in my Lopi Answer, too. It's a deeper orange color than the bright yellow flames that come directly off wood. Looks more like gases igniting.
 

David.Ervin

Burning Hunk
Jan 17, 2014
243
O-H
A really strong secondary burn looks a lot like a natural gas flame, maybe with some yellow mixed in. Looks like you've got plenty of both primary and secondary going in there at the same time.
 

mjrotor

New Member
Oct 15, 2018
25
CT
@saydinli if i shut air all the way down, I will see more dancing flames at the top. ( more blue ) It definitely does not last as long when shutting the air down. I don't think I will see 12 hours of burn time as advertised.
 

Jan Pijpelink

Minister of Fire
Jan 2, 2015
1,605
Lindenwold, South Jersey
I have your stove's cousin. I wait till stove top temp is 400+. I close the air for 90% and blue flames shoot out of the tubes.
 

saydinli

Burning Hunk
Nov 6, 2016
233
Near Fergus Ontario
@saydinli if i shut air all the way down, I will see more dancing flames at the top. ( more blue ) It definitely does not last as long when shutting the air down. I don't think I will see 12 hours of burn time as advertised.
Ya 12 hours burn times are very subjective. 8 hours is more realistic and 10 hours is achievable once you perfect burning with your stove. If you are seeing more flames above when turned down , thats a good thing you're burning clean.
 
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mjrotor

New Member
Oct 15, 2018
25
CT
I have your stove's cousin. I wait till stove top temp is 400+. I close the air for 90% and blue flames shoot out of the tubes.
What thermometer are you using? I had a rutland, but the spring kept coming off. I returned it

Sent from my Nexus 6P using Tapatalk
 

Jan Pijpelink

Minister of Fire
Jan 2, 2015
1,605
Lindenwold, South Jersey
What thermometer are you using? I had a rutland, but the spring kept coming off. I returned it

Sent from my Nexus 6P using Tapatalk
On both our stoves we have the Inferno. Checked with IR gun, very accurate.
 

Corey

Minister of Fire
Nov 19, 2005
2,425
Midwest
I don't really see a lot of secondary burn going on in that video. For true secondary burn, you'd have the appearance of flames shooting out of the holes in the burn tubes. (though it's actually air/oxygen coming out of the holes then igniting the smoke / wood gas in the firebox).

This is partly due to the angle of the video - you can only really see the front tube right by the glass, and I never noticed any flame there. Maybe the tubes further back in the stove have some burning going on and the smoke is already burned up by the time it gets to the front tube. But that wood also looks to be pretty far along in the cycle given the blue/purple translucent look of the flames and the decent coating of ash on the wood. So already a pretty clean primary burn going on... may not be much smoke left to ignite in the secondaries.
 
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Ludlow

Minister of Fire
Jun 4, 2018
1,082
PA
What thermometer are you using? I had a rutland, but the spring kept coming off. I returned it

Sent from my Nexus 6P using Tapatalk
I have a Rutland and it reads 100 degrees cooler than my IR gun at the same location. Is there a real quality accurate magnetic available?

Oh, I see the inferno was mentioned.
 

Pertzbro

Feeling the Heat
Aug 2, 2016
297
NW Iowa
Slow memorizing secondary combustion:


This video shows full bore primary and secondary at first, then close the air control and it goes to mostly secondary. End of video is full bore again.


The strength of the secondaries depends on strength of draft, temperature of firebox and wood moisture content. I have the best secondaries in the the super cold of winter, a hot box (3+ hours burning) with cordwood on bottom and 2 ecobricks on top with air control fully closed.
 

MAD MARK

Feeling the Heat
Jan 31, 2016
352
Pittsburgh PA
Pertzbros first video is true secondaries.

OPs MJRotor video looks to be in a stage where the wood has already offgassed mostly. The primary air would need turned down more to see if any more offgassing could be occurring.
 

Chimney Smoke

Minister of Fire
Nov 24, 2013
674
Maine
You are mostly down to the coaling stage where little if any secondaries are happening.
 

TradEddie

Minister of Fire
Jan 24, 2012
863
SE PA
I have the same insert and that doesn't look like much secondary combustion to me, compared to what's possible. Once I've got temperatures above 400, I can pull that bottom air lever fully out then push it back in just the slightest detectable amount, maybe 1/16" and have roaring secondary flames with barely a glow from the bottom of the logs. That gives long, clean, efficient burns. I rarely need more heat than minimal cruising, but if I did, another 1/8" is plenty. "Medium" air setting (lever half way?) is what I use to get to 400, keeping it there for an hour sounds like wasted heat up the chimney to me.

It also depends on wood type, and of course, how well it's seasoned. Hickory produces the most secondaries of the wood types I've got.

TE
 

mjrotor

New Member
Oct 15, 2018
25
CT
Pertzbros first video is true secondaries.

OPs MJRotor video looks to be in a stage where the wood has already offgassed mostly. The primary air would need turned down more to see if any more offgassing could be occurring.
And that's what I was wondering. I am still trying to figure this out for a slow burn. I could have turned the air down more. It seems when the air is fully closed the flames dance but it really does not last long. I don't see the flames coming from the secondary tubes for a long period. I might see a lot of flames coming out , with air closed, for 10 minutes. After this the flames will dance in the stove. i do see blue flames but I guess I am expecting more flames out of the secondary tubes. Does it not last long with a lot of flames coming from the secondary ? Today the flame in the video lasted for 3 hours. I would say I got a burn from 11 am to 5 pm. I could have went a few more hours before reloading. I typically run my first fire hot to get a good coal bed. The second fire i will run hot for 15 to 20 minutes. Then I will start turning down the air. I guess it's s balancing act. I enjoy everyone's input and advice.

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weatherguy

Minister of Fire
Feb 20, 2009
5,360
Central Mass
Yes it's a balancing act. Try to turn it down as much as you can, for me its fully closed and see how that burns.
 

MAD MARK

Feeling the Heat
Jan 31, 2016
352
Pittsburgh PA
The amount of secondaries relies on

1. The amount of wood in stove
2. The amount of offgassing left in said wood.

The larger load and an early stage of offgassing could give you over hours of it. At the same time, if you run a large load with primary air set too high and you bypass the offgassing stage, you wont see much.

Just like it was said, balancing act. That second fire you talk, try turning down the air all the way, then just open til lazy dancing flames after 15 minutes.
 

KJamesJR

Feeling the Heat
Jan 8, 2018
339
New Hampshire
The secondaries in my Oslo are never purple. You must have some magical wood there


PS

How do you like the EcoFan? I was thinking of picking up the large version.
 

Ludlow

Minister of Fire
Jun 4, 2018
1,082
PA
Mine gets the slow floating purple ghost flame. Looks like the Northern Lights.
 

prezes13

Minister of Fire
Jan 12, 2014
912
Connecticut
When the flame dies open up primary air a touch. Like people said it all depends on a wood moisture content, how hot the fire box is wood species etc. you keep you primary air open too much and too long, but if your wood is it dry enough that is the only way to burn.