Creosote help?

lsucet

Minister of Fire
May 14, 2015
1,552
San Ysidro, New Mexico
Just follow their recommend way of how to burn and in no time you will be enjoying nice secondary burn. Start from scratch following their instructions.
 

Alpine1

Feeling the Heat
Apr 27, 2017
299
Eastern Alps, Italy
..for a second i felt a huge weight of relief when i read what you wrote :)
but that picture was taken at just the right time. seconds later all the flames went out completely so i definitely didnt have a secondary burn

i may be confusing what a secondary burn actually is. perhaps with the F55, the flame doesnt actually shoot out of the small holes?
Can be. First and foremost, check your wood, the lower the MC the better (and no more than 20% anyway!), then learn how your stove reacts when you close the primary air in small increments. The pic you posted in the other thread shows good secondaries (maybe a bit too yellow, but that can be due to wood species) and if they went out seconds after the pic was taken, you should have given a pinch of air more... that’s learning your stove, pipe, wood and weather. Don’t overthink it, as someone on the forum said... it’s just a fire, burn it!
 
  • Like
Reactions: Jotel me this

sutphenj

Burning Hunk
Nov 19, 2010
160
West MI
I have a f55 and it shoots out the holes...in fact pretty vigorously with good dry wood but the stove can be finicky in terms of shutting down too early....the stove reacts quickly to air adjustments. It take patience. What is your stove top temp when you shut the air down? This stove requires incremental adjustments from my experience.
 
  • Like
Reactions: Alpine1

Jotel me this

Member
Sep 21, 2018
237
Pennsylvania
I have a f55 and it shoots out the holes...in fact pretty vigorously with good dry wood but the stove can be finicky in terms of shutting down too early....the stove reacts quickly to air adjustments. It take patience. What is your stove top temp when you shut the air down? This stove requires incremental adjustments from my experience.
i think the top is around 450F when i start to shut it down.
so you actually see flames coming out those holes?
 

kennyp2339

Minister of Fire
Feb 16, 2014
4,386
07462
The flames do no actually shoot out of the holes, but the at times give off that appearance. Air comes out of those holes and quickly ignites the gases in top of firebox.
Secondary tube stove combustion works like this: main fire burns, when the internal temps hit approx. 1,100deg f the flue gases separate above the baffle, the hotter flue gasses (complete burnt stuff) rises and goes out the chimney while the heavier cooler flue gases recycle back into the stove through those air tubs, while going through the tubes they mix with the secondary room air, once back in the hot firebox they get re-burnt completing the cycle.
It is important at the initial fire to get it hot enough before shutting down the main air, 500deg stove tops work with most stoves, once you start shutting the air down the actual fire box temp will get warmer because the draft if forced to slow a little keeping more heat in the firebox, on cold stove starts with good dry wood it should take approx. 30min before you can shut it down, sometimes even longer if there is no ash on the bottom brick, (ash acts like an additional layer of insulation, minimum 1" of ash is recommended on the bottom of the firebox for normal operation)
 
  • Like
Reactions: Jotel me this

Jotel me this

Member
Sep 21, 2018
237
Pennsylvania
Secondary tube stove combustion works like this: main fire burns, when the internal temps hit approx. 1,100deg f the flue gases separate above the baffle, the hotter flue gasses (complete burnt stuff) rises and goes out the chimney while the heavier cooler flue gases recycle back into the stove through those air tubs, while going through the tubes they mix with the secondary room air, once back in the hot firebox they get re-burnt completing the cycle.
It is important at the initial fire to get it hot enough before shutting down the main air, 500deg stove tops work with most stoves, once you start shutting the air down the actual fire box temp will get warmer because the draft if forced to slow a little keeping more heat in the firebox, on cold stove starts with good dry wood it should take approx. 30min before you can shut it down, sometimes even longer if there is no ash on the bottom brick, (ash acts like an additional layer of insulation, minimum 1" of ash is recommended on the bottom of the firebox for normal operation)


oooh. this just answered all of my question. printing. hanging on fridge. :eek:
 
  • Like
Reactions: Alpine1

begreen

Mooderator
Staff member
Nov 18, 2005
78,577
South Puget Sound, WA
Secondary tube stove combustion works like this: main fire burns, when the internal temps hit approx. 1,100deg f the flue gases separate above the baffle, the hotter flue gasses (complete burnt stuff) rises and goes out the chimney while the heavier cooler flue gases recycle back into the stove through those air tubs, while going through the tubes they mix with the secondary room air, once back in the hot firebox they get re-burnt completing the cycle.
It is important at the initial fire to get it hot enough before shutting down the main air, 500deg stove tops work with most stoves, once you start shutting the air down the actual fire box temp will get warmer because the draft if forced to slow a little keeping more heat in the firebox, on cold stove starts with good dry wood it should take approx. 30min before you can shut it down, sometimes even longer if there is no ash on the bottom brick, (ash acts like an additional layer of insulation, minimum 1" of ash is recommended on the bottom of the firebox for normal operation)
This is not actually correct. The hot flue gases do not recycle back through the air tubes. The air direction through the tubes is one way only, there is no recirc. As the primary air is closed the draft forms a vacuum in the firebox. This draws air from the secondary air intake through the tubes. That air turbulates hot gases at the top of the firebox and reburns them.

Additionally, waiting for a 500F stove top temp can lead to excessively high flue temps, especially on a cold start. In our stove secondary combustion is already happening with a 250º stove top on a cold start. (On our Jotul F400 this was around 300º.) It takes time for the mass of the stove to heat up, even though the firebox is already up to temperature. Waiting too long to start turning down the air wastes fuel and can cause flue temps that may exceed the pipe rating. It's better going with flue temp than stove top temp. Start turning down the air when the probe flue temp is around 400-500º. (Surface flue thermometer temp around 250ºF) If it's not possible to read flue temp then one should use their eyes to determine when to start closing down the air.
 
Last edited:

kennyp2339

Minister of Fire
Feb 16, 2014
4,386
07462
This is not actually correct. The hot flue gases do not recycle back through the air tubes. The air direction through the tubes is one way only, there is no recirc. As the primary air is closed the draft forms a vacuum in the firebox. This draws air from the secondary air intake through the tubes. That air turbulates hot gases at the top of the firebox and reburns them.

Additionally, waiting for a 500F stove top temp can lead to excessively high flue temps, especially on a cold start. In our stove secondary combustion is already happening with a 250º stove top on a cold start. (On our Jotul F400 this was around 300º.) It takes time for the mass of the stove to heat up, even though the firebox is already up to temperature. Waiting too long to start turning down the air wastes fuel and can cause flue temps that may exceed the pipe rating. It's better going with flue temp than stove top temp. Start turning down the air when the probe flue temp is around 400-500º. (Surface flue thermometer temp around 250ºF) If it's not possible to read flue temp then one should use their eyes to determine when to start closing down the air.
Yea, I really butchered that one, I thought I knew what was up.
upload_2018-10-22_13-54-51.png
 
Last edited by a moderator:
  • Like
Reactions: bholler

Chimney Smoke

Minister of Fire
Nov 24, 2013
674
Maine
I don't have the exact same stove as you but I have a tube stove. You'll likely only see the jets of flame from the secondary tubes after a fresh reload when the most off gassing is happening. This usually happens for me for around 1-2 hours. After that I see the slowly rolling ghost flames for another hours or two. After that the wood is mostly down to a large pile of coals and little to no secondary burn is going on.