Secondaries burn intensity related to stove top temps, or is it something else?

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fishingpol

Minister of Fire
Hearth Supporter
Jul 13, 2010
2,049
Merrimack Valley, MA
With the recent power outage, I had plenty of time to familiarize myself with my new to me F3. I noticed that upon loading large splits, it seems the secondaries are different in intensity with almost every reload. With a good coal beds, two splits and an open air intake, the stove top temps would rise in no time. Once the new splits were well caught, I closed the damper down completely and let the secondaries take off. I did not need to close it in increments.

The question is: Has anyone tried to close the primary down at different stove top temps and found a different intensity in the secondary combustion. I imagine wood species may play into it as well as MC.

Is there an ideal temp to close down the primary air to get the most efficient, clean burn? It would seem like raging secondaries would consume wood quicker.

Let's hear your observations. You can probably tell I did not have much going on without electricity to notice this.
 
I always close it down in steps. Starting at 400 degrees stove top. You can actually "shock" the fire by doing it too soon. You have a little leeway with the small firebox on the F3 because it gets pretty hot in there pretty fast. With a larger firebox you need more time.

Can't comment on secondaries. I quit worrying about them years ago. A lot of times that light show is just annoying and means I did something wrong. As long as the secondary air is picking off the stray gases that didn't burn down at the wood I am a happy camper with a clean chimney.
 
When to close down primary varies all the time. I generally know its time at 400 degrees stove top and how much depends on the draft. There are times I've had the primary right down to just a sliver maybe the thickness of a sheet of paper and the secondaries are raging. That also encourages temps to rise. I never do encrements like most. When its time its time and I know my stove and how it behaves. I don't think secondaries are wood consumers as much as the yellow flames. Less yellow the better for me.
 
BrotherBart said:
I always close it down in steps. Starting at 400 degrees stove top. You can actually "shock" the fire by doing it too soon. You have a little leeway with the small firebox on the F3 because it gets pretty hot in there pretty fast. With a larger firebox you need more time.

Can't comment on secondaries. I quit worrying about them years ago. A lot of times that light show is just annoying and means I did something wrong. As long as the secondary air is picking off the stray gases that didn't burn down at the wood I am a happy camper with a clean chimney.

Can you explain "shocking" the fire?
Thanks
 
I'll try closing it on increments. Still have the learning curve going on. I am pretty impressed with the overall performance of the stove. I'm enjoying longer burn time between reloads than the F-100. More time for napping in between them.
 
Only reason I close the primary down rather quickly is to force the secondaries to come alive. If the wood is real dry and condition are just right I can force them to appear even sooner.
 
I cheated myself out of many a longer burn time by shutting it down in increments. If the firebox is hot with a hot bed of coals, I just add the new splits and give it just enough air to light, and then shut it down. Orange dancing flame stays pretty steady from the start and stack temp stays around 350, so it works for me.
 
jatoxico said:
Can you explain "shocking" the fire?
Thanks

Close down primary too soon and you lose the flames. And end up sitting there with the primary back open waiting for the fire to build back up so you can start all over again. And be late getting to bed.

If you ease it down in steps the fire adjusts to the lower intake in steps and the stove top temp levels out.

Everybody here loves the "run it up to 600 and slam it down and watch the light show" thing. I had fun with it the first year with the 30 but soon got back to just having a nice long burning fire without all of the drama.
 
Wkpoor- I agree on that too. When the firebox is running nice with a good coal bed, the reloads catch easy and I find I can shut the primary down without stepping down.
 
fishingpol said:
With the recent power outage, I had plenty of time to familiarize myself with my new to me F3. I noticed that upon loading large splits, it seems the secondaries are different in intensity with almost every reload. With a good coal beds, two splits and an open air intake, the stove top temps would rise in no time. Once the new splits were well caught, I closed the damper down completely and let the secondaries take off. I did not need to close it in increments.

The question is: Has anyone tried to close the primary down at different stove top temps and found a different intensity in the secondary combustion. I imagine wood species may play into it as well as MC.

Is there an ideal temp to close down the primary air to get the most efficient, clean burn? It would seem like raging secondaries would consume wood quicker.

Let's hear your observations. You can probably tell I did not have much going on without electricity to notice this.

Question #1, Secondary combustion depends on the air being preheated, so the hotter the stove is, the better the preheat, and the easier it gets to light off the secondaries and the better they work (more intense).

Question #2, The secondaries are dependent on fuel from the primary fire, smoke and hot gases, and do not burn the wood directly. A raging primary fire will gobble wood quicker but the secondaries are just burning the byproducts of that fire and giving off free heat that otherwise would go up the chimney as smoke.

With my stove I notice that it's hard to get the stove top over 400 without the secondaries. It's a balancing act to try to get enough fuel from the primary fire, super-heated secondary combustion air, and keeping it all under control. Stove design plays in here as well. Mine has unrestricted secondary air intake whereas I believe some models regulate secondary air along with the primary.

I'm somewhat new to non-cat EPA stoves too and still quite entertained by closing the primary air supply off once the stove is hot enough and watching the secondaries rage. Reloading a hot stove and leaving the primary damper open to about 20% or so after a reload produces some awesome secondary fire until the wood charcoals over adequately and things settle in for the long haul.
 
BrotherBart said:
jatoxico said:
Can you explain "shocking" the fire?
Thanks

Close down primary too soon and you lose the flames. And end up sitting there with the primary back open waiting for the fire to build back up so you can start all over again. And be late getting to bed.

If you ease it down in steps the fire adjusts to the lower intake in steps and the stove top temp levels out.

Everybody here loves the "run it up to 600 and slam it down and watch the light show" thing. I had fun with it the first year with the 30 but soon got back to just having a nice long burning fire without all of the drama.

OK I think I may be guilty of shutting down too fast sometimes.
The only time I have been able to go smoke free, and I mean absolutely smoke free, is while running it up hot and slamming down as you say.
If I cruise at 450-500 I generally have some smoke, nothing excessive but it's there. I've been led to believe these EPA stoves can be run "smoke free" most of the time which is what I'm trying to do.
Is this a realistic goal IYO or more like sometimes/often but not always.
There is a video that has been posted here showing a top down start with reload after raking and they show zero smoke throughout.
I can get pretty smoke free on start but no so much on reload (at 250-300). When cruising at temps I mentioned it's clean but not crazy clean. Sorry I know I'm hitting you with a lot but any thoughts?
 
Dry wood with a stove top temp over five hundred should be giving you nothing but heat waves. Don't mistake steam for smoke. Steam dissipates within twenty feet of coming out of the pipe. Smoke doesn't. Steam comes from moisture in the wood and in the air the stove is drawing from your house.

Go outside at night and shine a flashlight up at the chimney and you will usually see steam. You don't see it in the daytime because of the sun.

Told the story last week. A couple of years ago the neighbor on the next place over that heats with propane came waltzing through the woods and said that he thought I said my stoves don't smoke and pointed at one of the chimneys. I told him he was looking at steam and marched him back over to his place where a twenty foot column of steam was coming out of his propane furnace chimney. Told him my steam was cheaper than his steam and walked away.
 
BrotherBart said:
Dry wood with a stove top temp over five hundred should be giving you nothing but heat waves. Don't mistake steam for smoke. Steam dissipates within twenty feet of coming out of the pipe. Smoke doesn't. Steam comes from moisture in the wood and in the air the stove is drawing from your house.

Go outside at night and shine a flashlight up at the chimney and you will usually see steam. You don't see it in the daytime because of the sun.

Told the story last week. A couple of years ago the neighbor on the next place over that heats with propane came waltzing through the woods and said that he thought I said my stoves don't smoke and pointed at one of the chimneys. I told him he was looking at steam and marched him back over to his place where a twenty foot column of steam was coming out of his propane furnace chimney. Told him my steam was cheaper than his steam and walked away.

Cheaper steam. that's pretty funny and that's most likely what I'm seeing then because it is gone within a few feet.

And yes I have been out in the middle of the night with flashlight many times checking things out. You may recall my smoking chimney scare a few weeks ago. I am sure my neighbor thinks there is something wrong with me. I am also sure he is right but not for the reasons he thinks. Thanks, good info.
 
BrotherBart said:
Can't comment on secondaries. I quit worrying about them years ago. A lot of times that light show is just annoying and means I did something wrong. As long as the secondary air is picking off the stray gases that didn't burn down at the wood I am a happy camper with a clean chimney.

I'm still on the learning curve with my '30 and I have read where you aren't concerned with the secondaries as long as they are picking off the stray gasses, but I'm confused.

If I let the secondaries go down to that level - I have the stove damped down where there are only a few flames coming off the splits and a small cloud of secondaries at the top rear of the stove. I can seem to maintain a 450-500ish stove top, but when I check the chimney it looks to me like smoke. Realize that up to now, from my old days with stoves there was smoke, more smoke and creosote to follow! With my cat stove, same wood as my '30, when the cat is doing it's thing - zero smoke. So I'm struggling with steam vs smoke from a visual.

When give the fire more air and the secondaries are going crazy, there is zero smoke. If I let the flame die to hot coals, all secondaries go out and the stove top temp drops to 400 or below and lot of smoke. But if I burn the stove with lots of fire off the logs and secondaries going crazy, I'm also sawing through a lot of wood whereas if I got the stove dampered down with a few flames off the logs and a small cloud of secondaries in the rear of the stove and a 450/500ish stove top with a slight discharge from my chimney, then I get a really long burn. How clean is it? I guess the proof in my smoke/steam observation will be when I give the chimney a cleaning.

In the mean time, I'm still learning and enjoying the Englander and the incredible fast heat out of it!

Thanks,
Bill
 
fishingpol said:
With the recent power outage, I had plenty of time to familiarize myself with my new to me F3. I noticed that upon loading large splits, it seems the secondaries are different in intensity with almost every reload. With a good coal beds, two splits and an open air intake, the stove top temps would rise in no time. Once the new splits were well caught, I closed the damper down completely and let the secondaries take off. I did not need to close it in increments. I often can do this . . . providing I have a nice coal bed . . . but typically I shut down things incrementally . . . it just seems to work better when I slowly reduce the oxygen in the firebox.

The question is: Has anyone tried to close the primary down at different stove top temps and found a different intensity in the secondary combustion. I imagine wood species may play into it as well as MC. I typically shut down when my flue temps reaches Temp X . . . the secondaries are almost always the same . . . the Portal to Hell effect . . . sometimes the Northern Lights (which I suspect is due more to a need for a little more oxgen) . . . the only time I have seen a real change in the intensity is a) when I have loaded up the firebox with well seasoned, light-weight wood (namely poplar), b) when I have re-loaded the firebox too early in the burning cycle and c) when I have had wood that has not been as well seasoned as it should have been.

Is there an ideal temp to close down the primary air to get the most efficient, clean burn? It would seem like raging secondaries would consume wood quicker. I close down my air when the flue temp reaches Temp X and the stove reaches Temp Y . . . and then the temp in the room soon rises to Temp Z . . . shortly thereafter I soon start producing some ZZZZZZZZs. I used to worry about the raging secondaries chowing through my wood too quickly . . . but it seems as though the burn time is almost always the same length of time regardless of how intense the fire is . . . of course this is just my subjective observations . . . no objective data.

Let's hear your observations. You can probably tell I did not have much going on without electricity to notice this.
 
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