Secondary combustion help

[Burningmadrone824]

My old man is a big wood burner and I have had my fair share of fires, but the stove I learned on was an old northern comfort with no windows, so learning this new, modern regency i2450 has been cool. I probably have 5 fires in the this stove, which was already in the house but only a year old, and am starting to realize that I don’t even know what I don’t know. Starting the fires aren’t my problem and I don’t struggle with keeping it lit. I know I should be aiming for secondary combustion, but an. Not certain what that looks like but I have some pics of what I think I should be at based on reading here. Can someone let me know if I’m close. Or if I should be doing something with the draft.

Stove: regency i2450
Wood: madrone
Outside temp: mid 40s

 

[NoGoodAtScreenNames]

Welcome. It can vary depending on where you are in the burn. It’s a little hard to tell from the pics - the second one looks most like it to me. Generally one of these:

- Flame coming directly off the wood and getting a boost around the burn tubes.

-Flames coming directly out of the tubes like a gas grill without a connection to a flame below from the wood.

- Lazy clouds of flame hovering over the wood often with mini bursts


If it’s your first year, I’m guessing your wood is still a little wet. Try burning a pack of compressed wood blocks or add a few pieces of scrap lumber in with the cord wood. For what it’s worth, I didn’t know what secondary looked like until my second year where I burned a pack of Bio-Bricks. It was good to see how the stove operates as designed with dry wood.

 

[EatenByLimestone]

Yeah, pic 2 definitely has secondary combustion.

 

[brenndatomu]

Secondary combustion is easiest to see when you have a nice dry load of wood and the fire "separates" after you turn the primary air down...you'll have very little to no active flame down on the wood itself, and there will be nice flames up top against the baffle/secondary air tubes.
Example: (though it may be an extreme example, since there is no active flame showing on the wood...doesn't always happen that way)

 

[Grizzerbear]

Your second pic definitely looks like the secondaries had just started. If you look at the pic I attached you can see the bright orange flame. That is the "primary" fire. It's coming directly off the wood. The purple and bluish flames that are see through are the secondary flames. They normally come from the top but not always. Some times when the air is really slowed down the smoke is catching fire immediately out of the firewood and can be hard to differentiate between secondary and primary when you are starting out. Stove temps have a lot to do with amount of secondaries. I normally don't get robust secondary action until I reach 350-400ish stove temps. When I hit 500 and beyond I get the propane grill....my favorite....flame action. This pic here is still with the air control at about 25% open and stove temps at about 300 I believe.

Edit: I would load a video for reference for you but it keeps telling me the file size is too large.

 

[Corey]

Yes - I'd say the pics ending in 'D0' and '32' both look really good. What I typically look for is a translucent flame (you can essentially see through the flame) vs the yellow opaque flames and the holes in the secondary air manifold look like a small lighter or torch with flames around them.

The other way to tell is that once you get an established fire and start shutting down the air to the stove, the stove temp rises. The more you shut down the air, the more the temp rises. Temp will keep rising to a point and level off, then you have control of the stove - shutting down the air more should lower the temp. It is sort of like tuning a carburetor for an engine - you want just the right mix of fuel and air for best combustion... but in the stove case, you control the air, not the fuel.

 

[Burningmadrone824]

Thanks for the info! The wood I got it pretty dry, although I don’t have a moisture sensor. There are some chunks and uglies that are a little on the wet side but I don’t use those until the stove is good and hot. I’ll keep playing with this to try and learn.
One thing I’ve noticed is this stove doesn’t seem to care if I step down the air or jump right to closed. The flames tend to do the same thing. But, that might be because I’m not sure what to look for yet.

 

[Burningmadrone824]

One more question: what would burn longer, getting into a good secondary combustion or doing an extended burn fire with raking coals to the front and letting it move from front to back?

 

[EatenByLimestone]

Its really going to depend on the stove as each system is going to perform a little different due to wood, chimney height, outside temperature, etc.

Some of the issue might be terms that you are using. These stoves excell at getting the most heat out of the wood being burnt, not necessarily burning the longest times. As an example, you fill up the firebox in an old stove and crack the primary air open. It may smoulder (burn) for 24 hours, and coat the inside of the chimney with creosote. That creosote is a lot of potential energy that was wasted.

If you put that same charge of wood into your new stove, it'll burn hotter, and faster. The smoke will reburn, getting more heat out of the wood burnt, and no creosote deposits. But it might only burn for 6 hours.

Typically you rake the coals to the front to help them burn down. Otherwise you may need to shovel them out, losing energy the stove could put into the room.

 

[wagdog]

Let me state upfront that I’m not an expert. I just started using an epa stove 3 weeks ago. I am getting the hang of it though. Here’s my stove after getting up to temp and shutting off the air. The sound you’re hearing is a stovetop fan.

 

[Caw]

Edit: I would load a video for reference for you but it keeps telling me the file size is too large.

I think it's a 20 mb limit to embed videos here. Try clipping or compressing it. If that doesn't work posting to YouTube is the easiest way.

 

[wagdog]

The other way to tell is that once you get an established fire and start shutting down the air to the stove, the stove temp rises. The more you shut down the air, the more the temp rises. Temp will keep rising to a point and level off, then you have control of the stove - shutting down the air more should lower the temp. It is sort of like tuning a carburetor for an engine - you want just the right mix of fuel and air for best combustion... but in the stove case, you control the air, not the fuel.

This is a really key point, in my opinion, and something that wasn’t obvious to me. My old stove would slow down quickly as I cut the air. These epa stoves don’t. As you mentioned, they get hotter initially as you bring the air down from fully open. They keep getting hotter until that optimum mix is achieved and only after that do they start to throttle down.

The part that’s been a challenge for me is finding that optimum setting after getting control of the fire. I suspect I’m overthinking it but it’s one of those “learning curve” things and I want to get it right.

 

[bigealta]

Here is a short 1:30 min. video of secondaries in jotul f400. It shows the secondaries and them ending the cycle. Hope this might help seeing this in action.