Secondary combustion

[Bob B.]

I'm new to wood burning in a Hearthstone Heritage and have a question regarding secondary combustion. My typical "shoulder season" burns start with kindling then 2-3 medium splits once the fire is going well. I then wait until I have the top center stone up to 350-400 degrees to start shuting down the intake air. When the stove is in the 350-400 degree range I have lots of secondary combustion, the tubes in the top of the fire box look like lit gas burners. My question is once I cut my intake air down to almost closed my stove cruises at 450 -500 degrees but the tubes aren't very active. I have nice lazy flames and alot of what I think are still considered secondaries, the blueish flames that appear 4 to 6 inches above the logs. The best way to describe them is sorta like northern lights in the sky. Is this typical of secondary combustion in an EPA non-catalytic stove? If I ran the stove with enough air to keep the tubes lit I think I'd over fire the stove in short order. What do the experts say?

 

[Sully]

That's how mine works. Those tubes don't always do that, seems to happen more when I have the primary air open. Once shut down they die down some and I will get exactly like you said, the flames that appear out of no where. Gas igniting. It is pretty cool to look at. I have osburn 2400. I usually get up to 700 cruise for awhile at 650 than long time at 550 to 600. Heats house quick. A little to hot here tonight.
That's about 3 hours later and it's at 600

 

[lopiliberty]

This is what mine looks like for the first hour or so then it settles down to those ghost like flames.

 

[Sully]

Yup, same here like a bunch of rockets

 

[Sprinter]

As more of your fuel gets burned, there will naturally be fewer gasses released, so the secondaries will seem to be less active. It sounds like your're doing good. Don't try for northern lights through the whole burn cycle. Eventually, most of the gas products will be gone and the secondaries will have nothing left to burn but the coals will still be pumping out heat.

 

[Bob B.]

I'll try to get a pic of the ghost flames but this is what it looks like prior to shutting the air down.

 

[DBoon]

I'd say what you are describing, to me anyways, are "lazy" secondaries. You are likely not burning off all of the gases like you would if the secondaries were more continuous. Don't get me wrong - the secondaries don't have to be like Dante's inferno to burn all the gases - but I'm guessing that if you went outside in the daytime when the secondaries were lit as you described, you might see some visible smoke coming out the chimney.

As it cools down more and you get a stronger chimney draft, you might find that the secondaries get more active and the burn gets a little more complete/cleaner.

 

[prezes13]

This is mine with the air shut down. It's 48degrees out side.

 

[Bob B.]

Lazy secondaries? Stove top at 425 with air shut.

 

[Bob B.]

I guess what I'm really asking is do the tubes at the top of the fire box need to be lit like gas burners to burn all the gases or not. Btw no visible smoke from chimney when the last photo was taken.

 

[thedriver]

I guess what I'm really asking is do the tubes at the top of the fire box need to be lit like gas burners to burn all the gases or not. Btw no visible smoke from chimney when the last photo was taken.

I am far from an expert but, If you exhaust is clean out the chimney and your stove temp is good you are doing just fine. don't overthink it . mine works exactly like that with no problems in the stove or chimney and we are very pleased with the good heat and the burn times we get. enjoy , and stay warm

 

[Chimney Smoke]

As has already been stated, the secondaries are going to look like jets at the beginning of the new burn cycle of a fresh reload because that's when the wood is offgassing the most. Once that is complete, there's not a lot of excess gas for the secondaries to reburn so you just see the lazy rolling flames.

 

[DBoon]

I guess what I'm really asking is do the tubes at the top of the fire box need to be lit like gas burners to burn all the gases or not

Every stove is different. I think a larger stove can burn with lazier secondaries where my smaller stove struggles a bit to burn super cleanly with intermittent, lazier secondaries. If the exhaust from your stove pipe is clean, then you are doing just fine.