if I damper down all the way, I lose myu secondary...

Try letting the wood char a bit longer and getting the firebox hotter and then shut it down slowly, 50% then 20% then 0. With your setup mabey 0 won't work, you might have to run 10-20% open.

Yep , Yep , Yep ............ what Gunner said.

Also make sure to have a nice coal bed before turning the damper down for long burns , little coal and a large load is a fight to keep going.

For extra heat make a "tent" on hard to burn woods ......... 2 pieces with a gap in the middle on the coals and a flat log on top to make a hot pocket in the middle.

Okay, newbie question here. Isn't the seondary burning more about the temperature than the actual visual of the dancing blue flames? That is to say, you don't always see the secondary burn, but it's there if the right temperatures are reached.

-Kevin

If you don't have the large amount smoke gases you wont have the secondary burn .........

If you don't have a high enough firebox temp you wont get them.
Dancing blue flame is always a good sign and ghost flames are a A+ too .

0 wont work for me I'm around 10-20 percent also depends on the wood I'm burning too.

Roospike said:

If you don't have the large amount smoke gases you wont have the secondary burn .........

If you don't have a high enough firebox temp you wont get them.
Dancing blue flame is always a good sign and ghost flames are a A+ too .

Click to expand...

What is responsible for a large amount of smoke gases? Does that depend on the type of wood? How full the box is with wood?

What would be the temperature needed to achieve secondary burns? Or does that depend on the stove? I've been running 450-600, trying to remain between 550-600, but haven't quite gotten the hang of everything yet. Is that enough temperature?

What are "ghost" flames?

-Kevin

Thanks BB I kind of wondered that myself

Thanks BB, your explaination answers many questions for me.

-Kevin

My furnace is an older non cat pre epa model with a spring loaded intake air flap on the ash door. It is what I am told is called a bottom burner. When the firebox temp goes down the spring contracts that is connected to a chain that opens the flap and vise-versa. My friend has the same type of furnace in his garage. He welded the flap closed and put a manual damper in his loading door. I don't want to do that because it seems like a pretty good safety device to me. It's hard to get a long burn because the flap automatically opens when the fire gets low and it eats wood like a woodchipper. It is adjustable, so if you keep an eye on it you can get it set to where you get a decent burn and still keep your chimney temps up. The other night I tried setting the damper with just a slight amount of slack in the chain. It was into secondary burn because it was producing very good heat and stayed constant for the hour or so I stayed up and watched it. I awoke the next morning and my house was a little chilly like it gets when the fire goes out. I went to church, then breakfast, then returned home at around 11 a.m. To my surprise the fire was still burning but my chimney temp was down to 130. There was still enough coals left so that all I had to do was rake and add wood. That was an 11 hour burn! The problem was that I don't know how long was a burn and how long was a smolder. There was a small amount of wet creasote on my loading door, but nowhere else that I could see. I have read here that if you burn a short hot fire you can burn fresh creosote before it becomes a problem. So I stoked it up with some small cherry and got my chimney temp to 700. Usually once my chimney gets past 250-300, it stops smoking. For about 15-20 mins. it belched black smoke then turned clear. I then returned to my normal air settings and got my temps into the normal range. I don't think I'll try that one again but it gives me hope that I can eventually find a happy medium. I am about 2 yrs. away from buying a modern wood furnace. Maybe by then I'll have this beast figured out.

I have an older wood furnace and I always get secondary combustion in the very back of my firebox. I have extra air that enters the back and this helps burn the gasses. Its cool when I peek in the door damper holes, almost invisible flames, mostly blue. When this happens, I can really close up the dampers and keep this all night, even with the furnace blower blowing around the firebox. I say my temps hit 600 to 700 degrees while this is going on. Whats nice is I can have a 7 to 8 hour burn with this kind of heat. At night it will burn mostly gasses for a while, while the wood is charring.

Can I ask a question? When you guys are talking about, for instance 'temps hitting 600 to 700 degrees' - where are you measuring from, and are you talking flue temperatures, top surface temperatures or internal temperatures (and if so, how do you measure those)?

Asking because I've had a couple of weeks of running my own stove roughly 12 hours each day, and the maximum stove pipe temperature I reached was 520F (single skin pipe, measured 14" above the stove) - at which point the heat emanating from the stove itself felt enough almost to singe my skin at 2' distance. So, 700 degrees for me would be (a) very very difficult to attain, and (b) probably dangerous as I'd be physically unable to approach the stove!

happy new year all,

john

My references are all stove top temperatures.

My secondary will also stop a minute or two after I close the primary damper completely (but it looks oh-so-cool before it happens). I usually leave it open 20% or so for long burning, and that keeps the stove temp at 650, with plenty of coals 8 hours later.

-- Mike

my temps are surface mount flue temps taken about 2' back and 8" above the stove. That's as high as I can mount it as that is where the stove pipe enters the chimney.

I too can't turn mine down all the way else I extinguish the secondary burn. Like everyone else stated, after starting a fresh fire it's within a half hour and then I can turn it down to about 50%. If I want to turn it down for an all night burn, I'm stuck at 50% for about an hour and a half from a cold start else, the secondary flames go out. With my setup, an all night burn is with the air set at 30-40% and any less and I'll extinguish the flames and kill the secondary burn.

Secondary burn needs flames, temperature, oxygen, and fuel to occur. I'm not a fan of turning it down so low you get the occasional flame that shoots up and ignites the secondary burn occasionally, and then the secondary burn goes out until a new flame can reignite it. Everytime that's happened doing a check of the smoke coming out my chimney it's blue telling me there's secondary fuel that isn't burning, my flames are too low and I need to turn up the air.

Rhonemas said:

I'm not a fan of turning it down so low you get the occasional flame that shoots up and ignites the secondary burn occasionally, and then the secondary burn goes out until a new flame can reignite it. Everytime that's happened doing a check of the smoke coming out my chimney it's blue telling me there's secondary fuel that isn't burning, my flames are too low and I need to turn up the air.

Click to expand...

I agree completely. I like to keep a steady flame hitting the secondary air plate to ignite the smoke.

-- Mike

The original poster is probably turning the burn down too soon or burning wood with a moisture content too high.

Once the secondary burn gets going such that the primary air can be turned down to 0, the secondary should be self sustaining and appear as a gas jet at the burn tubes (assuming your stove has them). As said, once all the initial volitals are driven out of the wood, you'll get the wood fibers burning. Frequently, the secondary burn can be very active with the entire firebox full of flame, even with the air control set at 0. If I have a full load of smaller splits the amount of flame and the amount of heat generated can still make me nervous. For full loads and overnight burns, larger splits are key so that the secondary burn doesn't cause an overly fast consumption of the wood. In typical daily operation of the stove, we tend to toss on 1-3 smaller splits frequently, and that will keep the secondary going but much more lazy and produce the hanging flames. These flames are the smoke burning via the secondary combustion of essentially a smouldering log. The Stove's primary is shut down low and causes the primary combustion to be very limited, causing the log to produce it's volitals (smoke), and the stove's secondary air and heat combine to burn the smoke, thus producing the continued heat. In that setting, the flames appear disconnected from the log and appear above the wood out of no where. It's really cool to watch.

For over night burns when the stove is loaded, I usually have a good bed of coals raked to the front of the stove and pile 1/2 a stove full on for about 5 minutes, open the air up all the way, then once the initial load is going, I'll fill the stove. This works if the splits are smaller (I'm still burning stuff I cut in anticipation of buying a Morso 1410) and this kind of load produces fast super heat. I prefer to load two logs/splits/chunks what ever you want to call them... that completely fill the stove. Then I must open the primary for a good 20 mintes to get the logs up to temp before I can shut down the primary. I like to see a very active secondary above the wood in this case prior to shutting the primary air down. This operation really is exactly what the CAT stove owners must do in order to get the CAT and stove up to operating temp.

I'm sure every stove/install is a little different, so you'll have to play with it for a while. Just remember these things are made to be HOT.

Reading this thread makes me wanna go home and light her up right now...