Learning how to Burn

[Stax]

Now that my insert is installed and I've had 2 break in fires, I'd like to pick your brains on how to burn. What is your insight, suggestions, tips in learning my stove?

P.S. What are "secondaries", and how do you get them?

 

[CodyWayne718]

Best learning tool I have had has been my stove thermometer. There will be more insight and explanation of secondairies.

 

[Swedishchef]

Stax: congrats on the new install! I hope it keeps you nice and warm.

I can chime in a bit concerning secondaries. Here's how they work (my understanding).

When you light a stove, the initial primary source of heat is the burning wood. This heat warms up other wood surrounding the flame contact spot (on the same piece of wood and on others). Once this other wood (not yet burning) starts to warm up, it will give off gases. This is AKA off gassing. These gases are not burned by the primary fire. They normally simply go up your stove chimney and to the outside world. Lots of these gases are VOCs (volatile organic compounds) and represent a fair source of polution. It is what we consider "smoke" coming out of a chimney. It also represents a huge potential of energy for a heat source.

In most stoves, you have a secondary air source (other than the primary one that you controlm AKA primary air intake). Usually this can not be controlled. The secondary source allows air to enter tubes at the top of the stove (or a baffle). When the inside of your stove gets hot enough and the off-gassing is going well, when those gases come in contact with oxygen along the burn tubes, they ignite. They create an amazing source of heat. Once this begins, you can turn down your stove's primary air intake reducing the primary combustion rate of the wood and allowing for these burning gases to help heat your house.

Long story short: new EPA stoves take advantage of off-gassing to produce another heat source. I know of people who used to have "smoke dragons" (non efficient stoves where the gases went straight up the chimney) and since they bought new ones, heat with about 2/3 the amount of wood used before.

If you use wet/damp wood, you will not get proper secondaries. The moisture content in the wood will "deter" burning during the off-gasing: how can you burn moisture mixed with those gases? Also, damp/wet wood will easily clog a chimney since water condenses at low temperatures (as gases rise in the chimney, they cool off).

Tips: use DRY seasoned wood. Most people around where I live hate new EPA stoves because they cut wood in the fall and burn it in the winter. They say "I have been burning for 30 years, I know what I am doing" yet have done no research on the new technologies involved in wood burning. SO start getting a huge wood pile (try getting 2013-2014 wood now if you want to burn Oak) and enjoy the winter.

Andrew

 

[begreen]

You'll need to close the bypass to see secondary burn. Steps are roughly:

1) start fire with kindling - air control wide open, bypass open
2) add a few small splits, get them burning pretty well
3) add some medium splits
4) when the fire has started to fully ignite the medium splits, close the bypass. Then reduce the air control just to the point where the flames start to get lazy.
5) let the fire progress, it should renew vigor after a few minutes. The secondaries may be firing at this time. It will look like fountains of flame at the top of the firebox.
6) After 5-15 min., reduce the air control again until the fire gets lazy. Now the secondaries should be fully firing.
7) Reduce the air more until the burn is lazy

 

[CTYank]

Re secondary combustion-

While there are still volatiles to be distilled from the wood (not down to coals) it is impossible to have input of controlled airflow sufficient for burning the solids (primary air) and the as-yet-unburnt gases (secondaries.) Result: visible smoke.

So, you split it. Primary air to burn the solids and keep the volatiles cooking. Preheated air is supplied above the fire to burn the volatiles.

Once you get the stove hot enough to have the mix of gases hot enough (>1000 deg F) above the fire, and there's something to burn, the secondaries will stay lit. This is NOT a startup phase. Much design/engineering work had to be done to have this work efficiently- to not add an internal firebox air-cooler.

For further cleanup, you might look into top-down fire-starting. Really reduces smoke there.

 

[Swedishchef]

Between BeGreen's comments as well as CTYank's, that pretty much sums it up.

A

 

[My Oslo heats my home]

You'll need to close the bypass to see secondary burn. Steps are roughly:

1) start fire with kindling - air control wide open, bypass open
2) add a few small splits, get them burning pretty well
3) add some medium splits
4) when the fire has started to fully ignite the medium splits, close the bypass. Then reduce the air control just to the point where the flames start to get lazy.
5) let the fire progress, it should renew vigor after a few minutes. The secondaries may be firing at this time. It will look like fountains of flame at the top of the firebox.
6) After 5-15 min., reduce the air control again until the fire gets lazy. Now the secondaries should be fully firing.
7) Reduce the air more until the burn is lazy

To add a few things to what BG has said. I will mix fuel types up at different times of the year. During the shoulder seasons I will burn all my junk (punks, ends, uglies etc.). Early part of winter I will use softer hardwood and during the really cold months straight to all oak and ash.

 

[firefighterjake]

Not much more to add other than to reinforce a few key points . . .

-- Burn seasoned wood. Burning less than optimal wood = less than optimal heat and less than optimal experience.

-- Top down fires . . . work well . . . plain and simple. It took a few tries on my part before I figured out how to make it work, but it works well.

-- Super Cedars . . . I think I was among the last hold outs (and I still have my newspaper in reserve), but just a quarter of the hockey puck and you're off to the races . . . no more balling up more newspaper and sticking it in the firebox after the first newspaper balls failed to catch the kindling on fire as they burned out too fast.

-- Secondaries . . . pretty well described as to what they are and how to get 'em . . . all I can say is what tends to work best for me is to slowly start cutting back on the air . . . a quarter mark at a time . . . wait for 5-10 minutes to make sure the fire is still burning well and then cut back again.

-- Thermometers . . . perhaps one of the best things I have ever bought for my stove. I use both the stove thermometer and a probe style thermometer for my stovepipe (which probably wouldn't work for you) -- together the thermometers give me some insight as to what is happening and more importantly give me the knowledge as to where I want the fire to go so I can make the appropriate changes to the air control.

 

[Stax]

Great posts guys. Thank you for the info. I'm just learning the controls now (bypass damper & air control). All of my wood is seasoned. I am using the top-down method and have noticed that the Super Cedars are working better than the newspaper. I have a Rutland thermometer 701 on order and will probably pick up a laser one as well. I am enjoying the learning curve.

 

[Wood Duck]

I generally start a fire by adding everything from medium size splits to small stuff and kindling all at once. I stack the medium or even largish wood on the bottom with some smaller stuff to fill large gaps between the wood. On the second layer I add a medium split or two and lots of wood around 1 to 2 inches in diameter/cross section. Among or on top of that wood I use a bunch of small kindling. I place part of a super-cedar fire starter near the top of the pile, but touching and below some of the smaller kindling. I light the super cedar and keep the air wide open. i might even leave the door cracked open. In about ten minutes, if I have stacked things right, the fire should be well on its way. In another 10 minutes it is really getting going and I shut the door but leave the primary air control (the primary is the only controllable one on my stove) wide open. After another 10 or 20 minutes it is time to reduce the primary air for whatever burn rate I see fit. In short, I add the wood all at once and after lighting the fire adjusting the air is all I do. If I want the longest burn possible I carefully pack the firebox full. If I want a smaller fire, I go maybe half full, but you can't have a good fire with too little wood. Three decent-sized pieces is the minimum required and four or five usually works better.

I see secondary flames near the top of my firebox within 5 or 10 mintues of lighting the stove, but at that time they are often mixed or very near the primary flame so you have to look closely. The secondary flame continues through a good part of the burn until the wood is mostly charcoal. At that time I can reload or, like today, just let it burn out because it is warm enough.

 

[mhrischuk]

I did my first top down fire startup last night. It really worked great at heating up the secondary tubes and baffle right away and reduced smoke substantially.

Place your big splits in, build your kindling fire on top. This way the first flames begin to heat up the secondaries right away. If you need to, crack the door open for a few minutes to get the draft going. Make sure your damper is wide open at startup.

If you start it conventionally with the kindling on the bottom, it tends to get really smoky as it begins to smolder the big splits. Heat can't get up to the secondaries to burn off that smoke/fuel.

If you can afford it, pick up a hand held IR gun for about $60-$80. Point and shoot. Direct temp readings anywhere you can hit it with the laser target.

How the stove works....

https://www.hearth.com/talk/threads/80208/