Wednesday, February 10, 2016

Where There's Smoke... (Firing Up, part 1 of 3)

Wood Heating Tip #1:

Smoke is fuel.

More specifically, it's nasty, toxic, partially-burned and unburned stuff that could have been used as fuel: flammable gases and tars, creosote and kerosene, soot particles, and some invisible combustion by-products like carbon monoxide, carbon dioxide, and steam.

If your chimney is putting out smoke, you are wasting fuel. And you are setting yourself up for messy, expensive, and unhealthy problems like creosote-accumulation and chimney fires.

What's the point in processing and storing and burning all that wood, if you're sending most of the juice out the chimney?

Whether you have a rocket mass heater or an old cast-iron stove, I invite you to go outside while it's burning, look up at the chimney, and check for smoke.

Smoke:  Wet wood plus a handful of damp leaves
makes a distinctly dirty, grey smoke. 
Even after the steam clears up,
a greyish residue that lingers in the air.
Smoke is grey, blue, or even yellow; it lingers in the air. Not the same as plain water vapor - that would look like a cloud that comes out clear, turns white, then disappears again. (Yes, wood burning makes water: hydrogen in the fuels, plus oxygen, makes H2O. Even bone-dry wood still produces more than half its own weight in water vapor.)
No smoke can look like this: nothing.
(The stove is running. 
Even on video, you can barely detect anything,
just heat waves around the rain cap.)

Clean exhaust can also look like this:
white fog that disappears as it rises. 
Note at the top of the foggy steam cloud,
where the puffs are evaporating,
there is no bluish haze or residue. 
The steam just disappears.

If you could safely get a whiff, there's also a distinct difference in the smell. Water vapor smells damp, and not very smoky... and it doesn't sting the eyes and nose. 

Can you tell smoke from steam?  Look at the pictures here, then go up to the top (with the cat) and see if you can decide whether that's smoke or steam.

If you see smoke, there are two things you can try right now to help the situation.

A) Air adjustment.
Getting the right mix of fuel and air will let the fire burn properly, maintain a good hot temperature, and get all the energy out of that smoke before releasing a cleaner exhaust. Go inside and confirm that your whole fuel load is burning nice and hot. (Don't refuel unless you really need to right now: new, cold fuel can temporarily increase the smoke output for any stove.) Fiddle with your air controls and/or damper, to get the flames nice and bright, then come back out and see if the smoke is gone. Adjust one thing at a time, until there is no smoke.

 B) More air, over a longer time:
Get your fuel as dry as possible, every time. 
  This means it's racked up with good ventilation in a dry storage shed for a year (or more) before you burn it. Surface drying logs in the house is not a good option; it takes too long, and you really don't want that much damp, buggy wood in your home. At least, I don't. Most people say to store fuel wood 30 feet from the house, in its own shed, to minimize the danger from fire or pests.

Signs your wood is not dry:
- It bubbles and boils water out the ends when you put it in the fire.
- It has not “checked,” or cracked; or the checks have swelled shut again. When wood is really dry, often a single crack will “win,” and looking at the butt of a log you'll be able to see exactly where you can strike to split the wood most easily.
- When you go to split damp wood, it screeches and twists and hangs together like a stringy piece of under-cooked meat. Good kindling is lively, as Ianto Evans puts it: it leaps off the stump when you get a solid whack with the hatchet, and small pieces bounce with a 'ting' like a snare drum stick.
- The person you are paying for “seasoned dry hardwood” does not have sheltered storage in his loading yard.
- The clerk at the camp store selling bundles of plastic-wrapped firewood from an unsheltered outdoor stack told you, “Sure it's dry, it hasn't rained in at least a week.”

Signs that your wood is fully dry:
- It weighs less - maybe half as much - compared to when you first cut and stacked it.
- It has been in good, dry storage, with good ventilation, for over a year
- It is easy to split, and small piece make a 'ping' sound when dropped
- If you like that sort of thing, you can check it with a moisture meter.

If you burn wet wood, it takes a lot of energy to boil away the water (meaning you may need twice the wood to actually heat the house). The water turns to steam, which expands enormously, displacing incoming air. This is why water is such a good fire extinguisher for small fires: it robs heat and oxygen at the same time. You do NOT want to be burning water; you are trying to burn wood.

If you're used to the old “airtight” stoves, I hear some people like to use green wood because “it lasts longer.” Storing heat in smoldering green wood is a super-dangerous option, which is why these stoves are no longer legal to sell or install in most places; they gunk up chimneys very quickly leading to spectacular chimney fires.

We can show you how to get all night heat with a lot less wood, and reduce the dangers of a night-time fire or chimney fire to almost zero. Please forget the airtight stove, and don't try to alter or ignore the operating instructions on a certified stove to make it act more “airtight.”

There are better ways. There is no reason you can't burn a good, clean fire even in an older stove, or with “crap” firewood like pine, willow, or cottonwood.

Next we'll show some tricks for preparing and laying a good fire, no matter what kind of stove or oven you have. ...

Do you have any questions you'd like us to answer, as we start building these basic fire tips?

Are you signed up for updates? This blog is getting more active, and we have more useful stuff coming down the pipe.

Drop a comment below, or send us an email at

Erica and Ernie Wisner

p.s.  Go to Part 2 for my answer to the Smoke or Steam challenge.

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