Where there’s no smoke, there’s fire: Time to turn your woodburning upside down?

Courtesy of John Gulland

Less than 10 minutes after lighting, this woodstove fire built in top-down style is fully ablaze and sending no smoke up the chimney.

Rising annoyance over backyard fire pits in Minneapolis and other cities is bringing renewed attention to wood smoke’s contributions to air pollution, especially in urban areas.

To the extent this helps people become more conscientious in how they use their fireplaces and wood stoves, it’s a good thing. But go looking for guidance on minimizing your smoke pollution and you’ll find a curious imbalance — lots about choosing equipment and fuels, little about how to use them.

For example, the Minnesota Pollution Control Agency offers plentiful suggestions about upgrading inefficient or dirty old equipment, selecting proper firewood, what not to burn, and so on. So does the U.S. Environmental Protection Agency.

But on technique, the official guidance pretty much starts and ends with recommendations to “Avoid smoky fires” or “Build small, hot fires.”

Well, yes. But how?

Perfect equipment, miserable results
It is quite possible – trust me, because I’ve done it – to put perfect firewood into a state-of-the-art stove, complete with catalytic converter and precision airflow controls, and still produce a steaming, smoldering mess that stinks up the neighborhood.

It is also possible, I have since learned, to arrange less-than-perfect wood in ordinary equipment — or even outdoors — and create a fire so fast and hot it produces almost no smoke and consumes everything save the finest, powdery mineral ash. Because smoke is essentially unburnt fuel, learning how to do this not only reduces pollution but raises efficiency.

Plenty of online woodburner communities promote best practices through shared expertise. Of these, woodheat.org has become my hands-down personal favorite.

That’s where I learned about the “top-down fire,” a relatively new approach that not only minimizes smoke pollution and maximizes fuel efficiency, but also eliminates nearly all the fuss of poking and restoking to keep the fire hot and high.

After some 50 years of building fires, it seems, I’d been building them upside down. Maybe you are, too.

Traditionally poor technique
Like a lot of guys, I learned to build a fire from my father. Unlike a lot of guys, he learned his technique from a moving-van driver.

Dad had grown up stoking coal furnaces at boyhood homes in West Virginia, but didn’t have a wood-burning fireplace until the winter of 1963, when we moved into a house in Indiana. Then he had two, but not a clue how to use them.

After the crew finished unloading our stuff, the driver found a few sticks of firewood somewhere, arranged them in a log-cabin stack around some twists of packing paper, opened the damper, lit a match — and turned an evening of unpacking into firelit magic.

Back then, people burned pretty much anything in their fireplaces – cardboard, glossy magazines, handfuls of chemical flakes that made brilliant colors as they sent nasty fumes streaming up the chimney.

My thrift-minded mother bought a contraption that rolled newspaper sections into “logs,” which burned poorly and sent a certain trash-fire ambience wafting through the rooms. If they burned especially poorly, she might splash a little kerosene to help.

Almost everything about those fires would run afoul of today’s guidance to homeowners — everything, that is, except the shape of the fires we build. Here we remain staunch traditionalists.

Typical fires, indoors or out, are still built from the bottom up, starting with twists of paper, firelighter sticks or other material that can be lighted with a match. Small sticks or finely split kindling is laid on top of the starter, larger sticks on top of that, and so on up to the biggest pieces on top. (Here I must acknowledge that I recommended essentially this approach in the first Earth Journal, last September. Live and learn.)

Unless they are built perfectly, such fires tend to struggle along through relightings, the piling on of more paper or kindling, and so forth.

But even if everything goes right, a fire built this way inevitably creates start-up smoke as wood above the initial flames is heated to the combustion point and then begins to burn, slowly, releasing the gases, tar droplets and water vapor that form a smoky plume which streams up the flue and out the chimney. This continues until the fire reaches the stage of high, bright flames that consume virtually all of the smoke components before they can escape.

Lots of things can go wrong, of course, and many fires never reach that happy stage. Wood that has been seasoned insufficiently, or dampened by snow and rain, may keep smoking until it’s charcoal. Even good wood can be arranged so a fire never reaches full potential and, worse, requires constant rearranging as partly burned pieces collapse or roll away. Opening the stove or fireplace doors to lay more wood on a high, hot fire of half-burned logs is an unpleasant chore and usually renews smoke production.

All of these problems can be reduced with skillful practice, but they can’t really be eliminated as long as the fire starts below the fuel.

Enter the top-down method
A much-bandied quote from John James Audubon’s journals may document the use of a top-down fire by woodsmen in Kentucky in 1810, and an article in a 1992 newsletter of the Masonry Heater Association suggests the method was used “in the old days” in Austria. But John Gulland, writer/editor of woodheat.org’s policy section, The Woodpile, traces its adoption by American enthusiasts to the early 1990s.

The basic method goes like this:

• The largest pieces of wood go on the bottom, laid in parallel and close together
• Smaller pieces are placed in a second layer, also with close spacing, crossways to the first
• A third layer of still smaller pieces is laid crossways to the second, this time with some spaces between
• A fourth layer of loose, small kindling and twisted newspaper sheets tops off the pile

John has an amazing photo sequence which illustrates what happens next:

• A single newspaper twist is lighted, instantly creating a hot fire at the top of the pile
• The rest of the newspaper and fine kindling quickly ignite, turning the whole top layer into a hot, smokeless fire
• As the fire spreads downward, each successive layer sends its gases streaming upward through flames that consume them before they can reach the flue
• Within 10 minutes, the fire is completely ablaze – and the firetending chores are done for at least a couple of hours
• When it’s time to refuel, fresh wood can be laid on a wide, even bed of glowing coals, hot enough to make it burst almost instantly into a new, smokeless fire

How much cleaner?
Although EPA uses extensive laboratory testing in the process of certifying various types of woodburning equipment, I find no evidence that anyone has evaluated woodburning techniques with similar rigor. (The Masonry Heating Association newsletter cites without detail a finding that a top-down fire in one appliance cut measured carbon monoxide emissions in half.)

John Gulland told me he has seen no such studies, either, and I tend to think that if anybody would have a line on such research it would be him.

However, he has other empirical evidence, registered repeatedly by his own eyes and nose — big, blazing fires indoors, no visible smoke and little if any odor outside — and he finds this more than persuasive.

So do I.