Top-down lighting reverses the loading order: logs at the bottom, kindling crossed above, the firelighter right at the top in the middle, primary air fully open at the start. The flame front travels down instead of up, so the gases released by the wood below pass through an already hot flame instead of leaving cold up the flue. That is what cuts visible smoke at start-up and the deposit on the glass. The technique will not, however, rescue wet wood or an appliance below the thresholds: the French CEE measure BAR-TH-112, in its vA46-3 version, asks for a seasonal energy efficiency of at least 66 % on logs and 80 % on pellets, with particulate emissions under 40 then 20 mg/Nm³.
Why top-down lighting changes wood combustion
Understanding the principle: the fire burns downward, the smoke burns better
With top-down lighting, you stack the large logs at the bottom, then kindling and firelighters on top. The flame starts at the top and the combustion zone gradually moves downward. The result: the unburnt gases produced by the wood pass through an already hot flame and ignite more easily.
Less visible smoke, less odor: what actually happens
With a classic start, the firebox is cold and tar-rich smoke goes up the flue before it has enough heat to burn. With top-down lighting, the temperature rises more cleanly, which reduces fine particles and limits odors around the stove or fireplace.
What you gain day to day: cleaner glass, steadier draft
You get a more even fire, with less soot depositing on the glass. The draft stabilizes faster, because the flue heats up smoothly. The payoff: cleaner glass and often easier reloading.
The top-down lighting technique, step by step (get it right)
Preparing the wood: logs, kindling, firelighters (amounts and placement)
Aim for dry wood. Plan on 2 or 3 medium logs, 8 to 12 pieces of kindling, then 1 or 2 firelighters. Place the logs at the bottom, slightly spaced apart. The kindling goes on top. The firelighter goes right at the top, in the centre.
Building the "stack" correctly: layer order and log direction
Build crossed layers to let air through. Layer 1, logs all facing the same way. Layer 2, kindling perpendicular. Layer 3, very small, finer wood, still crossed. The fire starts at the top, heats and dries what's below, then burns down cleanly.
Setting the air intake at startup: the right moves for each appliance
At the start, put the air fully open. On a stove or insert, open the primary air and the secondary air if there is one. On an open fireplace, open the damper and avoid smothering the fire. Once the flames are well established and the first layer of logs catches, gradually reduce the air to keep a lively flame without smoke.
Choosing the right wood for a clean fire in 2026
Dry wood: how to check it on site (moisture level, storage)
On site, a moisture meter is ideal. Aim for 20% maximum. Measure on a freshly split face, not on the bark. For storage, wood should be split, set on pallets, under a ventilated shelter, protected from rain but open on the sides. Wood that sounds hollow, splits easily and shows cracks is usually ready.
Species and sizes: what burns best depending on your use
To hold heat, favour hard hardwoods (oak, beech, hornbeam, ash). For lighting and reviving the fire, well-dried kindling and softwoods do the job. In terms of size, 25 to 33 cm covers most stoves and inserts. Mixing logs and split pieces helps keep a lively fire and limits smoke.
Avoiding common mistakes: treated wood, too large, too damp
Rule out any treated or painted wood, as well as panels, plywood and marked pallets. Also avoid logs that are too large, which smother the flame and cause buildup. If the wood beads moisture, smokes white for a long time and blackens the glass quickly, it's still damp. Better to burn less, but dry.
| Criterion of measure BAR-TH-112 vA46-3 | Log appliance | Pellet appliance |
|---|---|---|
| Seasonal energy efficiency, Etas | ≥ 66 % | ≥ 80 % |
| Particulate emissions | ≤ 40 mg/Nm³ | ≤ 20 mg/Nm³ |
| Gaseous organic compounds | ≤ 120 mgC/Nm³ | ≤ 60 mgC/Nm³ |
| Carbon monoxide | ≤ 1 500 mg/Nm³, that is 0.12 % | ≤ 300 mg/Nm³, that is 0.02 % |
| Oxides of nitrogen | ≤ 200 mg/Nm³ | ≤ 200 mg/Nm³ |
| Test standard | EN 13240, EN 14785, EN 15250 for stoves, EN 13229 for closed appliances and inserts, EN 12815 for cookers | same standards by appliance type |
| Accepted equivalence | the Flamme verte label is deemed to meet the pollutant emission conditions only, never the Etas | same |
Concentrations are expressed in mg/Nm³ at 13 % O₂, and the performance has to be backed by tests from a laboratory independent of the manufacturers, accredited to ISO/IEC 17025. The conventional service life retained by the measure is 15 years, and its scope is limited to existing single-family houses. Those are the lines an inspection looks at, not the quality of your fire.
Adapting lighting to the equipment: insert, stove, open fireplace
Stove and insert: optimizing primary and secondary air from the start
In a stove or insert, fully open the primary air intake at the start. Place dry kindling on top (top-down lighting) to heat the flue quickly. Once the flame is stable, reduce the primary air and keep the secondary air slightly open for cleaner combustion.
Open fireplace: limiting smoke and securing the draft
In an open fireplace, draft is the priority. Open the damper, avoid overloading, and use well-dried wood. Start with a small load and place the fire toward the back. If the room is very airtight, crack a window open for a few minutes to help draw air in.
When the fire "won't catch": quick diagnosis and fixes
If it's smoking or going out, look for the cause before adding more fuel. A simple fix often avoids buildup.
- Damp or oversized wood. Start again with kindling.
- Closed air intake. Open it, then close it gradually.
- Cold flue. Light a short, small fire first to get the draft going.
Cutting smoke further: good practices around the technique
Clean reloading: keeping embers and avoiding smothering
Before reloading, keep a bed of embers. Fully open the air intakes for 1 to 2 minutes, then add 2 to 3 logs of dry wood, preferably thin ones. Close the door gently. Avoid packing or overloading. Smothering is what causes smoke.
Maintenance and safety: sweeping, flues, air intake
A clean appliance smokes less. Have the flue swept at least once a year, often twice depending on local rules and your insurance. Check the door seals, the condition of the flue and the cowl. If in doubt about compliance, particularly regarding chimney flue lining, check it before the heating season. Keep the air intake fully clear. A carbon monoxide detector is a real plus. On a new installation, Argile guides the technician through use, position and flue outlet, and checks the flue termination rules.
Useful signs: what clean combustion looks like and when to adjust
When all is well, the flames are lively, the glass stays fairly clear and the ash is light grey. If the smoke stays black, the smell is acrid, or the glass blackens quickly, adjust. Increase the air, reduce the load, and go back to drier wood.
