How To Start A Fire In A Log Burner: (And Keep Your Chimney Safe)

A well-lit log burner heats your home efficiently, burns cleanly, and keeps your chimney in good condition. A poorly lit one smokes out your living room, leaves a sooty mess on the glass, and sends more pollutants up your flue than it needs to. The difference usually comes down to technique, fuel choice, and airflow — all things you can get right every single time once you understand how they work together.

At The Sweeping Company, we see the results of good and bad burning habits in every chimney we sweep. A stove that’s been lit correctly and fed the right fuel leaves a clean flue with light, powdery soot. A stove that’s been smouldering on damp logs or shut down too early leaves a flue coated in tar and creosote. This guide will take you through exactly how to light your log burner properly, how to keep it going once it’s lit, which vents to use and when, and which firewood to avoid altogether.

How do you light a fire in a log burner?

There are two established ways to light a log burner: the traditional method and the top-down (or upside-down) method. Both work well. The top-down method is now the one most manufacturers and HETAS recommend, as it gets your flue up to temperature faster and produces less smoke while you’re lighting up.

To light using the top-down method:

1. Lay two small logs across the base of the firebox, spaced a little apart.
2. Stack kindling in a criss-cross pattern across the logs, leaving small gaps for air to move through.
3. Tuck one or two firelighters into the gaps between the kindling.
4. Open your air controls fully.
5. Light the firelighters and close the door.
6. Leave it alone. Resist the urge to keep opening the door to check on it — every time you do, you let heat escape and slow the whole process down.
7. Once the kindling has burned through and the logs beneath are glowing and charred, add your first proper logs.

To light using the traditional method:

1. Loosely scrunch two sheets of newspaper (or use firelighters) and place them in the firebox.
2. Build kindling over the top in a rough pyramid shape, allowing air to circulate.
3. Open the air controls fully and light the paper or firelighters.
4. Once the kindling catches and burns steadily, add small logs, then build up to larger ones as the fire strengthens.

Whichever method you choose, always use dry, seasoned kindling and firelighters designed for stoves rather than household accelerants. Never use firelighter fluid, petrol, or barbecue lighter fuel in a log burner — the flare-up this causes is dangerous and can damage the glass and seals.

What vents should be open on a wood burner?

Most log burners have two air controls: a primary vent and a secondary vent. Understanding what each one does makes lighting and running your stove far easier.

The primary vent feeds air in from below the fire bed, driving combustion during the lighting stage and giving your fire the oxygen it needs to get going. The secondary vent, sometimes called an airwash, feeds air in above the fire and along the glass. This is what keeps your glass clean and helps burn off the smoke and gases produced once the fire is established.

When you’re lighting your stove, open both vents fully to get plenty of oxygen into the firebox. Once your fire is well established and you’ve added your first proper logs, you can start closing the primary vent down gradually. Most stoves run best with the primary vent mostly or fully closed and the secondary vent doing the ongoing work, since this gives you a slower, more controlled burn and a cleaner glass. Check your manufacturer’s handbook, as exact vent positions and labelling vary between stove models.

How to keep a log burner going

Getting your fire lit is only half the job. Keeping it burning well through the evening takes a bit of ongoing attention, though nowhere near as much as most people expect.

Once your fire is established, add logs before it burns right down to embers rather than waiting until it’s nearly out. Adding fuel to a hot bed of embers reignites quickly and cleanly. Adding it to a cold or dying fire causes smoke and a longer, smokier catch. Two or three medium logs at a time work better than one large one, as they allow air to circulate around the wood.

Adjust your secondary vent rather than constantly opening the door. A log burner that’s running too fast will burn through fuel quickly and waste heat up the flue; one that’s choked down too far will smoulder, produce excess smoke, and coat your glass and flue with soot and tar. You’re aiming for a steady, visible flame rather than a roaring blaze or a dull glow.

Don’t overload the firebox. Manufacturers specify a maximum log size and quantity for a reason — packing in too much wood restricts airflow and causes incomplete combustion, which is exactly the sort of burning that leads to a heavy build-up of creosote in your flue.

Can you leave a log burner on and go out?

No. A lit log burner should never be left unattended, whether that means popping out to the shops or going to bed for the night. Even with the door closed and the vents shut down, a stove can develop unpredictable draughts, sparks can escape if the door seal isn’t perfect, and a build-up of unburned gases can ignite unexpectedly.

If you need to leave the room or the house, let the fire burn down and close the vents to reduce it to embers before you go, or extinguish it properly. The same applies overnight — most manufacturers advise against trying to keep a stove running unattended while you sleep, even on a low setting. If you want warmth into the evening, feed the fire generously before bed and let it burn down naturally rather than trying to bank it up and leave it.

What’s the worst firewood to burn?

The fuel you burn has a direct effect on how well your stove performs and how much maintenance your chimney needs. Some types of wood and other materials should never go anywhere near your log burner.

• Unseasoned or wet wood: Freshly cut or improperly dried wood contains high moisture content, which means more energy goes into evaporating water than producing heat. This causes smouldering, heavy smoke, and rapid creosote build-up in your flue. Always burn wood with a moisture content of 20% or below, and look for the Ready to Burn certification when buying.
• Treated, painted, or varnished wood: Old furniture, fence panels, pallets, and skirting boards often contain chemicals, glues, and coatings that release toxic fumes when burned and leave harmful residue in your flue.
• Driftwood: It looks appealing to burn, but the salt content corrodes your stove and flue liner over time and produces toxic fumes.
• Chipboard, MDF, and plywood: These are bonded with resins and glues that release harmful chemicals and produce a dense, sooty smoke.
• Conifers and heavily resinous softwoods in excess: Woods like pine and spruce burn hot and fast but leave behind more soot and resin deposits than hardwoods such as oak, ash, or beech. They’re fine in moderation for kindling but shouldn’t form the bulk of your fuel.

Sticking to well-seasoned hardwood or properly kiln-dried logs makes a genuine difference to how clean your stove burns and how quickly your flue accumulates deposits.

Why regular chimney sweeping matters for your log burner

Even with perfect technique and the best fuel, burning wood produces soot and creosote inside your flue. Over time, this builds up, restricts airflow, and increases the risk of a chimney fire. A well-lit fire with clean secondary combustion still deposits far less than a smouldering one, but no wood-burning stove runs without some build-up.

HETAS and most stove manufacturers recommend sweeping a wood-burning stove flue at least once a year if you burn dry, seasoned wood, and more frequently if you burn softwoods regularly or notice your fire struggling to draw. A clean flue means better draught, easier lighting, more efficient burning, and a significantly lower fire risk.

At The Sweeping Company, we sweep and service log burners across Somerset, Bristol, and the South West, and we’re always happy to talk through your setup, your fuel, and how your stove is drawing if something doesn’t feel quite right. If your fire’s been harder to light lately, your glass is blackening faster than it used to, or it’s simply been a year since your last sweep, get in touch with our team. A clean, well-maintained flue is what keeps every fire you light this way burning safely and efficiently.