Problems & Repairs
Smoke rolling out of the stove door instead of up the flue is the single most common complaint we get called about, and it is almost never the stove itself. A stove is a simple box; what makes it work is the column of hot air in the chimney above it pulling combustion gases upward. When that pull — the draw — weakens or reverses, smoke takes the easiest route out, which is into your living room.
The useful thing about diagnosing spillage is that the causes fall into a predictable order. Work through them from the cheapest and most likely to the most involved, and you will usually find the culprit before you spend anything.
Start with the flue itself
A partially blocked flue is the first thing to rule out, because it is both the most common cause and the easiest to confirm. Soot builds gradually, so the loss of draw creeps up on you over a season and you adapt to it without noticing. Birds' nests, on the other hand, appear suddenly — a stove that drew perfectly in March and spills in September has usually acquired a nest over the summer.
A sweep with a camera can settle this in one visit. Our CCTV survey equipment shows the inside of the flue on screen, so you see the blockage rather than take our word for it.
- Soot and tar build-up narrowing the flue bore
- Birds' nests, particularly after a spring and summer unused
- Fallen render, mortar or brick debris sitting on a bend
- A cowl clogged with soot or nesting material
Then look at the air coming in
A flue can only pull out what the room lets in. Modern draught-proofing, replacement windows, sealed floors and extractor fans all reduce the air available to the fire. If your stove spills only when the kitchen extractor or a bathroom fan is running, you have found your answer — the fan is winning the competition for air.
Ventilation requirements are assessed as part of any installation survey we do, and they can be retro-fitted where a room has been sealed up since the stove went in.
Cold flue syndrome
An external chimney stack, or a flue that has stood unused for weeks, holds a plug of cold, dense air. Light the fire and the smoke meets that plug and stops. This is why spillage is often worst on the first lighting of the day or the first fire of the season, then settles once things warm through.
The fix is technique rather than repair: warm the flue first with a rolled newspaper taper or firelighter held up near the throat, and build the fire top-down so the heat rises early. If your flue is uninsulated and running up an outside wall, an insulated liner makes a permanent difference.
Fuel and operation
Wet wood is a draw killer. Water in the timber boils off instead of burning, cooling the flue gases and dropping the temperature that drives the draw — and it deposits the tar that narrows the flue for next time. Seasoned or kiln-dried wood below 20% moisture burns hot and clean.
Also check the obvious: air controls closed too early, an overloaded firebox, or opening the door in one quick movement rather than easing it ajar for a few seconds first.
Structural and terminal causes
If the flue is clear, the room is ventilated and the fuel is dry, the remaining causes are structural. A flue that is too short for the roof pitch, a stack overshadowed by a taller building or a mature tree, cracked parging letting the draw leak away, or an oversized flue for a small stove will all produce persistent spillage. These need a survey rather than a guess, because the remedy — lining, raising the stack, fitting an anti-downdraught cowl — depends on what is actually wrong.
Frequently asked questions
Is smoke coming into the room dangerous?
Visible smoke is a warning that combustion gases are not leaving properly, which means carbon monoxide may also be entering the room. Stop using the appliance, ventilate the room, and have the flue checked. A carbon monoxide alarm should be fitted in any room with a solid fuel appliance.
Will sweeping the chimney fix the smoking?
It fixes it when the cause is a blockage or soot build-up, which is the most common scenario. If the flue comes back clear, sweeping has still been worthwhile because it rules out the biggest variable and lets us look at ventilation, flue sizing and terminal height with evidence rather than assumption.
Why does it only smoke when it is windy?
That points to downdraught — wind striking a nearby roof, hill or tree and pushing air back down the stack. An anti-downdraught cowl fitted to the pot is the usual remedy, and it is a straightforward job on most chimneys.
My stove is new, so surely it cannot be the installation?
New stoves fitted to old, unlined chimneys are a common source of spillage, because a modern efficient stove produces cooler flue gases than the open fire the chimney was built for. An insulated liner sized to the appliance usually resolves it.
Get a smoking stove diagnosed properly
We can sweep, run a CCTV survey and check ventilation in one visit, so you get a cause rather than a guess.