How to stop a log burner from smoking
If your log burner has begun producing excessive smoke, the best practice is to address the issue immediately. The gases entering your home are composed of pollutants and particulate matter, which can irritate the body in large amounts.
To solve the issue, you must identify the cause. Smoke could be entering your room for many reasons, some of which are quick to fix and others which may require professional help.
Creosote build-up
Creosote is a dark, sticky substance that forms when organic matter is burnt.
As a product of combustion, it accumulates inside the chimney or flue as a by-product of burning wood. When smoke rises through a cooler chimney, the gases condense and leave behind this tar-like residue.
Why is removing creosote important?
Creosote becomes difficult to remove, particularly if it’s left to harden over time.
If an accumulation of creosote builds up inside the chimney, it can be a major fire hazard. It can also restrict airflow to this fire, which makes it difficult for the wood burner to draw air correctly and causes smoke to spill back into the room.
Homeowners can prevent this build-up by keeping the vents of their log burners open.
Allowing a steady flow of oxygen will help the wood burn more completely. You should also contact professional chimney cleaning services to prevent creosote from accumulating to dangerous levels.
Unsuitable wood
The fuel you burn in your log burner can also affect smoke levels.
Chemically treated wood often contains paint, varnish, or other additives that release toxic fumes when burned. These chemicals harm indoor air quality and produce a thick residue that causes excessive smoke.
What is burnt or ‘wet’ wood?
Freshly cut wood, often referred to as “green wood,” has a high moisture content. When burnt, fresh wood leads to incomplete combustion. It releases steam and can cause creosote to build up more rapidly in the chimney.
What is ‘ready to burn’ wood?
To avoid these problems, it’s best to burn seasoned or kiln-dried wood. Ready-to-burn firewood has been dried to a moisture content of 20% or less. These logs create a cleaner burn that releases less smoke — a win-win!
In the UK, the "Ready to Burn" certification mark helps homeowners identify wood that meets the recommended moisture level. Homeowners should shop for firewood with this certification to minimise the risk of excessive smoke.
Chimney issues (blockage, height, negative pressures)
The chimney’s primary function is to direct smoke away from the stove and out of the house. It creates a draft, which then draws in oxygen necessary for combustion. Blockages, issues with the chimney’s height or low air pressure can contribute to
How can chimney height cause excessive smoke?
The height of the chimney affects the upward movement of air that carries smoke out of the stove and through the flue. A chimney that is too short may not generate enough draft, causing smoke to enter the home.
On the other hand, a very tall chimney can create problems if it is not well insulated. The combustion gases may cool too quickly and reduce the draft’s efficiency.
How can chimney blockages cause excessive smoke?
Blockages are a worrying barrier to airflow. These blockages can occur due to various reasons, such as:
- Creosote build-up: Creosote can narrow the chimney’s passage and restrict airflow.
- Debris: Leaves, twigs, and even animal nests can obstruct the flue, especially if the chimney is not covered with a cap or guard.
- Soot: If you have been burning unsuitable wood, such as wet or treated wood, excess soot can build up in the chimney, creating blockages.
How can negative pressure cause excessive smoke?
Negative pressure occurs when the air pressure inside the house is lower than the outside, which forces smoke back down the chimney and into the room. Negative pressure is often caused by:
- Mechanical ventilation: Extractor fans in kitchens and bathrooms can pull air out of the house.
- Tightly sealed homes: Modern homes are designed to be airtight for energy efficiency. While this is great for insulation, it can prevent the log burner from drawing enough air.
Determining if any of these structural issues are causing your log burner to smoke excessively will require help from a professional. To find out more, homeowners can book an appointment with a local HETAS-approved chimney sweep.
Large single door
If your log burner’s interior is only accessible via one large door, this design feature may be another contributing factor to smoke levels.
When using one of these log burners, it’s vital to open it slowly. A sudden rush of air into the stove can push smoke back into the room. Instead, crack the door open slightly to allow the pressure to equalise gradually.
Before opening the door, you can also try opening the air vents to allow more oxygen into the fire. Doing this increases the temperature inside the stove, and by warming the chimney, you encourage better airflow!
Cold/windy weather
Two unavoidable causes of excessive smoking, cold weather and windy conditions, can also disrupt a log burner’s operational efficiency.
During cold weather, the air inside the chimney can become cool. Lower temperatures make it harder for the smoke to rise and exit efficiently. These conditions also create resistance and slow down the draft, which usually pulls smoke upwards.
Equally troublesome is windy weather. Strong gusts can push air down the chimney, a phenomenon known as "down-draught." When this occurs, the smoke that should be venting outside is forced back into the stove and, eventually, into your room.
Consider installing a chimney cap or cowl to prevent downdraught. Designed to stabilise airflow, an anti-downdraught cowl can help keep the wind from forcing its way into the chimney.
Shop for wood-burning stoves with Fires2U!
Learning about your stove’s operating practices takes time. By reading the manufacturer's instructions and using the fire itself, homeowners can eliminate the cause of excessive smoke.
At Fires2U, we’re here to supply everyone with safe, energy-efficient heating appliances this winter. Why not discover our vast range of wood-burning stoves from brands like Portway Stoves, Stovax Stoves and many more?
