If your wood burning stove is smoking more than usual then there may be an issue with the wood, the operation of the stove or even a problem with the stove itself.
As many different elements of having a fire in a wood stove need to come together for a successful fire, there can be a number of reasons why a wood stove would be smoking.
So why does a wood stove smoke?
The main reasons why a wood burning stove is smoking can be:
- The wood is too wet.
- The stove or wood is too cold.
- The draft is poor.
- The fire didn’t get going well.
- The air vents aren’t open enough, or were closed down too soon after lighting the fire.
- The stove door was closed too soon after lighting the fire.
- The fire is too small.
- The room is too airtight.
- The damper is closed.
- The chimney is blocked.
When a fire in a wood stove burns the wood inefficiently, there is a higher chance for the fire to be smoking as a result. The main reasons why your wood stove smokes can therefore be typically narrowed down to the main components of a fire in a stove that affect either the wood or the air supply.
We’ve had issues with our wood burning stove and multi fuel stove smoking over the years and so I’ve explained the main reasons why wood stoves smoke in more detail below.
Why Does My Wood Stove Smoke?
The Wood Is Too Wet
One of the most common reasons why a wood stove smokes is due to burning wood that is too wet.
Wood needs to be dry enough to burn efficiently in a fire. Wood that is freshly cut is high in moisture content, which is why wood needs to be dried out (known as seasoning) over a period of time before it’s dry enough to be used on a fire without causing issues.
One of the main problems with burning wet wood in a stove is that it can cause more smoke to be produced than usual. For the fire to burn the wood efficiently to produce heat, the fire needs to first burn off any excess moisture within the wood. The higher the moisture content of the wood, the harder it will be to burn.
When the wood is being burnt inefficiently, such as when the wood is too wet, more smoke can be produced as a result.
Small amounts of smoke can be part of the normal operation of a wood burning stove. If you’re seeing unusual amounts of smoke being produced, check to see whether you’re using wood that has been ‘well-seasoned’ or ‘kiln dried’, as these terms typically denote wood that has been dried long enough to be used as firewood.
You can also season your own wood, and I’ve explained how we do it here.
Moistures meters will be able to give you an accurate reading of the moisture content of your wood. Look for a moisture content readings of around 20% or less. The lower the moisture content of the wood, the better it will burn and the less likely it is to produce smoke.
Compared to wet wood, wood that is dry enough to burn:
- Is darker at the ends.
- Has less visible green colors.
- Is lighter in weight.
- Can be splitting at the ends.
- Makes a hollow sound when hit together.
- Has bark that can be easier to peel off.
The Stove Or Wood Is Too Cold
A stove that is too cold, or wood that is too cold, can cause a fire in a wood stove to smoke.
It takes longer for a fire to bring cold wood up to combustible temperature compared to wood that is at room temperature. During this time the wood can be burning inefficiently, and the fire can smoke as a result.
We bring in our wood from storage outside at least a day before using it on a fire in our stoves. We have a storage box near the stove that we like to keep the wood in, and by bringing it in from the cold outside the wood has time to warm up to room temperature.
Ensuring that wood is at near to room temperature before being added to the stove helps it to burn more efficiently and produce less smoke as a result.
A cold wood stove can also cause a fire to smoke. Cold air trapped within the stove can push down on the fire and cause any smoke being produced to leak out into the room.
If smoke and waste gases can’t leave your stove effectively then less fresh air can get to the fire. A fire that smolders due to a lack of oxygen can start to smoke because it can’t burn the wood very well.
We therefore typically leave the door on our wood stove open for a while before starting a fire. With the door closed, the stove is shut off from the air in your home and can be colder as a result.
Leaving the door open helps to bring the stove up to room temperature before being used, and can help prevent your fire from smoking.
The Draft Is Poor
If there is insufficient draw on your stove from the flue, then this can prevent waste gases and smoke from being pulled up the flue and out of your home.
The draft helps to circulate air into the stove from your home and out through the flue. Cold air trapped within the flue can prevent sufficient draw on your stove to start a fire, and so you can use a heat source before having a fire to help warm up the flue and start the draft.
To help warm up our own wood stove before starting a fire we like to place a lit piece of rolled up newspaper under the flue outlet inside the stove.
The heat from the flames provides rising warm air that helps to displace any cold air trapped within the flue. If you can see smoke from the newspaper rising up into the flue then you’re in good position to be able to light a fire in your stove.
The Fire Wasn’t Started Correctly
At the start of any fire in a wood stove we want to bring the stove up to operating temperature as quickly as possible.
If the fire struggles to get going after being lit then more smoke can be produced.
To help a fire to get going, we lay a bed of crunched up newspaper at the bed of our stove (a bed of ash an inch or two deep can also help improve the efficiency of your fires.)
Small bits of kindling can then be added on top of the newspaper in a crisscross pattern to help the air to circulate between the wood. Be sure to use dry pieces of wood, and softwood is more useful at this stage of the fire compared to hardwood because it catches alight and burns more quickly.
Before lighting any fires, ensure to open the air vents on the stove all the way.
By lighting the newspaper at a couple of locations across the stove, the fire can spread evenly to the wood. By leaving the stove door open, the fire should catch hold of the wood quickly and start to rapidly burn through the initial bits of kindling.
If you aren’t supplying enough air to the stove at this stage of the fire, or using wood that isn’t dry enough, then the fire will struggle to get going and can start to produce smoke as it’s trying to burn through the wood.
The Air Vents Aren’t Open Enough
If the fire doesn’t receive enough oxygen to burn through the supply of wood in your stove, then it can start to smoke due to inefficient combustion.
A lack of oxygen can be a result of air vents on the stove that are closed or not open enough.
All air vents on your wood stove should be fully open before lighting a fire and remain fully open while the fire catches hold of the wood.
As the fire burns through the initial bits of wood to form a bed of hot coals, progressively larger sized logs can be added to the fire to produce more heat. To improve the efficiency of the fire, the air vents should be closed down until the fire is calmly burning through the wood, without causing it to smolder and produce smoke.
It’s generally inefficient to leave the air vents on your wood stove wide open throughout a fire because it can rapidly burn through the wood, and you’ll need to add more logs to the fire more often.
If the air vents are closed down by too much, then a lack of oxygen can cause the fire to smoke due to incomplete burning of the wood. Be sure to not close down the air vents too soon after lighting a fire to help prevent the fire from smoking.
To help prevent the wood stove from smoking, open up the air vents in stages until you can see the flames gently burning through the wood and not producing any more smoke.
Our wood stove only has one controllable air vent, which is located underneath the stove and controlled by a handle that sticks out the front. If the fire is struggling and smoking as a result, to increase the airflow to the fire we simply need to pull the handle towards us to open up the vent.
Many other wood stoves can have two controllable vents. Wood burns better with a source of air from above the fire and so you’ll want to open up the secondary air vent (typically located near the top of the stove) to increase the airflow to the fire from above.
On multi fuel stoves, open up the secondary air vent to control the help stop the fire from smoking as it serves oxygen to the fire from above. The primary vent serves air to below the fire in a multi fuel stove, and so this vent won’t make as much of an impact to a wood fire as the secondary vent.
The Stove Door Was Closed Too Soon
Much like how closing down the air vents on a wood stove too soon after the fire has been lit, closing the door on the stove too soon can also cause the fire to smoke.
On our wood stove we’re able to close the door quite soon after lighting a fire because enough air can get to the fire through the air vents. If there is insufficient air getting to the fire through just the vents, the fire can start to smoke due to lack of oxygen.
If you’re finding that your wood stove is smoking when closing the stove door, leave the door open for a while longer to help get the fire going as it burns through the first bits of wood.
It’s recommended not to leave the door to your stove open for the duration of the fire, and you can find out why in another article here.
The Fire Is Too Small
To maximize the efficiency of your wood stove and to prevent the fire smoke producing smoke, you’ll need to built and maintain fires that aren’t too small for your particular model of stove.
If you’re underutilizing your stove by having small fires then the stove will struggle to get up to operational temperature, where a cleaner burn of the wood will be provided and less smoke will be produced.
To help reduce the chance that your wood stove smokes, be sure have fires that are sized in line with the size of your stove.
Our stove thermometer shows the different operating temperatures of a stove.
At the lower temperatures, creosote can be produced because the wood is being burnt inefficiently and can be producing smoke as a result of poor combustion. Small fires can contribute to lower stove temperatures.
You’ll want your stove to be within the middle temperature range, labeled as ‘best operation’, where the fire is producing the most amount of heat from every piece of wood.
If your stove is burning ‘too hot’ then the stove is producing more heat but the fire is burning through the wood too quickly and inefficiently.
Be sure to also not build fires that are too big for your stove, as this can cause ‘over firing’. You can read more about over firing on wood stoves and how you can prevent it here.
The Room Is Too Airtight
If your room or home is too airtight, then the fire can struggle and produce smoke due to a lack of fresh air.
Hot air that leaves the stove via the flue needs to be replaced fresh air from the room. Air within the room can be replaced either with air from other areas of the house, or from the outside through a vent in the wall.
Wood burning stoves will typically require a vent to be installed during installation if the house is deemed to be too airtight.
Because our house is newer and therefore more airtight, we have a vent in our living room where our wood stove is located to ensure that there’s always a fresh supply of air for the fire.
If your wood stove is smoking, try to increase the air supply to the fire by:
- Opening any doors to the room.
- Opening any vents in the room.
- Cracking open a window slightly.
The Damper Is Closed
If your wood stove has a damper (typically located in the stovepipe above the stove) then it must not be fully closed during a fire or it can cause the fire to smoke due to a lack of oxygen.
A wide open damper can allow much of the warmth generated by the fire in a stove to be lost up the flue. A damper can be used to throttle back how quickly warm air and waste gases leave the stove in order to produce more heat through processes such as secondary combustion.
A damper that is closed during a fire can act as a barrier, preventing smoke from leaving the stove. This in turn can prevent fresh oxygen from getting to the fire and causing the fire to smoke due to incomplete combustion of the wood.
To help prevent your stove from smoking, ensure not to fully close the damper during a fire.
The Chimney Is Blocked
A flue that is dirty of blocked can also restrict the flow of air up the flue, and in turn cause the fire to smoke.
It’s recommended that chimneys and flues are cleaned at least once per year, and more often if you’re burning wood regularly in your home.
Burning wood can release creosote, which is a substance that can line the inside of your flue and reduce its effectiveness of providing a draft on the stove. Creosote can be produced in higher quantities when the wood isn’t being properly combusted and the fire is releasing smoke.
If your wood stove is smoking, have your flue or chimney swept if it hasn’t been so within the last year.
How To Use A Wood Burning Stove
How A Wood Burning Stove Works
Parts Of A Wood Burning Stove Explained
Why Smoke Comes Out Of Your Wood Burning Stove When Opening The Door
How To Efficiently Use A Wood Stove
How To Clean Glass On A Wood Stove And Keep It Clean
Why Your Wood Stove Isn’t Getting Hot