You need heat, fuel, and oxygen to make and sustain fire. While open fireplaces get oxygen naturally and burn fast, stoves have vents that feed a firebox, creating an enclosed environment that extends the burn time.
You can find stove vents above and below the glass, with the bottom vent being the primary vent and the top vent secondary.
Controlling the vents lets you adjust the oxygen flow to the chamber and, in turn, how quickly the fuel burns and the stove temperature.
But precisely how do you control wood-burning stove vents? This guide explores everything you need to know to keep your fire roaring.
What Are Wood Stove Air Vents?
When your stove door is shut, all the air entering it comes from the vents.
Wood stove air vents are gaps in the stove casing that allow air to enter – but not escape – the firebox. Stoves need air to burn fuel and circulate gases, so they move up the flue and out of the chimney.
Every wood-burning stove has a top and bottom air vent that you control, and some have a tertiary (rear) air vent that is fixed. The idea is to control air flowing into the firebox to increase or reduce the fire ferocity and temperature.
You can starve your fire of oxygen by keeping the vents closed and equally overdo it by keeping the vents wide open all the time.
Under-fueling a stove with air produces smoldering fire at a low temperature while overdoing it burns through firewood too rapidly. Thus, controlling air vents is crucial to owning a small stove and getting the most out of it.
The good news is that you don’t have to man your stove all the time – but you do need to watch for signs that it needs oxygen or less of it.
Unlike central heating systems and generators, which magically work once you press a button, or the timer comes on, wood-burning stoves require care and attention for optimal running, but this is all part of their charm!
How to Use Wood-Burning Stove Vents Effectively
Firstly, you should familiarize yourself with how the vents on your stove work.
Your wood-burning stove will have a handle sticking out at the front or side to control the bottom and top vent - we recommend playing with the handles to see how much tilt opens, partially closes, and closes them for efficient control.
Additionally, the bottom and top vents serve different purposes. The bottom vent fuels the fire from the bottom, increasing how quickly and hot the fire burns, while the top vent has a more significant role in moving air around the firebox.
Every wood-burning stove has unique characteristics, but generally, you open both vents when lighting a fire and close them gradually once the fire is established.
Here’s how to use wood-burning stove vents:
This method aims to throttle down the top vent while keeping the bottom vent in action to keep air flowing without turbulence.
It is crucial to remember that the top vent circulates air within the firebox more so than the bottom vent, so if you have partially lit firewood or the fire is hotter on one side than the other, the top vent offers ultimate control.
The bottom vent keeps the fire raging and the embers hot – wood burns best with a bed of ash, and the bottom vent keeps air flowing through it.
Displacing the ash is usually required once the first logs have burned down to ash with only a few embers remaining. This will ensure that any new fuel you throw on the fire gets lots of air to feed combustion.
Lastly, air vents won’t save a fire without any embers – once the embers are gone, you must clear the stove bottom and start a new fire.
When to Have Wood Burner Vents Open or Closed
You should have both vents open when starting the fire and for ten minutes afterward, during which the flames will peak and die down as the firewood combusts. After ten minutes, you can partially close the top vent.
The bottom vent should stay fully open until all the fuel is completely burnt – without the bottom vent open, the fire won’t last an hour.
While some guides recommend closing the bottom vent partially, this increases the risk of smoldering fire because insufficient air will get through the ash bed. This will stunt burning and reduce the temperature inside the firebox.
If your stove fire dies and needs help, the bottom air vent might not be fully open, or you can open the top air vent to circulate air. You should also add more fuel once the logs have burnt down into red embers.
You can also save a smoldering fire by opening the firebox window and displacing the ash bed, increasing air flowing to the embers. Keep the bottom and top vents open to maximize airflow and introduce kindling as a combustion aid.
If you want to kill the fire within half an hour to an hour, you can close both vents, and it will die down without any fuss.
How to Control a Wood-Burning Stove Fire
Oxygen is but one element of controlling a wood-burning stove.
People’s biggest mistake with wood-burning stoves is assuming the air vents will do all the work of making a rip-roaring fire, but there is more to it than that.
The air vents supply oxygen to slow or speed up combustion - but they are only one element of a fire. To make a good fire, you first need to build a fire from the top down, so everything combusts evenly, and then add more fuel when you have a bed of hot embers.
You need heat, fuel, and oxygen – ultimate stove control is achieved by mastering each element since they are intrinsically linked.
Here’s how to control a wood-burning stove correctly:
You might also experience a few problem scenarios. Here's how to handle issues that might arise.
Overall, controlling a wood-burning stove isn’t rocket science. Providing that you build the fire correctly and keep air flowing to it via the vents, you can maintain a healthy fire, extend the burn time, and reduce fuel consumption.
Almost all wood-burning stoves have the same start-up sequence, but since all installations have quirks – be it stainless steel instead of a vermiculite baffle or a larger flue due to the design of the building – it can take a little time to get the hang of them.