Multi fuel stoves have dedicated air vents and controls in order to be able burn a number of different types of fuel.
Whereas wood burning stove may only have one controllable vent, multi fuel stoves can have multiple controllable air vents to allow you to change between using different types of fuel such as wood and coal.
This guide explains how to use the air vents on a multi fuel stove to control the fire.
To control a fire in a multi fuel stove:
- Ensure that all the air vents are fully open before lighting the fire.
- Light the fire and close the stove door (the door can be left slightly open to maximize airflow to the fire if required).
- Once the fire has caught hold of the fuel, partially close down the air vents to reduce the supply of oxygen to the fire.
- Allow the stove to get up to operating temperature, and use the vents as required to control the rate at which the fire burns through the fuel.
We have a multi fuel stove in the family and so I’ve explained in detail below how we use the vents on our multi fuel stove to control the fire, from lighting the fire to keeping the stove burning.
How To Use The Vents On A Multi Fuel Stove
The air vents on a multi fuel stove are used to control the fire. Controlling the supply of oxygen to the fire using the air vents helps to produce the most amount of heat from each piece of fuel.
Multi fuel stoves are fairly simple appliances with only a few controls, but in reality it can be hard to control a fire inside a multi fuel stove because of the many circumstances and variables that come together when having a fire.
These can include the outside temperature and weather, the moisture content of the wood and even how well the fire has been built.
As every fire can be different, it’s important to understand where the air vents are located on your multi fuel stove, and how they can be used to control the fire.
The air vents control the supply of oxygen to the fire, which is needed by the fire in order to burn the fuel. The more air that is supplied to the fire, the quicker it can burn through the fuel, and in turn produce more heat.
Multi Fuel Stove Controls – Example
We have a multi fuel stove that we’ve been using regularly for a number of years. It was installed inside our open fireplace to help produce more heat when burning through our supply of wood gathered from our property.
Here’s what our multi fuel stove looks like:
On this particular model of multi fuel stove there are two controllable air vents.
The primary air vent is located on the front of the stove, and supplies oxygen to the base of the fire from below through the ash pan compartment.
On this model of multi fuel stove the vent can be opened and closed by rotating it.
The primary vent can be left in any position between fully open and fully closed, allowing you to precisely control how much air is being provided to the fire through this vent.
Primary vents are typically located in this position on a multi fuel stove (on the front of the stove near the bottom).
The secondary air vent is located underneath the stove, and supplies oxygen to the fire from above.
On this stove, the air travels around the body of the stove before being fed to the top of the fire, which helps to warm up the air before being used by the fire, and also for the secondary burn and air wash systems inside the multi fuel stove.
As the vent is located underneath the stove and out of reach, it’s controlled using a handle that sticks out the front of the stove.
Pulling the handle towards you opens the secondary vent while pushing it towards the stove closes the vent. This vent can be left in any position between fully open and fully closed, allowing the air supply through this vent to be accurately controlled.
Secondary air vents on a multi fuel stove are typically found on the front of the stove at the top, or underneath the stove.
All models of multi fuel stoves from different manufacturers are designed and operated differently, and so the air vents on your multi fuel stove may differ to ours. The concept of using the air vents to control the fire remains the same however.
How To Control A Multi Fuel Stove
On a multi fuel stove the air vents should be fully open when lighting the fire, and partially closed down when the fire has caught hold of the kindling. The vents should be adjusted accordingly throughout the duration of the fire to increase or decrease the temperature of the stove to optimum temperatures as necessary. Which vents are adjusted will depend on the type of fuel being burnt inside the multi fuel stove.
The entire duration of the fire can be controlled using the air vents on a multi fuel stove.
Opening the vents increases the flow of oxygen to the fire and helps to increase the heat output by burning through the fuel more quickly. Closing down the air vents reduces the supply of oxygen to the fire, and therefore the heat output.
However, more air doesn’t always necessary mean more overall heat.
The aim of a multi fuel stove is to burn the fuel as efficiently as possible, which means burning both the fuel and the waste gases to produce even more heat. The process of burning off waste byproducts from a fire is known as secondary combustion (or secondary burn). I’ve explained secondary combustion in more detail here if you want to know more.
Controlling the air supply helps to keep waste gases inside the stove’s firebox for longer, which in turn produces more heat. In fact, secondary combustion in multi fuel stoves can produce more heat output than simply burning the fuel itself, which is why stoves can throw out much more heat into a room than a traditional open fireplace.
Supplying large quantities of fresh oxygen to a fire can prevent this process from occurring.
It’s therefore typical to only leave the air vents on a multi fuel stove slightly open during use, rather than open all the way.
1) How to Control A Multi Fuel Stove – Lighting A Fire
When lighting a fire inside a multi fuel stove, all of the air vents should be fully open to allow as much air to the fire as possible.
This helps the fuel catch alight more easily, and the air supply is vital at this point of the fire. A lack of oxygen after lighting can cause the fire to go out before the flames have a chance to take hold of the fuel.
Below are pictures showing the vents on our multi fuel stove fully open before the fire has been lit:
2) How To Control A Multi Fuel Stove – After Lighting A Fire
After lighting a fire in a multi fuel stove the door to the stove can be closed. If you regularly have trouble getting a fire going in your stove, leaving the door slightly open for a few minutes during this period is fine.
The air vents should remain fully open as the flames take hold of the fuel.
Once the fire has got going, the air vents should be partially closed down to reduce the supply of air to the fire.
The type of fuel being burnt will dictate which air vents are to be closed down, and by how much.
Wood burns best with a supply of air from above the fire, which is supplied by the secondary air vent typically located underneath the stove, or near the top on the front.
When burning wood, the primary air vent that feeds air to below the fire can be closed down until it’s almost shut (or even completely closed in some circumstances). The primary vent should then be left in this position for the remainder of the fire.
The secondary air vent should be used to control a multi fuel stove when burning wood, and so this vent should be partially closed down after the fire has started to control the oxygen supply. This vent can then be used as the sole control for the multi fuel stove for the duration of the fire.
Unlike wood, coal burns best with a supply of air from below.
The primary vent is therefore used to control a coal fire as it provides oxygen to the base of the firebox.
The secondary vent becomes less important when burning coal, and so this vent can be mostly closed down and left in a partially open position for the remainder of the fire.
On many multi fuel stoves the secondary vent needs to remain open to provide a flow of air for the airwash system, which helps keep the glass door clear.
2) How To Control A Multi Fuel Stove – The Remainder Of A Fire
For the remaining duration of the fire, the main air vent associated with the type of fuel that you’re burning can be used to control the fire.
- When burning wood, use the secondary air vent to control the multi fuel stove, typically found at the top front or underneath the unit.
- When burning coal, use the primary air vent to control the stove, typically found on the front of the unit at the bottom.
Opening the vent increases the airflow to the fire, which increases the rate at which the fuel is burnt and in turn increases the heat output.
Closing down the vent decreases the flow of oxygen to the fire, which reduces how quickly the fuel is consumed and therefore the heat output.
To get the most amount of heat per piece of fuel consumed, the temperature of the multi fuel stove should be kept within the ‘optimum’ temperature range for your particular model of stove.
Our multi fuel stove came with an optional thermometer that sticks to the stove. The temperatures ranges are shown on this thermometer:
If the temperature inside the stove is too low, the fire can produce creosote, a highly flammable substance than can line the inside of the flue.
The air vent should be incrementally opened until the temperature of the stoves reaches the ‘best operation temperature range, and then partially closed back down again to keep the stove at this temperature.
If the temperature of the stove is too high, damage can occur the stove through prolonged use at high heat.
The air vent should then incrementally be closed down until the stove’s temperature has returned the ‘best operation’ zone. Adjust the air vent as required to keep the stove within this temperature range.
Each model of multi fuel stove is different and it takes time to fully understand how to use the air vents on your stove to control a fire.
Keep using your multi fuel stove to practice and you’ll soon learn how to produce the most amount of heat from your stove!