Multi Fuel Stove Firebox Labeled

Parts Of A Wood Burning Stove Explained (With Labeled Pictures)

In Indoor Fireplaces, Wood Burning Stovesby James O'KellyLeave a Comment

Wood burning stoves help to improve the efficiency and heat output when burning wood in your home compared to using open fireplaces. Whereas a traditional fireplace can have an efficiency of around 20%, wood burning can reach around 80% efficiency, meaning far more heat is provided to your home than lost up the chimney.

Although each model of wood burning stove is designed and constructed differently, stoves generally comprise of the same main components that help to get the most heat from burning wood.

The main parts of a wood burning stove can include:

  • Firebox
  • Air Vents
  • Air Vent Controls
  • Baffle
  • Flue Collar
  • Stove Pipe
  • Flue
  • Doors
  • Ash Pan
  • Damper
  • Catalytic Combustor

We have a number of wood burning stoves in the family, and so I’ve put together labeled diagrams for two of our stoves to help show what each part is on a typical wood stove.

I’ll be using both a wood burning stove and a multi fuel stove as examples. Multi fuel stoves are slightly different wood burning stoves, but both are used regularly to burn wood and so I’ve included and explained both types of stove in this article.

I’ll be referring to both as ‘wood burning stoves’.

I’ve also explained each component in further detail, using pictures from our stoves to help illustrate what their function is, and how it’s performed.

Parts Of A Wood Burning Stove Diagram

Here’s the main components you can see when looking at our wood burning stove:

Parts Wood Burning Stove Labeled
Parts Wood Burning Stove Firebox Labeled

We also have a multi fuel stove, and so below are labeled pictures of this stove:

Multi Fuel Stove Parts Labeled
Multi Fuel Stove Firebox Labeled

Firebox

The firebox is the main compartment inside a wood burning stove. It’s where the fire is located and where more fuel is added.

The glass door of the stove is at the front of the firebox, providing you with a view of the fire. The firebox is lined on the back and sides with heat-resistant materials such as masonry firebricks, cement or metal.

At the base of the firebox, further fire-resistant materials can be found for wood burning stoves, or a metal grate in multi fuel stoves. At the top of the firebox is the baffle, with the flue collar located just behind.

Here are pictures taken of the fireboxes in both of our stoves:

The firebox on our wood burning stove
The firebox of our multi fuel stove

In general, the larger the firebox, the more fuel can be added to the stove, and the more heat can be generated. Heat output can also be influenced by the efficiency of the stove, meaning how well it converts the energy stored in the wood into heat. More heat output can be generated through providing the cleanest burn of wood possible, by keeping waste gases in the firebox for as long possible to allow for secondary combustion to occur.

For more information explaining secondary combustion in wood burning stoves, I’ve put together another article here.

Air Vents

Every model of wood burning stove has a set, or multiple sets, of air vents that are designed to provide fresh oxygen to the fire in specific locations around the firebox.

There are three main types of air fed to the fire in a wood stove:

  • Primary Air
  • Secondary Air
  • Tertiary Air

Primary air is typically fed to the base of the firebox to provide oxygen to the main area of the fire, and is most useful when starting the fire and getting the stove up to fully operational temperature. Primary air becomes less important further into a fire, where secondary and/or tertiary air takes over as the main source of oxygen to a firebox.

Secondary air can either be fed into the stove from below or above, meaning that the secondary air vent can generally be found underneath the stove, or on the front at the top. Secondary air helps to provide oxygen for secondary burn of gases released by the fire, as well as providing air for the stove’s air wash system to help keep the glass door clean.

Tertiary air can replace secondary air as the main source of oxygen for secondary burn. Tertiary air vents are typically located at the back of the stove, and can’t be manually contolled.

The way in which air is delivered into fireboxes is different between each model of stove, including where the air vents are located and how they operate.

Depending on the design or type of stove, it may or may not provide all three forms of air to a fire.

Our multi fuel stove has a primary air vent located on the front of the unit, and air flows through the ash pan and the grate to reach the firebox. The secondary air vent is located underneath, and there’s no tertiary air vent.

Primary air vent on a multi fuel stove
Secondary air vent on a multi fuel stove

On our wood burning stove, both the primary and secondary air vents are located underneath, while the tertiary air vent is located on the back, which feeds air to the small holes located at the back of the firebox as shown below.

Tertiary air vents in a wood burning stove firebox

To get the most heat from your wood burning stove it’s important to understand how each air vent works, and which parts of the stove they feed air to.

To help you make the most of your stove, I’ve put together further guides on the types of air provided to a stove, and air wash systems:

Primary, Secondary and Tertiary Air Explained

Air Wash System On A Stove Explained

Air Vent Controls

Primary and secondary air in a wood burning stove can typically be manually operated using controls, while tertiary air vents generally can’t be closed.

By manually opening or closing primary and secondary air vents, you can control the how quickly and efficiently the fire in the firebox burns through the wood. The vents on varying models of wood stove are operated differently, and so it’s important to read your user manual to understand how to best use the vents on your particular stove to get the most heat from burning wood.

Our multi fuel stove has the primary air vent located on the front, and rotating the vent controls the airflow to the base of the fire. This vent should be fully open when starting a fire to get as much oxygen to it as possible. The vent can then be mostly closed down when the fire is really going, and the secondary air vent becomes the main source of air.

Primary air vent fully open
Primary air vent mostly closed down

The secondary air vent on this stove is located underneath, and is controlled by a slider that is operated using a handle that sticks out the front.

The handle to control the secondary air vent located underneath the stove

This vent should be also fully open when starting a fire to provide as much oxygen as possible during its early stages, and can then be used throughout the rest of the fire to control the rate at which it burns through the wood. This secondary air vent is also used to control the stove’s air wash system, which helps keep the glass on the door clear for an uninterrupted view of the fire.

On our other stove, a similar handle also controls the primary and secondary air vents located underneath the stove.

This wood burning stove has tertiary air vents but there’s no way to control them, and so the handle for the primary and secondary air vents is the only way to control the fire.

Baffle

The baffle is a metal plate located at the top of the firebox, and helps to keep byproducts released from the fire in the firebox for longer.

A large proportion of the heat generated by burning wood can come from the secondary combustion of waste gases. By keeping these gases in the firebox for longer using the baffle, more time is provided to help burn off the gases.

Here’s what the baffles look like in our stoves:

Baffle plate in a multi fuel stove
Baffle plate in a wood burning stove

The baffle is required to handle the high temperatures generated by the fire, but can be damaged if the heat output exceeds that of the designed operating temperatures of the stove.

Over firing your stove can cause long term or permanent damage to components such as the baffle, and so I’ve put together another article on what over firing of a stove is, and how you can prevent it from happening.

Flue Collar

The flue collar is located near the top of the fireplace, but typically behind the baffle and above the firebox. The flue collar is where the wood burning stove meets the stove pipe, which provides a passageway for waste gases from the fire to safely leave your home.

In our wood burning stoves, the flue collar is located on the top of the stoves, and can be seen just above the baffle.

The flue collar located just above the baffle in one of our stoves

Depending on the model of wood stove, the flue collar may be located on top of the stove or on the back; to suit which way the flue is heading out of your home.

Stove Pipe & Flue

The stove pipe is connected to the stove via the flue collar, and connects the stove to the flue.

The flue can either extend up vertically through the ceiling, go out at an angle through an external wall, or extend up to the roof through the inside of a chimney.

Our wood burning stoves were installed within existing chimneys, and so the stove pipes extend from the stoves vertically into the flues located within the chimneys.

The stove pipe from our multi fuel stove
The stove pipe from our wood burning stove

The chimneys have then been capped off where the stove pipe meets the flue to ensure that all air flow is provided through the stoves.

A metal plate capping off the base of our chimney
The base of this chimney sealed around the flue

Doors

The door on a wood burning stove is located on the front of the stove, and typically incorporates a large glass screen to allow you to view the fire when it’s closed.

Stove doors have a seal around the inside to prevent any air from getting into the stove through the door, ensuring that all air getting into the firebox is going through the air vents and can therefore be managed.

The images below show what the inside of the doors look like on our wood stoves:

The rear of a multi fuel stove door. There are separate seals for the door and the ash tray compartment
The back of the door on our wood burning stove

An air wash system on a wood stove helps to keep the glass on the door clean for a full and uninterrupted view of the fire. Both our stoves have air wash systems incorporated, but the images below show one air wash system is working more efficiently than the other one.

Our wood stove glass starting to blacken

Ash Pan

Multi fuel stoves typically have ash pans while wood burning stoves typically don’t. Ash pans on multi fuel stoves are located just beneath the firebox and catch ash as it falls through the firebox grate.

Coal needs a source of air from below to burn efficiently, while wood doesn’t. Multi fuel stoves therefore incorporate metal grates at the base of the firebox rather than a flat piece of fireproof material found in wood burning stoves.

Air is provided to the base of a multi fuel stove firebox through the ash pan and grate. Because multi fuel stoves need a grate, an ash pan is required to collect any ash that falls through.

The image below shows the metal grate at the base of the firebox on our multi fuel stove

The metal grate in our multi fuel stove
The ash pan on our multi fuel stove

This grate can be controlled using a lever on the side of the stove, which rotates the grate and helps ash to fall through from the firebox into the ash tray.

Our other wood burning stove doesn’t have an ash tray, and so any excess ash needs to be manually removed from the firebox.

No ash pan compartment on our wood burning stove

Many stove manufacturers recommend to leave a layer of ash at the base of the firebox to help protect the components inside the firebox or ash pan from the heat of the fire, and also to help insulate the coals as the fire gets up to the right temperature.

I’ve written another article right here explaining how much ash you should be leaving in your wood burning stove and why.

Damper

Some older models of wood burning stove may have a damper located inside the stove pipe, which is a plate that can be manually opened or closed to help control the draw on the stove.

A damper can therefore be used in conjunction with the stove’s air vents to help control the rate at which the fire burns through the fuel, and therefore the overall heat output.

Our wood burning stoves are fairly new and don’t incorporate any form of damper.

For my complete guide to fireplace dampers, and to learn more about what dampers look like, what they do and how to operate one, click here.

Catalytic Combustor

Some high efficiency wood burning stoves include a catalytic combustor as a component to help further reduce the pollutants leaving your home.

A catalytic combustor helps to lower the temperature in the stove at which gases burn, therefore providing an overall cleaner burn and lower emissions.

Further Reading

I’ve put together a number of other articles on wood burning stoves that may help you, whether you’re looking to buy a wood stove, or wanting to understand your current stove and increase its heat output.

Installing A Wood Burning Stove In An Existing Fireplace

Things To Consider Before Buying A Wood Burning Stove

Reasons To Buy A Wood Burning Stove

Secondary Combustion In Wood Stoves Explained

Air Wash Systems In Wood Stoves Explained

Primary, Secondary And Tertiary Air In Wood Stoves Explained

What Over Firing Is On A Wood Stove

How Much Ash To Leave In Your Wood Burning Stove

Guide To Fireplace Dampers

Guide To Fireplace Hearths

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