Pellet Stove Combustion Chamber

Do Pellet Stoves Have A Clean Burn?

In Pellet Stoves by James O'KellyLeave a Comment

Pellet stoves burn fuel in the form of pellets to produce heat, while in comparison wood burning stoves use firewood as fuel in the form of logs and kindling.

Pellets for pellet stoves are compressed forms of material such as wood chippings that may need to meet certain regulations for both moisture and ash content, and so do pellet stoves burn clean as a result?

Pellet stoves can produce a very clean burn that can be more efficient than other forms of fireplace or stove. The quality of the pellets being used can affect how clean the burn is, with good quality pellets helping to keep wastage low for both emissions and ash.

Our own pellet stove provides a very clean burn of the fuel and much less ash can be produced within our pellet stove compared to our open fireplace or wood burning and multi fuel stoves.

We’ve explained in more detail below why pellet stoves can provide a clean burn using our own pellet stove as an example.

Do Pellet Stoves Burn Clean?

Pellet stoves are considered to be one of the more cleaner burning fireplaces or stoves.

Pellet stoves burn the fuel in such a way as to promote:

  • As few emissions as possible.
  • Reduced wastage in the form of ash.

As pellet stoves are solid fuel burning appliances, they have real flames and are able to generate heat for a room or home from the combustion of solid fuel using a real fire.

Pellet Stove Front
Our pellet stoves provides a cleaner burn that even our efficient wood stoves do

The combustion process of solid fuels such as wood produces a number of by-products including heat, leftover material (such as in the form of ash), gases and smoke.

These by-products can’t be removed completely because they are the natural by-products of having a real fire. However, they can be reduced to as low as possible through a number of means and this is part of what a pellet stove aims to help achieve.

A clean burn within solid fuel burning appliances such as stoves can be promoted through adjustments of the:

  • Fuel.
  • Air supply.
  • Airflow out.

Pellet stoves are clever forms of solid fuel burning appliance and use a number of electronic components (that need an electricity supply) to help make the process of combusting more automated and controlled in order to help provide a clean burn.

Top Of Pellet Stove
A control panel on the top of our pellet stoves ensures a continuous clean burn with no user input required

The ways in which pellet stoves help promote a cleaner burning of fuel compared to other forms of stove or fireplace include:

  • Using fuel that is very low in moisture and ash content and compacted so that a lot of energy is stored in a small area.
  • Only delivering what is necessary to the fire in terms of fuel for optimum heat output and efficiency.
  • Keeping the fire within a sealed combustion chamber and under high pressures using gaskets and baffles to promote a cleaner burn of both the fuel and waste gases.
  • Regulating both the intake of fresh air and the venting of waste air to promote the most clean and efficient burn.
  • Using a central control panel to manage all of the processes automatically for the cleanest burn possible.

Pellet Fuel

The pellets used as fuel for a pellet stoves are typically made to certain standards to be as clean burning as possible.

These pellets are manufactured and can be made from a range of materials, with the most common typically being wood by-products such as chippings or sawdust.

Bag Of Wood Pellets
Using high quality pellets helps a pellet stove to provide a clean burn

The manual for our own pellet stove states wood pellets of Class A1 must be used with the following parameters:

  • Maximum moisture content 8%.
  • Maximum ash content 0.5%.

In comparison to wood burning stoves, the recommended moisture content for firewood is 20% or under while the maximum moisture content of the pellets we burn in our pellet stove will be 8%.

Higher moisture content of any form of wood fuel can lead to struggling fires with less heat produced, more emissions given of in the form of smoke and gases, and an overall poor burning experience.

Minimal amounts of ash are also typically produced by pellet stoves.

We find that the ash builds up much quicker within our wood burning stove compared to our pellet stove.

Pellet Stove Ash Tray
Minimal ash production means that we don’t have to clean out the ash tray on our pellet stove too often

The quality of the pellets used within a pellet stove therefore plays an important role in how clean the burn is but using the right quality of pellets in line with the manufacturer’s guidelines will give a very clean burn that wouldn’t be possible with many other forms of fireplace or stove.

Fuel Delivery

Pellet stoves are electronic appliances and use a central control panel to manage all of the stoves functions, including the rate at which the fuel is delivered to the fire in the combustion chamber.

Pellet stoves have integrated hoppers in which the pellets are stored. The front door to a pellet stove does not need to be opened during fires to add more fuel and the pellets are fed automatically to the fire from within the stove.

Pellets are fed to the combustion area from the hopper down a chute. The rate at which the fuel is fed to the fire is regulated using a motorized auger, which is controlled from the central control panel.

Pellet Stove Combustion Chamber
Pellets are automatically fed to the combustion chamber of a pellet stove for the most efficient burn

The actual area of combustion in a pellet stove is fairly small. Pellets fall into this area at a regulated rate to ensure there isn’t too much or too little fuel being burnt at any one time.

Pellet stoves therefore help to provide a clean burn thanks to automatically releasing the right amount of fuel to the fire as and when required for an optimal combustion.

Sealed Combustion Chamber

Much like wood burning stoves, pellet stoves have a sealed combustion chamber to ensure that all of the air is entering and leaving is via dedicated vents to help promote the cleanest burn possible.

If a pellet stove has a door to the combustion chamber then that door will have a gasket to help keep it airtight, like on our pellet stove.

Pellet Stove Combustion Area
The combustion chamber of a pellet stoves will be sealed for efficiency purposes

In our particular model of stove, air comes in from below the fire and leaves at the top of the combustion chamber. Baffles located at the top of the chamber can help to slow down the rate that air leaves the chamber, allowing more time for gases to be burnt to produce even more heat and have an overall cleaner burn.

A sealed combustion chamber on a pellet stoves helps to promote a clean burn of the fuel where the airflow can be managed more effectively.

Regulating Air Flow

Wood burning stoves rely on the draft to help remove waste air from a stove and in turn pull fresh air in.

Pellet stoves use a blower within a fume extractor to forcefully remove waste air from the combustion chamber and out of a home through the flue.

This creates a vacuum within the combustion chamber and in turn sucks fresh air into the stove.

The fume extractor on a pellet stove is automatically controlled to ensure the cleanest burn possible by regulating the flow of air through the stove and therefore ensuring that the fire receives the right amount of oxygen.

Centrally Controlled

A central control unit on a pellet stove helps to automate the whole burning process and maximize the potential for a clean burn of the fuel for reduced emissions and higher heat efficiency.

Pellet Stove Control Unit

The manual for our particular model of pellet stove explains that for the control panel:

The control unit is equipped with a system for monitoring and controlling of the burning process. It ensures higher efficiency and optimizes the fuel consumption for minimizing emissions.’


Our own pellet stove has an efficiency rating of 87.76%, which is higher than what even our wood burning and multi fuel stoves are available in achieving in terms of efficiency.

A control panel on a pellet stove can help to promote a clean burn of the fuel by using a range of sensors within the combustion chamber and at the flue outlet to collect and analyze the data to optimize the burn for efficiency.

Further Reading

Pellet Stove Venting Requirements

What’s Inside A Pellet Stove

Do Pellet Stoves Give Off Heat?

Things To Know About Pellet Stoves

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