Pellet Stove Flue Socket

Do Pellet Stove Build Up Creosote?

In Pellet Stoves by James O'KellyLeave a Comment

Creosote can be an unwanted by-product of the solid fuel combustion process and can be most prevalent when burning low quality firewood in wood burning stoves or fireplaces.

Pellet stoves can in many cases have a cleaner burn than the average wood burning stove, potentially meaning fewer by-products, but do pellet stoves still build up creosote?

Pellet stoves can typically produce less creosote compared to other wood burning stoves and fireplaces, but this can be subject to using a pellet stove correctly and burning adequate quality pellets. Using poor quality pellets high in moisture content may lead to higher than average creosote production.

Our own pellet stove produces far less creosote than our open wood burning masonry fireplace and less than our wood burning and multi fuel stoves.

We’ve explained in more detail below using our own pellet stove as an example:

  • What creosote is and how it’s produced.
  • What pellets stoves do to help minimize creosote production.

Do Pellet Stove Build Up Creosote?

Creosote is a tar-like substance that can be produced as a by-product of the combustion process of wood, commonly used as firewood within fireplaces and stoves to generate heat.

Creosote is also a flammable material, meaning that it can become a hazard in the form of chimney fires when released and sticking to the internal walls of a chimney or flue.

Creosote is a by-products of the wood burning combustion process

That’s why it’s recommended to have your chimney or flue swept at least once per year, or more often if you’re regularly burning wood, and ideally before the main burning season to help ensure that chimneys remain free from large deposits of creosote that could become a fire risk.

Not all wood fires, including pellet stoves burning wood pellets, will produce creosote in large enough quantities for it to become a problem.

Creosote is often produced in higher quantities as a result of poor combustion of wood. Poor combustion can be due to a lack of sufficient fresh air or burning wood that is too high in moisture content.

Minimizing creosote production is therefore an important aspect of solid fuel burning appliances, including for pellet stoves.

Pellet Stove Front
Creosote production is typically low in pellet stoves when used in line with the manufacturer’s guidelines

Pellet stoves are a more automated form of stove and can typically provide a cleaner burn compared to other forms of stove. The main aspects of a pellet stove that help it to produce minimal creosote build-up include:

  • Using fuel in the form of pellets that must typically be low in moisture content to meet regulations.
  • Creating a contained environment where the fuel can be burnt as cleanly as possible.
  • Controlling the amount of fuel in the form of pellets being fed to the fire.
  • Controlling the rate at which waste air leaves the stove and in turn controlling how much fresh air is provided to the fire.

All of these things work together within a pellet stove to help ensure that the fuel in the form of wood pellets is being burnt as cleanly as possible with minimal creosote production.

Pellet Stove Pellets

The quality of the wood pellets used within a pellet stove can have a big impact on how much creosote is produced.

With traditional wood burning fireplaces and stoves that use firewood as fuel rather than pellets, the recommended moisture content for firewood is for 20%. This is to help ensure that it burns well with reduced creosote production. However, as moisture content goes over this amount the firewood can become progressively harder to burn well.

Poorly combusting firewood due to high moisture content can lead to greatly increased creosote production, in turn leading to more creosote being deposited with a chimney or flue and more regular sweeping required to keep it under control.

Wet Firewood
Burning wet wood high in moisture content can be the biggest cause of creosote production

This can be the same for pellet stoves, but moisture content in firewood isn’t as regulated as it can be for moisture content levels within wood pellets for pellet stoves.

For example, the instruction manuals for our wood stoves state that properly seasoned firewood should be burnt, while our pellet stove requires a certain class of pellets be used.

The manual for our particular model of pellet stove states that only wood pellets that meet Class A1 should be used. The pellets we need to use have a maximum moisture content of 8%, meaning that they can burn well and keep creosote production to a minimum.

Bag Of Wood Pellets
Burning good quality pellets that are sufficiently low in moisture content will help keep creosote production from a pellet stove to a minimum

However, expect that creosote can build up faster within the chimney flue of a pellet stove if poor quality wood pellets with higher moisture content are burnt.

Pellet Stove Clean Burn

Pellet stoves are set up to help burn the fuel as cleanly as possible to help reduce emissions and wastage and in turn reduce creosote production.

Fires within a pellet stove are kept within a sealed environment where both the fuel and air supply can be controlled by electronic components and a central control unit to ensure optimum burn of the fuel to promote heat output, efficiency and reduced emissions.

The parts of a pellet stove that help to minimize creosote production include:

  • A sealed combustion chamber with gasket seals on any doors.
  • Controlled feeding of the pellets from the hopper to the combustion chamber using an auger.
  • Controlled removal of waste air from the combustion chamber using a blower within the fume extractor. This in turn creates a vacuum and allows fresh air to be sucked in at a controlled rate.
Pellet Stove Combustion Area
Pellet stoves are set up to provide a clean burn and keep creosote production low

For more information we have another article on clean burning within pellet stoves.

Pellet Stove Cleaning & Servicing

Alongside regular cleaning of the ash tray and other internals of a pellet stove, a pellet stove should also be subject to seasonal maintenance by a certified professional who will clean out the main components and this will include any creosote build-up internally within the stove.

It’s also recommended that like traditional chimneys and other stove flues, pellet stove chimneys/flues should be cleaned at least annually to remove any creosote.

The manual for our particular model of pellet stove explains:

The chimney to which the pellet stove is connected to must be cleaned once a year. Check that there is a regulatory standard for this in your country. If periodic inspection and cleaning of the chimney is not undertaken, there is an increased probability of a fire.’

Pellet Stove Flue Socket
Small amounts of creosote may be deposited within the flue of a pellet stove even through normal operation and so seasonal cleaning and maintenance should still be undertaken.

Keeping Pellet Stove Creosote Build Up Low

The amount of creosote produced by a pellet stove is typically low but can be increased when standard procedures for using a pellet stove aren’t followed.

However, there are some things you can do to help keep creosote production from burning wood pellets in a pellet stove low.

To help keep creosote build up low in pellet stoves:

  • Burn good quality pellets in line with the manufacturer’s guidelines to ensure that the pellets are low in moisture to reduce the chance for creosote to be produced.
  • Install and use a pellet stove in line with the manufacturer’s guidelines to help ensure a clean burn of the pellets.
  • Have the pellet stove and the flue chimney cleaned at certain intervals in line with the manufacture’s guidelines.
  • Burning hotter pellet stove fires can help prevent any creosote being produced and from depositing within the chimney flue.

Further Reading

What’s Inside A Pellet Stove With Pictures

Things You Need To Know About Pellet Stoves

Can You Burn Wood In A Pellet Stove?

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