Pellet stoves contain a real fire inside and you’ll commonly find a glass panel fronting the combustion chamber in which to view the flames through.
This glass front can start to stain, blacken or simply build up with dirt over time, which can be a natural occurrence when using a pellet stove but there are a few things that can be done to help keep the glass clearer.
Ways in which to help keep the glass on a pellet stove clean, and to help prevent blackening of the glass, include:
- Keeping on top of cleaning the glass.
- Burning good quality pellets.
- Maintaining the right air supply to the fire using the damper (if available).
- Maintaining the air inlet through regular cleaning.
- Periodically checking for leaks.
- Cleaning the stove regularly in line with the manufacturer’s requirements.
- Having the stove serviced at intervals outlined by the manufacturer.
Why Does The Glass On My Pellet Stove Turn Black?
Glass on a pellet stove turning black can be caused by an issue with either the fuel or the air supply leading to a poorly combusting fire that’s not burning as cleanly, and releasing more by-products such as creosote as a result. Increased creosote production can lead to increased glass blackening.
Pellet stoves are solid fuel burning appliances and utilise a real fire inside the combustion chamber in order to generate heat.
Pellet stoves therefore require a source of fuel and fresh air in order to keep a fire going.
A problem with either of the fuel or air supply can result in poorly combusting fires that aren’t burning as cleanly and efficiently, and increasing the production of by-products such as creosote.
This in turn can cause the glass on a pellet stove to turn black more quickly.
For example, a pellet stove can have poorly burning fires and increased glass blackening due to:
- A lack of sufficient oxygen supply getting to the fire, or a leak causing the airflow to be uncontrolled.
- Poor quality pellets that may be higher in moisture content and ash content.
A lack of sufficient air getting to the fire (and therefore a lack of oxygen) can lead to a fire that’s struggling to burn the pellets properly.
A leak somewhere in the stove can upset the controlled flow of air through the stove and affect the carefully managed fuel-to air ratio.
Using poorer quality pellet fuels, such as those higher in moisture content, can prevent the fire from burning them as effectively with more energy required to first burn off the excess moisture content.
Either a lack of sufficient air supply or sufficient fuel can cause inefficiently burning fires that are producing more by-products such as creosote, which can stain the glass on a pellet stove more quickly when being released in higher quantities.
How To Keep Pellet Stove Glass Clean (And From Getting Black)
1) Clean The Glass Regularly
Keeping on top of cleaning the glass on a pellet stove regularly can help to prevent blackening or staining of the glass over time.
If pellet stove glass isn’t cleaned regularly then it can be harder to clean once blackening or staining has become more prominent, and more rigorous cleaning using harsher cleaning products may be required further down the line to bring the glass back to looking new.
Manufacturers of pellet stoves will typically request that the inside of the glass is cleaned regularly such as daily or before each fire to help prevent particulates from building up and causing the glass to blacken.
For example, the manufacturer for our own pellet stove explains in the instruction manual to clean the glass as part of the daily cleaning regime for the stove:
‘Clean the glass when it’s cold. If necessary, use appropriate detergent.’
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We therefore try to remember to wipe down the inside of the glass door on our pellet stove (when cold) between fires so that the glass doesn’t start to stain and affect the experience.
As we keep on top of this glass cleaning, we haven’t needed to undertake a deep clean of our pellet stove glass, but the effects of not doing so can be seen on our other forms of wood stove where we haven’t been so careful.
2) Use Good Quality Pellets
The quality of the pellets can have an impact on the cleanliness of the glass.
Lower quality pellets that may not meet the same stricter quality guidelines as other more premium quality pellets can be higher in both moisture and/or ash content.
Lower moisture content is favoured for solid fuels as it means less energy is required by the fire to burn off the excess moisture before the fuel can be properly combusted.
Pellets that are of lower quality are therefore typically harder to burn efficiently and more by-products can be released as a result of incomplete combustion.
Good quality pellets are therefore always recommended by manufacturers of pellet stoves.
For example, the instruction manual for our particular model of pellet stove requires us to use good quality wood pellets that meet Class A1 standards.
The manual also explains:
‘The use of pellets with lower quality results in a need for more frequent cleaning of the combustion chamber.’
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These cleaning requirements can also include needing to have to clean the glass more often if poorer quality pellets are used.
To help keep the glass clean on your pellet stove look to use the best quality pellets available near you or as good quality as possible, but always aim to burn the quality of pellets as recommended by the manufacturer.
3) Maintain The Right Air Supply
Newer models of pellet stove typically automatically control the airflow through the stove for the most efficient fuel to air ratio but in many older models the air supply to the fire can be manually adjusted using a damper.
In manually adjustable pellet stoves, the right damper positioning will be required for the ideal flame.
While allowing too much air into a pellet stove can lead to a hotter and faster burning flame, preventing enough air from getting to the fire can lead to poorly combusting pellets that are struggling to burn efficiently due to lack of oxygen (producing more sooty by-products as a result).
The damper on a pellet stove should therefore always be adjusted throughout a fire to ensure that the fuel is burning effectively. The look of the flames will give an indication as to whether enough air is being supplied.
For pellet stoves with manually operated dampers and airflow control should be set to the right place to ensure enough oxygen is being supplied to the fire to prevent blackening of glass due to poor combustion.
This won’t be such an issue with pellet stoves that automatically control the airflow through the stove using a combustion blower and central control unit.
4) Clean The Air Supply
The route for the clean air through a pellet stove must be clear of any dust or other debris to ensure that a fire is always receiving enough oxygen.
The air inlet into a pellet stove should therefore be regularly inspected and cleaned out as required to prevent any problems occurring that could lead to blackening of the glass.
Fresh air in our own pellet stove comes in through the back and enters the combustion chamber from below the fire.
We clean out this area fairly regularly to ensure that ash and bits of pellets don’t build up and block this air inlet up.
The burn pot (where is the actual fire is located) also needs to be cleaned more regularly to ensure that the holes remain free for air supply purposes.
Keeping on top of cleaning out the air supply route within a pellet stove can help prevent the glass from blackening due to reduced air supply and in turn poor combustion.
5) Check For Leaks
For efficiency purposes, pellet stoves are set up to be sealed systems where the airflow in and out of stove can be fully controlled.
A leak somewhere within the stove can lead to the wrong fuel to air ratio which in turn can affect the how cleanly the fuel is burnt and how quickly the glass can start to stain.
Common areas on a pellet stove that should be periodically checked for any leaks include:
- The door gasket seal
- The flue socket
The seal around the glass fire door of a pellet stove can start to deteriorate over time and should be changed every so often before the performance of it starts to cause problems such as air leaks.
The flue system that’s connected up to the back of a pellet stove through the flue socket should also be periodically inspected for any issues.
Periodically checking for leaks within a pellet stove, whether that’s ad-hoc or as part of a service, will help to keep the system sealed for maximum burning efficiency and reduced emissions that could lead to blackening of stove glass.
6) Cleaning The Stove
Alongside cleaning the air inlet and burn pot, the combustion chamber, including the ash tray, should be cleaned regularly and in line with the manufacturer’s guidelines to ensure that the stove remains operating as efficiently as possible.
The instruction manual for our particular model of pellet stove sets out daily, weekly, seasonal and annual requirements (which we discuss more about maintenance here) so that it continuous to run smoothly.
Keeping on top of cleaning out a pellet stove can help to minimize staining and blackening of the glass over the long term.
7) Getting The Stove Serviced
Pellet stoves can be complex appliances with a number of mechanical and electrical components found inside.
While ongoing cleaning by the user is extremely beneficial, pellet stoves typically require periodic servicing to be undertaken by a qualified professional to clean and maintain parts of a pellet stove that can’t be as easily accessed.
This includes servicing of the control panel, sensors, baffles, air ducts, ignition system and more.
To help keep blackening of pellet stove glass to a minimum, ensure that a stove is serviced in line with what the manufacturer recommends and at the required intervals.
Further Reading
Parts Of A Pellet Stove Explained