We have a number of wood burning stoves in the family and both of my parents have wood stoves located in their living room fireplaces.
The stoves are fairly new and incorporate what’s known as an ‘air wash’ system.
Although the two wood stoves both incorporate air wash systems, there are slight differences between the two models of stoves.
So what is an air wash system on a wood burning stove and what is the purpose of it?
An air wash system on a wood stove is a feature that forces air over the inside of the glass door of the stove, for the purpose of helping to keep the door clean and prevent blackening of the glass.
The term ‘air wash’ denotes the use of air to help wash over the glass to help prevent the build up of soot and creosote that is released by burning wood.
The way in which air wash occurs in a wood stove differs for each manufacturer and model, and each brand has their own terminology for the feature.
I explain air wash systems on wood burning stoves in more detail below using two real world examples of wood stoves with this feature.
Air Wash System On A Wood Stove
As the fire in a wood burning stove is locked away behind closed doors, it’s far more enjoyable to watch the flames through a clean and clear glass door.
Soot released from the burning of wood can line the inside of the glass door through use, just as it can build up in a chimney or flue. The more often wood is burnt, the quicker the blackening of the stove glass can occur.
Each model of wood burning stove that has air wash technology is specially designed with certain vents and pathways for air that allows it to flow across the inside of the glass door.
Air is forced over the glass, typically in a downward motion, and prevents any soot from settling on the inside of the glass.
As a result, the glass on wood burning stoves without air wash technology generally blackens much more quickly than those with integrated air wash systems.
Reasons for your stove glass turning black can also include burning wood that is too wet or not using the air vents effectively to facilitate the air wash. I’ve listed the reasons why the glass on your stove could be turning black here.
The air wash feature is typically controlled by the secondary air flow into the stove, while the primary air feeds the base of the fire.
In some models of wood burning stove, a separate vent is located above the door that provides the airflow for the air wash system. This provides the shortest route for air to wash over the inside of the glass door, but the air doesn’t have time to heat up before it flows over the glass.
My parent’s wood burning stoves (which I go into detail below) both have air wash systems that are fed by the air vents located underneath the stove. This gives the air the opportunity to heat up before flowing over the glass door.
Air Wash on A Wood Stove (Example 1)
Here’s my dad’s wood burning stove:
An air wash system is built into this wood burning stove manufactured by Cleaview Stoves, who market this feature as a ‘hot air wash’ system.
The air is fed to the glass door around the body of the stove allowing it to heat up to high temperatures along the way. Clearview Stoves state that this allows for a clear view of the fire, as well as efficient combustion.
There are two controllable air vents located on this model of stove: one on the front of the stove, and one underneath.
The front air vent controls the primary air to the stove by providing a feed of fresh oxygen to the bed of the fire. This vent doesn’t provide any air to the air wash system.
The air vent located underneath the stove is used to provide air to the firebox for both secondary burn and air wash purposes.
Secondary burn is the combustion of waste gases produced by the fire to help improve the efficiency of the stove and increasing the overall heat output. More information about secondary burn can be found here.
Sliding the handle located at the base of the stove door controls the vent underneath the stove. This air vent must be open at least a small amount in order to provide air for the air wash system.
Air from this vent flows over the baffle located at the top of the stove, and falls down over the inside of the door to help prevent the build up of soot on the glass.
The air wash system on this wood burning stove has kept the glass on the door pretty much clean for the entity of its use over a number of years.
The glass hasn’t yet needed to be cleaned as a result, but it’s looking like it might need a small clean in the near future.
Air Wash on A Wood Stove (Example 2)
My mother’s wood burning stove can be seen below:
This wood stove also has an air wash system built into it, but there’s only one controllable vent on this model.
The vent is located underneath the stove, and provides both primary and secondary air to the firebox. The primary air is supplied to the base of the fire while the secondary air is fed to the air wash system to keep the stove door clean.
Again, this vent must be open for the air wash system in the stove to operate.
Interestingly, the glass on this wood burning stove has blackened more quickly than our other stove.
As both primary and secondary air flows are controlled by the same air vent, it can’t due to this vent being closed otherwise the fire would continuously be going out. It may be that the wood being burnt is too high in moisture content or the logs are being placed too near the glass for the air wash system to work effectively.
Benefits of Having An Air Wash System On A Wood Stove
Some of the main benefits of having a wood burning stove with an air wash system include:
- It can greatly reduce the need to regularly clean the glass on the stove door.
- Allows you to enjoy the flames through clear glass throughout the duration of the fire.
- A clean pane of glass keeps your stove looking nice for when not in use.
Air Wash System On A Wood Stove
Air wash systems on wood burning stoves help to keep the fire in view without the need for regularly cleaning.
As the idea behind an air wash system is fairly simple, the majority of wood burning stoves on the market today have the functionality already built in as standard.
It’s therefore important to understand how best to use the air vents on your particular model of wood burning stove to help keep the air wash system working effectively.
Look through your wood stove manual to see whether your stove has an air wash system built in, and to find out which vent is providing the secondary air to your air wash system. It may also explain how to properly control this vent to ensure that the air wash system is working as it should.
As an example, on one of our wood burning stoves the vent located underneath the stove provides the secondary airflow for the air wash system. It’s recommended that this air vent is left open between 25% and 50% of the way to ensure that the air wash is working to its maximum, while also providing the right amount of air to the fire.
You may also be interested in reading all of the things we had to consider before buying these particular wood burning stoves.