Most modern woodburners incorporate an airwash system. This is when the secondary tair supply – the air vent at the top of the stove – is used to direct a thin layer of air over the inside of the stove glass to prevent soot and dirt from settling.
How to operate airwash
When lighting your stove, both the primary and secondary (airwash) vent should be open. That’s because you want to allow as much oxygen as possible into the stove to help the fuel to start burning. Get more information on how to light your stove.
Once the stove is lit, you will no longer want the vents to be wide open because that will allow too much oxygen in and cause the stove too operate at too high a temperature, potentially causing damage to the internal parts of your woodburner.
Burning wood while using airwash
If you are burning wood, you can close the primary (bottom) vent completely once the stove is lit properly. Wood needs an air supply from above to burn effectively, so the secondary air vent does this.
You should also close the secondary vent from its open position during the lighting position BUT don’t close it completely.
Leaving the secondary vent slightly open will allow the airwash system to function correctly, while also allowing sufficient oxygen to the fuel to keep the fire lit. The warm air that is allowed into the firebox also causes unspent flammable gases to be burned before they escape up the flue pipe.
Burning coals while using airwash
If you are burning smokeless or manufactured coals in a multi-fuel stove, you will need to leave the primary (bottom) vent open slightly in order to burn the fuel effectively. Coals burn best with an air supply from below, so it’s important not to fully close the vent.
Avoiding dirty stove glass
Whether burning wood or coal, if the secondary air vent is closed then the stove glass is likely to cover with soot. You just need to experiment to find the optimum level of air supply to ensure the airwash continues to function while still burning your fuel as efficiently as possible.
Remember, airwash helps to keep your glass clean but some build-up of soot is inevitable.
Finish the cleaning process with a spray of specialist stove glass cleaner.