We cannot think of any current model stove, certainly none that that The Stove Yard sell, which does not feature an Airwash System to help keep the glass clean. Some manufacturers have given their Airwash Systems their own fancy names – but don't be confused, they are all essentially the same thing with the Secondary Air and the Airwash being one and the same 'system'. When you control the Secondary Air you are effectively controlling the Airwash.
The Airwash function is generally delivered by Secondary Air (top air) diverted down along the front of the glass by means of a baffle (not to be confused with the baffle plate). You can clearly see this baffle in the photo of the Dunsley Highlander 5 (below) which runs along the top of the entrance to the fire chamber. The air is heated as it is drawn inside the fire chamber to feed the fire and as it does this it is sent over the top of the baffle and drawn down along the front of the hot glass to 'wash' away any dry particulates which have settled there during the early stages of the fire cycle.
What an airwash system won't do however, is remove any sticky tars from the glass which are derived from burning unseasoned wood (wood with a moisture content of more than 20%) or prohibited fuels such as plastics. Wet wood introduces moisture into the fire chamber, consequently dropping the fire chamber temperature, which in turn further reduces the effectiveness of the airwash system. Long periods of slumber burning could also affect the airwash system's performance.
As a wood fuel load is burned away then the heat output is naturally reduced and again this limits how well the Airwash System will perform. This is most noticeable when you return to the stove the next day when most stoves will suffer from some minor sooting at the bottom of the glass as the fire has died down. This is perfectly normal and if the wood you have used is properly seasoned then you should be able to easily remove this soot with some kitchen roll or newspaper without the need for a proprietary stove glass cleaner.
Most multi fuel stove manufacturers recommend only using approved smokeless mineral fuels when not burning wood in their stoves and therefore the Secondary Air / Airwash System should not be needed. These smokeless fuels should be naturally cleaner burning and, because they are not wood, do not therefore require a supply of Secondary Air from the top, instead relying on the Primary Air from beneath the grate to combust efficiently.