These WAUs can have asbestos material within the unit as a small vertical panel at the side of the heat unit or a horizontal sheet lower down above the plenum chamber or as rope or putty on the duct or flue pipe. And these will tend to be the more hazardous AIB.
Some may have none within but a panel on the cupboard door or ceiling - again AIB
It really depends on the model, and installation crew or area of the UK
The duct work is invariably metal with glass fibre wool wrap and no asbestos, but sometimes an outer casing used to hide the duct can be AIB
Some may have none within but a panel on the cupboard door or ceiling - again AIB
It really depends on the model, and installation crew or area of the UK
The duct work is invariably metal with glass fibre wool wrap and no asbestos, but sometimes an outer casing used to hide the duct can be AIB