Flues in Voids
From January 2013 Gas Safety inspections must include visual inspections of gas flues every 1.5 metres or at bends in the flue. To comply, hatches will have to be fitted to enable the engineer to inspect the flues.
A gas flue is the flue/pipe which takes the waste from a gas boiler to the outside. If the flue has a break in it or your boiler is not operating correctly, carbon monoxide could enter the property.
If the engineer cannot access the flue it will fail the gas safety inspection and you will be responsible for any eventual risk which could result in a serious incident. The penalties for injury or death are a fine and/or imprisonment.
Flues can be concealed. In blocks of flats the flues can pass through flats above before eventually venting to the outside.
You do not have a flue in a void if the boiler is fitted to an external wall and directly vented out to the outside. You would be clearly able to see a grille with a vent immediately on the outside of the building.
If you are not sure if you have a flue in a void: