COMBUSTION AIR
Obviously, when burning hydrocarbon fuel the chemistry requires available oxygen, from air - other makes require "airbricks" to supply air to the appliance... a non-sense when you have built or refurbed your home to a "Super Green Eco standard", the last thing you wish to do is leave cold air in and lessen the thermal efficiency of your home. Vintage has improved on this principle by drawing combustion air directly from outside to the burners.
This has several major benefits; increasing combustion efficiency, as cold outside air contains a higher percentage of oxygen, enables you to, should you wish, install an extractor fan above the cooker for removal of steam and fumes, this does not affect the operation of the burners, as is the case with other makes and of equal importance it renders the running sound of the burners, to a low background level (the gas burners are virtually silent). I originally applied this design principle to Heritage.