Most appliances installed in commercial kitchens under canopy systems are designed to operate without a flue (Type A, as described in CEN CR 1749). Others would normally require connection to a dedicated flue system (Type B, as described in CEN CR 1749) e.g. some types of convection ovens and deep fat fryers. Due to the possible adverse effect on flue performance, particularly in those kitchens with powerful mechanical ventilation systems installed, many manufacturers permit the installation of type B appliances without the use of the flue, but under a canopy. Therefore, the canopy/extraction system is performing the same function as a flue system. Regulation 27(4) of the Gas Safety (Installation & Use) Regulations (GSIUR)deems this as a “power operated flue” system and requires an interlock, which will shut off the gas supply to such a appliance in the event of an air mov