Ducted air circulation systems in dwellinghouses with storeys over 4.5 m

In a dwellinghouse with a storey more than 4.5 m above ground level, any system of ducted air circulation should – (a) not be fitted with transfer grilles between any room and a protected stairway; (b) not have supply and return grilles more than 450 mm above floor level; (c) where air is ducted to a protected stairway – have the return air ducted back to the heater; (d) where a duct passes through the enclosure to a protected stairway – have the joints between the duct and the enclosure fire-stopped; and (e) where warm air heating is ducted – have a thermal cut out with maximum setting of 27ºC, which turns off the heater and any circulation fan if the ambient temperature exceeds that setting.