Aside from other requirements, the Ontario Building Code waives the requirement for fire dampers if the duct serves air-conditioning or combined air-conditioning and heating units. Does anyone know why fire dampers are NOT waived if the duct serves heating only units?
Does NFPA have a similar relief for this situation?
18.104.22.168. Fire Dampers Waived
(1) Fire dampersneed not be provided in noncombustible branch ducts that have a melting point above 760°C and that penetrate a required fire separation provided the ducts,
(a) serve only air-conditioningunits or combined air-conditioning and heating units discharging air not more than 1 200 mm above the floor and have a cross-sectional area not more than 130 cm2.