Embodiments of the invention provide a ventilation system comprising a housing. The housing includes an inlet through which air is received and the housing is capable of being installed within a structure. A ventilating assembly can be supported within an interior of the housing. The ventilating assembly can be operable to generate a flow of air and can be in fluid communication with the inlet. The system can include a thermal damper assembly comprising an aperture and a substantially non-metallic curtain. The damper assembly is capable of being coupled to the housing so that the aperture of the thermal damper assembly and the inlet of the housing are in fluid communication with each other. In some embodiments, the thermal damper assembly is configured and arranged to be uncoupled from the housing after the housing has been installed within the structure to provide access to the interior of the housing.