fire dampers

[John Bosyj]

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?

3.1.8.8. 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.

 

[ChasBean1]

It sounds like a matter of semantics to me. Whether it’s heated or cooled air should not factor into fire stopping. It says to me that a ~5” by 5” duct or smaller should not require a fire damper at a rated penetration.