Heres the language that was added to IMC 607.6.2.1. The first paragraph stayed the same, all this was added:
607.6.2.1.1 Dynamic systems. Ceiling radiation dampers installed in heating, ventilation and air-conditioning systems designed to operate with fans on during a fire shall be listed and labelled for use in dynamic systems.
607.6.2.1.2 Static systems. Static ceiling radiation dampers shall be installed only in systems that are not designed to operate during a fire.
Exceptions:
1. Where a static ceiling radiation damper is installed at the opening of a duct, a smoke detector shall be installed inside the duct or outside the duct with sampling tubes protruding into the duct. the detector or tubes within the duct shall be within 5 feet of the damper. Air outlets and inlets shall not be located between the detector or tubes and the damper. The detector shall be listed for the air velocity, temperature and humidity anticipated at the point where it is installed. Other than in mechanical smoke control systems, dampers shall be closed upon fan shutdown where local smoke detectors require a minimum velocity to operate.
2. Where a static ceiling radiation damper is installed in a ceiling, the ceiling radiation damper shall be permitted to be controlled by a smoke detection system installed within the same room or area as the ceiling radiation damper.
3. A static ceiling radiation damper shall be permitted to be installed within a room where an occupant sensor is provided within the room that will shut down the system.
There's a whole lot of issues with the new language, beginning with the fact that radiation dampers aren't even actually tested as static or dynamic. Then there's the whole issue of controlling them with duct smoke detectors or having the dampers close when the air handler fan is off, even just if it cycles off normally???? Radiation dampers have nothing to do with controlling smoke spread and aren't even motorized. They are a heat barrier and "controlled" by a fusible link. The third exception is just plain bizarre in that you shut down the air handler if the room is occupied????
Its like they are cobbling together a few code sections that apply to fire dampers and to smoke dampers, and mash them into one new section applied to radiation dampers. We'll probably end up amending this out and going beck to the 2018 language.