# Static and dynamic radiation dampers



## klarenbeek (Apr 2, 2020)

Just got the new 2021 IMC and found that the static/dynamic requirements for fire dampers have been extended to radiation dampers as well. After doing some checking online, it appears that all ceiling radiation dampers are static, no dynamic.  In fact, the specs for them don't even address the issue. I just found some information/discussion that they are ALL static only.  The problem is I most often see them in apartment dwelling units, where the furnaces do not shut down in the event of a fire. Does anyone have any more info on this?


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## tmurray (Apr 2, 2020)

Same situation as you, the only ones I have seen are static only.


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## klarenbeek (Apr 3, 2020)

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.


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## rgrace (Apr 7, 2020)

FS64-18, as modified by committee. This is a good example why it is important to get involved with the code development process. This is broken and needs to be fixed. Code change proposals for this 2024 IMC/IBC section are due by January 11, 2021. I would be happy to work offline with anyone willing to take a stab at this


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## steveray (Apr 7, 2020)

Seems easier and smarter to just shut the unit down on detection......Problem solved?


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## klarenbeek (Apr 7, 2020)

At first glance shutdown seems like a good option, until you stop and think of some of the most common places radiation dampers are  .  The majority I see are on small residential style systems in apartments or on bathroom exhaust fans in either apartments or hotels, places where there is no requirement for shutdown. Not even sure how you would do that on an 80 CFM bath exhaust fan. 
Then there's the whole question of whether shutdown is even needed, since from what I'm hearing radiation dampers aren't even tested for static or dynamic standards


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## steveray (Apr 7, 2020)

Code section does not require static ones to be listed or tested it would appear....Relays or something will make it work I am sure....Or the damper industry is going to make a lot more money selling dynamic product...


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## rgrace (Apr 7, 2020)

steveray said:


> Seems easier and smarter to just shut the unit down on detection......Problem solved?



We tried to keep it simple by adding the following technical amendment to our codes:

*717.6.2.2 Equipment shutdown. *Where ceiling radiation dampers are listed as static dampers, the HVAC equipment shall be effectively shut down to stop the airflow prior to the damper closing using one of the following methods:

1. A duct detector installed in the return duct.
2. An area smoke detector interlocked with the HVAC equipment.
3. A listed heat sensor installed in the return duct.

We have plenty of time before we go through the 2021 code adoption process to decide what we want to do with this 2021 language


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## Paul Sweet (Apr 7, 2020)

The IMC wording sounds like you would need a smoke detector for every ceiling diffuser. $$$$!, especially when duct detectors are used.

Rgrace's amendment makes more sense.  The main problem is that smaller residential systems usually just have a central return grille, and it is often on the return plenum.


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## Shaun Ray (Aug 11, 2020)

The 2021 IMC Exceptions added to *607.6.2.1.2 Static systems *stemmed from similar changes proposed to the 2021 IBC.  At the time, the proponent noted that there were *no* existing dynamic ceiling radiation dampers on the market to meet the language of the 2015 and 2018 IMC/IBC pertaining to dynamic ceiling radiation dampers (DCRDs).  However, the market now has DCRDs available and more will certainly be coming to compete and reduce the product cost.  DCRDs provide a simple solution (no electronics or sensors) to ensure compliance with Code.  

A detector at the return air that can control a central fan to shut down during a fire event has been discussed.  However, detection within 5 feet of each ceiling damper is specified in the Code.  Specific ceiling designs contained in UL's fire resistance directory are all (with exception of ceiling design M557) tested under fully "static" conditions.  Providing detection at the return air of an air handler could be considered an improvement, however the time it takes for the air handler to shut down after a fire occurs in an adjacent room will likely not equate to the critical test standards of a UL263 fire exposure to a ceiling that has only been evaluated under static conditions.


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## Shaun Ray (Sep 17, 2020)

rgrace said:


> FS64-18, as modified by committee. This is a good example why it is important to get involved with the code development process. This is broken and needs to be fixed. Code change proposals for this 2024 IMC/IBC section are due by January 11, 2021. I would be happy to work offline with anyone willing to take a stab at this



I would be glad to work with you on clarification of code language for the 2024 edition as it pertains to dynamic ceiling damper usage.  You can contact me at shaunr@mtlfab.com.


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