# Air Handler Shutdown



## Michael Brown (Aug 27, 2018)

I am seeing more and more engineers interlocking apartment A/C systems with their local smoke alarms so that the systems are shut off should the smoke detector sound the alarm.  I've been looking around and have not been able to find any code references other than the IMC requirement for systems above 2000 cfm.   Does anyone out there know where this requirement is coming from?


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## cda (Aug 27, 2018)

Shutting down individual units

Or the big ones??

The smoke alarms in the units??


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## Michael Brown (Aug 27, 2018)

cda said:


> Shutting down individual units
> 
> Or the big ones??
> 
> The smoke alarms in the units??



 Shutting down the small units (600-800 cfm average)  in each individual apartment when that apartment's smoke alarm goes off.


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## chris kennedy (Aug 27, 2018)

Michael Brown said:


> Shutting down the small units (600-800 cfm average)  in each individual apartment when that apartment's smoke alarm goes off.


Do they have outside air intakes?


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## classicT (Aug 27, 2018)

May not be based upon a code requirement. Could be owners wanting to limit smoke damage within an individual unit.

Would also keep tenants from messing with the smokies since it would shut down the HVAC.


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## cda (Aug 27, 2018)

Michael Brown said:


> Shutting down the small units (600-800 cfm average)  in each individual apartment when that apartment's smoke alarm goes off.




Have not seen or heard of it.

I wonder how the smoke alarm
Talks to the a/c?

Seems like there would be a language barrier???


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## chris kennedy (Aug 27, 2018)

cda said:


> Have not seen or heard of it.
> 
> I wonder how the smoke alarm
> Talks to the a/c?
> ...


The smoke alarm manufactures have listed relays available for just such applications. Opens the 24V control wiring to the AHU.


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## cda (Aug 27, 2018)

chris kennedy said:


> The smoke alarm manufactures have listed relays available for just such applications. Opens the 24V control wiring to the AHU.




Unit stand alone smoke alarms??

Or are you talking a system smoke detector


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## chris kennedy (Aug 27, 2018)

I believe we are talking interconnected smoke ALARMS in a dwelling unit. Relays are available to accomplish many functions (F/A notification common in multi family) including AC shut down. If no outside air intake I don't see the point but I don't do dwelling units.


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## Michael Brown (Aug 27, 2018)

chris kennedy said:


> Do they have outside air intakes?



They do not. I was thinking the same thing but I looked back at the drawings and there are none.


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## Michael Brown (Aug 27, 2018)

cda said:


> Unit stand alone smoke alarms??
> 
> Or are you talking a system smoke detector



Unit smoke alarms. Not duct mounted.


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## Michael Brown (Aug 27, 2018)

Ty J. said:


> May not be based upon a code requirement. Could be owners wanting to limit smoke damage within an individual unit.
> 
> Would also keep tenants from messing with the smokies since it would shut down the HVAC.



I’m thinking that may be it.


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## rgrace (Aug 29, 2018)

Actually, I think it is because of language contained in the 2015 IMC, Section 607.3.1 which added "ceiling radiation dampers" in its requirement to be labeled for use in dynamic systems. As far as I know, there are no ceiling radiation dampers labeled for such use, so this is the alternative.


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