Air Handling Unit Shutdown (Fire Alarm)

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Shujinko

Senior Member
Is there anywhere in code that requires A/C unit shutdown for the activation of any fire alarm initiating device type besides a duct smoke detector? I've looked but have not found anything besides the requirement of shutdown upon activation of a duct smoke detector. I'm trying to follow the requirements of the Florida Building Code in a Business type occupancy. Thanks for any help provided.
 

mgookin

Senior Member
Location
Fort Myers, FL
Any activation of a general alarm is required to shut down the air handler supplying a means of egress. Whether it's return air stream or supply is something you'll have to check (they flip flop constantly on that one) and another issue is size of tenant space being served. It should be in the FMC which you can access for free online at floridabuilding.org

http://www2.iccsafe.org/states/Florida_Codes/index.htm

ok I looked it up for you
SECTION 606 SMOKE DETECTION SYSTEMS CONTROL

606.1 Controls required.
Air distribution systems shall be equipped with smoke detectors listed and labeled for installation in air distribution systems, as required by this section. Duct smoke detectors shall comply with UL 268A. Other smoke detectors shall comply with UL 268.

Exception: Structures classified as R-3 occupancy type.

606.2 Where required.
Smoke detectors shall be installed where indicated in Sections 606.2.1 through 606.2.3 and NFPA 90A.

Exception: Smoke detectors shall not be required where air distribution systems are incapable of spreading smoke beyond the enclosing walls, floors and ceilings of the room or space in which the smoke is generated.


606.2.1 Supply air systems.
Smoke detectors shall be installed in supply air systems with a design capacity greater than 2,000 cfm (0.9 m3/s) in the supply air duct.

Exception: Smoke detectors are not required in the supply air system where the space served by the air distribution system is protected by a system of area smoke detectors in accordance with the Florida Fire Prevention Code. The area smoke detector system shall comply with Section 606.4.
606.2.2 Common supply, return air and supply air systems.
Where multiple air-handling systems share common supply or return air ducts or plenums with a combined design capacity greater than 2,000 cfm (0.9 m3/s), the return air and supply air system shall be provided with smoke detectors in accordance with Section 606.2.1.

Exception: Reserved.
606.2.3 Return and supply risers.
Where return air and supply air risers serve two or more stories and are part of a return air and supply air system having a design capacity greater than 15,000 cfm (7.1 m3/s), smoke detectors shall be installed at each story. Such smoke detectors shall be located upstream of the connection between the return air riser and any air ducts or plenums and between the air supply source and the first branch or take-off to the areas served.
 

Shujinko

Senior Member
Mgookin, my question is if a manual pull station or smoke detector are activated, where in code does this require A/C shutdown? I don't think your code citations address this. That code citation does not state that in general alarm the a/c units should be shut down. I'm confused.
 

xformer

Senior Member
Location
Dallas, Tx
Occupation
Master Electrician
Is there anywhere in code that requires A/C unit shutdown for the activation of any fire alarm initiating device type besides a duct smoke detector? I've looked but have not found anything besides the requirement of shutdown upon activation of a duct smoke detector. I'm trying to follow the requirements of the Florida Building Code in a Business type occupancy. Thanks for any help provided.

I would say look at 760.1
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Mgookin, my question is if a manual pull station or smoke detector are activated, where in code does this require A/C shutdown? I don't think your code citations address this. That code citation does not state that in general alarm the a/c units should be shut down. I'm confused.

Per the model IBC, no. YMMV based on local amendments. Also, typically the duct smoke detectors are supposed to report as supervisory devices, not alarm devices. They are not meant, based on the national codes as written, to evacuate the building. Again, local AHJ's may feel differently and amend accordingly.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Your Milage May Vary. A humorous way of making a disclaimer to go with generalizations.

The reason for shouting down the ventilation when smoke is detected in the ducts may not be present when other sensors or a manual pull station is activated.

Tapatalk!
 
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gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Your Milage May Vary. A humorous way of making a disclaimer to go with generalizations.

The reason for shouting down the ventilation when smoke is detected in the ducts may not be present when other sensors or a manual pull station is activated.

Tapatalk!

I had a brief visual of you yelling into a 24" square duct, trying to make the fan shut down! :lol:
 

kwired

Electron manager
Location
NE Nebraska
Your Milage May Vary. A humorous way of making a disclaimer to go with generalizations.

The reason for shouting down the ventilation when smoke is detected in the ducts may not be present when other sensors or a manual pull station is activated.

Tapatalk!

Shouting may or may not work, but IMO we need to shut down air supply in any fire situation so we are not supplying more air to the fire. One exception is cooking hoods and associated ducting, keeping the fan running in those instances usually means keeping the fire contained to the duct.
 

mgookin

Senior Member
Location
Fort Myers, FL
Mgookin, my question is if a manual pull station or smoke detector are activated, where in code does this require A/C shutdown? I don't think your code citations address this. That code citation does not state that in general alarm the a/c units should be shut down. I'm confused.

My mistake. Sorry and thanks to those who caught it.
 

RICK NAPIER

Senior Member
Location
New Jersey
These are the usual requirements from the 2012 IMC.

SECTION 606 SMOKE DETECTION SYSTEMS CONTROL

606.1 Controls required.
Air distribution systems shall be equipped with smoke detectors listed and labeled for installation in air distribution systems, as required by this section. Duct smoke detectors shall comply with UL 268A. Other smoke detectors shall comply with UL 268.

606.2 Where required.

Smoke detectors shall be installed where indicated in Sections 606.2.1 through 606.2.3.

Exception:
Smoke detectors shall not be required where air distribution systems are incapable of spreading smoke beyond the enclosing walls, floors and ceilings of the room or space in which the smoke is generated.

606.2.1 Return air systems.

Smoke detectors shall be installed in return air systems with a design capacity greater than 2,000 cfm (0.9 m3/s), in the return air duct or plenum upstream of any filters, exhaust air connections, outdoor air connections, or decontamination equipment and appliances.

Exception:
Smoke detectors are not required in the return air system where all portions of the building served by the air distribution system are protected by area smoke detectors connected to a fire alarm system in accordance with the International Fire Code. The area smoke detection system shall comply with Section 606.4. 606.2.2 Common supply and return air systems.
Where multiple air-handling systems share common supply or return air ducts or plenums with a combined design capacity greater than 2,000 cfm (0.9 m3/s), the return air system shall be provided with smoke detectors in accordance with Section 606.2.1.

Exception:
Individual smoke detectors shall not be required for each fan-powered terminal unit, provided that such units do not have an individual design capacity greater than 2,000 cfm (0.9 m3/s) and will be shut down by activation of one of the following:1. Smoke detectors required by Sections 606.2.1 and 606.2.3.2. An approved area smoke detector system located in the return air plenum serving such units.3. An area smoke detector system as prescribed in the exception to Section 606.2.1.

In all cases, the smoke detectors shall comply with Sections 606.4 and 606.4.1.606.2.3 Return air risers.
Where return air risers serve two or more stories and serve any portion of a return air system having a design capacity greater than 15,000 cfm (7.1 m3/s), smoke detectors shall be installed at each story. Such smoke detectors shall be located upstream of the connection between the return air riser and any air ducts or plenums. [F] 606.3 Installation.
Smoke detectors required by this section shall be installed in accordance with NFPA 72. The required smoke detectors shall be installed to monitor the entire airflow conveyed by the system including return air and exhaust or relief air. Access shall be provided to smoke detectors for inspection and maintenance.

[F] 606.4 Controls operation.

Upon activation, the smoke detectors shall shut down all operational capabilities of the air distribution system in accordance with the listing and labeling of appliances used in the system. Air distribution systems that are part of a smoke control system shall switch to the smoke control mode upon activation of a detector.

[F] 606.4.1 Supervision.

The duct smoke detectors shall be connected to a fire alarm system where a fire alarm system is required by Section 907.2 of the International Fire Code. The actuation of a duct smoke detector shall activate a visible and audible supervisory signal at a constantly attended location.

Exceptions:
1. The supervisory signal at a constantly attended location is not required where the duct smoke detector activates the building?s alarm-indicating appliances.2. In occupancies not required to be equipped with a fire alarm system, actuation of a smoke detector shall activate a visible and audible signal in an approved location. Duct smoke detector trouble conditions shall activate a visible or audible signal in an approved location and shall be identified as air duct detector trouble.
 
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