Tie Duct Detectors to Sprinkler Monitoring Panel?

11/26/2025

We are completing a buildout for a spec suite; the shell warehouse building was just constructed and has a fire sprinkler supervising panel.

The fire department is saying we have to tie the duct detector into the fire alarm panel. This building does not have fire alarm, only sprinkler monitoring.

Are they correct in saying we have to tie in the duct detector?

Thank you!

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6 Comments

Brett

11/26/2025 08:18:10 am

Short answer - it's open to what the AHJ interprets
"fire alarm system" to mean across multiple documents.

Long answer:

The sprinkler monitoring system is defined in NFPA 72 as a dedicated function fire alarm system so it is not a building fire alarm system as you pointed out.

NFPA 90A requires duct detectors to monitored if the building has an approved fire alarm system. To me, this means building fire alarm system and not just a dedicated function fire alarm system but it isn't spelled out explicitly like that.

IBC/IFC 907.3.1 requires duct smoke detectors to be monitored, but with two exceptions (summarized below - not copied word for word):

1. Supervisory signal is not required if the duct detector activates fire alarm notification in the building.
2. If there is no fire alarm system, the duct detector has to activate a visible and audible signal in an approved location.

The IBC/IFC defines fire alarm system differently than NFPA 72 does, so this is again open to interpretation. My interpretation is that it means building fire alarm system as defined in NFPA 72, but your AHJ may interpret it differently.

So, the IBC/IFC will most likely be the driving factor here since at minimum a visible/audible signal is required in an approved location and don't forget that "approved" is also a defined IBC/IFC term.

I work for a fire sprinkler / alarm contractor and we include monitoring of duct detectors when we do sprinkler monitoring systems. There is a strong argument for local visible/audible signal only but it's simply not worth the argument from our perspective.

Glenn Berger

11/26/2025 08:26:33 am

Concur with Brett's response.

You may want to check the archives here -- I think that there was a very similar question asked recently.

Scott McCormick

11/26/2025 08:32:26 am

If in an I Codes town, they are wrong. A fire sprinkler monitoring system is Not a Fire Alarm System. The Code States, "Duct Detectors Must Be Tied into the Building Fire Alarm SYSTEM" Fire sprinkler monitoring is a dedicated system and not a fire alarm system

Paul Pinigis link

11/26/2025 08:40:20 am

While it’s a reasonable idea, it’s not a code requirement. Since you done have a fire alarm system, you don’t have to tie accessory monitoring into anything.

chad

11/26/2025 09:10:15 am

This one is a bit of a gray area

2019 NFPA 72

23.3.3.2* Dedicated Function Fire Alarm Systems.
23.3.3.2.1

In facilities without a building fire alarm system, a dedicated function fire alarm system shall be permitted and shall not be required to include other functions or features of a building fire alarm system.

This section strongly infers that you do not, but does not call out duct smokes specifically.

23.8.2.3

Where the building is not served by a building fire alarm system, independent dedicated function fire alarm systems and/or releasing fire alarm systems shall not be required to be
interconnected to function as a single system.

This section specifically excluded releasing panels.

But I also agree its AHJ interpretation. And its worth doing, IMO.

Greg Collier

12/3/2025 10:26:00 am

They should be saying that the Duct detectors will require audible supervisory signal at a constantly attended location.

We sometimes (usually) see them supervised by the FACU or the FACP rather than installing the visible and an audible signal in an approved location referenced in exception #2

With that said, a bit of wire and programed supervisory signal is pretty easy...

IBC 2021 - 907.3.1 Duct smoke detectors.

Excerpt:

Activation of a duct smoke detector shall initiate a visible and audible supervisory signal at a constantly attended location and shall perform the intended fire safety function in accordance with this code and the International Mechanical Code. In facilities that are required to be monitored by a supervising station, duct smoke detectors shall report only as a supervisory signal and not as a fire alarm.

Exceptions:

1.The supervisory signal at a constantly attended location is not required where duct smoke detectors activate the building's alarm notification appliances.

2.In occupancies not required to be equipped with a fire alarm system, actuation of a smoke detector shall activate a visible and an audible signal in an approved location. 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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Tie Duct Detectors to Sprinkler Monitoring Panel?

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