Here are some bullet points that may be helpful concerning Duct Detectors.

1. Often a duct smoke detector will come with the RTU Roof Top Unit and not all duct smoke detectors have to be tied into the fire alarm system. If the RTU units are under 2000cfm then often the duct detectors are not connected.

2. When a roof top unit is over 2000cfm it normally requires 1 duct detector and if the RTU is over 15000 cfm then most of the time it will require a duct detector on supply and return.

3. Duct Detectors or Induct Detectors often will required when you have fire smoke dampers. The fire alarm contractor can connect to existing duct detectors to monitor them and when needed the fire alarm contractor can monitor if the duct detector goes into alarm or if the damper is open or closed and with relays the fire alarm contactor can provide a relay output to do global shutdown of all the RTU units or you can just shut down the one unit.

4. Duct Detectors can be zoned (Conventional) or they can be addressable.

5. Duct Detectors can be low voltage 24V or high voltage 120V/240V

6. Duct Detectors can be 2 wire or 4 wire detectors.

7. Some duct detectors come with a relay for fan shut down and others don’t

8. What you don’t want happening is air being brought in during a fire so the RTU air handlers will shut down. Smoke Control systems are different, they allow the fire department to move smoke in or out of areas depending on the needs at the time.

9. Much of the time a RTS Remote Test Switch is required down where they can be seen and these switches can come with LED lights or with a key switch depending on what you need to accomplish.

10. Most Duct Detectors come with a set of tubes that will allow smoke to be drawn in via holes in the tubes and then it goes through the housing and back out another tube. The tubes need to be ordered to the correct size for the duct.

11. Often Induct Detectors will not require the long tubes.

12. Some Duct Detectors come with the smoke head and others just come with the housing and the smoke head needs to be ordered separately. On zoned or conventional duct detectors you can have an addressable module tied to the duct detector or if the alarm zone goes to the fire panel directly it can be monitored by an alarm zone on a conventional zoned panel.

13. Some duct detectors are mounted inside under the roof and others are mounted inside the RTU rooftop air handlers and others are mounted on the outside of the units.

14. Most Duct Detectors can be tested with a magnet although it is not a UL listed approved method of testing so have your fire alarm company test them properly as per the manufactures instruction.

15. Besides needing to be tested periodically Duct Detectors need to be cleaned as well as the long and short tubes that need to be cleaned. Open the housing and take out the smoke head, clean the head and the housing. Canned air is a good method for cleaning the housing and for the smoke head use the appropriate method as per the manufacturer.

16. Here at Johnson Controls Fire Protection we have Simplex Duct Detectors and we can help with the projects where you would coordinate with the HVAC contractor and the Electrical Contractor to get them hooked up and with us to have them programmed, tested and certified.

    Call Larry Love Larry.Love@jci.com 801 898 6003 for more information or with corrections

17. Larry Love works for Johnson Controls Fire Protection. Larry is a NICET level 2 in fire alarm and has been in the industry for 28 years+.

    Duct Detector 4098-9755 and the Remote Test Switch is 2098-9806 this is for use on Simplex Fire Alarm Systems. The 4098-9858 is a 71 inch tube.

18. In duct sensor housing with relay model numbers are 4098-9750, 4098-9714 smoke head and 2098-9806 for the remote test switch.

19. We also do VESDA systems, Mass Notification, Voice Evacuation, Fire Alarm, Area of Refuge systems, TWV Two Way Voice and our security division does Cameras, Keyless Entry Access Control and Security Intrusion systems.