The Brand Story
System Sensor: The Quiet Sentry Inside the Ductwork
In a commercial building, the air handler is the lungs. It pulls air from every floor, conditions it and pushes it back out through miles of duct. That is exactly what makes it dangerous in a fire. Left running, a rooftop unit can take smoke from one smoldering room and deliver it to every office on the floor. The device that prevents that is small, gray and easy to overlook: a duct smoke detector bolted to the side of the ductwork, sampling the airstream and waiting for the moment it needs to shut the fan down. System Sensor has spent four decades building devices like that one.
Chapter 1 · 1984
A company built around one job: detection
System Sensor was founded in 1984 as a manufacturer of fire and life safety devices, and it has stayed close to that mission ever since. Its catalog covers smoke detection, carbon monoxide detection and notification: the horns, strobes and speakers that tell occupants to leave. The company is based in St. Charles, Illinois, west of Chicago, and today it is part of Honeywell's building technologies business.
That focus matters to HVAC contractors because fire safety and air distribution meet at the duct. Building and mechanical codes commonly require smoke detection on larger air handling systems so that the fan can be shut down when smoke is detected, and System Sensor's HVAC duct detectors are designed to tie into both the air handler's controls and the building's fire alarm system.
Chapter 2
Sampling the airstream
A duct smoke detector does not sit in the middle of the duct. It mounts on the outside, and a sampling tube, cut to the width of the duct and drilled with inlet holes, reaches across the airflow. Moving air enters the tube, passes through the detector's sensing chamber and returns to the duct through a shorter exhaust tube. When smoke is present, the detector trips relays that can stop the fan, close dampers or report to a fire alarm panel.
System Sensor's Innovair Flex family was built around that idea with installation in mind, and the accessories that surround it, such as remote test stations, annunciators, relays and replacement tubes, are what turn a single detector into a working, testable system.
The Lineup
What System Sensor builds today
System Sensor makes smoke detectors, carbon monoxide detectors, beam detectors, horns, strobes, speakers, relays and modules for commercial fire alarm systems. The pieces HVAC365 carries are centered on the duct:
- Duct smoke detectors: the D4120 and DUCTSD low-flow detectors, the 2D51 detector for low-flow applications, and the D4P120 power board component.
- Sampling and exhaust tubes: DST1 Innovair Flex sampling tubes, ETX exhaust tubes and P48-21-00 end caps for metal sampling tubes.
- Remote indicators and notification: the APA151 remote annunciator, the AOS add-on strobe and the MHW mini horn, which let a detector hidden above a ceiling report where people can see and hear it.
- Relays and installation parts: the PR-1 multi-voltage relay for interlocking with fans and dampers, and conduit accessories such as the A2440-00.
At a Glance
System Sensor in brief
- Founded
- 1984
- Location
- St. Charles, Illinois
- Parent company
- Honeywell
- Focus
- Fire and life safety devices
- HVAC product
- Innovair Flex duct smoke detectors
- Other lines
- CO detection, horns and strobes
Questions
Frequently asked questions about System Sensor
Who owns System Sensor?
System Sensor is part of Honeywell and sits within Honeywell's building technologies business.
When was System Sensor founded?
System Sensor was founded in 1984 as a manufacturer of fire and life safety devices, and is based in St. Charles, Illinois.
What does a duct smoke detector do?
A duct smoke detector samples the air moving through an HVAC duct and, when it senses smoke, signals the system to shut down the fan or close dampers so smoke is not spread through the building.
Why does the sampling tube length matter?
The sampling tube has to reach across the width of the duct so it draws air from the full airstream. Tubes are sold in set lengths and cut to fit the duct being protected.
What is a remote annunciator used for?
Duct detectors are often hidden above ceilings or on rooftops. A remote annunciator shows the detector's status in an accessible spot, so alarms and trouble conditions can be seen and the detector can be tested.
