A refrigerant leak in a chiller plant room is an event that must be detected early in terms of personnel safety, refrigerant loss, and operating costs. The reference CETCI application illustrates an architecture with two infrared ART transmitters + QCC controller in a plant room housing two chillers.
The source application highlights that many refrigerant gases can behave as heavier than air and may accumulate in low-lying areas with low air movement close to the floor.
Why Use an Infrared Refrigerant Gas Sensor?
The reference document highlights that ART transmitters utilise infrared refrigerant sensors, offering the advantages of low maintenance requirements, long sensor service life, and accurate measurement at low concentrations. The specific refrigerant to be measured is the primary input for sensor selection.
Why Two Sensors for Two Chillers?
In the source example, two ART detectors are positioned to cover potential leak and gas accumulation zones around each chiller. The sensor quantity is evaluated not merely on a "two units = two sensors" logic, but to ensure coverage of leak sources and airflow patterns.
Mounting Height
For heavier-than-air refrigerant gases, the reference system exemplifies mounting ART transmitters approximately 10–18 inches above the floor. This height was selected both for proximity to the gas accumulation zone and for calibration/maintenance accessibility.
Automated Safety Scenario with QCC
The QCC is positioned externally, near the entrance. When a leak is detected, pre-defined relay scenarios—such as audible alarms, remote strobe/sirens, mechanical ventilation, and, if required, chiller shutdown—can be executed within the source architecture.
BAS Integration
The source QCC supports Modbus RS-485 communication in addition to analogue/digital transmitter inputs; the document specifies that BACnet MS/TP output can optionally be utilised for building automation system (BAS) integration.
Dual Chiller Plant Room Checklist
| Check | Rationale |
|---|---|
| Refrigerant type used | Correct sensor/calibration selection |
| Potential leak points | Sensor positioning |
| Low elevations and airflow | Capturing gas accumulation zones |
| Display outside entrance | Status check prior to entering the room |
| Fan and chiller interlock | Automatic action following alarm |
| BAS communication | Centralised monitoring and incident management |
Which Refrigerant Gas Detector Should Be Preferred for a Chiller Plant Room?
The selection of refrigerant directly determines the sensor technology. NOVEL's refrigerant gas detectors category includes diverse refrigerant leak detection solutions. In fixed plant room monitoring projects, target gas, anticipated leak concentration, sensor mounting height, centralised alarming, and BAS/BMS integration must be evaluated together. View Refrigerant Gas Detectors.
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Frequently Asked Questions
Where is a refrigerant gas sensor installed in a chiller plant room?
Taking into account the accumulation of heavy refrigerants close to the floor, the source example positions ART sensors at a height of approximately 10–18 inches above the floor.
What is the advantage of an infrared refrigerant sensor?
The reference document highlights the advantages of low maintenance requirements, long service life, and accurate measurement at low concentrations.
If there are two chillers, are two sensors mandatory?
Two ARTs are used in the source example. The actual sensor count is determined via engineering evaluation based on chiller count, leak points, room geometry, and airflow.
Can chillers be shut down automatically in the event of a gas leak?
In the source system, it is indicated that QCC relays can trigger pre-defined actions such as chiller shutdown and ventilation.
Can it be connected to a BAS system?
The reference document specifies BAS integration via Modbus RS-485 and, where required, BACnet MS/TP.
Why is the controller located outside the room?
It is positioned outside the entrance to allow verification of gas levels and alarm status before entering.
Reference and Technical Note
The application architecture and model-specific technical details in this article have been compiled from an application document provided by Critical Environment Technologies Canada Inc. . As source materials may be superseded, current product codes, certificates, measuring ranges, and local regulations must be independently verified prior to project design or procurement.
Author: NOVEL Technical Team
Publication date: 7 September 2026