Trusted Integration: CET Gas Detection + Ventilation Fans for Safer, Smarter Buildings

In today's energy-conscious and safety-focused building designs, integrating gas detection systems with ventilation fans is no longer optional—it's essential. Whether in parking garages, mechanical rooms, or spaces using refrigerant-based HVAC systems, this partnership plays a critical role in maintaining air quality, protecting occupants, and optimizing energy use.

Gas detection systems continuously monitor the air for harmful gases such as carbon monoxide (CO), nitrogen dioxide (NO2), and refrigerants. When these gases reach predefined thresholds, the system triggers ventilation fans to respond accordingly. This interaction ensures that contaminated air is quickly diluted and expelled, restoring safe conditions.

CET's gas detection systems integrate effortlessly with a wide range of ventilation fans, including models from Greenheck, Cook and many more. By pairing CET detectors with compatible fans, you create an intelligent, energy-efficient ventilation solution that enhances safety while reducing operational costs. The system activates fans only when necessary, optimizing energy use.

Fan operation is controlled via variable speeds using 0—10 VDC signals or relays, depending on specific application needs.

CET Outputs:

• SPDT dry contact relays (up to 5A @ 240VAC) for direct fan control
• Analog outputs (0—10 VDC or 4—20 mA) for variable speed control
• Digital communication via BACnet MS/TP or Modbus RTU for integration with BMS.

Fan Inputs:

• EC Motors with 0-10 VDC on-demand speed control
• Motor starters for relay-based control and overload protection
• Controlled via BACnet-compatible BMS systems for centralized scheduling and monitoring.
• Quick-connect terminal strips for control and power wiring.

Wiring Examples:

• CET controller relay output -> Fan motor starter or control panel.
• CET analog output -> EC motor input (0—10 VDC).
• CET BACnet output -> BMS -> Fan control logic.

Sequence of Operations:

1. Normal Conditions

• Continuously monitor for CO, NO2 or refrigerants.
• Gas below alarm thresholds.
• Fans off or low speed for baseline ventilation.

2. Low-Level Alarm Triggered

• Gas levels reach the low alarm threshold.
• Detector sends 0—10 VDC signal/relay output to fan system.
• Fans ramp up to low-speed operation to ventilate.
• Alarm status logged/optionally sent to BMS.

3. Mi-Level Alarm Triggered

• Gas increases to the mid alarm threshold.
• Gas detector increases fan speed.
• Fans ramp up to medium speed.
• Visual/audible alarms alert depending upon configuration.

4. High-Level Alarm Triggered

• Gas concentration reaches the high alarm threshold.
• Gas detector sends a max. output signal or activates internal relay(s).
• Fans run at full speed for rapid ventilation.
• Emergency protocols may be triggered (e.g., evacuation, shutdowns).

5. Gas Levels Normalizes

• Gas concentrations fall below alarm thresholds.
• Gas detector initiates purge timer to ventilate.
• Fans return to baseline operation or shut off.
• System resets and resumes monitoring.

Scheduled Operation (Optional)

• Controller or BMS can schedule fan operation during peak hours.
• Programmable overrides for maintenance/manual control. CET gas detection systems are built for seamless interoperability and proven through hundreds of successful partner projects. With over 30 years of experience, we deliver integration that works—streamlining workflows, and ensuring our products work together effortlessly.

The result: reliable, scalable solutions that drive success and customer confidence every time.