ACI-CO2-Room

Supported Applications

The ACI Carbon Dioxide Room Series (A/CO2-R2) monitors carbon dioxide (CO2) levels in commercial, school, and office-type environments. The device measures CO2 concentration as an indication of overall indoor air quality for building climate control applications. Data from the transmitter can be used with Building Automation Systems or Demand Control Ventilation to optimize energy consumption while maintaining a healthier indoor climate.

Operating Conditions & Performance

The series utilizes single-beam, non-dispersive infrared (NDIR) sensing technology via diffusion. The default measurement range is 0 to 2,000 ppm, with factory-set extended ranges available up to 10,000 ppm. Accuracy for the standard range is +/- 40 ppm and +/- 3% of reading (@ 15-35°C; 20-70% RH and 101.3 kPa). For extended CO2 ranges, accuracy is specified as +/- 30 ppm and +/- 5% of reading.

Operating conditions span an ambient temperature range of 32 to 122°F (0 to 50°C) with a humidity rating of 0 to 95%, non-condensing. The response time is less than 2 minutes via diffusion, and the warm-up time is less than 1 minute (< full specs < 15 minutes). Accuracy is defined after minimum three (3) ABC periods (1 period = 8 days) of continuous operations.

Power supply requirements are 24 VAC +/-20%, 50/60 Hz (half-wave rectifier) or 16.5-40 VDC maximum. Power consumption is 3 VA for 24 VAC, and 3W for 24 VDC (peak); <0.9W (average). The device features polarity protection as a fail-safe mechanism.

Configuration Options

The series offers configurable outputs, sensor options, and control signals to accommodate specific integration needs:

• Analog Outputs: Output 1 provides 0-5 VDC or 0-10 VDC (Default); Output 2 provides 4-20 mA with a maximum load of 500 Ohm. The 4-20mA output requires 3 wire.
• Sensor Options: Thermistor temperature outputs are available, including options such as 1.8K, 3K, AN (Type III), CP (Type II), and others listed in the ordering grid.
• Control Signals: Configurations include setpoint indication and override signals via screw terminal blocks for controller analog inputs or dry contact overrides.
• Housing & Mounting: The enclosure is ABS, Plastic, White (UL94-HB) with dimensions of 4.50" height x 2.75" width x 1.12" depth. Recommended mounting height is 4-6 ft for a sensor coverage area maximum of 7,500 sq. ft.
• Calibration: The series includes ABC (Automatic Baseline Correction) software to eliminate manual calibration. Note that building CO2 levels must drop to 400 ppm at some time during the week for ABC to function; if occupied 24 hours/day, ABC must be turned off.

Key Product Differences

The series is distinguished by configuration codes that define specific capabilities:

• R2: Standard Room transmitter with CO2 outputs (0-5 VDC, 0-10 VDC, or 4-20 mA).
• R2O: Room configuration with Override signal.
• R2S: Room configuration with Set Point indication.
• R2SO: Room configuration with both Set Point and Override signals.

Temperature sensor options (e.g., 1.8K, 3K, AN, CP) are appended to the model number based on specific controller compatibility requirements. Slidepot configurations allow for various direct-acting or reverse-acting resistance ranges (e.g., A01: 0 to 100K Direct Acting). Custom calibration gas options are available via ACI Technical Support.