Therm-Flexible-Ave

Supported Applications

The ACI Thermistor Flexible Averaging Sensors are multi-point temperature sensors designed for use with electronic controllers in commercial heating and cooling building management systems. The series provides a better average temperature of the air inside ducts compared to single point duct sensors.

• Ducted HVAC applications requiring averaged air temperature measurement

Operating Conditions & Performance

The Flexible Averaging Series operates within specific environmental limits and offers performance characteristics dependent on sensor type, length, and operating temperature. The series is limited to applications where high humidity, chemical resistance, and UV light sources are not required.

• Measurement Range: 0 to 75 °C (32 to 167 °F)
• Ambient Temperature Range: -20 to 75 °C (-4 to 167 °F)
• Storage Temperature Range: -20 to 75 °C (-4 to 167 °F)
• Operating Humidity Range: 10 to 90% RH, non-condensing
• Response Time (63% Step Change): 15 Seconds nominal

Accuracy varies by sensor series and probe length. For standard thermistors at 8' & 12' lengths, accuracy is +/-0.20 °C (+/-0.36 °F), except for the A/1.8K Series which lists +/-1.00 °C (+/-1.80 °F) and the A/10KS Series at +/-0.60 °C (+/-1.10 °F). At 24' & 50' lengths, standard accuracy remains +/-0.20 °C (+/-0.36 °F), with similar exceptions for specific series.

Configuration Options

The series supports a wide configuration envelope including multiple sensor curves, probe lengths, and enclosure types to accommodate various installation requirements.

Sensor Elements & Output Signals

• A/1.8K: 1.8 KΩ nominal (Red/Yellow)
• A/3K: 3 KΩ nominal (White/Brown)
• A/AN (Type III): 10 KΩ nominal (White/White)
• A/AN-BC: 5.238 KΩ nominal (White/Yellow)
• A/CP (Type II): 10 KΩ nominal (White/Green)
• A/CSI: 10 KΩ nominal (Green/Yellow)
• A/10KS: 10 KΩ nominal (White/Blue)
• A/10K-E1: 10 KΩ nominal (Gray/Orange)
• A/20K: 20 KΩ nominal (Brown/Blue)
• A/50K: 50 KΩ nominal (Brown/Yellow)
• A/100KS: 100 KΩ nominal (Black/Yellow)

Probe Lengths & Sensing Points

Sensors are available in four standard lengths, with the number of sensing points varying by length:

• 8' and 12' Lengths: Four sensing points
• 24' and 50' Lengths: Nine sensing points

Housing & Enclosure Options

The series offers four enclosure types with distinct materials, ratings, and dimensions:

• -GD (Galvanized): Galvanized Steel; NEMA 1 (IP10)
• -PB (Plastic Box): ABS Plastic, UL94-HB, Plenum Rated
• -BB (Bell Box): Aluminum; NEMA 3R (IP 14)
• -4X: Polystyrene Plastic, UL94-V2; NEMA 4X (IP 66)

Cable & Construction Details

The sensing element utilizes an 18 AWG Plenum Rated cable with a Low Smoke PVC jacket rated CL2P | CMP. The sensor diameter is 0.170" (4.32mm) nominal. Electrical connections are provided via two, 12 inch 22 AWG Etched Teflon colored lead wires.

Approvals & Certifications

• RoHS2
• WEEE
• NIST Certificate (available as an option)

Optional accessories include copper capillary mounting clips and universal plastic mounting clips. NEMA/IP weatherproof enclosures are available.

Key Product Differences

The series distinguishes between sensor types primarily by their nominal resistance at 25 °C (77 °F) or specific reference temperatures, lead wire color coding, and accuracy specifications. The A/1.8K Series exhibits a wider tolerance (+/-1.00 °C / +/-1.80 °F) compared to the standard thermistor range of +/-0.20 °C (+/-0.36 °F). Probe length directly influences both the number of sensing points (four for 8' and 12'; nine for 24' and 50') and power dissipation constants.

Enclosure selection varies by environmental exposure requirements, ranging from indoor plenum-rated plastic boxes (-PB) to outdoor or washdown-capable NEMA 4X enclosures. The -BB Bell Box enclosure provides a hinged cover design in aluminum with NEMA 3R (IP 14) rating.

Installation notes specify that the entire length of the sensor coil must be installed completely inside the duct, and flexible averaging sensors should not be used where UV lights are present due to lack of UV protectant on the outer cable jacket. When bending copper tubing in related configurations, bends should be a minimum of 2" (50.8 mm) to avoid kinking.