Aci A/RH3-1K-2W-O Outdoor Humidity Sensor 4-20ma Rtd

Product Description

The ACI A/RH3-1K-2W-O is an outdoor relative humidity sensor designed for building automation and HVAC control applications. It delivers a default 4-20 mA analog output signal and also supports 0-5 and 0-10 VDC output configurations, giving controls technicians flexibility when integrating with DDC systems and building management controllers. The sensor achieves 3% RH accuracy and incorporates a 1,000 ohm RTD (two-wire) for simultaneous temperature sensing. Power requirements are 24 VAC or 24 VDC. The unit is housed in a Euro-style enclosure rated for outside air mounting, making it suitable for exterior installation on rooftops, equipment yards, or building facades.

This sensor is intended for outside air monitoring in commercial and light-industrial HVAC systems. Typical applications include economizer control, outdoor air reset strategies, and building envelope monitoring. Controls technicians and licensed HVAC mechanics are the primary installers. The 4-20 mA default output makes it compatible with virtually all modern DDC controllers and data acquisition panels that accept standard analog inputs.

Key Features

• Default 4-20 mA output with selectable 0-5 VDC and 0-10 VDC options
• 3% relative humidity accuracy
• Integrated 1,000 ohm RTD temperature element, two-wire configuration
• Operates on 24 VAC or 24 VDC power
• Euro enclosure rated for outdoor air (OSA) mounting
• Dual sensing in one unit: humidity and temperature in a single housing

Compatibility

Designed for outside air applications in commercial HVAC building automation systems. Compatible with DDC controllers and BAS panels accepting 4-20 mA or 0-10 VDC analog input signals.

Installation Notes

Installation should be performed by a licensed HVAC controls technician or instrumentation specialist familiar with low-voltage building automation wiring. De-energize the control panel and verify 24 VAC or 24 VDC supply is off before making wiring connections. Mount the Euro enclosure on an exterior wall or equipment surface per the manufacturer orientation guidelines to avoid direct solar radiation and moisture intrusion on the sensing element. Wiring must comply with applicable NEC low-voltage control wiring requirements for the jurisdiction.

Technical Specifications

• Output Signal: 4-20 mA (default); 0-5 VDC; 0-10 VDC
• RH Accuracy: 3%
• Temperature Element: 1,000 ohm RTD, two-wire
• Power Requirements: 24 VAC or 24 VDC
• Mounting Location: Outside air (OSA)
• Enclosure Style: Euro enclosure

Standard Information

• Brand: ACI
• Manufacturer Part Number: A/RH3-1K-2W-O