Temperature Humidity Transmitter (External Sensor)

Description

When to Use an External Probe

A built-in sensor works well when the transmitter can be mounted directly where measurement is needed. An external probe becomes necessary whenever that's not physically practical, or when accessing the sensing location for maintenance is inconvenient, restricted, or disruptive. This includes measuring inside a cold room while keeping the display and wiring outside it, sensing air quality inside ductwork through a wall penetration, monitoring at height in a high-bay warehouse while the unit itself stays at an accessible working height, or reaching inside equipment or enclosures too tight for a full transmitter body.

When to Use an External Probe

A built-in sensor works well when the transmitter can be mounted directly where measurement is needed. An external probe becomes necessary whenever that's not physically practical, or when accessing the sensing location for maintenance is inconvenient, restricted, or disruptive. This includes measuring inside a cold room while keeping the display and wiring outside it, sensing air quality inside ductwork through a wall penetration, monitoring at height in a high-bay warehouse while the unit itself stays at an accessible working height, or reaching inside equipment or enclosures too tight for a full transmitter body.

Probe Configurations

The probe features a stainless steel body, suitable for food-grade or humid environments where hygiene and corrosion resistance matter. Configurable cable and probe lengths allow the sensing tip to reach the exact measurement point required, whether that's a cold room interior, a duct wall penetration, or a high-mounted position in a warehouse, without needing to relocate the transmitter's display and wiring unit.

Features

• Fast response digital sensor (Switzerland)
• IP65 enclosure
• High accuracy of ± 0.5°C and ± 2%RH
• In-built buzzer alarm

Applications

• Cold Room Measurement: Places the probe inside the cold room while keeping the transmitter body outside, allowing readings and maintenance access without repeatedly opening the cold room door
• Duct Measurement: Inserts the probe through the duct wall to measure temperature and humidity directly within the airstream, while the transmitter remains externally mounted
• High-Bay Warehouse Monitoring: Positions the probe at high level, where temperature stratification is most relevant, while keeping the transmitter unit at an accessible working height for maintenance
• Equipment and Enclosure Monitoring: Reaches inside tight equipment cabinets or enclosures where a full transmitter body wouldn't fit, using only the compact probe tip
• Pharmaceutical GDP Storage: The external probe design is particularly valued in pharmaceutical GDP applications, where T/RH must be measured at the storage location but the transmitter must be accessible for maintenance without entering the controlled area

BMS Integration

With RS485 Modbus communication, the transmitter feeds real-time temperature and humidity data from the probe location directly into a Building Management System, supporting centralized monitoring and compliance logging across cold rooms, ducts, warehouses, and controlled storage areas from a single accessible point.

Frequently Asked Questions (FAQs)

1. What is the AI-RHT1-PH Temperature Humidity Transmitter?

The AI-RHT1-PH is a temperature and humidity transmitter with an external sensing probe designed for continuous environmental monitoring. The remote probe measures conditions at the required location while the transmitter housing remains mounted nearby for easy access to the display, wiring, and maintenance. It is ideal for cold rooms, HVAC ducts, environmental chambers, and other applications where the sensing point is separate from the control panel.

2. What does the AI-RHT1-PH measure?

The transmitter continuously measures:

• Temperature
• Relative Humidity (RH)

The measured values are transmitted to the Building Management System (BMS), PLC, or HVAC controller for monitoring, data logging, and environmental control.

3. Why choose an external probe temperature humidity transmitter?

An external probe allows measurements to be taken exactly where environmental conditions need to be monitored, while keeping the transmitter electronics outside the monitored area. This makes installation, maintenance, and calibration much easier, especially in cold rooms, ducts, or enclosed spaces.

4. Where is the AI-RHT1-PH commonly installed?

Typical applications include:

• Cold rooms
• Walk-in freezers
• HVAC ducts
• Environmental chambers
• Pharmaceutical storage areas
• Cleanrooms
• Warehouses
• Food processing facilities
• Laboratories
• Greenhouses
• Museums
• Industrial process applications

5. How long can the cable between the transmitter and probe be?

Standard probe cable lengths are available from 1 to 10 metres.

Longer cable lengths can also be provided using shielded cable to minimize electrical interference. For installations where the probe is located more than 10 metres from the transmitter, additional signal conditioning may be recommended. Our engineering team can recommend the most suitable configuration for your application.

6. Can the external probe be used inside a cold room?

Yes. The AI-RHT1-PH is specifically designed for cold room applications.

The sensing probe is installed inside the cold room at the measurement location, while the transmitter housing, display, and wiring terminals remain mounted outside the cold room. This allows maintenance personnel to access the transmitter without entering the refrigerated area, simplifying servicing and calibration verification.

7. Is the probe suitable for high-humidity environments?

Yes. The stainless steel sensing probe and humidity-resistant sensor are designed to operate reliably in environments with up to 95% relative humidity.

This makes the AI-RHT1-PH suitable for applications such as:

• Cold storage rooms
• HVAC duct systems
• Incubators
• Environmental chambers
• Food processing facilities
• High-humidity industrial environments

8. What accuracy can I expect from the temperature and humidity sensors?

The AI-RHT1-PH uses high-quality factory-calibrated sensors.

Typical performance is:

• Relative Humidity Accuracy: ±3% RH (within the 10 - 90% RH range)
• Temperature Accuracy: ±0.3°C

Both sensors are calibrated against traceable standards to ensure reliable and stable long-term measurements.

9. Can the AI-RHT1-PH be integrated with a Building Management System (BMS)?

Yes. The transmitter supports industry-standard communication options, including:

• RS485 Modbus communication
• 4 - 20 mA output
• 0 - 10 V output (depending on model)

These outputs enable seamless integration with Building Management Systems, PLCs, SCADA systems, and HVAC automation controllers.

10. Can the transmitter help improve HVAC energy efficiency?

Yes. By continuously monitoring temperature and humidity, the Building Management System can optimize heating, cooling, humidification, and dehumidification based on actual environmental conditions, reducing unnecessary energy consumption while maintaining the desired indoor climate.

11. Is the AI-RHT1-PH suitable for continuous monitoring?

Yes. The transmitter is designed for reliable 24×7 continuous operation in commercial, industrial, pharmaceutical, healthcare, and food processing applications.

12. Does the transmitter require calibration?

The AI-RHT1-PH is factory calibrated before shipment. Periodic verification is recommended for applications requiring high measurement accuracy, particularly in pharmaceutical manufacturing, laboratories, environmental chambers, and regulated environments.

13. Is installation easy?

Yes. The remote probe design makes installation flexible and convenient. The probe can be positioned exactly where measurements are required, while the transmitter remains easily accessible for wiring, maintenance, and monitoring.

14. What are the advantages of using the AI-RHT1-PH?

Key benefits include:

• Remote sensing with external probe
• Continuous temperature and humidity monitoring
• High measurement accuracy
• Suitable for cold rooms and HVAC ducts
• Easy BMS and PLC integration
• Multiple communication outputs
• Reliable industrial-grade performance
• Low maintenance

15. Who typically uses the AI-RHT1-PH?

The AI-RHT1-PH is widely used by:

• Cold storage operators
• Pharmaceutical manufacturers
• Food processing facilities
• HVAC contractors
• Building automation integrators
• Laboratory managers
• Warehouse operators
• Environmental chamber manufacturers
• Industrial maintenance engineers

16. Why choose ACE Instruments?

ACE Instruments has over 30 years of experience in manufacturing environmental monitoring solutions. Customers choose our products for their high measurement accuracy, industrial-grade reliability, easy BMS integration, multiple communication options, calibration support, responsive technical assistance, and proven performance across commercial, pharmaceutical, healthcare, food processing, and industrial facilities.

17. How do I choose the right External Probe Temperature Humidity Transmitter?

Choosing the right AI-RHT1-PH depends on your application, probe cable length, communication requirements, environmental conditions, and installation location. Our application engineers can help you select the most suitable configuration for cold rooms, HVAC ducts, environmental chambers, warehouses, and other temperature and humidity monitoring applications.

Specifications