Extech RHT20 Humidity and Temperature Datalogger User Manual

1. Introduction

The Extech RHT20 is a humidity and temperature datalogger designed for monitoring environmental conditions. This device records up to 16,000 humidity and 16,000 temperature readings, providing comprehensive data for various applications. It features a user-programmable sample rate, USB interface for data transfer, and an LCD display for real-time readings and alarm status. This manual provides essential information for the proper setup, operation, and maintenance of your RHT20 datalogger.

• Accurate Humidity & Temperature Monitoring: Measures relative humidity from 0-100% and temperature from -40 to 158 °F (-40 to 70 °C).
• Large 16,000-Point Memory Capacity: Stores 8,000 humidity and 8,000 temperature readings with time and date stamp.
• USB Data Transfer to PC: Connects to a computer for data download, analysis, and reporting using included software.
• Calculates Dew Point Automatically: Provides precise dew point values.
• Compact & Portable Design: Lightweight and battery-powered for various monitoring locations.

2. Safety Information

Please read and understand all safety instructions before operating the device. Failure to comply with these instructions may result in damage to the device or personal injury.

• Do not expose the device to extreme temperatures, direct sunlight, or high humidity for extended periods.
• Avoid dropping or subjecting the device to severe impact.
• Do not attempt to open or modify the device. Refer all servicing to qualified personnel.
• Dispose of batteries according to local regulations.
• Keep the device away from strong electromagnetic fields.

3. Package Contents

Verify that all items are present and in good condition upon unpacking:

• Extech RHT20 Humidity and Temperature Datalogger
• Lithium Metal Battery (installed)
• Mounting Bracket
• USB Cable
• Software CD
• User Manual (this document)

4. Product Overview

The Extech RHT20 datalogger features a compact design with an integrated LCD display and control buttons.

Figure 4.1: Front view of the Extech RHT20 Humidity and Temperature Datalogger, showing the LCD display, 'TEMP/%RH' button, and 'MAX/MIN' button.

Key components include:

• LCD Display: Shows current temperature, humidity, time, date, and alarm status.
• TEMP/%RH Button: Toggles between temperature and relative humidity display.
• MAX/MIN Button: Displays maximum and minimum recorded values.
• USB Port: Located at the bottom, used for connecting to a PC for data transfer and configuration.
• Sensor: Integrated sensor for humidity and temperature measurements.

5. Setup

5.1 Battery Installation

The RHT20 comes with a pre-installed Lithium Metal battery. If replacement is necessary:

1. Unscrew the two small screws on the battery compartment cover located on the back of the device.
2. Remove the cover and the old battery.
3. Insert a new 3.6V Lithium Metal battery (e.g., 1/2 AA size) ensuring correct polarity.
4. Replace the battery cover and secure it with the screws.

5.2 Software Installation

The RHT20 requires proprietary software for full configuration and data analysis. The software is provided on a mini-CD. It is recommended to check the Extech website for the latest version and drivers.

1. Insert the software CD into your computer's CD/DVD drive. If your computer does not have a CD drive, download the software from the official Extech support website.
2. Follow the on-screen instructions to install the software and USB drivers.
3. Ensure the installation completes successfully before proceeding.

5.3 Connecting to PC and Initial Configuration

Connect the datalogger to your PC using the supplied USB cable to set up logging parameters and synchronize time.

Figure 5.1: The Extech RHT20 Datalogger connected to a computer via its USB port for data transfer and configuration.

1. Connect the mini-USB end of the cable to the datalogger and the standard USB end to an available port on your PC.
2. Launch the Extech Datalogger software.
3. Within the software, select the "Connect" option. The software should detect the device.
4. Navigate to the "Logger Set" or "Parameter Settings" section. Here you can configure:
   • Sampling Rate: Choose from 2s, 5s, 10s, 30s, 1m, 5m, 10m, 30m, 1hr, 2hr, 3hr, 6hr, 12hr, or 24hr.
   • Alarm Thresholds: Set high and low limits for both humidity and temperature.
   • Logging Mode: Options typically include stopping when memory is full or overwriting the oldest data.
   • Unit of Measurement: Select Celsius or Fahrenheit for temperature.
   • Date and Time: Synchronize the datalogger's clock with your PC.
5. Apply the settings to the datalogger. The device is now ready for data logging.

6. Operating the Datalogger

6.1 Starting Data Logging

Once configured via the software, disconnect the datalogger from the PC. Press and hold the "TEMP/%RH" button for approximately 3 seconds until the "REC" indicator appears on the LCD, signifying that logging has started. Place the datalogger in the desired monitoring location.

Figure 6.1: The Extech RHT20 Datalogger mounted on a shelf, actively monitoring environmental conditions in a storage facility.

6.2 Viewing Current Readings

While logging, the LCD will continuously display the current temperature and humidity. Press the "TEMP/%RH" button to toggle between displaying temperature and relative humidity.

6.3 Viewing MAX/MIN Readings

Press the "MAX/MIN" button to cycle through the maximum and minimum recorded temperature and humidity values since logging began. Pressing it again will return to current readings.

6.4 Stopping Data Logging

To stop logging, press and hold the "TEMP/%RH" button for approximately 3 seconds until the "REC" indicator disappears from the LCD.

6.5 Data Download and Analysis

After logging is complete, connect the datalogger to your PC via USB. Open the Extech Datalogger software and select the "Download Data" option. The software will retrieve the recorded data, which can then be viewed in graphical or tabular format, exported to a spreadsheet (e.g., .xls or .txt), or saved in a proprietary format for later analysis.

7. Maintenance

7.1 Cleaning

Wipe the device with a soft, damp cloth. Do not use abrasive cleaners or solvents. Ensure the device is dry before use or storage.

7.2 Battery Replacement

Refer to Section 5.1 for instructions on replacing the Lithium Metal battery. Replace the battery when the low battery indicator appears on the LCD.

7.3 Storage

When not in use for extended periods, store the datalogger in a cool, dry place, away from direct sunlight and extreme temperatures. It is advisable to remove the battery if storing for several months to prevent leakage.

8. Troubleshooting

• Device not turning on: Check battery installation and ensure the battery has sufficient charge. Replace if necessary.
• "REC" indicator not appearing: Ensure the "TEMP/%RH" button is pressed and held for the required duration (approx. 3 seconds). Verify that the device is not connected to a PC, as logging typically starts after disconnection.
• Software not detecting device:
  • Ensure the USB cable is securely connected to both the datalogger and the PC.
  • Verify that the USB drivers for the RHT20 are correctly installed. Reinstall if necessary.
  • Try a different USB port on your PC.
  • Restart the software and/or your computer.
  • Check for any firewall or antivirus software blocking the datalogger software.
• Inaccurate readings: Ensure the sensor is clean and unobstructed. Allow the device to acclimate to the environment for a few minutes before taking critical measurements.
• Data logging stops unexpectedly: Check the battery level. If the logging mode was set to stop when memory is full, download data and clear the logger to resume.

9. Specifications

10. Warranty and Support

10.1 Warranty Information

Extech instruments are warranted against defects in parts and workmanship for a specified period from the date of shipment (typically one year). For detailed warranty terms and conditions, please refer to the warranty card included with your product or visit the official Extech website. This warranty does not cover defects resulting from user modification, misuse, improper handling, battery leakage, or unauthorized repair.

10.2 Technical Support

For technical assistance, troubleshooting, or service inquiries, please contact Extech customer support. You can find contact information and additional resources on the official Extech website: www.extech.com/support. Please have your product model number (RHT20) and serial number ready when contacting support.