Extech RH350 Dual Input Hygro-Thermometer Psychrometer
The Extech RH300 is a portable psychrometer that measures and displays relative humidity, air temperature, dew point, wet bulb temperature, and—when used with an optional external probe—external probe temperature and differential readings (T1–T2). With a triple-display interface, twist-on protective cap, and features like Data Hold, Min/Max, and auto power-off, it is well suited for HVAC, environmental monitoring, and field diagnostics.
Description
The RH300 is built for field use, providing a compact yet powerful solution for environmental measurement. It uses an internal humidity sensor and temperature sensor (called T1) to continuously monitor ambient conditions. From those measurements, it computes dew point and wet bulb temperature. The instrument’s display can show % RH, air temperature, and a third parameter such as dew point, wet bulb, or external probe temperature simultaneously. When an optional Type K/T probe (T2) is connected, the RH300 can also measure that probe’s temperature and compute the T1–T2 temperature difference and T2 minus dew point. The device is designed with a twist-close sensor cap to protect the sensor during storage and transport. User controls allow for toggling units (°C/°F), holding readings (Data Hold), storing min/max values, and automatic power-off (which may be disabled). The RH300 is powered by two AAA batteries and comes with basic utility for reliable environmental measurement in the field.
Features
- Simultaneous triple display showing relative humidity, air temperature, and a third value (dew point, wet bulb, or probe temperature).
- Calculates dew point and wet bulb temperature automatically — no manual slinging required.
- Supports optional external temperature probe for T1–T2 differential and T2 minus dew point calculations.
- Twist-on protective sensor cap shields the sensor during storage and transport.
- Selectable °C/°F temperature units with 0.1° resolution.
- Data Hold and Min/Max memory functions for quick analysis.
- Auto power-off feature with disable option to conserve battery life.
- Wide measurement ranges: humidity 10 % to 90 %, air temperature –20 °C to +50 °C, external probe temperature –20 °C to +70 °C.
- Dew point range –68 °C to +49.9 °C and wet bulb range –21.6 °C to +49.9 °C.
- Compact and lightweight design (178.5 × 48.4 × 24.7 mm, 95 g) powered by two AAA batteries with approximately 80 hours of use.
Includes
- Data Hold,
- Auto Power Off
- MAX/MIN reading
- Complete with 2 AAA batteries
