Indoor Temperature & Humidity Controller – LCD Display, Relay Output & Alarm

This indoor temperature and humidity controller is a reliable solution for environments requiring accurate climate monitoring and control. Designed for use in buildings, data centers, and storage areas, it combines high-performance sensing with user-friendly operation in a compact, attractive housing.

The controller features a clear LCD backlit display showing real-time temperature and humidity readings, along with built-in relay output and alarm functions for automatic system responses. It uses imported high-precision sensors for excellent stability and measurement accuracy over time.

Engineered with strong anti-interference protection—including resistance to surges, static discharge, and group pulses—it ensures reliable operation even in electrically noisy environments. Installation is quick and easy using a standard wall switch box, and users can adjust offsets directly for temperature and humidity values, ensuring field flexibility.

Key Features:

• Dual temperature and humidity display on a backlit LCD

• Compact design with standard wall switch box mounting

• Built-in relay control and alarm function for automated responses

• High-precision imported sensors for long-term stability

• Adjustable temperature and humidity offsets for on-site fine-tuning

• Excellent anti-interference protection: surge, static, voltage spikes

• Optional passive temperature output

• CE and RoHS certified for quality and safety

• Ideal for computer rooms, buildings, warehouses, and HVAC zones

LEFOO Indoor Temperature and Humidity Transmitter LFH21 Relative Humidity Sensor Digital type Range 0%~100%RH Output RS485/Modbus,0~10VDC Accuracy ±3%@ 20℃ & 20~80%RH Response time ≤10s (20℃, slow flow air) Temperature Sensor Digital or passive thermal resistor, details refer to selection table Range 0~50℃, -20~60℃, etc Output Signal RS485/Modbus,0-10VDC Thermal Resistance Details in selection table and thermal resistance graduation table Accuracy Digital sensor: ±0.3℃@20℃, See table below ; Passive thermal resistance: typical ±0.2~0.4℃@25℃, refer to selection table Power Supply RS485:15-35VDC/24VAC±20% Voltage:15-35VDC/24VAC±20% Note: when RS485 and voltage type uses AC power supply, an isolation transformer is required Output load Output Load ≥10kΩ(voltage output) Display Accuracy 0.1℃,0.1%RH Display and buttons LCD display and keys with unit display and backlight Alarm Function 1xBUZZER,1xLED Relay 2 x SPST, 3A / 30VDC, 3A / 250VAC Shell Material PC Working Environment -20~60℃, 5%-95%RH (Non-condensing) Protection Grade IP30