Wall-Mount Humidity and Temperature Transmitter

A. Product overview

This Wall Mount Humidity and Temperature Transmitter is an industrial-grade instrument designed to continuously measure relative humidity (0–100% RH) and temperature (0–50°C) in indoor and controlled environments. It converts both measurements into standard two-wire 4–20 mA signals, making it easy to integrate with PLCs, BMS controllers, DCS/SCADA, data loggers, and panel indicators.
The unit uses a capacitive humidity sensor and temperature sensor, is housed in an IP65 ABS enclosure, and is built for stable operation in non-condensing humidity environments.

B. Working principle

1. Humidity sensing (capacitive):
   A capacitive RH sensor contains a hygroscopic dielectric material whose capacitance changes with moisture content in the air. As relative humidity increases or decreases, the sensor’s capacitance changes proportionally.

2. Temperature sensing:
   The transmitter measures this resistance and converts it into temperature.

3. Signal conversion to 4–20 mA:
   Internal electronics linearize and scale both sensor readings and convert them into two-wire 4–20 mA outputs. The current loop signal is robust for long cable runs and electrically noisy industrial environments, and it is widely accepted by PLC/BMS inputs.

C. Why it is used

• To maintain indoor comfort and process stability by monitoring humidity and temperature continuously

• To control HVAC equipment such as AHU, humidifiers, dehumidifiers, and ventilation systems

• To prevent condensation-related issues like corrosion, fungal growth, and product spoilage

• To support compliance and quality control in sensitive areas such as pharma, laboratories, storage rooms, and clean environments

• To feed reliable analog signals (4–20 mA) into automation systems for closed-loop control, alarms, and reporting

D. Suitable buyers (who should purchase this)

• HVAC contractors and system integrators (AHU rooms, duct/room monitoring, building HVAC upgrades)

• Building management system (BMS) integrators and automation panel builders

• Industrial plants needing ambient monitoring in production, packaging, or utility areas

• Pharmaceutical, food, and chemical facilities requiring stable humidity/temperature monitoring

• Data centers, server rooms, telecom rooms, and electrical/control panels needing environmental monitoring

• Warehouses, cold storage operators (ambient zones), and quality storage facilities

• Laboratories, hospitals, cleanroom operators, and facility maintenance teams

FAQ 

1. What does a wall mount humidity and temperature transmitter do?
It measures relative humidity and temperature in a room/area and sends the readings as standard analog signals (4–20 mA) to a PLC, BMS, DCS, SCADA, or indicator for monitoring and control.

2. What are the outputs of this transmitter?
It provides two-wire 4–20 mA outputs for both humidity and temperature (separate loops). This is ideal for industrial control and building automation systems.

3. What is the humidity range and accuracy?
Humidity range is 0–100% RH with an accuracy of ±2% RH, repeatability of ±0.6% RH, and response time under 15 seconds.

4. What is the temperature range and accuracy?
Temperature range is 0–50°C using the sensor, with accuracy specified as ±0.2% of full span.

5. What power supply is required?
It operates on 12–36 VDC, commonly powered from 24 VDC control panels.

6. Is it suitable for HVAC and BMS applications?
Yes. The 4–20 mA output is widely used in HVAC controls and building automation. It can connect to most PLC and BMS analog input modules.

7. What is the enclosure rating and material?
The enclosure is IP65 and made of ABS, suitable for dusty environments and water splashes (not for direct high-pressure washdown).

8. Can it be used in high humidity conditions?
It supports 0–100% RH (non-condensing). For condensing environments, proper placement and protection are recommended to avoid water droplets directly contacting the sensing area.

9. What is the operating temperature limit?
Operating temperature is 0–55°C for weatherproof use, and up to 0–85°C for Ex-proof environments (as specified). Storage temperature is 0–80°C.

10. What cable and terminals does it support?
It uses screw terminals and supports cable size up to 2.5 mm² (AWG 14), with a PG7 cable gland for entry.