COMET H3021 – Temperature & Humidity Controller with External Cable Probe, 2 Relays

COMET H3021 – Temperature & Humidity Controller with external cable probe –30 to +105 °C / 0–100 %RH, dew point, 2 relays (50 V/2 A), IP65

The COMET H3021 is a powerful temperature and humidity controller (humidistat + thermostat) with an external cable probe (1 meter, optional longer versions) and two relay outputs – the ideal solution for precise climate control in warehouses, cold rooms, greenhouses, drying systems, technical centers, server rooms, or production areas. With IP65 protection and an acoustic alarm (switchable), it is perfectly suited for both indoor and outdoor use (–30 to +80 °C), wherever temperature and humidity must be actively controlled or monitored – with a flexible probe design for hard-to-reach locations.

The external combined probe measures temperature from –30 to +105 °C (±0.4 °C) and relative humidity from 0 to 100 %RH (±2.5 %RH from 5–95 % at 23 °C). The dew point is calculated with high accuracy (±1.5 °C at T<25 °C and RH>30 %). In addition, all other humidity parameters are available: absolute humidity, specific humidity, mixing ratio, and specific enthalpy. The large dual-line LCD displays all measured values and relay statuses. The two relay outputs (max. 50 V / 2 A / 60 VA) can be freely programmed based on temperature, humidity, or dew point thresholds – ideal for direct control of fans, heaters, dehumidifiers, alarms, or compressors.

The robust IP65 housing protects against dust and water jets – ideal for humid or dusty environments. The acoustic alarm (buzzer) provides a warning when limits are exceeded and can be deactivated. Power supply 9–30 V DC – simple and flexible. The controller is maintenance-free, long-term stable, and available with a traceable calibration certificate (according to EN ISO/IEC 17025) – maximum quality for critical applications. The external probe allows optimal sensor placement independent of the controller’s location.

Why the COMET H3021 is the professional T+RH controller with cable probe:

• External cable probe – flexible for hard-to-reach measuring points
• 2 relay outputs – 50 V / 2 A / 60 VA – for direct control
• 3-in-1: temperature + humidity + dew point – all humidity parameters available
• High precision – Temp. ±0.4 °C | Humidity ±2.5 %RH | Dew point ±1.5 °C
• Acoustic alarm – switchable buzzer for limit exceedances
• IP65 housing – weatherproof for indoor & outdoor use
• Large dual-line LCD – displays values & relay status
• Wide power supply – 9–30 V DC
• Long-term stable & maintenance-free – with calibration certificate

Technical data H3021:

• Temperature range: –30 to +105 °C (±0.4 °C)
• Humidity range: 0 to 100 %RH (±2.5 %RH from 5–95 % at 23 °C)
• Dew point: –60 to +80 °C (±1.5 °C at T<25 °C and RH>30 %)
• Relays: 2 × max. 50 V / 2 A / 60 VA
• Resolution: 0.1 °C / 0.1 %RH
• Probe cable length: depending on selected version
• Power supply: 9–30 V DC
• Operating temperature: –30 to +80 °C
• Protection class: IP65 (electronics), IP40 (probe)
• Dimensions: 136 × 159 × 45 mm; probe Ø 18 mm, length 88 mm
• Weight: approx. 350 g
• Warranty: 3 years

Perfect for:

• Warehouses & cold rooms (climate monitoring)
• Greenhouses & agriculture
• Drying & ventilation systems
• Server rooms & technical centers
• Direct control of fans / dehumidifiers
• Alarm & limit monitoring
• Stand-alone control without cloud
• Humidity & temperature control in damp environments

Installation & commissioning – done in minutes

Mount the device on a wall or pole, connect power (9–30 V DC) and relays, place the probe at the desired location – done! Set thresholds using the buttons and LCD or fine-tune via PC software. No calibration required when replacing the probe.

Available versions:

• Cable length 1 meter
• Cable length 2 meters
• Cable length 4 meters

Summary:

• Humidistat with two relay outputs
• For indoor and outdoor environments
• Humidity and temperature probe on cable
• Measured values are converted into additional humidity parameters: dew point temperature, absolute humidity, specific humidity, mixing ratio, and specific enthalpy.

Scope of delivery:

• H3021 – according to selected cable length (see above)
• User manual
• Traceable calibration certificate
• Free TSensor software for transmitter configuration