omni instruments | sensors and data acquisition equipment

Sales & Technical Support

Need Help?

Rotronic

HygroFlex HF3S & HF3R Transmitter

The Rotronic HygroFlex3 (HF3) Space and Room series is designed for commercial and industrial settings where precise environmental tracking must seamlessly integrate into the architectural landscape. Utilising advanced digital processing and premium sensor integration, the HF3 monitors relative humidity and temperature with exceptional accuracy. Unlike standard HVAC transmitters, it functions as a highly customisable solution capable of translating physical measurements into linear analogue signals for immediate BMS (Building Management System) integration.

What truly sets the HF3 Space/Room series apart is its unique combination of aesthetic design, advanced configuration options, and mechanical flexibility. It features configurations for both fixed integrated probes and retractable variants, optional integrated digital displays, and an exceptionally low order hurdle, allowing specialised options and custom configurations for batch requirements as small as 20 units.

Key Features

  • Flexible Mechanical Profiles: Available as a standard Space Mount with fixed integrated probe (Type S) or a Retractable probe design (Type R) for low-profile architectural needs.
  • Low Customisation Minimums: While the lower-tier HF1 requires large-scale orders, alternative options and specialised builds for the HF3 are accessible for orders over just 20 units.
  • Optional Digital Display: Features an optional integrated onboard display (Type D) for direct local readout of environmental values (available for device types R and S).
  • Versatile Electrical Topologies: Configurable as a 2-wire loop-powered circuit (HF320-/HF332-) with a 4-20 mA output, or a low-voltage 3-wire layout (HF335-) delivering either current or 0-10 V signals.
  • Pre-configured Temperature Ranges: Tailored out-of-the-box scaling available for varying regional demands, covering 0 to 50°C, -40 to 60 °C, or 0 to 100 F.

Commercial Availability Note: The listed models are available for flexible volumes, the other version are subject to a Minimum Order Quantity (MOQ) of 20 units per order block.

Applications

Maintaining stable environmental loops inside modular air handling units (AHUs), ventilation tracking arrays, and roof-top fan ventilation setups.
Providing continuous indoor climate feedback parameters to automated PLC building controllers across office parks and public complexes.
Reliable ambient storage validation for non-hazardous materials requiring stable, non-condensing temperature tracking boundaries.
Budget-conscious environmental data logging for schools, administration buildings, and transit terminals.

Frequently Asked Questions

▶ Q: What is the advantage of the retractable probe (Type R) variant?
A: The retractable probe configuration allows the sensing element to be neatly recessed within the housing during construction, painting, or heavy maintenance periods. This protects the delicate sensor from dust, mechanical damage, and contamination, and allows it to be easily extended once the environment is clean and operational.
▶ Q: Why does the 2-wire version (HF320-) lack a backlight and communication interface?
A: The 2-wire model operates entirely on a loop-powered circuit (4-20 mA), which strictly limits the available electrical current. To maintain measurement accuracy without exceeding the loop's power budget, the energy-intensive display backlight and digital mini-USB communication interface are omitted. If you require field configuration or enhanced display visibility, choose the 3-wire models (HF332- or HF335-).
▶ Q: Can I order the HF3 with custom temperature ranges or custom scaling?
A: Yes. While the standard options include pre-configured ranges (0 to 50 °C}, -40 to 60 °C, and 0 to 100 F, Rotronic offers specialised configurations and alternative hardware options. Unlike lower-tier lines that require massive volumes, the HF3 series opens up these custom options for project orders over just 20 units.
▶ Q: What is the difference between the "B" output parameter and other variants?
A: The "B" designation signifies that the transmitter tracks and outputs both relative humidity (0 to 100 %RH) and temperature simultaneously across its dual analogue outputs. This ensures a comprehensive, dual-channel environmental data stream is sent directly to your automation or building management system.
Click the ‘See More Details’ button to build the version required.
HF320-S Transmitter

HF320-S Transmitter

HygroFlex HF3S Transmitter for relative humidity and temperature measurement in an enclosure with integrated probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF320 has 2 x 2-Wire Transmitter with 4-20mA Outputs. Operating...

See More Details
HF320-R Transmitter

HF320-R Transmitter

HygroFlex HF3R Transmitter for relative humidity and temperature measurement in an enclosure with retractable probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF320 has 2 x 2-Wire Transmitter with 4-20mA Outputs. Operating...

See More Details
HF332-S Transmitter

HF332-S Transmitter

HygroFlex HF3S Transmitter for relative humidity and temperature measurement in an enclosure with integrated probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF332 has 3-Wire Transmitter with two 4-20mA Outputs. Operating Temperature:...

See More Details
HF322-R Transmitter

HF322-R Transmitter

HygroFlex HF3R Transmitter for relative humidity and temperature measurement in an enclosure with retractable probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF332 has 3-Wire Transmitter with 4-20mA Outputs. Operating Temperature: -10...

See More Details
HF335-S Transmitter

HF335-S Transmitter

HygroFlex HF3S Transmitter for relative humidity and temperature measurement in an enclosure with integrated probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF335 has 3-Wire Transmitter with two 0-10V Outputs. Operating Temperature:...

See More Details
HF335-R Transmitter

HF335-R Transmitter

HygroFlex HF3R Transmitter for relative humidity and temperature measurement in an enclosure with retractable probe. Temperature Range Options: 0-50°C; -40 to+60°C and 0-100F, plus Humidity 0-100%RH with Accuracy <±2%RH. The HF335 has 3-Wire Transmitter with 0-10V Outputs. Operating Temperature: -10...

See More Details

If you require a different configuration than those listed above, please contact to discuss your options.

CONTACT US

8:30am to 5pm Monday to Thursday
8:30am to 3pm on Friday.

A real person will answer the phone and deal with your enquiry.
You can also click the button below and fill in our online enquiry form.

Technical Sales

We are here to help

Need help with your products or have a question for us on our custom systems? Use the form below to send us a message and our experts will be in touch to help.

Call us on +44 (0)1382 443000