Best Psychrometers for HVAC: Air Temperature and Humidity
Compare JL3RH and Testo 605i for connected air-condition readings, or the newer Testo 625 for a local display. These three cover distinct viewing and placement choices without padding the list.
3 picks · 1 full reviewUS-focusedResearch-based recommendations
Product image: Fieldpiece. Check the listing for included accessories.
Temperature, humidity and derived wet-bulb values are different from a direct airflow measurement.
HOW TO CHOOSE
What matters for the work
Match measurement location
Room conditions and in-duct conditions can differ. Choose a probe that can be placed at the required location.
Plan paired measurements
A single probe may not cover simultaneous supply and return measurements. Check kit contents and the planned receiving device.
Keep derived readings in context
Document dry bulb, humidity and measurement locations. A temperature split alone does not diagnose every fault.
We compared manufacturer specifications and documented features. We have not hands-on tested these products. Read our recommendation method →
Detailed picks
Useful differences, meaningful drawbacks and the specifications behind each recommendation.
OPTION 1
Product image: Fieldpiece. Check the listing for included accessories.Remote air-condition readings
Remote air-condition readings
Fieldpiece
JL3RH Flex Psychrometer Probe
Best for: Job Link users measuring air temperature and humidity at suitable locations.
JL3RH measures air conditions as part of a connected diagnosis. Place it where the actual measurement is required; a temperature split alone does not establish delivered airflow or equipment capacity.
Remote air-condition readings: Dry bulb / wet bulb / RH. One probe is not a complete paired air-measurement kit, and humidity does not measure airflow. Compare this configuration with the alternatives below and price the accessories needed for your actual jobs.
Readings: Dry bulb / wet bulb / RH
Format: Flexible probe
Connection: Job Link wireless
Readings
Dry bulb / wet bulb / RH
Format
Flexible probe
Connection
Job Link wireless
Main tradeoff: One probe is not a complete paired air-measurement kit, and humidity does not measure airflow.
Product image: Testo. Check the listing for included accessories.Testo connected air probe
Testo connected air probe
Testo
605i Wireless Thermohygrometer
Best for: Testo users needing app-based air-temperature and humidity readings.
605i is a compact connected air-condition probe. Its app workflow can fit an existing Testo kit, while its measuring role remains separate from an airflow instrument.
Testo connected air probe: Temperature and RH. Requires supported app viewing; paired measurements may need a second instrument. Compare this configuration with the alternatives below and price the accessories needed for your actual jobs.
Readings: Temperature and RH
Head: Bendable probe
Viewing: Testo Smart app
Readings
Temperature and RH
Head
Bendable probe
Viewing
Testo Smart app
Main tradeoff: Requires supported app viewing; paired measurements may need a second instrument.
Product image: Testo. Check the listing for included accessories.Standalone-display alternative
Standalone-display alternative
Testo
625 Digital Thermohygrometer (0563 1625)
Best for: Technicians who prefer a local display with the documented newer 625 configuration.
The newer 625 provides a local-display alternative to app-only probes. Compare its generation and complete part number, since older 625 listings describe another instrument configuration.
Standalone-display alternative: Temperature and RH. 625 part numbers identify different generations; match 0563 1625 and confirm the US offer. Compare this configuration with the alternatives below and price the accessories needed for your actual jobs.
Readings: Temperature and RH
Viewing: Local display
Connection: App capable
Readings
Temperature and RH
Viewing
Local display
Connection
App capable
Main tradeoff: 625 part numbers identify different generations; match 0563 1625 and confirm the US offer.
