Quick answer: The testo 162 H2 uses a connected external temperature/humidity probe to monitor conditions at a location separate from its display-equipped logger body. Choose a supported probe, mount it at the actual monitoring point, commission Wi-Fi/cloud access and test the two measured parameters. Do not treat the H2 body as an independent room RH sensor without its probe.
Why choose H2 rather than H1?
The 162 H2 is manufacturer part 0572 1625. It provides an external temperature/RH probe connection and display, making it useful when the measurement point is inside a cabinet or in a location where the display should not be mounted. Testo lists compatible probes such as a plug-in temperature/RH probe and a cabled temperature/RH probe. Verify actual part numbers and cable requirements before installation. For a comparable external-probe setup, see testo 160-E external probe configuration.
Unlike the H1’s integrated sensors, the external H2 element determines the relevant measurement conditions. The H2 may therefore show the enclosure’s microclimate rather than the ambient room where its housing is attached.
Install the external sensor
- Identify where the relevant object, stock or process experiences temperature and moisture.
- Choose a supported cabled or plug-in temperature/RH probe, checking its allowable temperature and humidity range.
- Route the cable so it is not crushed by doors or exposed to unsuitable liquids; preserve the intended enclosure seal.
- Mount the housing and probe separately, avoiding heaters, direct radiant light and unrepresentative cold surfaces unless part of the measurement objective.
- Connect the probe and verify that the displayed temperature and RH channels respond plausibly in stable conditions.
- Enroll the unit with the supported app/cloud service; set alarms and document channel labels and the exact sensor location.
Two positions can give two correct readings
Hypothetical: a cabinet probe records 19.6 °C and 48% RH, while a calibrated instrument outside records 21.1 °C and 41% RH. The differences are 1.5 °C and 7 percentage points RH. They do not establish a probe defect because the sampling environments differ. To assess agreement, co-locate both sensors in the same stable air before making an accuracy judgement. For a focused comparison of differing RH readings, see Why Do Two Hygrometers Show Different Readings.
Configure Wi-Fi, license and alarm response
Current Testo pages describe Wi-Fi transfer and the testo Smart App/Smart Connect environment, and specify a Data Monitoring license. Test the alert path with an approved controlled change or simulation. A missed text or email can reflect contact settings, connectivity or a licensing issue rather than a humidity-sensor fault. For related guidance, see testo 150-T1: How to Configure Temperature Monitoring and Alarms.
What to check when RH stays blank
| Observed issue | First check |
|---|---|
| Neither T nor RH appears | Probe connection and supported sensor model |
| Temperature appears but RH is absent | Sensor compatibility, channel mapping and probe status |
| Local display works, remote graph is stale | Wi-Fi/service connection and timestamp |
| Readings disagree with a reference | Same-air placement, response time, calibration records |
Do not misinterpret the result
The H2 reports air temperature and RH at the external probe. It cannot directly determine water content in a wall, condensation inside a concealed cavity or the cause of a mold patch. Those require additional measurements and inspection. Keep the probe calibration and location together with exported reports. For the related distinction between air humidity and wall-surface condensation, see Why Condensation Forms on One Wall but Not Another.