Data-centre rack temperature and humidity monitoring
Measure rack inlet and exhaust temperatures with TES-21 probes, add a selected humidity transmitter, and keep each point's position, history and alarms together in Edge.
- Measure
- Temperature at identified rack positions and relative humidity from a separate transmitter
- Sensors
- TES-21, one external temperature probe per monitoring point TES-2X datasheet (PDF, opens in a new tab)
- On site
- ZGW-20 Gateway, Edge keeps trends and runs configured local rules ZGW-20 datasheet (PDF, opens in a new tab)
Choose the humidity instrument as well as the temperature points
The TES-21 measures temperature. Relative humidity needs a separate transmitter selected for its range, accuracy, calibration and intended mounting. The example below uses its externally powered 4–20 mA output through a ZIO-20. A 0–10 V transmitter needs a ZVO interface; Modbus RTU needs a ZMB interface on a suitable bus; a supported Ethernet protocol can connect to Edge directly. Agree the actual instrument and interface before ordering the complete system.
Hardware for rack environmental measurements
Count identified temperature positions, then add an interface for each selected humidity signal and a Gateway for the surveyed wireless coverage area.
Temperature at a labelled inlet, exhaust or room reference position
1 steel probe, 2 m lead
±0.2 °C from 0 to 70 °C, ±0.5 °C over the full −40 to 105 °C range
Reads the selected third-party humidity transmitter's externally powered 4–20 mA signal; the transmitter is supplied separately
Collects the wireless measurements, keeps local history and runs configured rules
TES-21 and ZIO-20 share one enclosure with different terminals inside, so the ordering code is what you specify.
Give every rack measurement a physical address
Record the room, row, rack, side, height and sensor serial number for every point. Inlet, exhaust and room-reference readings answer different questions; the equipment airflow and the site's cooling design decide the locations.
System architecture
How rack conditions reach Edge
Temperature probes and the selected humidity transmitter feed the site Gateway through their own measurement paths.
Field measurement and interface
TES-21
Temperature sensor
ZIO-20
4–20 mA input
On site
ZGW-20Gateway
EdgeLocal monitoring, history and rules
Optional output
| Position | What it tells you | Reference | Sensor |
|---|---|---|---|
| Rack inlet positions | The air temperature at the selected equipment intake positions | Record height and airflow direction; keep the probe clear of surfaces that would turn an air measurement into a contact measurement DOE measurement guide | TES-21 (on this page), inlet |
| Rack exhaust or room reference | A separate temperature against which the intake trend can be interpreted | Label the position explicitly and do not treat exhaust temperature as equipment inlet temperature ASHRAE data-centre guidance | TES-21 (on this page), reference |
| Relative humidity position | The selected transmitter's RH reading at its documented position | Record manufacturer, model, range, calibration and output scaling; ZIO-20 acquires the signal rather than measuring humidity itself ZIO-2X datasheet (PDF, opens in a new tab) | ZIO-20 (on this page) |
| Measurement freshness | Whether the temperature and humidity points are still reporting | Choose expected reporting intervals and test the missing-data response for each point | ZGW-20 (on this page) |
One rack is not a whole room. Choose additional points where rack loading, airflow or containment differs. The example quantities do not establish coverage for another installation.
Humidity belongs to its own instrument. There is no humidity measurement in the TES probe or ZIO input. Agree the external transmitter and its electrical interface before treating the bill of materials as complete.
Survey the operating enclosure. Metal cabinets and changed door positions can alter the wireless path. Test with rack doors closed and the room in its normal operating configuration.
Keep rack identity, trends and missing data visible in Edge
Name points by their physical positions and configure rules around the operator's response procedure. Temperature limits and response times come from the equipment and site design.
- Compare identified positions
- Trend inlet and exhaust points together while retaining their individual names. A difference can help an investigation, but it does not on its own measure cooling capacity or airflow.
- Use explicit alarm limits
- Configure high and low limits and any delay around the documented equipment requirements. Test alarm onset, recovery and the intended operator notification path.
- Treat a silent point as missing data
- Configure activity monitoring for each expected reporting interval. An old normal reading must not stand in for a current rack condition; prove the missing-data alarm during commissioning.
- Keep local and onward evidence separate
- Edge keeps the local measurements. If a BMS or monitoring platform needs them, configure the supported export and verify timestamps, point names, values and receiving-platform acceptance separately.
Commissioning checks
Complete these checks against the agreed rack drawing and the selected instruments before relying on the alarms.
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Match every name to its installed position
Photograph each probe and RH transmitter, label the rack, side and height, and compare serial numbers with Edge.
Pass when every displayed point resolves to one documented physical position and its purpose.
-
Compare readings with a suitable reference
Record the instrument calibration details and compare temperature and RH with appropriate reference instruments at the same positions after stabilisation; account for the specified uncertainty and response time.
Pass when readings meet the agreed acceptance tolerance and any offset or uncertainty is recorded, rather than silently adjusted away.
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Prove humidity scaling end to end
Check the transmitter's output range, loop supply and input configuration, then compare the transmitter's reference reading with the value in Edge.
Pass when the displayed RH and units match the selected instrument across the agreed commissioning checks.
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Test wireless reporting with rack doors closed
Observe every point with rack doors closed, normal containment and the room operating as expected; repeat at the agreed reporting interval.
Pass when the required points report consistently over the agreed observation period and any coverage changes are documented.
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Make a point go stale
Use a controlled reporting interruption for a selected sensor and then restore it; observe the activity alarm and recovery.
Pass when the stale-data condition is visible and notified as configured, and restoration does not hide the missing interval.
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Exercise alarm and receiver paths
Use a bounded test to exercise an agreed limit and its recovery; if exporting, compare the received values and timestamps with Edge.
Pass when the intended operator receives the alarm and recovery, and any optional platform accepts the correct point identity and reading.
What rack environmental monitoring establishes
This system records selected measurement positions. Its usefulness depends on the point plan, instrument selection and a tested operational response.
- These readings do not certify cooling design, equipment operating limits, data-centre compliance or uptime.
- A separate RH transmitter, its power supply and its calibration requirements must be specified; the EpiSensor hardware list alone is not a complete humidity system.
- Probe count and position are site-specific. A room average cannot establish every rack's inlet conditions.
- Local rule execution does not guarantee delivery through an unavailable external notification or platform connection.
- This guide does not establish a safety interlock or authorise automatic changes to cooling equipment.
Sources and related guides
Sources
- TES-2X temperature sensor datasheet (opens in a new tab) EpiSensor. External temperature probe configurations; this does not establish a rack placement rule or humidity capability.
- ZIO-2X analogue signal sensor datasheet (opens in a new tab) EpiSensor. Analogue current acquisition; the primary RH transmitter and its calibration are specified separately.
- Data Center Energy Efficiency Measurement Assessment Kit Guide and Specification (opens in a new tab) U.S. Department of Energy. Rack air-intake and exhaust sensing, temperature and humidity collection, wireless transfer, logging and alarm-handling requirements.
- ASHRAE Handbook chapter: Data Centers and Telecommunication Facilities (opens in a new tab) ASHRAE. Equipment-inlet environmental conditions, temperature and moisture considerations, and the need to apply equipment-class guidance rather than one universal limit.
- TES-2X Probe Temperature Sensor datasheet (opens in a new tab) EpiSensor. Specifications, ranges and ordering codes.
Related
- Indoor environmental monitoring Application guide Temperature in the occupied zone, an outdoor reference and the plant state that explains both, with the limits of an indicative air-quality reading.
- Meter integration for a BMS or SCADA system Application guide What Edge reads, what it serves onward, and the settings both ends have to agree on before a register becomes a point in your BMS.
- Chiller performance monitoring Application guide Measure chiller electrical input and delivered cooling over the same interval, calculate COP and kW per ton in Edge, and prove the numbers before using them.
- Commissioning 4–20 mA and 0–10 V monitoring Knowledge Base A field method for loop power, voltage headroom, scaling, fault states, isolation, sampling and acceptance of analogue process signals.
- 4–20 mA scaling calculator Engineering tool Scale a 4–20 mA signal to engineering units or back, and check the loop has enough supply voltage.
Reviewed by EpiSensor Engineering on . Revision 2.
Plan the rack points and the humidity instrument
Share the rack layout, airflow arrangement and equipment limits. We will scope the temperature positions, RH transmitter interface, wireless coverage and commissioning checks.