Temperature & Humidity Data Loggers for Cold Rooms, Stores, Labs and Transport
A temperature and humidity data logger is a self-contained, battery-powered instrument that measures air temperature and relative humidity (RH) at a fixed interval and stores every reading with a time stamp. The record is downloaded later as a PDF, spreadsheet or cloud report, giving documented proof of the conditions a product, room or vehicle was kept in, including overnight, over weekends and during power cuts.
Ecotao supplies Wi-Fi, Bluetooth, USB and large-display PDF loggers from Cape Town to customers across South Africa and neighbouring countries. Use the selection guide below to match a logger to your application, or compare all eight side by side.
Browse data loggers at the Ecotao StoreHow to choose a temperature and humidity logger
Start with how the data has to reach you, then check range, memory and reporting. These four questions settle most choices:
- Who needs to know, and how fast? If someone must be alerted the moment a fridge or cold room drifts out of range, even after hours, you need a connected logger with remote alerts (Wi-Fi). If a record checked on delivery or at the end of the week is enough, a Bluetooth, USB or PDF logger costs less and needs no network.
- Where will the sensor sit? Inside a freezer, chamber or sealed enclosure, use an external probe so the logger and display stay outside. In a room, cabinet or vehicle, an internal sensor is simpler.
- What range and accuracy does the process need? Check the lowest and highest temperature the logger will see, not just the set point. For humidity, look at the accuracy across the band you actually work in; most sensors are specified at ±3 %RH between about 10 and 90 %RH.
- What does the record have to look like? Auditors and clients usually want a tamper-resistant PDF with min, max and alarm events. Engineers usually want CSV or Excel to plot trends. Some loggers produce both without installing software.
Remote alerts, 24/7
Cold rooms, vaccine and pharmacy fridges, server rooms.
→ COEUS-WIFIIn-transit, read by phone
Refrigerated trucks, containers, produce consignments.
→ TZ-BT06 · TZ-BT04Daily visual check + PDF
Storerooms, labs, clean rooms, warehouses.
→ YDP-20 · Extech RHT30Probe inside, display outside
Freezers, incubators, test and stability chambers.
→ YDP-20EPressure as well
Calibration and test labs, weighing rooms, weather trends.
→ YEM-70LWalk-round surveys
HVAC commissioning, damp and condensation inspections.
→ TA622C handheldTemperature & humidity data loggers from Ecotao
Every logger below records both temperature and relative humidity. Store-listed models link to their own product page for current stock and lead time; for temperature-only loggers, see our data logger temperature page.
COEUS-WIFI Wi-Fi Cloud Logger
Live readings and SMS, email or app alerts from cold rooms, fridges and stores, with no gateway to install.
The COEUS-WIFI connects straight to an existing Wi-Fi router and uploads temperature and humidity readings to a cloud platform, so you can see a cold room, pharmacy fridge or storeroom from your phone or a PC instead of walking past it. When a limit is crossed it raises an alarm on the unit (red flashing light and buzzer) and sends SMS, email or app push notifications, so someone is told about a failing compressor before the stock is lost.
If the Wi-Fi drops, the logger keeps recording to its own 120,000-reading memory and uploads the backlog once the connection returns. A 2600 mAh rechargeable battery keeps it running through power cuts. Ecotao's store listing states that the unit carries an ICASA type-approval certificate for use in South Africa. Two inputs accept optional external probes, so one logger can watch the room and a freezer compartment at the same time.
- Temperature−30 to +60 °C, ±0.5 °C basic
- Humidity0–100 %RH, ±3 % (20–80 %RH)
- Memory120,000 readings, circular
- ConnectivityBuilt-in Wi-Fi to cloud and app
- AlertsSMS, email, app push, buzzer, LED
- Battery2600 mAh Li-ion, about 60 days at 15-min interval
- Probe inputs2 for optional external probes
- PowerUSB-C, 5 V/2 A adapter included
Best for: Cold rooms, pharmacy and vaccine fridges, freezers, server rooms and any site where someone must be alerted remotely.
TZ-BT06 Bluetooth 5.0 Logger
Read live and logged data from a phone without opening the truck, fridge or container.
The TZ-BT06 is a compact IP65 logger with an LCD that alternates between temperature and humidity. It records up to 32,000 readings and broadcasts its live values over Bluetooth 5.0 Low Energy, so a driver, receiving clerk or lab technician can check conditions and download history from a smartphone app without breaking the cold seal.
Range depends on mode and transmit power: about 120–150 m in standard mode and 200–300 m in long-range mode, which needs a phone with Bluetooth 5.0 or later. Reports can be emailed from the app or printed on a Bluetooth printer at delivery, which makes it a practical proof-of-condition record for refrigerated transport and fresh produce. The 620 mAh battery is user-replaceable and rated for about a year.
- Temperature−20 to +60 °C, ±0.3 °C (−20 to 40 °C)
- Humidity0–90 %RH, ±3 %RH (10–90 %RH)
- Memory32,000 readings
- Interval10 s to 18 h (default 10 min)
- WirelessBluetooth 5.0 LE, up to 300 m long-range
- ProtectionIP65
- Battery3 V, 620 mAh, replaceable, about 1 year
- Size86 × 48 × 12 mm, 40 g
Best for: Refrigerated transport, cold chain hand-overs, fresh produce, museums and archives.
TZ-BT04 Compact Bluetooth Logger
A small, screenless Bluetooth logger to drop into a box, fridge or archive shelf.
The TZ-BT04 has no display, which keeps it small enough to place inside a carton, a medicine fridge or between archive boxes. It stores up to 15,000 temperature and humidity readings and sends them to the free Temp Logger app on an Android phone over Bluetooth 4.0, at distances of up to about 50 m depending on walls and terrain.
Pairing is done by scanning the QR code on the back of the unit. A single button starts and stops logging, and green and red LEDs confirm its state. Choose the TZ-BT04 when you need several low-cost logging points that are read from a phone; choose the TZ-BT06 when you also want a live on-device display, IP65 sealing and longer range.
- Temperature−40 to +125 °C, ±0.3 °C (store listing)
- Humidity0–100 %RH, ±3 %RH
- Memory15,000 readings
- WirelessBluetooth 4.0 LE, up to about 50 m
- AppTemp Logger (Android)
- Battery3 V, 600 mAh built-in
- IndicatorsGreen/red status LEDs, no display
Best for: Multiple logging points in fridges, cartons, archives and labs, read from an Android phone.
YDP-20 Large-Display PDF Logger
A wall or bench logger with a large screen and audit-ready PDF reports.
The YDP-20 is built for rooms and cabinets that are checked every day: a large LCD shows the live temperature and humidity, the alarm state, battery and logging status at a glance, while the logger quietly stores up to 25,920 readings in the background. High and low limits trigger audible and visual alarms.
At the end of a period the logger produces its own PDF, XLS, TXT, CSV or DLG file, so a quality manager can file a report without retyping numbers. The free PoChain software handles longer-term analysis and lets you apply an offset calibration. It runs on three AAA alkaline batteries (included).
- Temperature−30 to +65 °C, ±0.3 °C basic
- Humidity0–100 %RH, ±3 % (10–90 %RH)
- Memory25,920 readings
- OutputPDF, XLS, TXT, CSV, DLG
- SoftwarePoChain (free), offset calibration
- AlarmsHigh/low, audible and visual
- StartButton or delayed start
- Power3 × AAA alkaline, included
Best for: Pharmacy storerooms, labs, clean rooms, warehouses and server rooms that need a daily visual check plus a PDF record.
YDP-20E PDF Logger with External Probe
Mount the display outside, run the probe inside: read a freezer or chamber without opening it.
The YDP-20E is the YDP-20 with an external probe (21 × 5 mm) on a 2 m cable. The logger and its large display sit outside the fridge, freezer, incubator or test chamber while the probe sits inside, so staff read the conditions without opening the door and letting the temperature recover.
The external probe extends the temperature range to −40 to +125 °C, which covers blast freezers and warm process spaces that an internal-sensor logger cannot sit in. Reporting, alarms and software are the same as the YDP-20: PDF, XLS, TXT, CSV and DLG files, free PoChain software, and 25,920-reading memory.
- Temperature−40 to +125 °C, ±0.3 °C basic
- Humidity0–100 %RH, ±3 % (10–90 %RH)
- Probe21 × 5 mm on 2 m cable
- Memory25,920 readings
- OutputPDF, XLS, TXT, CSV, DLG
- AlarmsHigh/low, audible and visual
- Power3 × AAA alkaline, included
Best for: Freezers, fridges, incubators, stability and test chambers, and sealed enclosures.
YEM-70L Pressure, Temp & RH Logger
Barometric pressure, temperature and humidity in one logger, read like a flash drive.
The YEM-70L adds a barometric pressure sensor (300–1100 hPa, ±1 hPa) to temperature and humidity logging. That matters for laboratories, calibration rooms and test labs whose methods require ambient conditions to be recorded alongside results, and for anyone tracking weather trends.
It stores 22,528 records and shows min, max and average values from memory. Plug it into a PC over MicroUSB and it appears as a USB drive with TXT, CSV and XLS files, so no software or driver installation is needed on locked-down company computers. Three AAA batteries last about a year.
- Pressure300–1100 hPa, ±1 hPa
- Temperature−30 to +65 °C, ±0.3 °C
- Humidity0–100 %RH (10–90 % usable), ±3 %
- Memory22,528 records
- OutputTXT, CSV, XLS via USB drive mode
- AlarmsHigh/low, audible and visual
- Power3 × AAA, about 1 year
Best for: Test and calibration labs, weighing rooms, quality labs and weather-trend logging.
Extech RHT30 USB PDF Logger
Extech's replacement for the 42270/42275: plug into USB and get a PDF or Excel report.
Extech lists the RHT30 as the replacement for the discontinued 42275 datalogger kit. There is no docking station: the logger has a standard USB connector and, when plugged into a PC, hands over its data as a PDF or Excel spreadsheet. It stores 48,000 readings (24,000 each for humidity and temperature) at intervals from 30 seconds to 2 hours.
A colour-coded LED shows at a glance whether conditions are inside limits, and the large LCD shows live readings. Adjustable high/low alarms with an alarm delay avoid nuisance alerts when a door is opened briefly, and password-protected log-in stops settings being changed in the field. Sensors are an NTC thermistor and a capacitive humidity element.
- Temperature−30 to +70 °C, ±0.5 °C
- Humidity0.1–99.9 %RH, ±3 %
- Memory48,000 readings (24,000 per parameter)
- Interval30 s to 2 h
- OutputPDF or Excel on USB plug-in
- Power2 × CR2032 coin cells
- Size110 × 40 × 19 mm, 90 g
- Warranty2 years (Extech)
Best for: Shipping containers, stores, archives and anyone replacing a 42270 or 42275.
TA622C Handheld Thermohygrometer & Logger
A handheld for walk-round surveys: RH, dew point, wet bulb and a K-type input.
The TA622C is a handheld thermohygrometer with a probe on a 2 m lead, rather than an unattended logger. It reads temperature, relative humidity, dew point and wet bulb on a backlit dual display, and a K-type thermocouple input (−50 to 1300 °C) measures surface and duct temperatures on the same instrument.
Its logging is session-based: readings are recorded against a running timer from the moment you press REC, for up to 99 hours, without a date stamp, and only temperature and humidity are stored. That suits HVAC commissioning, damp surveys and spot checks during an inspection. For continuous, time-stamped records, pick one of the loggers above.
- Temperature−10 to +80 °C, ±0.5 °C
- Humidity0–100 %RH, ±3 % (10–90 %RH)
- DerivedDew point and wet bulb, ±0.4 °C
- ThermocoupleK-type, −50 to 1300 °C (display only)
- LoggingSession timer, up to 99 h, no date stamp
- InterfaceMicro-USB, free PC software
- Power3 × AA (not included)
Best for: HVAC commissioning, damp and condensation surveys, building inspections.
Looking for the Extech 42270 or 42275 datalogger kit? Extech has discontinued the 42275 Temperature/Humidity Datalogger Kit (the 42270 logger with a USB docking station and PC software) and names the Extech RHT30 as its replacement. The RHT30 needs no docking station and produces a PDF or Excel report straight from USB. Existing 42270 users who need a networked or alarmed system should also look at the COEUS-WIFI.
Temperature and humidity data logger comparison
Figures are from the manufacturer or the Ecotao store listing for each model. Accuracy is the basic figure; check the product page for the full specification.
← Scroll to see full table →
| Model | Connection | Temperature range | Humidity range / accuracy | Memory | Report output | Display | Best for |
|---|---|---|---|---|---|---|---|
| COEUS-WIFI | Wi-Fi to cloud + app | −30 to +60 °C | 0–100 %RH / ±3 % | 120,000 | Cloud, app; SMS/email alerts | Large LCD | Remote alarms, cold rooms |
| TZ-BT06 | Bluetooth 5.0, up to 300 m | −20 to +60 °C | 0–90 %RH / ±3 %RH | 32,000 | App, email, BT printer | LCD | Transport, IP65 sites |
| TZ-BT04 | Bluetooth 4.0, up to 50 m | −40 to +125 °C | 0–100 %RH / ±3 %RH | 15,000 | Android app | LEDs only | Low-cost multi-point |
| YDP-20 | PC (PoChain) | −30 to +65 °C | 0–100 %RH / ±3 % | 25,920 | PDF, XLS, CSV, TXT, DLG | Large LCD | Rooms and cabinets |
| YDP-20E | PC (PoChain) | −40 to +125 °C | 0–100 %RH / ±3 % | 25,920 | PDF, XLS, CSV, TXT, DLG | Large LCD | Freezers, chambers (2 m probe) |
| YEM-70L | MicroUSB drive mode | −30 to +65 °C | 0–100 %RH / ±3 % | 22,528 | TXT, CSV, XLS (no software) | LCD | Labs; adds pressure |
| Extech RHT30 | USB | −30 to +70 °C | 0.1–99.9 %RH / ±3 % | 48,000 | PDF or Excel on plug-in | LCD + status LED | 42275 replacement |
| TA622C | Micro-USB | −10 to +80 °C | 0–100 %RH / ±3 % | Session log | PC software | Backlit dual LCD | Handheld surveys |
Connection types compared
← Scroll to see full table →
| Type | How you get the data | Strength | Limitation |
|---|---|---|---|
| Wi-Fi / cloud | Automatically, to a web dashboard and phone | Real-time alerts from anywhere | Needs a Wi-Fi network on site |
| Bluetooth | Phone app within range | Read without opening the load | Alerts only when a phone is nearby |
| USB / PDF | Plug into a PC | Simple, audit-ready report | Data is seen only after download |
| Handheld | On-screen during a survey | Dew point, wet bulb, spot checks | Not for unattended logging |
What a temperature and humidity logger does in each application
Pharmaceutical and vaccine storage
Medicines and vaccines are typically stored at 2–8 °C or at controlled room temperature, and a gap in the record can mean stock has to be quarantined. A continuous logger proves storage conditions between manual checks and captures excursions with their duration. The COEUS-WIFI adds out-of-hours alerts; the YDP-20E keeps the display outside the fridge.
Cold chain and refrigerated transport
A Bluetooth logger travels with the load and records every minute of the journey. At the receiving dock the driver or receiver downloads the history to a phone, without opening the doors, and can email or print a report as proof of condition before signing for the goods.
Warehouses, archives and museums
Paper, textiles, timber and packaging absorb moisture. Humidity that stays high encourages mould, and swings in humidity cause warping and cracking. A logger shows whether a store holds a stable band day and night, and which corner or season causes the problem.
Laboratories, clean rooms and calibration
Test methods and quality systems often require ambient temperature and humidity to be recorded alongside results. The YDP-20's PDF output files directly into a quality record; the YEM-70L also logs barometric pressure for weighing and calibration rooms.
Server rooms and electrical panels
Electronics fail early when hot, and condensation forms when cool equipment meets humid air. A logger with high/low alarms catches a failed air-conditioner before equipment shuts down, and the record shows whether the cooling copes on the hottest afternoons.
Shipping containers and export produce
When a container moves between warm, humid air and a cool hold, moisture can condense on the cargo and inner walls (often called container rain). Logging humidity alongside temperature shows when the air reached its dew point and supports a claim or a change in packing.
Temperature and humidity logging in South African conditions
- Load-shedding and power cuts. Every logger on this page runs on batteries and keeps recording when mains power fails. The record shows exactly how far a cold room drifted during an outage and how long recovery took, which is the evidence needed to decide whether stock is still usable. The COEUS-WIFI also buffers readings if the router goes down and uploads them once power returns.
- Coastal humidity. Durban and other coastal sites see high humidity for much of the year, and Cape Town's wet winters push indoor humidity up in stores and archives. Long periods above about 70 %RH raise the risk of mould and corrosion.
- Dry Highveld winters. Inland, winter humidity can fall low enough to dry out timber, paper and some materials and to increase static discharge around electronics. Logging both ends of the year shows whether humidification or dehumidification is needed.
- Long-distance road freight. Consignments travelling between the coast and inland or into neighbouring countries can cross large temperature swings. A logger travelling with the load records the whole route, not just loading and delivery.
- Pharmaceutical distribution. Wholesalers and distributors working to SAHPRA's Good Wholesaling Practice guidelines are expected to monitor and record storage and transport temperatures. A time-stamped logger record supports that documentation.
Why log humidity, not just temperature? Relative humidity changes with temperature: the same air reads a higher RH as it cools, and condenses when it reaches its dew point. Recording both lets you calculate the dew point after the event and explain condensation, mould or product damage that a temperature log alone cannot. For live dew point readings, see our temperature, humidity and dew point meters.
Related Ecotao pages
Temperature and humidity data logger questions
What is a temperature and humidity data logger?
A temperature and humidity data logger is a battery-powered instrument that measures air temperature and relative humidity (RH) at a set interval, for example every 5 or 15 minutes, and stores each reading with a time stamp. The stored record is later downloaded over USB, Bluetooth or Wi-Fi as a report or spreadsheet, giving documented proof of the conditions a product, room or vehicle was kept in.
What is the difference between a data logger and a thermohygrometer?
A thermohygrometer shows the current temperature and humidity and may hold a min/max value. A data logger records every reading over time with a time stamp, so you can prove what happened overnight, over a weekend or during a journey. Handheld units such as the TA622C sit in between: they record a session but are not designed to be left unattended for weeks.
Which temperature and humidity logger sends alerts to my phone?
The COEUS-WIFI sends SMS, email and app push alerts through its cloud platform whenever a limit is crossed, wherever you are. The TZ-BT06 and TZ-BT04 Bluetooth loggers show alarms in their app, but only when a phone is within Bluetooth range.
Do these data loggers keep recording during load-shedding or a power cut?
Yes. All of the loggers on this page run on batteries and keep recording when mains power fails. The COEUS-WIFI also stores readings locally when the Wi-Fi router goes down and uploads them once the connection returns, so a power cut shows up in the record instead of leaving a gap.
Which humidity loggers produce a PDF report without extra software?
The Extech RHT30 produces a PDF or Excel file when plugged into USB, and the YDP-20 and YDP-20E generate PDF, XLS, CSV and TXT files themselves. The YEM-70L appears as a USB drive with TXT, CSV and XLS files, so it also needs no installed software, but it does not create a PDF.
What logging interval should I use?
Match the interval to how fast conditions can change and how long the logger must run. Refrigerated transport and fridges are commonly logged every 1 to 5 minutes; rooms, warehouses and archives every 10 to 30 minutes. Divide the logger's memory by the number of readings per day to check it will not fill up before the next download.
What relative humidity causes mould and corrosion?
Mould growth becomes likely when relative humidity stays above roughly 70 % for extended periods, and condensation forms when a surface drops below the dew point of the surrounding air. Many archives, museums and electronics stores aim to hold humidity in a stable band of about 40 to 60 %RH. A humidity logger shows whether a space stays in that band day and night, not just when someone checks.
What replaced the Extech 42270 and 42275 humidity dataloggers?
Extech has discontinued the 42275 kit and its 42270 logger and names the RHT30 USB Humidity/Temperature Datalogger as the replacement. The RHT30 needs no docking station: it plugs straight into USB and produces a PDF or Excel report. Ecotao can quote on the RHT30 on request.
Should I choose a Bluetooth or a Wi-Fi temperature and humidity logger?
Choose Wi-Fi (COEUS-WIFI) for a fixed site with a router where you want remote alerts and cloud records around the clock. Choose Bluetooth (TZ-BT06 or TZ-BT04) for vehicles, containers and sites without Wi-Fi, where someone reads the logger on a phone during rounds or at delivery.
Does Ecotao deliver temperature and humidity loggers outside South Africa?
Ecotao supplies from Cape Town across South Africa and to neighbouring countries including Namibia, Botswana, Zimbabwe, Mozambique, Lesotho and Eswatini. Contact sales@ecotao.co.za or call +27 21 911 5835 for delivery and lead times.
Need help choosing a temperature and humidity logger?
Tell us what you are monitoring, the temperature range and how you need the report, and we will recommend a logger and confirm stock and lead time. Supplied from Cape Town across South Africa, Namibia, Botswana, Zimbabwe, Mozambique, Lesotho and Eswatini.
- Head Office: +27 21 911 5835
- Zak: 086 142 8716
- Zaid: 082 390 3989
- sales@ecotao.co.za
- aqua@ecotao.co.za