® Establishing a Bluetooth connection ............. 9 6.3.1 ® Establishing a Bluetooth connection to the testo Smart App ....10 Using the product ................11 Controls on the measuring instrument ..........11 7.1.1 Implementing settings ................12 7.1.2 Opening configuration mode ..............13 7.1.3...
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PDF Export ..................30 Perform Firmware update ..............31 Maintaining the product ..............32 Inserting / changing batteries ............... 32 Cleaning the instrument ............... 32 Technical data for testo 425.............. 33 Tips and assistance ................34 11.1 Questions and answers ............... 34 11.2 Accessories and spare parts..............
Only perform maintenance and repair work on this instrument that is described in this documentation. Follow the prescribed steps exactly when doing the work. • Use only original spare parts from Testo. Batteries • Improper use of batteries may cause the batteries to be destroyed, or lead to injury due to current surges, fire or escaping chemicals.
• At the end of its useful life, deliver the product to the separate collection point for electric and electronic devices (observe local regulations) or return the product to Testo for disposal. • WEEE Reg. No. DE 75334352 Testo-Direct sales@GlobalTestSupply.com...
4 Intended use The testo 425 is a compact instrument for measuring flow velocities and temperatures by means of a permanently connected flow/temperature probe (hot wire probe). It is intended for indoor use only.
1 Control keys 2 Display 3 Probe 4 Battery compartment Explanation of icons Refer to instruction manual CAUTION Damage to sensor possible! - Do not touch sensor! - Close the protective sleeve after the measurement. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
Symbol explanation Do not allow children under 6 years of age to play with batteries. Do not throw batteries in the trash. Do not charge batteries. Do not place batteries near fire. Batteries are recyclable. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
The display turns off. 6.2.3 Switching the display illumination on and The measuring instrument is switched on. Press and hold down (2 sec) the MENU/ENTER key. The display illumination is switched on or off. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
6 First steps ® Establishing a Bluetooth connection The instrument can be connected to the testo Smart App via ® Bluetooth connection The measuring instrument is switched on. ® To enable the Bluetooth connection for the first time, press and hold ◄...
If necessary, switch the instrument to be connected off and on again to restart the connection module. When the testo Smart App is connected to the measuring instrument, icon appears on the measuring instrument display. The measuring instrument automatically synchronizes its date and time settings with the testo Smart App.
7 Using the product 7 Using the product Controls on the measuring instrument The instrument is switched on. The testo Smart App is installed on the smartphone and connected ® to the instrument via Bluetooth Settings and controls are implemented either on the instrument or via the app.
Decrease value, select option On/Off (long press) Switches the instrument on or off MODE/END Select or end multi-point or continuous mean calculation. Display illumination (long press) OFF (display illumination not active) or ON (display illumination active) Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
7.1.3 Setting the unit Configuration mode is open, “UNITS” is displayed. ◄ ► Press to choose between metric (“METR”) and imperial (“IMPER”) units of measurement and confirm with MENU/ENTER. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
MENU/ENTER: NO: Do not carry out reset. YES: Carry out reset. All concealed menus that were hidden via the testo Smart App are displayed again. The instrument returns to measurement view. Testo-Direct sales@GlobalTestSupply.com...
Read the measured values on the display. 7.2.1 Changing the measurement channel display - Switch between the display of temperature (°C, °F) and calculated volume flow (m3/h, l/s, cfm): ► Press Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
The number of readings recorded is displayed in the upper line, while the current reading is displayed in the lower line. To record readings (in the desired quantity): Press MENU/ENTER (several times). To end measurement and calculate the mean value: Press MODE/END. flash. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
MENU/ENTER each time. To end measurement and calculate the mean value: Press MODE/END. flash. The measurement period and the calculated continuous mean value are displayed. To switch back to the measuring view: Press MODE/END. Testo-Direct sales@GlobalTestSupply.com 1.888.610.7664 www. .com...
A testo Bluetooth /IRDA printer (order no. 0554 0621) is connected via Bluetooth and switched on. When first setting up a connection between the testo measuring ® instrument and the testo Bluetooth /IRDA printer, the initialization phase can last up to 30 seconds.
8 Controls via testo Smart App 8 Controls via testo Smart App If the measuring instrument is connected to the testo Smart App, it is primarily operated via the app. The measuring instrument remains in the measurement view and settings menus cannot be opened on the measuring instrument.
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8 Controls via testo Smart App Additional symbols on the user interface of the app (not numbered) One level back Exit view Share measurement data/report Searching Favourite Deleting Further information Display report Multiple selection Main menu can be accessed via the icon at top left.
Select Instrument information. The version number of the app and the ID are displayed. 8.2.3 Displaying the tutorial The tutorial guides you through the first steps in operating the testo Smart App. Click on Select Help and Information. ...
8 Controls via testo Smart App Application menus 8.3.1 Selecting an application menu Click on A selection of menus for various applications is displayed. Select the required application. Your selected application is displayed. 8.3.2 Setting favourites Click on ...
8 Controls via testo Smart App Making measuring instrument settings The measuring instrument is connected to the testo Smart App. Click on The main menu opens. Click on Sensors. Sensors menu opens. Click on the required measuring instrument.
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8 Controls via testo Smart App Click on the blue text under a setting heading to activate or disable settings or to open an input window to enter a specific value or select a unit. For details on the settings options, see the following sub-sections.
8 Controls via testo Smart App 8.4.1 Configuring the measuring instrument menu The testo Smart App can be used to set which settings menus should be available or hidden on the measuring instrument itself. Settings tab in the Sensors menu is open.
8 Controls via testo Smart App Deactivate the checkboxes for the measuring instrument menus that are no longer to be displayed on the measuring instrument itself. The menus belonging to the deactivated entries will no longer be displayed in the measuring instrument menu after the next synchronization.
For example: If 20% of the area is covered, the correction factor must be set to 0.8 (80% free space). The correction factor can only be set via the testo Smart App and not directly on the measuring instrument. Settings tab is open.
8 Controls via testo Smart App Enter the value for the cross-sectional area and save. The changes are transferred to the measuring instrument and synchronization with the app is confirmed on the measuring instrument via “SYNC DONE”. Display of the readings The available readings can be displayed in different views.
Create PDF with all readings is only possible up to 30 pages, due to the resulting file size and number of pages. In the testo DataControl software, however, PDF reports can be created for all measurements without any restrictions. ...
8 Controls via testo Smart App Perform Firmware update Ensure that the option for Enable update for connected instruments Instrument Information is always enabled. If a new firmware is available for your measurement instrument, an update notification is shown after connecting the instrument with the testo Smart App.
9 Maintaining the product After the update the measuring instrument is restarting. The firmware can be checked in the instrument menu or via the app. A restart of the testo Smart App is recommended after the instrument update. 9 Maintaining the product...
• Adjustment conditions for flow probes: Adjustment in free jet Ø 350 mm, reference pressure 1013 hPa, based on testo reference Laser Doppler Anemometer (LDA). • Low flow velocities may result in greater measurement uncertainties during humidity and temperature measurement! The probe should be switched on outside a duct under the following conditions: Ambient temperature: 20°C...
• ® Display: BT Fail Bluetooth connection Check Bluetooth could not be established connections. • Restart measuring instrument, restart testo Smart App. • ® Check Bluetooth Display: Print Fail Printout could not be connections, switch off performed successfully and then on again if necessary.
Question Possible cause Possible solution Display: OTA Fail The update process "over Restart the measuring the air" of the measuring instrument and testo Smart instrument could not be App and check the ® completed successfully. Bluetooth connection. Display: APP Lost...
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