Testo 435 Multifunction HVAC and IAQ Meter
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This meter requires probes that must be purchased separately. See the accessories tab.


  • Programmable functions
  • Integrated differential pressure measurement
  • Data recording for up to 10,000 readings
  • PC software for analyzing, archiving and documenting data
  • Printing to the test IR printer
  • Wide selection of optional probes: Four function IAQ probe (temp. RH, CO2, and absolute pressure), thermal probe with integrated temperature and humidity measurement, wireless temperature probes, flow measurements with both vane and thermal probes

Or get everything you need in a kit:

The Testo 435 multifunction HVAC and IAQ meter is perfect for monitoring, analyzing and diagnosing indoor air quality anywhere you need to take important IAQ measurements - in the office, in the warehouse, or on the production floor. You can easily pinpoint and troubleshoot problems with HVAC systems and see the results of corrections immediately.

The Testo 435, is designed to accept a variety of standard and wireless probes depending upon your application, making it possible to measure everything from IAQ to velocity. For basic HVAC checks, temperature and humidity measurements have been integrated in the new thermal probe, with a measurement range of -4 to 158°F, for measurements in ducts. This probe also has an accuracy of ±0.5°F. Flow speed, volume flow, air humidity and air temperature can easily be measured in one sequence.

The vane probe, with a diameter of 2.4" and measurement range of 50 to 4,000 fpm, is suited for integrated measurements at registers. For duct measurements, a 0.6" vane probe with a broad range, 118 to 8000 fpm, is available. The Pitot tube is ideal for higher air temperatures and velocities. A 10" H20 differential pressure probe is integrated into the Testo 435-3 and Testo 435-4 for this purpose.

For important IAQ measurements the unique IAQ probe measures CO2, relative humidity and room air temperature, over a range of 0 to +10000 ppm CO2, in order to evaluate room air quality plus absolute pressure. The thermal velocity probe offers ±0.5°F, ±2%RH (2 to 98% RH), and ±(6fpm + 4% of rdg) accuracies paired with measurement ranges of -4 to 158°F, 0 to 100% RH and 0 to 4000fpm.

The degree of air velocity, or draftiness, in any room can easily be determined with the turbulence probe which offers measurement ranges of 0 to 120°F and 0 to 1000fpm, with matching accuracies of ±0.5°F and ±(6fpm + 4%rdg). Determine the true illumination (lux) of those low-lit areas that affect working conditions daily with the light probe.

Surface temperature measurements of motors, cooling coils, heat exchangers, etc. are easily performed with the cross-band probe. Its unique design reaches the actual surface temperature in just a few seconds and features a Class 2 accuracy over a measuring range of -76 to 572°F.

Required Components
These additional components are required for the operation of your product. We strongly advise you to purchase these components unless you already own them or own a suitable alternative.
Testo Temperature Probes
Temperature probes for Testo Meters
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Testo 435 Air Quality Probes
Air quality probes for the Testo 435 multifunction HVAC and IAQ meter
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Testo 435 Air Speed Probes
Air speed probes for the Testo 435 multifunction HVAC and IAQ meter
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Testo 435 Light Probe
Light probe for the Testo 435 multifunction HVAC and IAQ meter
Testo Wireless Probes
Wireless probes for use with Testo meters
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Testo Wireless Probe and Upgrade Kit D (RH)
Measurements up to 65 ft
Please consider these optional accessories.
Testo Wireless Module
Wireless module for upgrading Testo meters to a wireless option
Testo Wireless Handle
Wireless handle for plug-in probe heads
Testo Infrared Printer
Testo printer with wireless IRDA and infrared interface
Testo Thermal Printer Paper
Thermal paper for Testo Infrared printer
Testo Plug-In Power Supply
Plug-in power supply for Testo 735, Testo 635 and Testo 435
Testo 0516 0035 Compact Service Case