• 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
This meter requires probes that must be purchased separately. See the accessories tab.


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 10inH2O 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.