The Testo 435-3 (0560 4353) Multi-Function HVAC/IAQ Meter with Integrated Differential Pressure is perfect for monitoring, analyzing, and diagnosing indoor air quality, wherever you need to take important IAQ measurements. In addition, you can easily pinpoint and troubleshoot airflow problems with HVAC systems, and immediately see the results of corrections. Commissioning, validating, benchmarking, or simply adjusting HVAC systems are all easy with the 435-3.

The 435-3 Multi-Function HVAC/IAQ Meter allows you to carry out the measurements that are necessary to check and adjust the airflow of air conditioning systems, and to assess the quality of indoor air. The 435-3 Multi-Function HVAC/IAQ Meter accepts a wide variety of probes to measure and record airflow, temperature, and indoor air quality readings. Probe dependent menus and selectable user profiles ensure that the 435-3 is always ready to use. Easy setup of user-defined IAQ and airflow/duct profiles allows for fast measurement of many different tasks, and with a wide variety of probe choices available, the 435-3 Multi-Function HVAC/IAQ Meter is ready to handle a vast array of indoor air quality applications.

Applications

Flow Measurement in Ventilation Ducts Using a Thermal Anemometer and Vane Anemometer

The Testo 435-3 Multi-Function HVAC and IAQ Meter is compatible with compact anemometer probes and pitot tubes for measuring the flow and volumetric flow in a ventilation duct. Selecting a suitable probe or measuring instrument depends on the flow velocity in the ventilation duct. This can be broken down into three sub-ranges: low flow velocities (0 to 5 m/s), medium flow velocities (5 to 40 m/s), high flow velocities: 40, 70, 100 m/s.

The flow sensors for duct measurement are all equipped with telescopes making them easy to use in large air ducts. Air temperature and humidity can also be measured with the same probe as the flow velocity if required. According to the required application, choose between a thermal probe, vane probe or pitot tube for measuring the flow measurement in the duct.

Measurement at the Air Outlet

Every duct inlet and outlet should only contain the volumetric flow that according to calculations is a basic prerequisite to an efficient functional system.

Large vane anemometers with 100 mm diameters are suitable for measuring the volumetric flows at duct outlets (order no. 0635 9435), as it integrates the flow velocity over a larger area, thereby determining disturbance from the air grille (loop method).

To measure the suction or blowing vents of air grilles and poppet valves, a volumetric flow rate funnel set is ideal (order no. 0563 4170), as is the large 100 mm vane anemometer (order no. 0635 9435). The entire volumetric flow is recorded with the aid of the funnel without the need for conversion on the basis of the flow velocity and area. This method of flow measurement is simple and reliable.

Measurement of the Air and Surface Temperature

For people to be comfortable and perform at their best, it is crucial that the rooms they occupy are correctly air conditioned. As well as the structural conditions and personal perception, the following factors also contribute significantly to the existence of a pleasant indoor climate: the indoor air and surface temperature of walls, windows, floors and ceilings.

There is a range of optional temperature probes available for the 435-3 Multi-Function HVAC/IAQ Meter. Temperature probes with a sprung cross-band sensor element for measurement on surfaces are an ideal option. The sprung cross-band sensor element fits on any surface, taking the actual temperature of the measured object in just a few seconds (for example the fast-reaction surface probe, order no. 0602 0393).

In order to allow a fast measurement of air temperature, the temperature sensor is free in Testo's air probes (e.g. NTC probe 0613 1712). Immersion/penetration probes can also be used for measurements in air. However, the response time is then about 40 to 60 times higher than the indicated value which was measured in water.

Measurement of Radiated Heat

The 435-3 Multi-Function HVAC/IAQ Meter is your reliable aid to measuring thermal comfort. The optional, attachable globe thermometer (order no. 0602 0743) enables measurement of radiated heat (that is, the operative or perceived temperature). The operative temperature measured with a Globe thermometer with a 150 mm diameter preferably corresponds with people's perceived temperature to +/- 0.41 K.

The temperature measurements in a room (air temperature and operative temperature) are to be taken in the same place and same general conditions as the measurement of indoor air velocities.

Differential Pressure Measurement on Filters

Air conditioning systems are equipped with filters which prevent dirt from the outside air entering the indoor air. These filters are to be inspected regularly to make sure they are still fully functional. To do this, the pressure is measured in front of and behind the filter. The result is the differential pressure. If it is too high, the filter is contaminated and needs changing.

The Testo 435-3 Multi-Function HVAC/IAQ Meter uses its integral sensor to measure the differential pressure within the 0 to 25 hPa range. The differential pressure measurement is temperature-compensated for exact readings. Magnets on the rear of the instrument allow hands-free work.

Measurement in the Ventilation Duct Using a Pitot Tube

Observance of air flows in the ventilation duct is of utmost importance for the function of the ventilation and air conditioning system.

The internal differential pressure sensor of the 435-3 is used for measuring in the case of high flow velocities and very contaminated flows, and the pitot tube for an air velocity ranging from 0 to 64 m/s. The 435-3 simultaneously displays pressure, flow and volumetric flow. Magnets on the rear of the 435-3 Multi-Function HVAC/IAQ Meter allow for hands-free work.

Measurement of Indoor Air Quality (CO2)

Bad indoor air quality due to high concentrations of CO2 can cause tiredness, lack of concentration and even illness. Therefore, to ensure sufficient indoor air quality, the CO2 concentration should generally not exceed 1000 ppm. Values of 700 to 1500 ppm can be viewed as the "reference range".

The IAQ probe (order no. 0632 1535) is particularly suitable for monitoring indoor air quality controls. This probe can be used to record CO2, temperature and relative humidity at the same time.

CO Measurement

Carbon monoxide (CO) is an odourless, invisible and tasteless gas, but also poisonous. It is produced during the incomplete combustion of substances containing carbon, such as coal, wood, oil, natural gas, etc., in heat sources and combustion engines. The CO concentration will increase quickly, particularly if there is not enough oxygen available. This may have adverse effects on health.

The ambient CO probe (order no. 0632 1235) and Testo 435-3 Multi-Function HVAC/IAQ Meter are able to detect even the smallest quantities of CO in ambient air.