testo 320 set - flue gas analysis set for heating engineers

Order-Nr.  0563 3220 75

  • Self-explanatory menu guidance with standardized measuring procedures for quick, easy handling

  • Sensors can be changed, integrated system for monitoring the sensor functions

  • Easy to operate thanks to single-hose connection

  • TÜV-tested according to EN 50379, Part 1-3 and to 1st German Federal Immission Control Ordinance (BImSchV), Part 1-2

The ideal equipment for heating engineers: with this testo 320 flue gas analysis set, you can carry out your measuring tasks on heating systems quickly and efficiently. Use the flue gas analyzer to measure flue gas, draught, pressure, ambient CO and CO2, differential temperature and also detect gas leaks. In the set you also get practical accessories to help you with your work.


Product Description

Heating engineers will find the testo 320 flue gas analyzer a reliable tool for performing measuring tasks on heating systems: e.g. for sorting out malfunctions and emergencies, for monitoring statutory limit values or for everyday routine tasks involved in servicing heating systems. This high-efficiency flue gas analyzer (in the complete package with flue gas probe) can undertake the measurement of flue gas, draught, pressure, ambient CO and CO2, differential temperature and carry out gas leak detection. In the set you also get practical accessories to make your work easier.

Standardized menu structures, which are stored in the flue gas analyzer specific to the country concerned, make for easy operation. Readings are easy to read off on the high-resolution colour display, even when the light is poor. Up to 500 measurement protocols can be saved in the flue gas analyzer.

Quality that you can depend on: the testo 320 flue gas analyzer is TÜV-tested according to EN 50379, Part 1-3 and to 1st German Federal Immission Control Ordinance (BImSchV), Part 1-2 (with integrated, H2-compensated CO cell also Part 3). When you purchase the flue gas analyzer, you get a 2-year warranty (for the instrument, probe, O2/CO sensor).

testo 320 flue gas analysis set: high-efficiency instrument, practical accessories

  • Ready to start measuring flue gas on heating systems: the testo 320 flue gas analyzer is equipped with two sensors – an O2 and a CO sensor. In this flue gas analysis set, the CO-sensor is H2-compensated. The instrument therefore offers a CO measuring range of up to 8,000 ppm (instead of 4,000 ppm without H2-compensation) and complies with the statutory provisions of the German Federal Immission Control Ordinance (BImSchV). For flue gas measurement, you need a compact or modular flue gas probe. A compact flue gas probe is included in the set. A temperature probe is integrated into the probe. Al relevant flue gas measurement parameters can therefore be calculated: CO2 value, efficiency and flue gas loss. The flue gas analyzer can also be used for flue draught measurements or pressure measurements
  • Changing probes is easy: the probes can be changed manually. This means that you can order other optional probes specifically required for your flue gas analysis (e.g. multi-hole probe, dual wall clearance probe, flexible flue gas probe)
  • Single-hose connection: just one hand movement is needed to securely connect all channels for the flue gas measurement via the probe coupling (gas paths, draught, temperature probe integrated in the flue gas probe)
  • Measurement data management: it is possible to export the measurement protocols in Excel optionally via mini-USB. Further options for managing the measurement data are offered by the PC software easyheat (optional) and the free app TestoDroid for android smartphones and tablets
  • Long service life thanks to the long-life Li-ion rechargeable battery
  • Built-in magnets enable the flue gas analyzer to be attached to the burner/boiler quickly and easily
  • Integrated condensate trap: easy to empty
  • Advantage of owning the set: in the set you get the flue gas analyzer with compact flue gas probe, combustion air probe with cone, USB mains unit (with USB cable), testo fast printer (with infrared interface) and instrument case

Fields of application for the testo 320 flue gas analysis set

  • Flue gas measurement (combustion air temperature, flue gas temperature, O2, CO and CO2 concentration, flue gas loss, gas/air ratio, efficiency)
  • Draught measurement
  • Gas flow and gas resting pressure (with optional pressure connection set)
  • 4 Pa measurement (with optional fine pressure probe)
  • Gas leak detection (with optional probe: CH4 and C3H8)
  • Ambient CO and CO2 measurement (with optional probe)
  • Differential temperature measurement to determine the spread between flow and return (with optional differential temperature set)

Delivery Scope

- testo 320 flue gas analyzer with O2 and H2-compensated CO sensor including replaceable Li-ion rechargeable battery (0632 3220)
- Compact flue gas probe: length 300 mm, Ø 6 mm (0600 9741)
- Combustion air probe with cone: length 190 mm (0600 9787)
- USB mains unit with USB cable (0554 1105)
- testo fast printer IRDA with wireless infrared interface for printing out data at the measuring location (0554 0549)
- System case (0516 3300)   

Technical Data

General technical data


573 g


240 x 85 x 65 mm

Operating temperature

-5 to +45 °C

Display size

240 x 320 pixels

Display function

Colour graphic display

Power supply

Battery: 3.7 V / 2,400 mAh; Mains unit: 6 V / 1.2 A

Maximum memory

500 Measurement values

Storage temperature

-20 to +50 °C

Flue gas CO (with H₂-compensation)

Measuring range

0 to 8000 ppm


±10 ppm or ±10 % of mv (0 to 200 ppm)

±20 ppm or ±5 % of mv (201 to 2000 ppm)

±10 % of mv (2001 to 8000 ppm)


1 ppm

Reaction time t₉₀

< 40 s

Flue gas COlow (with H₂-compensation)

Measuring range

0 to 500 ppm


±2 ppm (0 to 39 ppm)

±5 % of mv (40 to 500 ppm)


1.0 ppm

Reaction time t₉₀

< 40 s

Differential Pressure flue gas Draught - Piezoresistive

Measuring range

-9.99 to +40 hPa


±0.02 hPa or ±5 hPa (-0.50 to +0.60 hPa)

0.03 to +1 hPa

±1.5 % of mv (+3.01 to +40.00 hPa)


0.01 hPa with fine draught option 0.001 hPa


Measuring range

-40 to +1200 °C


±0.5 °C (0 to +100.0 °C)

±0.5 % of mv (Remaining Range)


0.1 °C (-40 to +999.9 °C)

1 °C (> +1000 °C)

Flue gas degree of effectivity, Eta (calculated)

Measuring range

0 to 120 %


0.1 %

Flue gas loss (calculated)

Measuring range

0 to 99.9 %


0.1 %

Flue gas CO₂ calculation (calculated from O₂)

Measuring range

0 to CO₂ max (Display range)


±0.2 Vol.%


0.1 Vol.%

Pressure measurement

Measuring range

0 to +300 hPa


±0.5 hPa (0.0 to 50.0 hPa)

±1 % of mv (50.1 to 100.0 hPa)

±1.5 % of mv (Remaining Range)


0.1 hPa with fine draught option 0.01 hPa

Flue gas CO (without H₂-compensation)

Measuring range

0 to 4000 ppm


±20 ppm (0 to 400 ppm)

±5 % of mv (401 to 2000 ppm)

±10 % of mv (2001 to 4000 ppm)


1 ppm

Ambient CO

Measuring range

0 to 500 ppm


±5 ppm (0 to 100 ppm)

±5 % of mv (> 100 ppm)


1 ppm

with CO probe 0632 3331

Ambient CO₂

Measuring range

0 to 1 Vol.%

0 to 10000 ppm


±75 ppm or ±3 % of mv (0 to 5000 ppm)

±150 ppm or ±5 % of mv (5001 to 10000 ppm)

with ambient CO₂ probe 0632 1240

Gas leak measurement for combustible gases (via gas leak detection probe)

Measuring range

0 to 10000 ppm CH₄/ C₃H₈; Display range


Signal optical display (LED) audible signal via buzzer

Reaction time t₉₀

< 2 s

with gas leak detection probe 0632 3330


Temperature probes

Connection cable

Order Number: 0430 0143


Ambient CO measurement in the heated environment

Carbon monoxide (CO) is a colourless, odourless and taste-free gas, but also poisonous. It is produced during the incomplete combustion of substances containing carbon (oil, gas, and solid fuels, etc.). If CO manages to get into the bloodstream through the lungs, it combines with haemoglobin thus preventing oxygen from being transported in the blood; this in turn will result in death through suffocation. This is why it is necessary to regularly check CO emissions at the combustion points of heating systems and the surroundings.

Measuring the flue gas parameters of the burner (CO, O2, and temperature, etc.)

The flue gas measurement for a heating system helps to establish the pollutants released with the flue gas (e.g. carbon monoxide CO or carbon dioxide CO2) and the heating energy lost with the warm flue gas. In some countries, flue gas measurement is a legal requirement. It primarily has two objectives:


  • Ensuring the atmosphere is contaminated as little as possible by pollutants; and
  • energy is used as efficiently as possible.


Stipulated pollutant quantities per flue gas volume and energy losses must never be exceeded. Measurement in terms of results required by law takes place during standard operation (every performance primarily using the appliance). Using a Lambda probe (single hole or multi-hole probe), the measurement is taken at the centre of flow in the connecting pipe (in the centre of the pipe cross-section, not at the edge) between the boiler and chimney/flue. The measured values are recorded by the flue gas analyzer and can be logged either for print out or transfer to a PC at a later stage.

Measurement is taken by the installer at commissioning, and if necessary four weeks later by the flue gas inspector/chimney sweep, and then at regular intervals by the authorised service engineer.

Measuring pressure on burners (nozzle pressure, gas flow pressure, etc.)

Standard readings taken during services of domestic heating systems include checking the gas pressure on the burners. This involves measuring the gas flow pressure and gas resting pressure. The flow pressure, also called supplied pressure, refers to the gas pressure of the flowing gas and resting pressure of the static gas. If the flow pressure for gas boilers is slightly outside the 18 to 25 mbar range, adjustments must not be made and the boiler must not be put into operation. If put into operation nonetheless, the burner will not be able to function properly, and explosions will occur when setting the flame and ultimately malfunctions; the burner will therefore fail and the heating system will shut down.

Measuring temperatures on radiators

When measuring the temperature on radiators, the flow and return temperatures are recorded in particular and assessed by the tradesman. The flow temperature is defined as the temperature of a thermal transfer medium (e.g. water) that the system is supplied with. The temperature of the medium flowing out of the system is accordingly called the return temperature. To prevent losses within the heat distribution system and achieve a better level of efficiency in modern, heating technology, spot recording of flow and return temperatures is necessary at certain radiator pipes or screw fittings. Implementation of relevant measures ultimately leads to hydraulic adjustment on the basis of knowledge about the flow and return temperatures. This defines a procedure with which every radiator or heating circuit of a flat radiator within a heating system is supplied at a set flow temperature with the precise amount of heat needed to achieve the ambient temperature required for the individual rooms. Flawed operating conditions will result in considerable excess consumption of electricity and heating energy.


Product Brochures