testo 320 Kit 1 – Standard flue gas analyzer with O₂ and CO sensors

The testo 320 Kit 1 provides HVAC/R professionals with a complete, ready-to-use solution for standard flue gas analysis. At its core is the testo 320 standard flue gas analyzer with integrated O₂ and CO sensors (up to 5,000 ppm CO), designed for daily commissioning, service and maintenance work on gas and oil-fired systems. The large 5.5" IPS touchscreen with app-like interface presents all key values at a glance and guides users step by step through typical measurement tasks, ensuring fast navigation and consistent results.
The kit includes a compact basic flue gas probe, an instrument bag with carrying strap and spare particle filters, so technicians have everything they need on site for reliable combustion checks. With measurement parameters such as O₂, CO, efficiency (η), flue gas loss, draught and flue gas temperature, the system covers all essential requirements in standard HVAC/R applications.
Via the integrated Bluetooth interface, the testo 320 connects to the testo Smart App and up to four wireless probes, enabling remote control, second screen operation and the integration of temperature, differential pressure, CO and CO₂ measurements. Central data management via testo Smart Connect and long battery life with fast USB-C charging support efficient workflows and uninterrupted operation throughout the working day.

O₂	Measuring range 0 to 21 Vol.%
Accuracy ±0.2 Vol.% ±1 Digit
Resolution 0.1 Vol.%

Measuring range

0 to 21 Vol.%

Accuracy

±0.2 Vol.% ±1 Digit

Resolution

0.1 Vol.%

Flue Gas Draft	Measuring range -4.00 to +16 InH₂O / -9.99 to +40 hPa
Accuracy ±1.5 % of mv (+1.20 to +16 InH₂O) ±1 Digit / ±1.5 % of mv (+3.01 to +40 hPa) ±1 Digit ±0.01 InH₂O (0.0 to +1.20 InH₂O) ±1 Digit / ±0.02 hPa (0.1 to +3.00 hPa) ±1 Digit ±0.002 InH₂O (0 to 0.0 InH₂O) ±1 Digit / ±0.005 hPa (0 to 0.1 hPa) ±1 Digit
Resolution 0.000 InH₂O (+0 to 0.0 InH₂O) / 0.001 hPa (+0 to 0.1 hPa) 0.00 InH₂O Remaining Range

Measuring range

-4.00 to +16 InH₂O / -9.99 to +40 hPa

Accuracy

±1.5 % of mv (+1.20 to +16 InH₂O) ±1 Digit / ±1.5 % of mv (+3.01 to +40 hPa) ±1 Digit

±0.01 InH₂O (0.0 to +1.20 InH₂O) ±1 Digit / ±0.02 hPa (0.1 to +3.00 hPa) ±1 Digit

±0.002 InH₂O (0 to 0.0 InH₂O) ±1 Digit / ±0.005 hPa (0 to 0.1 hPa) ±1 Digit

Resolution

0.000 InH₂O (+0 to 0.0 InH₂O) / 0.001 hPa (+0 to 0.1 hPa)

0.00 InH₂O Remaining Range

Temperature	Measuring range -40° to 2192 °F / -40 to +1200 °C
Accuracy ±0.5 % of mv (Remaining Range) ±1 Digit ±0.9 °F (32° to 212.0 °F) / ±0.5 °C (0.0 to +100.0 °C) ±1 Digit
Resolution 1.0 °F (Remaining Range n2{+#0} {%S2}) / 1 °C Remaining Range 0.1 °F (-40° to 1831.8 °F) / 0.1 °C (-40 to +999.9 °C)

Measuring range

-40° to 2192 °F / -40 to +1200 °C

Accuracy

±0.5 % of mv (Remaining Range) ±1 Digit

±0.9 °F (32° to 212.0 °F) / ±0.5 °C (0.0 to +100.0 °C) ±1 Digit

Resolution

1.0 °F (Remaining Range n2{+#0} {%S2}) / 1 °C Remaining Range

0.1 °F (-40° to 1831.8 °F) / 0.1 °C (-40 to +999.9 °C)

Efficiency testing (η)	Measuring range 0 to 120 %
Resolution 0.1 %

Measuring range

0 to 120 %

Resolution

0.1 %

Flue gas loss	Measuring range 0 to 99.9 %
Resolution 0.1 %

Measuring range

0 to 99.9 %

Resolution

0.1 %

CO₂ (calculated from O₂)	Measuring range 0 to CO₂ max (Display range)
Accuracy ±0.2 Vol.% ±1 Digit
Resolution 0.1 Vol.%

Measuring range

0 to CO₂ max (Display range)

Accuracy

±0.2 Vol.% ±1 Digit

Resolution

0.1 Vol.%

Pressure measurement	Measuring range -40 to +80 InH₂O / -100 to +200 hPa
Accuracy ±0.2 InH₂O (0 to +20.0 InH₂O) ±1 Digit / ±0.5 hPa (0 to +50.0 hPa) ±1 Digit ±1 % of mv (+20.0 to +40.0 InH₂O) ±1 Digit / ±1 % of mv (+50.1 to +100.0 hPa) ±1 Digit ±1.5 % of mv (+100.1 to +80 InH₂O ±1 Digit / ±1.5 % of mv (+100.1 to +200 hPa ±1 Digit
Resolution 0.00 InH₂O / 0.01 hPa

Measuring range

-40 to +80 InH₂O / -100 to +200 hPa

Accuracy

±0.2 InH₂O (0 to +20.0 InH₂O) ±1 Digit / ±0.5 hPa (0 to +50.0 hPa) ±1 Digit

±1 % of mv (+20.0 to +40.0 InH₂O) ±1 Digit / ±1 % of mv (+50.1 to +100.0 hPa) ±1 Digit

±1.5 % of mv (+100.1 to +80 InH₂O ±1 Digit / ±1.5 % of mv (+100.1 to +200 hPa ±1 Digit

Resolution

0.00 InH₂O / 0.01 hPa

CO (without H₂ compensation)	Measuring range 0 to 5000 ppm
Accuracy ±10 % of mv (2001 to 5000 ppm) ±1 Digit ±5 % of mv (401 to 2000 ppm) ±1 Digit ±20 ppm (0 to 400 ppm) ±1 Digit
Resolution 1 ppm

Measuring range

0 to 5000 ppm

Accuracy

±10 % of mv (2001 to 5000 ppm) ±1 Digit

±5 % of mv (401 to 2000 ppm) ±1 Digit

±20 ppm (0 to 400 ppm) ±1 Digit

Resolution

1 ppm

Ambient CO	Measuring range 0 to 2000 ppm (internal/flue gas probe) 0 to 500 ppm (external with CO probe)
Accuracy ±3 ppm (0 to 29 ppm) ±1 Digit (external with CO probe) ±10 % of mv (101 to 2000 ppm) ±1 Digit (internal/flue gas probe) ±10 ppm (0 to 100 ppm) ±1 Digit (internal/flue gas probe) ±10 ppm (30 to 500 ppm) ±1 Digit (external with CO probe)
Resolution 1 ppm (external with CO probe) 1 ppm (internal/flue gas probe)

Measuring range

0 to 2000 ppm (internal/flue gas probe)

0 to 500 ppm (external with CO probe)

Accuracy

±3 ppm (0 to 29 ppm) ±1 Digit (external with CO probe)

±10 % of mv (101 to 2000 ppm) ±1 Digit (internal/flue gas probe)

±10 ppm (0 to 100 ppm) ±1 Digit (internal/flue gas probe)

±10 ppm (30 to 500 ppm) ±1 Digit (external with CO probe)

Resolution

1 ppm (external with CO probe)

1 ppm (internal/flue gas probe)

General technical data	Operating humidity 15 to +90 %rH (non-condensing)
Weight approximately 24 oz. / approximately 685 g
Dimensions approximately 9 x 4 x 2 in. (LxWxH) (incl. probe connection) / approximately 227 x 102 x 47 mm (LxWxH) (incl. probe connection)
Operating temperature 23° to 113 °F / -5 to +45 °C
Protection class IP40
Connectable probes 4 x digital Bluetooth® probe or testo Smart Probe; connectable: Smart Probes (°C, Delta P), CO + CO₂ probes
System requirements requires iOS 17 or newer; requires Android 14 or newer
Battery life 10 h
Display type 5.5" IPS touch display, HD 1280 x 720 pixels
Power supply Rechargeable battery, USB mains unit
Guarantee 24 + 12 months (with app registration)
Operating time ~60 min (25 °C)
Maximum ≤1,000,000 readings
Interface Bluetooth® 4.2
Radio range Up to 100 m (with no obstructions)
Battery charging option Quick charge
Battery charging time 20 min
Storage temperature -4° to 122 °F
Charging temperature 0 to +95 °F / 0 to +35 °C

Operating humidity

15 to +90 %rH (non-condensing)

Weight

approximately 24 oz. / approximately 685 g

Dimensions

approximately 9 x 4 x 2 in. (LxWxH) (incl. probe connection) / approximately 227 x 102 x 47 mm (LxWxH) (incl. probe connection)

Operating temperature

23° to 113 °F / -5 to +45 °C

Protection class

IP40

Connectable probes

4 x digital Bluetooth® probe or testo Smart Probe; connectable: Smart Probes (°C, Delta P), CO + CO₂ probes

System requirements

requires iOS 17 or newer; requires Android 14 or newer

Battery life

10 h

Display type

5.5" IPS touch display, HD 1280 x 720 pixels

Power supply

Rechargeable battery, USB mains unit

Guarantee

24 + 12 months (with app registration)

Operating time

~60 min (25 °C)

Maximum

≤1,000,000 readings

Interface

Bluetooth® 4.2

Radio range

Up to 100 m (with no obstructions)

Battery charging option

Quick charge

Battery charging time

20 min

Storage temperature

-4° to 122 °F

Charging temperature

0 to +95 °F / 0 to +35 °C

General technical data	Weight 49.4 oz. / 1400 g
Dimensions 10 x 20 x 5 in. ((LxWxH)) / 256 x 516 x 135 mm ((LxWxH))
Product colour Black

Weight

49.4 oz. / 1400 g

Dimensions

10 x 20 x 5 in. ((LxWxH)) / 256 x 516 x 135 mm ((LxWxH))

Product colour

Black

General technical data	Diameter probe shaft 0.236 in. / 6 mm
Cable length 4.921 ft. / 1.5 m
Length probe shaft 7.087 in. / 180 mm
Product colour Black
Temperature maximum 932 °F / 500 °C
Diameter 0.2 in. / 6 mm
Weight 12 oz. / 346 g

Diameter probe shaft

0.236 in. / 6 mm

Cable length

4.921 ft. / 1.5 m

Length probe shaft

7.087 in. / 180 mm

Product colour

Black

Temperature maximum

932 °F / 500 °C

Diameter

0.2 in. / 6 mm