| 327-1 | 320B | 320 Bluetooth | 300 | 300LL |
| Fuels available | Oil, gas, solid fuels | Oil, gas, solid fuels | Oil, gas, solid fuels | Oil, gas, solid fuels | Oil, gas, solid fuels |
| Measurement sensors | O2, CO | O2, CO | O2, CO | O₂, CO
NO optional | O2, CO H2-compensated, NO optional |
| Measuring ranges | CO: 0 to 4000 ppm
CO2: 0 to CO2 max | CO: 0 to 4000 ppm
CO2: 0 to CO₂ max | CO: 0 to 4,000 ppm
CO2: 0 to CO2 max | CO: 0 to 4,000 ppm
CO2: 0 to CO2 max | CO H2-compensated: 0 to 30,000 ppm (via fresh air dilution) |
| CO measurement
(H2-compensated) | | | | | |
| Long-life CO sensor with up to
6 years' service life | | | | | |
| Gas pressure testing | | | | | |
| Draught measurement | Parallel to flue gas
measurement | Parallel to flue gas
measurement | Parallel to flue gas
measurement | Parallel to flue gas
measurement | Parallel to flue gas
measurement |
| Flow/return temperature
measurement | | | | | |
| Error and sensor diagnosis | | | | | |
| Zeroing of analyser in flue
possible | | | | | |
| Create digital measurement protocol directly in the App and
send via email | | | | | |
| Warranty (sensor and
instrument) | 3 years | 3 years | 3 years | 3 years | 4 years |
| Warranty with product registration (instrument,
sensors, probe) | n/a | n/a | n/a | 4 years | 5 years |
| Display | 4-line alphanumeric LCD display | Colour display | Colour display | 5” HD touchscreen display | 5” HD touchscreen display |
| Memory | | 20 measurement protocols | Up to 500 measurement
protocols | 1 million measured values | 1 million measured values |
| Software/App | | Export values to Excel file | testo Combustion App | testo EasyHeat PC software | testo EasyHeat PC software |