Combustion testing is an important part of many heating contractors businesses. Having an instrument that they are confident in and can trust is very important. Testo is one of the leading brands when it comes to combustion analysis. The Testo 320 Combustion Analyzer is the premier residential combustion analyzer that they offer and it has many features that are important to technicians. First off, the unit has a 2 year warranty, Bluetooth capabilities and storage for 500 tests.