testo 310 II Combustion Analyzer HVAC – Combustion Leak Tester for Temperature, Flue Gas & Pressure – Natural Gas Leak Detector with Smart App and Probe

I was able to use this to confirm a cracked heat exchanger on my old furnace. I also used it to confirm my new furnace was working correctly.

Please don't buy! I opened it right away and turned it on and gave me O2 sensor code and will not work. I called Testo and they said the O2 sensor needs to be replaced and will not cover it under warranty. I bought three and they are all the same! Don't recommend buying these!

Works well for residential systems, able to quickly tune furnaces and boilers for optimal AFUE. I routinely get 83-86% out of standard 80% furnaces after using this tool. Make sure you know what values to look for when balancing a system, such as excess air percentages and O2/CO2/CO levels, etc. Nice to be able to take static pressures on duct work as well as temperature splits, although the temperature readings take a while to even out. Easy to use, easy to switch from propane to nat gas, only gripe is that it didn't come with the printer. Do yourself a favor and buy the kit that includes the printer. Easy to prove your readings instead of writing down values on your invoices.

Can use on homeowner and commercial applications

Easy to use.... but $$$. But sometimes you have no choice. I got this because I was having serious problems with my Gas Furnace and after 3 attempts with professionals ($$$$$) fiddling with the Gas Control without testing the exhaust, I ordered the the Analyzer. It took me roughly 10 Minutes to read the Manual and another 10 to set the combustion correctly. Great product...

Quit working 5 min after I turned it on. Piece of junk. I didnt realize it was used so thats my fault, but you sold me a piece of crap for $300. I tried returning it, got no reply and Testo was no help either since I didnt buy it from them.

Solid,reliable,and affordable compared to others

Works great. Had to buy the printer separate because they were out of kits. Maybe splurge and buy the one compatible with the app though