I have a Bacharach Gas Hunter gas detector for sale. It detects flammable gases, CO, oxygen level, and flue pressure. The oxygen sensor needs to be replaced and calibrated.
With the oxygen sensor, you can check for cracked heat exchangers. But as it is, it still detects flammable gas and CO.
This is a sophisticated device that utility companies use. I want to sell it because it’s really more than I need.
If interested, shoot me an email to email@example.com