Is the offset pressure correct? Continuing our maintenance and service series with Navien, Inc on their fire tube combi boiler, we look at the correct offset gas pressure using a dual port manometer. Manometer used in video: Testo North America 510. On the next video we'll touch on ignition transformer troubleshooting. Watch the full video right now on YouTube. Link on my story or subscribe to the HVAC Know It All YouTube channel. #hvac #firetubeboiler #tanklessboiler #hvacsystem #domestichotwat