I have just installed a Rinnai hot air direct vent furnace. After converting the appliance to propane, I adjusted the gas pressures with a manometer according to the manufacturers instructions. The flame is mostly blue with orange at the ends of the flames. I also have a plume of what looks like moisture coming out of the exhaust manifold. Could I have adjusted the LPG pressure too high? The instructions call for 1.06 in/H2O at low manifold pressure and 3.8 in/H2O at high pressure. Can anyone suggest a solution? Thanks in advance, Jeffrey.

  • 1
    Hello, and welcome to Home Improvement. This may be better answered by the Rinnai support department. And, you should probably take our tour so you'll know how best to participate here. Jan 15, 2020 at 1:35
  • If I'm not mistaken, this requires proper pressure and airflow for exhaust and sometimes there is programming needed on the control boards or differnt nozzles and or flow regulators used. It's not burning clean it seems. Have to agree with @DanielGriscom since its brand new.
    – noybman
    Jan 15, 2020 at 3:03

1 Answer 1


This sounds normal. It sounds like you have the proper air fuel mix and the moisture is normal, I have had almost every home owner call be on a cold morning saying there furnace is smoking, it is actually the moisture and it shows up as a fog on cold mornings , sounds like things are just fine.

  • Does LPG burn more orange than LNG?
    – Mazura
    Feb 15, 2020 at 2:29
  • With proper air fuel mix they are very close but not the same btu’s.
    – Ed Beal
    Feb 15, 2020 at 3:13
  • "The flame is mostly blue with orange at the ends of the flames." - that's normal, +1
    – Mazura
    Feb 15, 2020 at 3:27

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