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High Altitude modifications for Embassy Onex 160C

colorado66 Member Posts: 1
I just installed an Embassy Onex 160C boiler and am having difficulty making combustion adjustments for an elevation of about 7300 ft. There is no information in the manual for this. Unit is set up for NG with the 9.1 mm orifice which comes with the unit for NG. Gas pressure good at 7.5- 9.5" inlet at gas valve during firing. Runs but with high excess air. Has anyone run into this problem? Any recommendations?


  • kcopp
    kcopp Member Posts: 4,452
    Having installed a fair number of these at/ near sea level they are not the easiest unit to dial in. I would call the manufacturer.
    Four one three .564.5694
  • captainco
    captainco Member Posts: 796
    When dealing with higher altitudes no one seems to understand that the gas you are using is de-rated below 1000 btus per cu.ft. ASHRAE did a study (2006) that stated much equipment up to 7000 feet does not need additional de-rating. Something I teach when in Denver is that 300 degrees at 5000 ft is the same as sea level. Set the boiler by combustion numbers. Forget gas pressure or cubic feet. They will end up where there need to be when you get the combustion correct.