Is this how it should be ?

[gaswizzard]

I thank your sir, i have found some to tell me what happens, go on then were all sat down................

Natural gas contains more hydrogen and less carbon per kg compared to fuel oil.

maybe the reason why more water vapour is produced when burning methane as opposed to oil?

Average flue gas dew point temp is around 8c lower when using oil as opposed to methane.

And yes you are correct libby looo looo , increasing excess air will lower dew point temp. ,