Just installed a VC Radiance on LP. Bought it used so I have little in the way of dealer support. Wondering how much the flame height control knob contributes to heat output. I don't notice much difference between "low" and "high" When the flame is on high its nice and big, blue at the base, deep yellow in the middle with wispy reddish orange at the top of the firebox. Does this indicate I am not getting enough air? Will my glass soot up over time? I have read on here about adjusting the air shutter but not sure where to start. If anyone can chime in that would be great!