Can;t get burner flame blue
I have a AO smith conservationalist Gold Series 50gal NG water tank.
Got it NOS, in anyevent, the adjustment for the air intake to the burner consists of a screw and a rotateable metal cover that either covers up or opens up the airway.
The issue is that it says in the manual to adjust till the flame burns blue, well I can;t get the flame to burn blue...at least not all blue like on my gas stove.
The actual flame from the cast iron burner when its on is pretty impressive as far as size goes.
As I cover the air intake the flame is more blue but not all...wide open air causes more yellow and red...
Even with the air control closed off, there is an opening that is always open so it is impossible to cut off all the air to the appliance.
My question is I think , is it acceptable to adjust it till its as much blue as possible and leave it at that, or are there other adjustments that can be made to increase the efficency of the flame....
This tank is from the series Conversationist with a Gold Label on the front..40000BTU burner, multiple settings on the hot-hotter-hottest settings..
R16 insulation, etc etc..I believe the current model that cross references for this is the XGV50.
Thank you in advance for your assistance.