I have a three year old Miller furnace CMF 80. I noticed toward the end of last season that the burner head was cracked. Last week in preparation for this winter, I pulled the Beckett burner unit to fix it. The burner tube was pretty deteriorated at the end where the burner head screws on, so I decided to change the tube also. No one in this area had the 3" tube, so I contacted the manufacturer directly in Ohio. They connected me to a Tech support person. I was able to get the new tube through them. My Beckett burner unit uses the F0 head. The Tech told me to use a F3 head on the unit. The F3 provides more air flow than the F0. They have found using the F3 head doesn't destroy the end of the tube as the F0 does ? Has anyone else heard of this, and does anyone have any input as to why I shouldn't use the F3 head when the furnace calls for the F0 head. Thanks.