wrote in message

If the heater is firing for 2 hours at 30,000 Btu, it is using the same
amount of fuel as a burner firing at 150,000 Btu for half that time.

No. The former uses 60K Btu. The latter uses 75K Btu.


Of course. What I typed is not what I was thinking. Point is, firing time
alone is not the determining factor for cost of operation. Longer time at a
lower rate can be cheaper than a huge inefficient burner cycling.