$1068 at 85% efficiency is $907 "effective" heating dollars. $971 at 94% efficiency is $912 so that passes a basic sanity check.
The major improvement is efficiency c es from runnimg higher volume at lower temperature differentials. This allows the "cold" side of the furnace/boiler to condense the water vapor in the combustion gasses and capture its latent heat.
$1068 at 85% efficiency is $907 "effective" heating dollars. $971 at 94% efficiency is $912 so that passes a basic sanity check.
The major improvement is efficiency c es from runnimg higher volume at lower temperature differentials. This allows the "cold" side of the furnace/boiler to condense the water vapor in the combustion gasses and capture its latent heat.