m Ransley errs again:

Now the fun part, measure blower amp draw where it is at, and at your
desired setting, , calculate run time , at present and new setting, run
your Kwh costs to reflect your increase in kwh and decrease in run time
if any. You just lost in electricity costs. For most of the US Kwh are
more expensive than NG so you are a net looser there. Oh did you
increase efficiency of the Ng side...

The heat exchanger will probably be more efficient at the higher airspeed.

Say your blower takes 375 watts and runs 8 hrs a day avg and cost is
.125kwh, mine is, your present avg cost is 9 kwh a day or $33.75 a month.

....8hx375W = 3 kWh, ie 3x$0.125/kWh = $0.375/day or $11.25/mo.

If you increase the airflow from 1100 to 1500 cfm, the blower may use
(1500/1100)^3x375 = 951 vs 375 watts, according to the fan laws. At
1100/1500x8 = 5.9 hours per day, it might use 5.9x951 = 5.6 kWh/day
or 5.6x0.125x30 = $20.92/mo.

Nick