"T.G. Lambach" wrote in message
...
Heatman, you're right, I read the heat rise off the furnace manual, not
a thermometer. This Sears FAG furnace (105,000BTU / 84,630 BTU) was
installed 1987, prior to the AFUE rating system. No changes have been
made from the (125 degree ON and 90 degree OFF) factory settings and
none are contemplated - they're fine.


Some of us won't use the term "FAG." Nothing personal, mind you....

Oh, your furnace was rated, but the AFUE rating wasn't that well known.


The blower is now set to run Med. Lo. (1,100 +/- cu ft/min).

The original question was if any BTU efficiency would be gained if the
blower speed were raised to say, Med. Hi. (1,315 cu ft/min).

Check your Delta T and see if it can be changed.