Can someone explain the difference between these settings in a furnace? My model is OH6FA072DV4. Curious on my ECM fan speed settings. Currently it's set at factory setting:

Heating CFM: 968
Low fire rise: 57 deg
Med fire rise: 69 deg
High fire rise: 86 deg

I'm curious as to what those numbers mean and if my house would benefit from either a change in dip switch settings and/or a different nozzle (currently have .60 x 80A)

I'm in New England in a 2 story colonial built in 1949 with updated windows and 1700 square feet.