Due to my main board being bad, (just replaced 1 yr ago too), and age of house/units (16 yrs), I am now needing to replace system. I am looking at Ruud and Lennox. Any guidance? House is split level, 2000 sq ft, estimates so far for 80% effic (75,000 BTU) gas furnace, 12 SEER 3 Ton AC unit. Also one company says 2.5 ton is good and 3 ton is too much (will produce cold, clammy house). Thoughts on this? No one has performed maesurements on house, only looking at existing units. Best sounding estimate so far is for 2.5 ton condensing unit, 3 ton coil, and 80% gas furn, all RUUD. I am concerned about price, dependability. One person said to stay away from "hot surface ignitors" and suggested Lennox "sure-light"system.