I am considering purchasing a two-stage furnance from either Heil or Goodman. However, in reading material related to the models, it seemed to me that the two-stage Goodman actually went from stage 1 to stage 2 on a timer, rather than by temp or some other computerized sensor. The Heil model seem to switch from stage one to stage two based on temp/heating needs, rather than a timer. Am I misresading or misunderstanding the material on these two units? In terms of quality/reliability, any recommendations? Thanks a lot.