Modulating goodman, installed last spring. 80K BTU, and now I believe it could have been the 60K, based on how much it runs. Dang, tried so hard to get it right, and I think my tech did too. In the end, it was me who told him go with the 80K, because the numbers were just too close at zero degrees. And I knew not to oversize!
Anyway, I do like the fact that I can use a hefty set-back, I like the house cool at night. But, during the weekend day when we are holding at about 69 degrees, it will come on and not go immediately to low fire, it will stay up at around 70% for quite a while. The manual says it will "learn" how to heat the house the best over time, so I would think it would know, based on cycle times, that once it is at temperature it can just maintain at 50%, or at least attempt to. I have the full communicating t-stat, and it never overshoots.
This spring, he will be adding a 3-ton HP to the system, which will add the outdoor temp sensor. Will that have any affect on how the furnace acts (when it is cold enough for the furnace to run) Any thoughts?