My 2-story home in central Minnesota currently has a Ruud HR-125JD gas furnace. Does anyone have any idea what kind of efficiency this model has? I've owned the home for 9 years, but I've no idea when the furnace was put in, though I doubt it is an original 1958 model.

It's rating is 125000 BTU/hr with 100000 BTU bonnet capacity. Can I use that as a wild guestimate for proper sizing of a new unit? Also, I intend on replacing the current junk US Steel windows as part of the entire project. Is it safe to assume my BTU needs should be less with energy star windows? I've got calls to set up estimates with the local Bryant, Trane, and Rheem dealers but haven't heard back yet. Given the approaching cold and rising NG prices, if they get back in the next few days I'll be pleased. I'm thinking I want to go 90+ efficiency on the furnace and replace my 3 ton(?) AC unit at the same time. I have a Trion electronic air cleaner and a Skuttle humidifier that I would like to be able to keep using as they are under 3 years old. Is this realistic or a pipe dream?

Anything you could assist with would be greatly appreciated. This forum is a great resource!