Our heat pump is about 15 years old. The last couple of years it seems that the auxiliary heat comes on quite often so I think it's getting close to replacement time. Our house is approx. 2,000 s.f. The current system is a Trane. I would appreciate any thoughts on who the best manufactures are these days and a ballpark on what this may cost. I've been told the new system could be as much as 40% more efficient, but I suspect the payback period will be very long. I need to decide whether to wait until it's almost dead or replace it now.