I have a 2,200 s.f. house, all on one level, over a basement/garage. The basement/garage is not heated or cooled. Excellent ducting is already in place, as per an HVAC pro who inspected the house. No new ducting, outlets, or returns will be necessary. I only need to replace an old natural gas furnace & air conditioning unit with a heat pump (I'm in East Tennessee). I was told I needed a 4 ton unit at a cost of about $10,000. This seemed excessive to me. My house is brick & I do have large windows. Any thoughts? Thanks.
I ran a simple block load on your home, using Knoxville as the Long/Lat, and took liberties to create a lot of windows and very weak insulation factors and loose construction. All of this is a SWAG at this point, but it points to the fact that 4 tons is most likely to large for your area and size. I came up with about 36,000 btu of total cooling needs and about 63,000 btu of total heat.
All of this is a guess until you give specific information and receive an accurate load calculation, but I was very liberal regarding your windows and insulation and my uninformed calc would say that 4 tons is big overkill.
Are you planning on going Dual-Fuel and end up with a gas furnace/heat pump combo. If it were me, that would be my route. And don't be wowed by ultra high efficiency equipment. the best bang for your buck, considering the age and overall efficiency of your home, both in utility and investment would be a high quality (read, not builder grade) 13 SEER Heat pump and an 80% gas furnace as a back-up heat source. Just my $.02 And, $10K is way on the high end of a change-out.
Good luck with your project.