I own a 1950s ranch in a nice Chicago suburb. We live here for the great schools, however the neighborhood is exorbitantly expensive. Moving to a bigger house would literally cost an extra $300-$400K. Consequently there is a strong desire to make this house work for us. That means our basement is hugely valuable living space. We are a family of 5 in a smallish ranch so the basement is truly the house's saving grace. The kids love it as is but it is not fully functional space for adults because of the massive ductwork (6' wide spanning the entire length).
With that in mind, I'm trying to determine the best solution for our HVAC. Both AC & furnace are dinosaurs and need replacing. Windows are all new dual-pane vinyl. Last spring I spent a weekend in the attic caulking/spray foaming any ceiling openings. I then rolled out R-30 insulation over the existing batts. The walls are brick and block with little/no insulation. To improve the wall's insulation I've thought about rigid foam over the existing plaster, then drywall but that is not a high priority. So the home's envelope is a mixed bag of good & bad.
I've been delaying replacing the air handler/furnace/ac because I really want to find an ideal solution that can eliminate the basement ductwork. My goals are 1) energy efficiency 2) comfort and 3) improving the basement's functionality so adults could be down there comfortably. The last goal is fairly important because our basement gives our family of 5 an extra 1,500sqft of living space in a 2100 sqft house. It's not the end of the world if the ductwork stays but if there was a smart way to remove the ducts I would absolutely pay a premium to have it.
I have been increasingly thinking of the following solution:
1) Mitsubishi or LG Mini-Split system for cooling (8 indoor units in basement & main floor). Could also be secondary heat source.
2) Rip out the ceiling drywall in the basement (it's 1/4", sagging and needs replacing anyway).
3) Install Radiant floor heating using a between the floor-joist retrofit. My thought is the heat source would be a dedicated hot water heater (not a boiler).
4) Tear out the duct work to make our basement more functional.
5) Put up new drywall once complete, giving us a 7' ceiling height throughout the basement.
This is definitely not the easy or low cost solution and I'm wondering if I'm crazy to consider it? I'm guessing a professional installation like this would be $30K+. Consequently I'd have to do a lot of the work myself (which I don't mind). I'd probably install the minisplit this year with the only professional work being the coolant charge. Next year I'd work on the radiant (keeping the existing furnace until then).
My final concern is whether this design would adequately heat the basement (could the PEX between the joists heat both floors?). If I need to retrofit radiant in the basement floor as well it probably tips the scale against this. I'm crazy but not insane. There is a tipping point when I decide to live with the low basement ceiling.
I'm open to any ideas. Moving the ducts to the attic would be an option but in a northern climate that seems like a childish/selfish way to get some headspace. Am I in fantasy land thinking I can find a reasonable solution that is comfortable & efficient while also making the basement a lot more adult/tall person friendly?