I bought a new furnace and central air widget once, following a flood. High-efficiency, dual stage furnace. There were cheaper options, but I didn't want the

I bought a new furnace and central air widget once, following a flood. High-efficiency, dual stage furnace. There were cheaper options, but I didn't want the cheapest option. I fixed it myself on two different occasions when I'd woken up to a super-cold house in the middle of the night, with both fixes relating to condensation building up where it shouldn't. (One of these was a manufacturing fault that was corrected by slightly shortening a rubber hose, and the other was an installation fault relating to the drain plumbing.) Sure, I could have called the next day and maybe they'd have shown up eventually to fix it (maybe for "free"), but meh: I got it sorted, my fixes were cromulent and safe, and I had a warm house sooner instead of later. The installation manual contained enough theory of operation that it wasn't too bad for me to get a solid understanding of the concepts at play and to proceed with good confidence. It was a scorching hot day in July before they showed up to charge the aircon so that it could be used, and they never did come back to set it up for two-stage operation despite promising to do so (so I paid extra for nothing). 4/10, at least they managed to graft on the new duct work with good transitions and reasonable tightness, and it was somehow reasonably well-balanced by default. (I'd have configured the dual-stage bits myself, too, but I didn't have the right tools. It's been a rather long ago now, but IIRC I needed two digital thermometers to make sure the heat rise was correct and a manometer to correctly set the first-stage blower speed. Buying these tools would have been cheaper than paying for a service call with another company and was kind of a no-brainer to me, but another flood came by before I had the chance and forever changed our perspective on living in that location.)