Ask for a higher efficiency system quote.One contractor is recommending a Trane XR14, which I'm leaning against both because I'd prefer a higher efficiency unit and a two-stage.
If you've had a two stage system, then installing a single stage system will likely increase your electrical consumption.So...
is installing a single-stage A/C a really bad idea?
NO!can the existing air handler be used with the new R-410A A/C's?