I currently have a gas furnace (regular vent - not high-efficiency) and 3 Ton Goodman heat pump (wired for a/c only). I spoke with my installer about having it changed over to work as a dual fuel, with a Trane TZEMT400BB3 thermostat. He doesn't have any experience with that dual fuel kit - though he didn't seem to think it would be an issue. Has anyone here installed the kit? Anything I should know? I really want a z-Wave thermostat, and this appears to be the only one around that does dual fuel.
I am also interested in knowing how much I would expect to save by running dual fuel as opposed to natural gas only. Is there some sort of napkin-calculation I could use to see how long it will take me to recoup the install cost?