Efficiency comparison
Heat pumps move heat rather than converting fuel to heat. Coefficient of performance (COP) indicates how many units of heat are delivered per unit of electricity; COP > 1 means the system delivers more heat than the electrical energy consumed. Compare the operating cost of your current heating (fuel or electric resistance) to the estimated cost of running the heat pump at your local electricity and fuel rates — the "annual heating cost savings" input should reflect that difference.
Break-even vs total ROI
Break-even year is when cumulative savings equal net investment; it does not by itself indicate total ROI, which depends on savings over the full lifespan. Compare break-even to expected system life: if break-even is close to or beyond lifespan, the investment may be marginal. See ROI vs payback period.