You just received an HVAC replacement quote. Maybe it's $8,000. Maybe it's $14,000. Maybe you got three quotes and they're all different by thousands of dollars for what sounds like the same job. You're not imagining the confusion. HVAC replacement quotes are among the hardest estimates for homeowners to evaluate — because the equipment is technical, the terminology is unfamiliar, and contractors have enormous latitude to include or exclude items that can mean thousands of do