Some HVAC warranties will drastically reduce your repair and replacement costs while others just pad the bill. HVAC extended warranties and service plans: What's actually worth paying for? For example, someone might purchase a manufacturer's extended warranty, a retailer protection plan and a separate home warranty with HVAC coverage. How to decide if an HVAC protection plan is worth itBefore paying for any HVAC protection plan, it can help to ask yourself a few questions, including:Does it cover something my existing warranty doesn't? The bottom lineExtended HVAC warranties and service plans aren't inherently good or bad purchases — their value depends on what's covered, what's excluded and how long you expect to own your system.