Repair vs Replace Your Furnace: The Complete Decision Framework

Your furnace is the backbone of your home's comfort system — and when it starts showing its age, you face one of the most consequential financial decisions in homeownership. A furnace repair might cost $150–$800. A full replacement runs $4,500–$12,000. The wrong call in either direction costs you thousands.

This guide applies three established decision frameworks — the 50% Rule , the Age-Efficiency Threshold , and the Total Cost of Ownership analysis — to help you make a data-driven decision instead of relying on a contractor's sales pitch.

Before evaluating repair vs. replacement, you need to understand where your furnace sits in its lifecycle: