Age is context, not a diagnosis
An old system deserves a condition assessment. Age alone does not tell you whether a repair is sensible, and a newer system can still have a major issue. Consider repair history, the current failure, parts availability, and your plans for the home.
Signs to put replacement on the table
Repeated breakdowns, a large repair, several deteriorating components, or persistent comfort concerns justify comparing options. Ask for the total repair cost and the installed replacement scope. A low equipment price is not the same as a complete installed project.
Lifespan and timing
There is no single retirement date that fits every system. Installation, use, exposure, and maintenance affect condition. If replacement is already likely, planning before a complete failure gives you time to compare designs and arrange the work.
Make the options comparable
Review matched equipment, duct changes, electrical work, controls, removal, startup, registration, and workmanship coverage. Ask which existing components remain. Financing changes how a purchase is paid; it does not change the need to understand the complete price and lender terms.
Compare three decisions, not just two prices
Start with the immediate repair: what restores operation, what caused the failure, and what costs are outside parts coverage. Then consider a repair with a planned replacement later: whether other known concerns make that path reasonable and what uncertainty remains. Finally compare a complete replacement: the work included, existing components reused, and comfort concerns addressed. There is no universal age or multiplication rule that makes the decision for every home. Ask for the diagnosis and complete scopes so you can choose based on the condition of your system and your plans.
General homeowner information from S&S HVAC. Equipment instructions and the approved project scope govern work on your system. Source links support the guidance; they do not imply a manufacturer endorsement.