Home › Guides › HVAC & appliances › When to replace (not repair) your furnace, AC and water heater
GuideFew home decisions are as stressful as a failing furnace, AC or water heater — usually at the worst time, with a repair-or-replace choice and real money on the line. Here's how to make that call rationally: the lifespans to expect, the simple cost rule, when efficiency tips the scales, and the warning signs that replacement is coming.
As a rough guide: furnaces last around 15–20 years, central AC around 10–15, and tank water heaters around 8–12 (tankless longer). These vary with maintenance, usage and quality, but once a system is in its final third of life, repair decisions should factor in that it's living on borrowed time. Well-maintained systems reach the upper end; neglected ones don't.
A widely used rule: if a repair costs more than about half the price of a new unit, and the system is near end of life, replacement is usually the smarter money. Pouring a big repair into an old system often just delays an inevitable replacement — and you lose the repair cost when it fails anyway. Weigh the repair against the remaining life.
An old furnace, AC or water heater can be so inefficient that it costs significantly more to run than a modern one. When you're on the fence, factor in the energy savings a new, efficient unit delivers every month — sometimes a replacement pays back the difference faster than expected, making it the better financial call even when a repair is possible.
Watch for rising energy bills, frequent repairs, uneven heating or cooling, strange noises or smells, a system that can't keep up, rust or leaks (especially on a water heater), and age in the danger zone. A water heater leaking from the tank itself is a replace, not a repair. Several of these together mean start planning before it fails.
The worst time to buy a furnace is the night it dies in January, or an AC in a July heat wave — you pay emergency rates and have no time to compare. If your system is showing age and warning signs, get it assessed in the off-season, understand your options, and replace on your schedule rather than the equipment's.
A trustworthy pro will tell you honestly whether to repair or replace, and quote both. On Genie, HVAC and water heater work goes to licensed, insured pros at an upfront or quoted price, with payment held until it's done — so you get a straight repair-or-replace answer and a firm number, not a pressured upsell.
Every task in this guide is something you can book on Genie — vetted, insured pros at an upfront price:
When a repair costs more than about half a new unit and the furnace is near end of life (roughly 15–20 years), or when a new efficient unit's energy savings make replacement the better long-term money. Frequent repairs and uneven heat are warning signs.
Around 8–12 years for a tank model, longer for tankless. A water heater leaking from the tank itself is a replacement, not a repair — and worth planning before it fails and floods.
Often worth considering if both are near end of life, since a matched, efficient system performs better and you handle one install instead of two. A pro can advise based on your specific equipment and age.
