How Long Does a Boiler Last? Signs to Replace

A boiler is one of the longest-lived appliances in your home — but it won't last forever, and in Ontario's climate you don't want it failing in January. So how long should a boiler last, and how do you know when it's time to plan a replacement?

Average Boiler Lifespan

A well-maintained gas boiler typically lasts 15 to 25 years. That's often longer than a forced-air furnace, partly because boilers have fewer moving parts. Modern condensing combi boilers tend to land in the 15–20 year range, while older cast-iron boilers sometimes ran 30+ years — though at much lower efficiency.

The single biggest factor in reaching the upper end of that range is annual maintenance: descaling the heat exchanger, checking pressure and combustion, and inspecting the venting and condensate.

What Shortens a Boiler's Life

Skipped annual servicing — the number-one cause of early failure
Hard-water scale building up in the heat exchanger (common in parts of the GTA)
Poor original installation — bad near-boiler piping or incorrect sizing
Running at constant high pressure or with persistent leaks
An oversized boiler that short-cycles, wearing components faster

7 Signs It's Time to Replace Your Boiler

If you're seeing several of these, it's smart to plan a replacement before a mid-winter breakdown:

Age: the boiler is 15–20+ years old and needs repairs every season
Leaks: water pooling around the base or visible corrosion
Kettling: banging or rumbling sounds from scale in the heat exchanger
Pressure problems: the system constantly loses pressure or needs topping up
Rising bills: gas costs climbing with no change in how you heat
Uneven heat: radiators slow to warm or rooms that never get comfortable
Frequent repairs: a repair bill approaching half the cost of a new unit

Safety note: If you ever smell gas or your carbon monoxide alarm sounds, leave the house and call Enbridge Gas emergency line from outside before anything else. Don't wait.

Repair or Replace?

The rule of thumb: if your boiler is under about 12 years old and the repair is minor, repair usually wins. Once it's 15+ years old, leaking, kettling, or facing a repair worth more than roughly half a new unit, replacement is the smarter long-term move — especially since a modern condensing unit will cut your gas use. See our boiler replacement page for how the process works.

Make It Last Longer

Whatever the age of your boiler, an annual service is the cheapest insurance you can buy — it catches small issues before they strand you without heat and keeps the manufacturer warranty valid. When it is time, our boiler installation team will size and install a replacement properly across Toronto and the GTA.

Boiler Lifespan — Common Questions

A well-maintained gas boiler typically lasts 15–25 years. Modern condensing combi boilers usually land in the 15–20 year range. Annual maintenance — descaling, pressure and combustion checks, and heat-exchanger inspection — is the biggest factor in reaching the upper end.

Key signs include age over 15–20 years with frequent repairs, water leaks or corrosion, kettling (banging from scale), constant pressure loss, rising gas bills, uneven heat, and repair costs approaching half the price of a new unit. Several of these together usually mean it's time to plan a replacement.

If the boiler is under about 12 years old and the repair is minor, repair usually makes sense. Once it's 15+ years old, leaking or kettling, or the repair costs more than roughly half a new unit, replacement is typically the better long-term decision — and a modern condensing unit lowers your gas bills.

Yes — significantly. Skipped maintenance is the number-one cause of early boiler failure. Annual servicing descales the heat exchanger, verifies safe combustion and correct pressure, and catches small problems before they leave you without heat. It also keeps your manufacturer warranty valid.

Once a year. In the GTA's moderately hard water, annual descaling matters for keeping efficiency and hot-water output up. A yearly service also inspects venting, condensate, and combustion for safety.

How Long Does a Boiler Last? Signs You Need a Replacement