How long should a furnace last in Michigan?

A well maintained gas furnace in Southeast Michigan should give you fifteen to twenty years. We see plenty still running at twenty five. We also see plenty dead at ten, and the difference is rarely the badge on the front.

What actually decides it

Whether it was sized correctly

An oversized furnace short cycles: it starts, satisfies the thermostat quickly, and stops, over and over, instead of running steadily. Every start is thermal stress on the heat exchanger. Oversizing is the most common installation mistake in this area, because it is easier to fit something bigger than to do a load calculation.

Whether the ductwork can breathe

A furnace fighting undersized or leaky ducts runs hot, trips its limits and delivers less heat for more gas. High static pressure kills equipment quietly over years, and almost nobody measures it. We do, on every visit, and the reading goes on your record so next year we can see whether it moved.

Whether anyone maintained it

A yearly clean and test is not a luxury. It is burners cleaned, gas pressure set to spec, combustion analysed and safeties tested. A system that gets that lasts noticeably longer than one that does not, and it is the cheapest thing on this page.

Signs the end is close

• Repairs getting more frequent and more expensive
• Rooms that were always fine are now cold
• Rust or soot around the burner compartment
• Gas bills climbing without the weather explaining it
• Any sign of a cracked heat exchanger, which ends the conversation immediately

The rough rule

If a repair costs more than a third of a new system and the unit is past fifteen years, replacement usually wins. Under ten years, repair almost always wins. Between the two it depends on what failed and what the rest of the system looks like, and you should get a straight answer rather than a push toward the bigger invoice.