Repair or replace your furnace? A decision framework for BC homeowners

The repair-versus-replacement decision starts with one question: what has actually failed? A furnace that will not light may need a $150 ignitor or a $700 control, and those are different decisions entirely. The diagnostic visit establishes the fault by testing, produces a repair price from the findings, and checks the two things that can end the debate immediately: the heat exchanger and the safety-critical components.

A heat exchanger confirmed cracked or failed takes replacement off the discussion table: manufacturers do not sanction field repairs, the furnace can no longer be run safely, and the standard outcome is a new furnace. The same is true for a furnace whose combustion produces carbon monoxide or whose safety history cannot be explained.

Do not let anyone quote a replacement without a diagnosis. A quote built on the furnace's age alone is a sales process, not a decision framework.

Age matters through the lens of parts and history, not the calendar alone. A 15-year-old condensing furnace with one failed part and a clean history is often worth repairing, because the repair restores a working system for a fraction of replacement cost. A 20-year-old furnace with its third motor failure, a leaking secondary heat exchanger, or discontinued control parts is a different case: the next failure is a matter of time and the efficiency gap to a modern furnace is real.

Repair frequency is the history factor to track. One repair is an event; two or three major repairs inside a few years is a pattern, and the money spent on the pattern is the real cost of keeping the old furnace. Keep the service records; they are the evidence for this part of the decision.

Parts availability is the practical constraint. Furnace manufacturers keep replacement parts for their active lines and, for a time, for discontinued ones. When a control board or motor for your exact model is no longer available, the repair price stops being the question.

Compare three numbers: the confirmed repair price, the replacement range for your house, and the furnace's expected remaining life if repaired. BC Wide's published guidance puts a typical residential high-efficiency furnace installation in Metro Vancouver at $4,500 to $8,500 depending on size, brand and venting; the estimator on this site applies that range with the documented price drivers.

A common rule of thumb says replace when the repair costs more than half the replacement price, but the useful threshold is lower for old furnaces and higher for young ones. A better test: if the repair is one-fifth of replacement on a 12-year-old furnace with a sound heat exchanger, repair. If it is half of replacement on an 18-year-old furnace, replace.

Remember that the replacement range is not the whole cost story: replacing an 80% furnace with a 95%+ furnace changes the venting, adds condensate handling and often involves duct and chimney work, which is why the estimator lists those drivers separately. The repair is a known number; the replacement is a scope.

An 80%-class furnace converts roughly 80 cents of every gas dollar into heat; a 95%+ furnace converts 95 or more. The difference is 15 to 18 cents per dollar of gas — real, but worth roughly $150 to $350 a year for a typical Lower Mainland house, not the hundreds some sales copy implies. Over the furnace's life that saving contributes to the replacement math, but it rarely justifies replacing a working furnace by itself.

Between two modern furnaces the efficiency gap is small: 96% versus 98% AFUE is about two gas dollars in every hundred. That is why this site's buying guidance treats staging, sizing and blower type as the real decisions and efficiency as the floor.

Some findings end the repair-versus-replacement debate regardless of cost: a failed heat exchanger, evidence of carbon monoxide from the appliance, flame rollout that cannot be explained and corrected, or gas-valve behaviour that cannot be trusted. If a CO alarm sounds or gas is smelled, the sequence is the same everywhere on this site: leave the building, call FortisBC at 1-800-663-9911 or 911, and only then call BC Wide.

A furnace that has repeatedly tripped its safety devices is also worth a hard look: the safeties protected the furnace, but the underlying conditions that tripped them (overheating from airflow starvation, for example) are the same conditions that shorten heat-exchanger life.