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“Should I repair or replace my furnace?” is one of the most common questions we hear, and the decision to repair or replace my furnace is rarely obvious. A failing furnace forces one of the more expensive decisions a homeowner makes: pay to fix it, or invest in a new one. The right answer is not always obvious, and it comes down to a handful of clear factors, chiefly the furnace’s age, the repair cost, and its efficiency. This guide walks you through each one. Our heating team helps Peel Region homeowners make this call every day.
The short answer: repair your furnace if it is under about 15 years old, the problem is a single part, and the repair costs well under half the price of a new unit. Replace it if it is 15 to 20 or more years old, needs frequent repairs, has a repair bill approaching half the cost of a new furnace, or has a cracked heat exchanger, which cannot be safely repaired. A useful rule of thumb is to replace when the repair cost is more than half the price of a new furnace.
Aire One Peel gives you an honest recommendation, with a written price for both options so the choice stays yours. Call 905-564-8545 for a free assessment, and we have served Peel Region since 1990.
Repair or replace: the deciding factors
Weigh these six factors together rather than any one alone. If most point the same way, your answer is usually clear.
| Factor | Lean toward repair | Lean toward replace |
|---|---|---|
| Age | Under 15 years | 15 to 20 years or more |
| Repair cost | Minor, well under half of new | Approaching half the cost of new |
| Breakdowns | First or rare | Frequent, most seasons |
| Efficiency and bills | Fairly new, high-efficiency | Old, low AFUE, rising bills |
| Heat exchanger | Intact | Cracked (safety, must replace) |
| Comfort | Even, reliable heating | Uneven heat, cold rooms |
When repair makes sense
Repair is usually the smart, cost-effective choice when your furnace is still relatively young, under about 15 years, and the fault is a single component such as an igniter, flame sensor, or blower motor. If the unit has been reliable, heats evenly, and the repair costs a few hundred dollars against a new furnace that costs thousands, fixing it is the sensible move.
A furnace under warranty is another clear case for repair, since parts may be covered. In these situations, a quality repair buys you years of continued service for a fraction of replacement cost.
When replacement makes sense
Replacement becomes the better investment when the furnace is 15 to 20 or more years old, near the end of its expected life, and repairs are becoming a yearly event. It also makes sense when the repair bill approaches half the price of a new unit, when your energy bills keep climbing because the furnace is inefficient, or when comfort has slipped with cold rooms and constant cycling.
One situation always requires replacement: a cracked heat exchanger, which can leak carbon monoxide and cannot be safely repaired. In these cases, continuing to repair an old furnace is often throwing good money after bad.
A new high-efficiency furnace in Mississauga runs about $3,500 to $7,500 CAD installed, and it may be worth comparing a heat pump at the same time, since heat pumps can qualify for Ontario rebates.
The 50 percent and $5,000 rules
Two simple rules help turn the decision into a number. The 50 percent rule says that if a repair costs more than half the price of a new furnace, replacement is usually the better value.
The $5,000 rule is even quicker: multiply the age of the furnace by the repair cost, and if the result is over 5,000, lean toward replacing. A 16 year old furnace with a $400 repair, for example, gives 6,400, which points to replacement.
These rules are guides, not gospel, but they keep the decision grounded in real dollars rather than guesswork.
The efficiency payoff of replacing
If your furnace is old, replacement is not only about avoiding repairs; it can lower your heating bills. Older furnaces often run at 60 to 80 percent efficiency, meaning a large share of the fuel is wasted, while a modern high-efficiency furnace reaches 95 to 98 percent.
Upgrading from an old unit can cut heating energy use meaningfully, and those savings offset part of the replacement cost over the furnace’s life. When you factor rising energy prices into the math, a new efficient furnace or a heat pump often pays back faster than homeowners expect.
How we help you decide
Not sure whether to repair or replace my furnace? Our team walks you through it.
When our technician assesses your furnace, we check its age, the condition of the heat exchanger and key components, its efficiency rating, and its safety, then give you a written price to repair alongside a quote to replace so you can compare real numbers. We will tell you honestly which option gives you the better value, and the decision always stays yours.
If replacement is the way to go, we can quote a furnace installation and walk you through any rebates you qualify for.
From our Peel Region service calls: [INSERT AIRE ONE PEEL DATA: for example, the average age of furnaces we recommend replacing, or the share of repair-versus-replace assessments that end in a repair. Use a real figure with its sample size, or remove this line.]
We give you a written price to repair and to replace, with a straight recommendation, from a licensed team serving Mississauga, Brampton, Etobicoke, Milton, Georgetown, Caledon, and Bolton since 1990.
Frequently asked questions
Should I repair or replace my furnace?
The choice to repair or replace my furnace is not one-size-fits-all.
Repair if the furnace is under about 15 years old, the fault is a single part, and the cost is well under half the price of a new unit. Replace if it is 15 to 20 or more years old, needs frequent repairs, the repair approaches half the cost of new, or the heat exchanger is cracked.
How long does a furnace last?
A well-maintained gas furnace typically lasts 15 to 20 years. Past that point, repairs become more frequent and efficiency drops, so replacement usually becomes the better value even if the unit still runs.
Is it worth repairing a 15 year old furnace?
Sometimes. A minor, inexpensive repair on a 15 year old furnace that still heats well can be worth it.
But if the repair is costly, breakdowns are frequent, or the heat exchanger is cracked, replacement is the smarter investment. The 50 percent and $5,000 rules help you decide.
What is the 50 percent rule for furnaces?
The 50 percent rule says that if a repair costs more than half the price of a new furnace, you are usually better off replacing it. It keeps the decision grounded in real dollars rather than emotion.
Does a new furnace lower my energy bills?
Yes, if you are replacing an old unit. Older furnaces often run at 60 to 80 percent efficiency, while modern high-efficiency models reach 95 to 98 percent, so upgrading can meaningfully cut heating energy use and offset part of the replacement cost over time.
The bottom line
Deciding whether to repair or replace my furnace comes down to a few clear factors.
The repair-or-replace decision comes down to age, repair cost, efficiency, breakdown frequency, and safety. Repair a younger furnace with a single, affordable fault; replace an old one that needs frequent or costly repairs, or has a cracked heat exchanger.
The 50 percent and $5,000 rules turn it into a number, and an honest in-home assessment confirms it. Book a free furnace assessment or call 905-564-8545.
Still asking whether to repair or replace my furnace? The answer depends on your unit’s age and repair history.
If you want to repair or replace my furnace the smart way, weigh the cost against the value. When you decide to repair or replace my furnace, a licensed technician can confirm the safest choice.
Related reading
- Best furnace repair near you in Mississauga
- Furnace installation and replacement
- Heat pumps and Ontario rebates
- HVAC protection and maintenance plans
Sources and references
- Natural Resources Canada, ENERGY STAR and furnace efficiency
- Technical Standards and Safety Authority (TSSA), Ontario
- Health Canada, Carbon monoxide safety
Pricing and efficiency details verified July 2026 and subject to change.
