The quick rule
If your furnace is older than about 15 years and needs a big repair, get a replacement price before you approve the repair.
If it's newer, or the repair is small, fixing it usually makes sense. Most furnaces fail one part at a time, and one new part doesn't mean the rest is worn out.
That rule is a starting point. The rest of this post covers what moves the decision either way.
How old is your furnace?
Look at the rating plate inside the furnace door. It lists the model and serial number, and many brands put the build year and month in the serial number. Some installers also leave a sticker with the install date. If you can't find it, take a photo of the plate and send it to us.
A well installed and maintained gas furnace usually lasts 15 to 20 years. Furnaces in Calgary run long hours, so the parts that move, like the inducer motor and blower, wear faster than in milder places.
Get a real diagnosis first
Don't decide on a guess. A furnace that blows cold air might need a new filter, a cleaned flame sensor, or a new control board. Those are very different bills.
A proper diagnosis checks the ignition sequence, the inducer and pressure switch, the flame sensor, the blower, the limit switches and the heat exchanger. Ask the technician to show you the failed part or the reading that proves it.
Before you call, check the easy things yourself: the thermostat is set to Heat, the furnace switch is on, the filter isn't clogged, and the two white PVC pipes outside aren't blocked by snow. A blocked pipe is one of the most common no-heat calls in Calgary.
What repair and replacement cost
Repair prices depend on the part that failed. A new furnace costs a lot more, and the type you choose matters. Our furnace repair page has the typical Calgary repair range, and our furnace cost guide breaks down what a new one costs.
Signs replacement is the better spend
Replacement is worth pricing when you see one or more of these:
- A cracked heat exchanger. This can let combustion gases into the airflow. On an older furnace, the fix usually costs close to a new unit.
- Repeat breakdowns. A few service calls over a winter or two means more are coming.
- A major part on an older furnace. An inducer motor, control board or blower motor is a big repair, and on an older furnace that money goes a long way toward a new one.
- Rooms that never get even, and a furnace that runs and runs. Old single-stage furnaces and tired blowers struggle to move air through the whole house.
- Gas bills creeping up with no change in how you live.
- A mid-efficiency furnace with a metal flue into a chimney. It burns more gas for the same heat than a new high-efficiency furnace.
How much gas a new furnace saves
New gas furnaces sold in Canada must be high-efficiency. If you have a mid-efficiency furnace now, a new one burns noticeably less gas for the same heat, and you see that every winter. If your furnace is already high-efficiency, the gain from a new one is small, so the decision comes down to repair cost and reliability.
When repair is the right call
Fix it when:
- The furnace is fairly new.
- It's a common, single part: a flame sensor, igniter, capacitor or wiring.
- It's been reliable, and this is the first real problem.
- It's already a high-efficiency furnace in good shape, so a new one wouldn't save much gas.
Thinking about a heat pump?
If you're replacing the furnace and your air conditioner is also getting old, price both jobs together. A new furnace with a heat pump instead of an AC gives you cooling in summer and cheaper heat on mild days, with the furnace as backup in the cold.
Even if you only replace the furnace now, ask for a model and thermostat that support a heat pump later. It saves replacing controls down the road.
Safety comes before cost
If you smell gas, leave the house, don't flip switches, and call ATCO's 24 hour emergency line at 1-800-511-3447 or 911 from outside.
If your carbon monoxide alarm goes off, get everyone out and call 911. Don't go back in to check the furnace.
A furnace that has a cracked heat exchanger or a failed safety control should be shut off until it's fixed or replaced. We'll tag it and explain why.
How we help you decide
When we diagnose an older furnace, we give you both prices: the repair and a replacement. We tell you the furnace's age, what else looks worn and what we'd do in your place. Then you choose. No pressure either way.
If you replace, you can spread the cost over monthly payments through Financeit.