Furnace System GuideThis guide covers typical furnace repair prices by part and the point at which repair stops making sense. Every figure below is tied to a dated cost reference and is attributed to the source it came from. Where a source did not publish a number, we leave it out rather than guess.
What an Average Furnace Repair Costs
Most furnace repairs fall well short of a full replacement. Carrier reports that the average furnace repair bill is about $300, with a range that runs from $65 for a small fix to $1,500 for a major part.
The spread is wide because the cost depends almost entirely on which component failed. A worn sensor is cheap. A cracked heat exchanger is not. The sections below break the price down by part so you can sanity check a quote before you approve it.
Cost by Common Repair Part
The most useful way to read a furnace quote is part by part. Carrier lists price ranges for the parts that fail most often, and those ranges include both the component and the labor to install it.
Carrier lists a flame sensor at $150 to $250, an ignitor at $150 to $500, an electronic control or circuit board at $200 to $600, and a gas valve at $200 to $600. Carrier lists the larger mechanical parts higher, with a draft inducer motor at $200 to $1,500 and a blower motor at $150 to $2,000.
The ignitor is the single most common failure, so it is worth a second reference. Today's Homeowner reports that the ignitor part itself runs about $25 to $50, while the average cost to replace a furnace ignitor with labor is $300 to $425.
The Expensive Repairs to Watch For
A few furnace parts cost enough that they change the repair-versus-replace math on their own. The heat exchanger is the main one.
Carrier lists a heat exchanger repair at $500 to $1,500. Carrier also lists an electronic control board at $200 to $600 and a gas valve at $200 to $600. When one of these fails on an older furnace, the repair estimate starts to approach the cost of a new system.
A cracked heat exchanger is also a safety issue because it can allow combustion gases into the home's air. When a technician condemns a heat exchanger, replacement of the whole furnace is usually the recommendation rather than a patch.
When Repair Stops Making Sense
At some point a repair is money spent on a furnace that is going to fail again. There is a common rule that helps you draw the line.
Carrier references the 50 percent rule, which says that if a repair costs 50 percent or more of a new system and the furnace is nearing the end of its life, replacement is the better choice. Carrier notes that furnaces over 15 years old are generally candidates for replacement, particularly when the repair estimate approaches 50 percent of the value of a new system.
Use the part prices above against that rule. A $250 flame sensor on a 10-year-old furnace is an easy repair. A $1,500 heat exchanger on a 16-year-old furnace is a signal to price out a replacement instead.