What drives the price
The furnace itself is under half the cost. Venting, gas line connection, a new thermostat, condensate drainage on high-efficiency units, electrical, permit and inspection make up the rest. Going from 80% to 90%+ efficiency changes the exhaust from metal flue to PVC, which is real work.
- Efficiency - 80% AFUE versus 95%+ changes the venting entirely
- Whether the existing ductwork and return are adequately sized
- Single-stage versus two-stage or modulating burners
- Attic, crawlspace or tight closet installations
- Whether the AC coil sitting on top gets replaced at the same time
Should you DIY this or call a professional?
Call a pro. A furnace is a combustion appliance connected to a gas line and a flue; a bad install produces carbon monoxide, and it is the failure mode that kills people in their sleep. Every jurisdiction requires a permit and inspection for good reason.
Signs you need this repair
- Furnace is 15-20+ years old and needs a major repair
- Cracked heat exchanger - replace immediately, this is a CO risk
- Short cycling that survives thermostat and filter changes
- Yellow rather than blue burner flame
- Rising gas bills with no change in weather or usage
How to not get overcharged
Ask for the model number and AFUE in writing, and get a separate line for the permit. Ask whether the quote includes a new thermostat and condensate pump - both are commonly added afterwards. Shoulder seasons, spring and early autumn, are when heating contractors discount.
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Red flags to watch for
- A cracked heat exchanger diagnosis with no photo or camera footage shown to you
- Replacement urged when the igniter or flame sensor is the actual fault
- No permit mentioned in the quote
- Refusal to itemise equipment against labour
Frequently asked questions
How much does it cost to replace a furnace?+
A gas furnace replacement typically runs $3,800-$8,500 installed, averaging near $5,500. High-efficiency condensing models add $1,000-$2,500 because they need new venting.
Can I replace a furnace myself, or should I hire a professional?+
Call a pro. A furnace is a combustion appliance connected to a gas line and a flue; a bad install produces carbon monoxide, and it is the failure mode that kills people in their sleep. Every jurisdiction requires a permit and inspection for good reason.
How long does it take to replace a furnace?+
4-8 Hours for a Like-for-like Swap. Scheduling and parts availability can extend the overall timeline beyond the hands-on work itself.
What makes the price of this job go up or down?+
Efficiency - 80% AFUE versus 95%+ changes the venting entirely. Whether the existing ductwork and return are adequately sized. Single-stage versus two-stage or modulating burners. Attic, crawlspace or tight closet installations. Whether the AC coil sitting on top gets replaced at the same time.
How do I avoid being overcharged?+
Ask for the model number and AFUE in writing, and get a separate line for the permit. Ask whether the quote includes a new thermostat and condensate pump - both are commonly added afterwards. Shoulder seasons, spring and early autumn, are when heating contractors discount.