A furnace quote can swing by thousands of dollars for what sounds like the same job, and most of that spread comes down to two things: efficiency rating and whether your ductwork needs work along with the unit itself. This isn’t a DIY replacement — gas lines and combustion venting are code-inspected work — so the goal here is knowing what’s driving your specific number.
What a Gas Furnace Actually Costs Installed
Installed gas furnace replacement runs $2,800 to $7,500 for most homes, with the national average for a mid-efficiency unit in a typical 1,500–2,000 sq ft home landing between $4,500 and $6,300. Larger homes, high-efficiency equipment, or a home needing duct modifications push toward the top of that range and beyond.
Equipment is roughly 60% of the total bill; labor, permits, materials, and disposal of the old unit make up the rest.
| Furnace Type | Typical Installed Cost |
|---|---|
| Mid-efficiency (80% AFUE) | $2,800 – $5,000 |
| High-efficiency (96%+ AFUE) | $3,500 – $7,500 |
| Larger home / duct modifications needed | up to $12,000 |
Is High-Efficiency Worth the Premium
A 96%+ AFUE furnace adds roughly 30% to the upfront price but can save $200–$400 a year on heating bills, which pays back the premium over roughly 6–10 years depending on climate and gas prices in your area. In a mild climate with a short heating season, the payback stretches out and a mid-efficiency unit is often the more rational buy. In a genuinely cold climate running the furnace half the year, high-efficiency tends to pencil out.
One Thing Worth Doing Yourself, While You’re At It
The furnace itself isn’t a DIY install, but if you’re already having the HVAC system worked on, pairing it with a DIY-friendly smart thermostat is a genuinely easy add that a homeowner can do in an afternoon.
- Sensi Lite Smart Thermostat — Explicitly built for DIY installation and Energy Star certified — a straightforward swap that pairs well with new, more efficient equipment.
Confirm compatibility with your specific furnace and any existing zoning system before buying — a multi-stage or variable-speed high-efficiency furnace sometimes needs a thermostat rated for it specifically, and the installer can confirm this in five minutes.
Get quotes that specify the AFUE rating and BTU output in writing, not just "furnace replacement." Two quotes that look close in price can be for meaningfully different equipment, and BTU output undersized for your home’s square footage is a common way a cheaper quote ends up costing more in comfort and gas bills over the life of the unit.
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