CostBeaverGas Furnace Guide: What It Costs, and Whether You Should Even Buy One Here
HVAC TIPSA gas furnace burns natural gas or propane to heat air, and its AFUE rating tells you what share of that gas becomes heat in your house — 80% for a standard model, 95%+ for a condensing one. Installed in Georgia and the Carolinas, expect $4,500–$9,000 for the furnace alone, or $8,500–$14,000 for a furnace-and-AC pair. In our mild winters a heat pump is usually the better buy, but a furnace still makes sense if you already have a gas line and a newer AC, or you're up in the mountains where winters actually bite.
The short version
- AFUE is the whole efficiency story: an 80% furnace sends 20 cents of every gas dollar up the flue; a 95%+ condensing model keeps nearly all of it.
- Budget $4,500–$9,000 installed for the furnace alone in 2026, or $8,500–$14,000 if the AC gets replaced at the same time.
- A well-kept furnace lasts 15–20 years — longer than the 12–16 a heat pump typically gets in our long cooling season.
- The federal 25C credit is gone for 2026 installs. Utility rebates are what's left, so check your gas and electric providers before signing.
What a furnace actually is, in one minute
A gas furnace is the simplest machine in the HVAC family: it burns natural gas inside a heat exchanger, a blower pushes your house air across that hot metal, and warm air comes out the vents. Combustion gases leave through a flue. That's it. No refrigerant, no reversing valve, no outdoor unit for the heating side.
The number that defines any furnace is AFUE — Annualized Fuel Utilization Efficiency. It's the share of the gas you pay for that becomes heat inside your home instead of exhaust. An 80 AFUE furnace turns 80% of the gas into house heat and sends 20% up the flue. A 96 AFUE model keeps 96 cents of every dollar.
Simple machine, long life. Which is exactly why the interesting question in Georgia and the Carolinas isn't the spec sheet. It's whether this is the right machine for a winter that barely shows up.
80% vs 95%+: the condensing difference
Walk into any quote and you'll be offered two tiers, and the difference is more than a number on a sticker.
A standard 80% furnace vents hot exhaust up a metal flue, usually through the roof. It's the cheaper box and the cheaper install, especially if a metal flue already exists.
A 95%+ condensing furnace squeezes so much heat out of the exhaust that the water vapor in it condenses into liquid. Cooler exhaust means it can vent sideways through the wall in cheap PVC pipe — but now the unit needs a condensate drain, and if your old flue was shared with a gas water heater, that flue may need relining once the furnace leaves it. That's a real line item people don't see coming. A tech in Kennesaw quoted a friend of mine $900 extra for exactly that reliner last winter, and it turned a clean swap into a negotiation.
Here's the twist for our region: the efficiency upgrade pays back through runtime, and Southern furnaces don't run much. In Minneapolis a condensing furnace repays its premium fast. In Charlotte, where the furnace might log ten real weeks of work, the extra $1,000–$2,000 for 95% can take over a decade to come back. If gas is cheap on your Piedmont Natural Gas or Atlanta Gas Light rate and the install is straightforward, fine. But nobody down here should feel guilty buying the 80.
In the Southeast, the AC sizes the system, not the furnace. Our cooling load dwarfs our heating load — Columbia is Famously Hot for a reason — so a matched furnace often carries more heating capacity than the house will ever use. Resist the contractor reflex to round up. An oversized furnace short-cycles: blasts of heat, then off, then on again, wearing parts and leaving rooms uneven. Ask for a Manual J load calculation by name, and see our sizing guide before anyone writes a tonnage on a quote.
What a gas furnace costs installed in 2026
Real ranges across Georgia and the Carolinas this year. Where you land inside each range tracks the AFUE tier, the brand (Goodman and Rheem anchor the value end, Trane and Carrier the premium end), and how much venting or ductwork surgery the install needs.
| Job | Typical 2026 installed cost | Notes |
|---|---|---|
| 80% AFUE furnace swap | $4,500–$6,500 | Metal flue, simplest install |
| 95%+ condensing furnace | $6,000–$9,000 | PVC venting, condensate drain |
| Furnace + new AC together | $8,500–$14,000 | One crew, one day, matched coil |
| Add if flue needs relining | $500–$1,500 | Common when a water heater shares the old flue |
If both the furnace and the AC are past 12 years old, price the pair — doing them together saves a second install charge and gets you a matched coil. And at that point, seriously price the heat pump too; more on that in a minute. Get your own local number on the HVAC calculator first, so the quotes have something to be measured against.
How long a furnace lasts
15 to 20 years is the honest range, and down here furnaces often reach the top of it because they work so little. Ten weeks of real heating a year is a light career.
The part that decides the end date is the heat exchanger. When it cracks, the furnace is done — a cracked exchanger can leak combustion gases into your air stream, and no reputable tech will patch one. Replacement exchangers cost enough that past year 12, the math almost always says new unit.
Change the filter, keep the annual inspection, and don't close off supply vents in unused rooms (it starves airflow and cooks the exchanger). That's most of furnace longevity right there.
The question before the quote: furnace or heat pump?
Time for the site's standing opinion, stated plainly. In the mild Southeast, a heat pump is usually the better buy. One system heats and cools, it feeds off the efficiency you'll use for five months of cooling, and our winters rarely get cold enough to expose its weak side. The full argument is in our heat pump vs furnace breakdown, and if the technology is new to you, start with what a heat pump actually is.
But a furnace still wins some hands, even here:
- You have gas and a newer AC. If your AC is five years old and humming, replacing just the failed furnace for $4,500–$6,500 beats scrapping a healthy AC to install a heat pump.
- You're in the mountains. The North Georgia foothills and western North Carolina get real winters. Gas — or a dual-fuel setup pairing a heat pump with a gas furnace for the cold snaps — earns its keep up there.
- You heat hard on cheap gas. Keep the house at 72 all winter on a low rate and the furnace's raw heating muscle costs less on the coldest stretches.
So here's the decision rule I'd give a neighbor: on gas with a 5-year-old AC? Replace furnace-for-furnace and don't overthink it. Both units old? Price the heat pump switch before you commit to anything. The quote costs nothing and the answer surprises people.
The safety part, briefly and seriously
A furnace burns fuel inside your house, which puts two obligations on you that heat pump owners get to skip.
First, a CO detector on every floor with bedrooms, and one near the furnace. Carbon monoxide is colorless and odorless, and a failing heat exchanger or blocked flue is exactly how it reaches living space. A plug-in Kidde with a digital readout runs about $40. Check the date on any you already own — detectors expire after 7–10 years, and the one that came with the house is probably past it.
Second, an annual inspection, ideally each fall before the first cold morning. A tech runs a combustion analysis, checks the exchanger for cracks, and tests the safety controls for $100–$200. That visit is also what keeps most manufacturer warranties valid, so skipping it costs twice.
And one you'd only learn the annoying way: after a hard rain, if the furnace won't fire, check that the sidewall PVC intake isn't blocked. Condensing furnaces pull combustion air through that pipe, and leaves, mud daubers, and one memorable frog have all shut furnaces down across the Lowcountry.
The 25C federal tax credit that once returned up to $600 on a high-efficiency furnace expired for anything installed after December 31, 2025. A 2026 furnace gets nothing from the IRS, so ignore any pitch that leans on a federal credit. What's left is utility money: gas utilities like Piedmont Natural Gas and Atlanta Gas Light have run high-efficiency equipment rebates, and if you go the heat pump route instead, Georgia Power, Duke Energy, and Dominion each run programs on the electric side. Confirm the utility that actually serves your address — Duke in Greenville, Dominion in Columbia — before you count any of it.
