No sales visit required to hear a number: on the northern Front Range, most furnace replacements run $5,500–$9,500 installed. Here's what moves it — and when you shouldn't replace at all.
Two houses on the same street can land at opposite ends of it. A straightforward swap — same size, same flue, easy access — sits at the low end. A bigger home going to a high-efficiency furnace that needs new venting, or an older home whose ductwork needs correction, climbs from there. The factors, in order of impact:
Furnace capacity has to match the house's actual heat loss on a cold Colorado night — not just copy whatever was installed in 2005. Oversized furnaces short-cycle: they blast, shut off, and never run long enough to heat evenly (if that sounds familiar, read our short-cycling guide). We size from a load calculation, which is also why our quotes occasionally come in a size smaller — and cheaper — than a competitor's copy-paste bid.
An 80% furnace vents up the existing metal flue and costs less up front. A high-efficiency condensing furnace (90%+ AFUE) squeezes more heat from the same gas but vents through new PVC pipe to an exterior wall and needs a condensate drain — real installation work that shows up in the price. Over a Colorado heating season the gas savings are genuine; whether they pay back fastest in your house depends on how long you'll be there. We'll show both numbers.
Single-stage furnaces are all-or-nothing. Two-stage units idle along at a lower fire most of the winter — steadier temperatures, quieter operation, fewer cold-spot complaints in two-story homes. Variable-speed blowers help airflow-challenged ductwork and make a real difference if someone in the house cares about even temperatures. Each step adds cost; two-stage is the common sweet spot here.
Venting changes (especially going high-efficiency), gas line adjustments, electrical, a proper condensate route, code items like drain pans and shutoffs, and the permit and inspection your city requires. Older homes around Fort Lupton, Longmont, and downtown Brighton often have heating-only duct sizing that's worth correcting while everything's open. All of it belongs in the written quote up front.
Equipment, load-calculation sizing, all labor, venting and condensate work as specified, thermostat hookup, permit and inspection, haul-away, and manufacturer warranty registration — itemized, one number per option, quoted by someone who isn't paid a commission to inflate it.
A furnace under about 12 years old with a modest failure — ignitor, flame sensor, capacitor, board — should almost always be repaired. The age-times-repair-cost rule from our repair-or-replace guide applies to furnaces too: under about $4,000, fix it; over about $6,000 on an old unit, put the money toward new. One exception that overrides the math: a cracked heat exchanger on an older furnace is a replacement conversation, full stop — it's a safety issue, and we'll show you the evidence, not just assert it.
Straight gas-furnace replacements have little rebate support in 2026 — the federal 25C credit ended December 31, 2025. The programs with real money target heat pumps: Colorado's $1,000 state credit, Xcel's cold-climate rebates, and United Power's program (much of the Carbon Valley and Fort Lupton is co-op territory). A popular middle path is dual-fuel: a heat pump handles most of the season, the furnace covers the coldest snaps. Details on the rebates & financing page — and GoodLeap financing is available when monthly payments beat a lump sum.
For a typical northern Front Range home, $5,500 to $9,500 installed covers most replacements. Size, efficiency tier, staging, venting changes, and permits move the number within the range — and the quote should itemize all of it before you sign anything.
Around 15–20 years with maintenance. Long heating seasons and hard day-night swings age them faster when they're neglected — and builder-grade furnaces in the newer subdivisions often hit major failures earlier than owners expect. A fall tune-up is the cheapest life-extension there is.
If both are old, usually yes — shared labor makes the combined job cheaper than two separate ones, and matched equipment runs better. If only one is failing, we'll tell you that instead. It's also the natural moment to price a heat pump, which is where 2026's rebates actually are.
Free replacement quote — measured, itemized, and honest about whether you even need one.