A gas furnace replaced on its own runs $4,500 to $9,000+, and a furnace and air conditioner replaced together falls in our $9,500 to $25,000 system range (our current ranges). In our Folsom service records since January 2024, 8 of 9 furnace replacements came with a new AC at the same visit, and 1 was a rooftop gas furnace on its own. The full service is on our furnace replacement page.
80 percent or 96 percent in a Folsom house
Seven of those eight furnaces were 80 percent AFUE models; one was a 96 percent two-stage furnace on a zoned system with new damper motors and two thermostats. The difference is more than the rating:
- An 80 percent furnace vents through a metal flue and needs no condensate drain, so it usually drops into the space the old furnace used.
- A 96 percent furnace condenses its exhaust, so it needs plastic vent piping to the outside and a drain for the condensate. In an attic that changes the installation, not only the efficiency.
| 80 percent AFUE | 96 percent AFUE | |
|---|---|---|
| Venting | Metal flue, often the existing one | Plastic vent piping to the outside |
| Condensate drain | None | Required |
| Our Folsom installs with an AC since 2024 | 7 | 1 |
The right choice depends on the house, the vent path and how long you expect to stay. Our replacement guidelines set out how we weigh it.
When a Folsom furnace should be repaired instead
A replacement is not the answer to every heating fault. Most Folsom furnace faults we see are a single failed part. A furnace with one failed part and sound combustion components is usually worth repairing; our Folsom furnace repair page lists what those repairs cost here.
Replacement becomes the better buy when failures repeat across several aging parts, when the heat exchanger is cracked, or when the furnace is due anyway and the AC is being replaced. Our guide to cracked heat exchanger symptoms explains the one finding that ends the repair conversation.
- How old is too old? Our guide to how long a furnace lasts in Sacramento sets a furnace's age against DOE's lifetime estimates and our own records on older units.
Gas and flue work on a Folsom furnace change
A furnace change is gas work as well as air work. In a 2025 Folsom replacement on a 31-year-old system, the scope listed the gas line and flue reconnection beside a new supply plenum and high-flow return grille. A 96 percent furnace replaces the metal flue with plastic venting, so its vent route belongs in the estimate. The duct test the state energy code adds when equipment changes is explained on our Folsom AC installation and replacement page.
Gas furnace or heat pump
A new gas furnace earns no SMUD rebate: SMUD's heating and cooling rebate pays only for heat pumps. If you would rather keep gas heat, the 80 and 96 percent choice above is the decision that matters. If the air conditioner is due too, a heat pump can replace both; our Folsom heat pump installation page sets out SMUD's tiers and our heat pump price ranges.
For the furnace on its own, call 916-848-5980 or book a visit online. Our Folsom HVAC service page covers the rest of our work in the city.
