Gas Insert Installation and Replacement in Fort Collins

A direct-vent gas insert installed in an existing Fort Collins fireplace runs $4,000 to $8,000, including the unit, the venting, the surround, the high-altitude kit, the permit, and the inspection. A new direct-vent fireplace framed into a wall during a remodel runs $5,000 to $12,000. A vented gas log set into a sound masonry fireplace is the budget route at $600 to $1,800 plus the gas line. Send a photo of the existing fireplace opening with a tape measure in it, and the room’s rough square footage, and you get a sized recommendation and a number.

We are a repair operation first. If your existing unit needs a thermopile, we will tell you that instead of selling you this page. The repair page is where most calls belong.

When replacement is the honest answer

• The gas valve is failing and the burner pan is corroded through, on a unit whose parts are no longer made.
• The firebox refractory or the glass frame is cracked, so the sealed combustion chamber is no longer sealed.
• The vent has failed: a rusted B-vent, a coaxial vent with a separated seam, or a chimney that will not pass inspection for a log set.
• A wood-burning masonry fireplace in Old Town or a 1970s neighborhood that you want to use without the smoke, the draft, and the wood.
• A house in unincorporated Larimer County where the county’s fireplace rules point you to gas anyway (more below).

Three ways to put gas in a fireplace

Direct-vent insert into an existing fireplace ($4,000 to $8,000)

A sealed steel firebox with ceramic glass slides into the old masonry or factory fireplace. Two liners, or one coaxial liner, run up the chimney: one brings combustion air in from outside, the other takes exhaust out. Nothing from the fire enters the room, which is why it is the right answer for a tight modern house and for anyone with respiratory concerns. Real heat, typically with a blower, and a thermostat or remote.

Sizing matters. A 30,000 BTU insert in a 200 square foot den will cook you out; a 20,000 BTU unit in a great room with a two-story ceiling on the Harmony corridor will disappoint. We size to the room, the ceiling, and whether it is ambiance or heat you are after.

New direct-vent fireplace in a remodel ($5,000 to $12,000)

A factory zero-clearance unit framed into a new wall, vented horizontally through an exterior wall or vertically through the roof. This is how the city’s late-20th-century southward expansion was built, and how Timnath and Windsor’s new phases are built today. The range is wide because framing, the vent run, and extending the gas line are all separate trades.

Gas log set in a masonry fireplace ($600 to $1,800 plus gas line)

Vented logs sit on a burner in the open fireplace, damper clamped open, exhaust up the chimney. Cheapest, most realistic flame, least heat. Vent-free logs burn cleaner and heat the room but add moisture and combustion products to the air. The gas logs page covers the choice.

Altitude, propane, and the kit

Fort Collins sits at 4,997 feet. The National Fuel Gas Code (NFPA 54 / ANSI Z223.1) calls for derating gas appliances installed above 2,000 feet by about 4 percent per 1,000 feet, and the installer is responsible for the adjustment. Manufacturers publish high-altitude orifice and conversion kits by elevation band, with natural-gas kits typically starting above 4,500 feet. Every unit we install gets the kit for its elevation and has its manifold pressure set and recorded. Skip this and a brand-new fireplace soots its glass in the first month and burns with lazy yellow flames.

Fuel matters as much. Xcel Energy natural gas serves Fort Collins and the county’s towns. In Estes Park at 7,743 feet the derate is well over 20 percent, and while Xcel’s 28-mile, 12-inch line up the Big Thompson Canyon serves the town, cabins off the mains run propane, which needs its own orifices and regulator setting. Rural addresses around Wellington on tank propane are the same story; the county even lists propane tank installation as one of its miscellaneous permits.

Permits and who pulls them

New appliances and new gas piping are permitted everywhere we work, and the permit is pulled in the installer’s name:

• City of Fort Collins. The city’s building permit list says gas fireplaces need a permit and that Poudre Fire Authority may require an additional, separate review. Permits submitted on or after April 1, 2026 fall under the 2024 International Codes with local amendments. Building Services is at 281 North College Avenue.
• Unincorporated Larimer County. A Miscellaneous Permit covers fireplaces, gas log inserts, and gas lines and gas appliances. The county’s fireplace handout, updated January 2026, requires a permit and inspection for factory-built fireplaces and inserts, with the manufacturer’s installation instructions on site so the inspector can verify clearances. It also says that in the county’s Restricted Area, any fireplace installed since January 1, 2002 must be gas, electric, or a Phase III certified wood appliance, which is why so many county remodels end up on this page.
• Loveland, Windsor, Timnath, Wellington, Greeley, Estes Park. Each runs its own building department and each has its own contractor licensing. Timnath adopted the 2024 codes effective January 1, 2026; Estes Park has contracted its building division to SAFEbuilt since 2020; Greeley requires a contractor license for permits starting January 1, 2027.

Gas piping is a separate item under the State Plumbing Board’s rules, which require a permit and inspections for all fuel gas piping work, with a rough inspection under air test and a final.

How the installation goes

1. Measure and size. Opening dimensions, chimney or wall route, room size, ceiling height, fuel, elevation.
2. Quote. Unit, venting, surround, kit, gas line if needed, permit at cost. In writing.
3. Permit. Pulled with the city, county, or town. Poudre Fire Authority review where required.
4. Install. Unit set, vent run and sealed, gas connected and leak-tested, altitude kit fitted, manifold pressure set.
5. Inspection. Manufacturer’s instructions on site, inspector verifies clearances and venting.
6. Commission. Test-fire, logs and embers set, remote paired, readings recorded, and you get shown how to relight it and clean the glass.

What it costs

Full ranges on the pricing page. We install across Fort Collins and out to Loveland, Windsor, Timnath, Wellington, Greeley, and Estes Park, and installation is the one job we would rather schedule in spring, when the calendar is open and nobody is waiting on heat.