Furnace Installation & Replacement in Louisville

The city grew from about 5,600 residents in 1980 to almost 19,000 in 2000, and most of today's single-family homes come from that period. Many are on a first replacement furnace from the 2000s, now near 20 years old. These homes usually have room for a condensing furnace and a straightforward sidewall vent route.

Of the 550-plus homes destroyed in Coal Creek Ranch and nearby neighborhoods, 532 were rebuilt or under construction as of August 2026. Their heating systems are new, so replacement isn't the issue for years. What we do see is warranty and setup questions, including whether the furnace was converted for altitude and whether the system was sized for the new house rather than the old one.

At 5,401 feet, furnaces lose about 22% of their sea-level rating. A 60,000 Btu/h input furnace delivers about 47,000 here after high-altitude setup. We size from a Manual J and verify combustion. Homes from the 1980s and 1990s often had their furnace sized before later window and insulation upgrades, so the new one is frequently smaller, which also leaves more room in the budget for a two-stage or modulating model that handles Louisville's windy, swinging winter days more evenly.

Since January 1, 2026, a new gas furnace sold in Colorado must meet 14 ng/J NOx or the current ENERGY STAR version (97% AFUE in the North since July 31, 2026). A 2024 contractor summary also reported a Louisville minimum of 96% AFUE for new or replacement furnaces. We could not confirm that on the city's site, so we check with Building Safety before quoting an 80% furnace. Our NOx guide explains the state rules.

The city issues a Furnace/AC/Water Heater/Heat Pump permit, pulled by a licensed mechanical contractor, and it allows only one contractor per permit. Electrical work isn't allowed on that permit type. For gas furnaces, a 15-minute pressure test at 5 psi is required, in person or by emailed video, and direct-vent appliances get an exhaust vent inspection. The contractor requests the final inspection. We handle all of it.

If you're weighing a heat pump, your electricity comes from Xcel, whose heat pump rebate amounts changed October 1, 2026, so confirm the current figures. A $1,000 Colorado tax credit for air-source heat pumps plus Power Ahead Colorado's $1,500 for cold-climate models apply, while the county's EnergySmart rebates are open only to income-qualified households this year. A heat pump needing a new circuit requires a separate electrical permit. See heat pump vs. furnace.