Furnace Installation & Replacement in Highlands Ranch

Expect about a 23% derate at this elevation. A furnace rated 80,000 Btu/h input at sea level runs at roughly 61,000 Btu/h here once orifices and gas pressure are set for altitude. We base the size on a Manual J. Two-story production homes often have a basement furnace that struggles to heat bedrooms above the garage; the duct system usually explains it, and a two-stage or variable-speed furnace with longer run times helps more than extra capacity.

Since January 1, 2026, a new gas furnace sold in Colorado must meet 14 ng/J NOx or the current ENERGY STAR version, which requires 97% AFUE in the North as of July 31, 2026. That leaves two paths for an 80% home: an ultra-low NOx 80% furnace that reuses the B-vent, or a 97% condensing furnace vented in PVC through a sidewall or the roof, with a condensate drain.

The second option changes the water heater's venting. With the furnace off the B-vent, the water heater is alone in a vent sized for two, and the fuel gas code requires it to be sized for one. We include that work and the drain in the quote. Where the furnace sits in an unfinished basement, the condensate can usually drain to a floor drain or a small pump; finished basements may need a pump routed to the laundry standpipe. Our NOx guide compares both paths.

Because Highlands Ranch is unincorporated, the Douglas County Building Division issues the basic mechanical permit, which we submit online. We file it and schedule the inspection. Xcel Energy supplies gas and electricity. A rebate tracker reports Xcel ended gas furnace rebates on January 1, 2026, so we verify before counting on one.

If your AC is as old as your furnace, which is common in Eastridge and Westridge, replacing both with a cold-climate heat pump and a compliant gas furnace as backup is worth pricing. A cold-climate unit can draw $1,500 from Power Ahead Colorado on top of the state's $1,000 air-source credit when the contractor applies first, and Xcel heat pump rebates changed October 1, 2026, so confirm current amounts. Don't plan on the federal 25C credit; it ended for systems placed in service after 2025. See how dual fuel works in Colorado.