Furnace Installation & Replacement in Castle Rock

Castle Rock's elevation means about a 25% derate. A furnace with a 60,000 Btu/h input rating at sea level runs at roughly 45,000 Btu/h here after altitude conversion. Manufacturers specify high-altitude orifices and pressure settings for this, and SWEEP has noted that some ultra-low NOx furnaces need a separate high-altitude kit. We confirm the kit is available before ordering the furnace, not after it arrives.

The Manual J sets the target. Founders Village split-levels and two-stories often turn out to need less capacity than their original furnace provided, which helps when you're choosing between single-stage and two-stage equipment. Castle Rock's sunny winter afternoons followed by cold nights also favor a furnace that can run at low fire for most of the day and step up only when the temperature drops.

Black Hills Energy supplies gas in most of town. Its 2026 Colorado program pays $260 for a 90% AFUE furnace, $350 for 95% and $375 for 97%, covering furnaces bought and installed in 2026, and claims must reach Black Hills by the end of January 2027. It requires an itemized invoice with model and serial numbers, and quotes aren't accepted as proof. We give you that paperwork at the end of the job.

Every new gas furnace sold in Colorado since January 1, 2026 must meet 14 ng/J NOx or the current ENERGY STAR version, now 97% AFUE in the North. A 97% condensing furnace usually vents through PVC out a sidewall, which is simple in most 1990s and 2000s homes. In the Craig and Gould district, an ultra-low NOx 80% furnace may be able to stay on a properly lined chimney, avoiding new wall penetrations on a historic house. If the furnace leaves the chimney, the water heater's vent is resized so it drafts on its own. Older Castle Rock homes sometimes have a furnace and water heater tucked into a crawlspace, and we confirm that a condensate line can drain there without freezing before recommending a condensing unit.

Inside town limits, the Town of Castle Rock Building Division issues the permit and schedules inspections through its eTRAKiT portal. If your parcel is outside the town boundary, Douglas County issues the permit instead, so we check the address before applying.

Electricity comes from CORE Electric Cooperative, so Xcel heat pump rebates generally don't apply. If you want to look at a cold-climate heat pump or dual fuel, a $1,000 Colorado tax credit for air-source heat pumps plus Power Ahead Colorado's $1,500 for cold-climate models still apply here. The federal 25C credit ended after 2025.