Castle Rock, CO — Douglas County

Furnace Replacement in Castle Rock

Replacing a furnace in Castle Rock means sizing for a 3°F winter design temperature, venting correctly at 6,224 feet, and pulling the right permit. We quote flat-rate, and the price we quote is the price you pay.

Licensed & insured • Family-owned since 2004 • Flat-rate pricing

✓ Upfront flat-rate pricing✓ Castle Rock permits handled✓ Carrier, Lennox & Trane✓ All major brands serviced
Furnace Replacement

Furnace Replacement for Castle Rock homes

Replacing a furnace in Castle Rock means sizing for a 3°F winter design temperature, venting correctly at 6,224 feet, and pulling the right permit. We quote flat-rate, and the price we quote is the price you pay.

We are a family shop, not a franchise call center. The tech who shows up can explain what failed and why, and the quote does not change after you say yes.

See our main furnace replacement page for how we approach this work across the metro.

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Load calculation and sizing

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Altitude setup

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Venting and condensate

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Permit and inspection

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Haul-away of the old furnace

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Warranty registration

Castle Rock service(303) 627-3395Flat-rate • 7 days
Castle Rock, CO — local facts

Furnace Replacement in Castle Rock: what’s different here

Castle Rock sits near the Palmer Divide and averages 57.5 inches of snow a year. Unlike most of metro Denver, homes here usually get gas from Black Hills Energy and electricity from CORE, not Xcel.

Altitude derate

Gas appliances are derated roughly 4% per 1,000 feet above 2,000 feet (the fuel gas code rule), so at 6,224 feet a furnace needs the correct orifices and manifold pressure to deliver its rating. We set it up for Castle Rock, not sea level.

Rebates in 2026

Black Hills Energy pays $260–$375 on a new 90%+ AFUE furnace for its gas customers. Xcel’s gas furnace rebates ended Jan. 1, 2026, and the federal 25C credit ended for anything installed after Dec. 31, 2025. If rebates matter, a cold-climate heat pump is where the money is.

Permit

Contractors must register with the Town before doing any work, backed by an ICC-comparable license from a testing municipality; unregistered contractors cannot pull permits.

Hytek pricing

Furnace Replacement: $3,500 – $8,500 installed. Flat-rate, approved before work starts. Free estimates on replacements.

Elevation & climate

6,224 ft. Avg January low 18°F, avg July high 85.7°F, design temp 3°F, about 57.5 in of snow a year.

Homes

71% of Castle Rock homes were built in 2000 or later (median year built 2007).

Utilities

Electric: CORE Electric Cooperative. Gas: Black Hills Energy.

Permits

Town of Castle Rock Building Division. Contractors must register with the Town before doing any work, backed by an ICC-comparable license from a testing municipality; unregistered contractors cannot pull permits.

Rebates and programs for Castle Rock homeowners (2026)

  • Black Hills Energy 2026 gas rebates: For Black Hills gas customers: $260 (90% AFUE), $350 (95%) or $375 (97%) on a new furnace, up to $30 on a tune-up every 3 years, up to $100 on a smart thermostat. Source
  • CORE Cool Credits: CORE Electric members with central AC or a heat pump earn bill credits for letting an eligible smart thermostat take part in summer demand events. Source
  • Power Ahead Colorado: $1,500 off a new ENERGY STAR cold-climate heat pump (ducted or ductless) in an existing home. Needs pre-approval through a Power Ahead-badged contractor before work starts; stacks with utility and state incentives. Source
  • Colorado heat pump tax credit: $1,000 for air-source systems in 2026, claimed by a registered contractor who must pass at least a third to you as an invoice discount.

More Hytek services in Castle Rock

Castle Rock neighborhoods we serve

The Meadows, Crystal Valley Ranch, Castlewood Ranch, Terrain, Plum Creek, Red Hawk, Founders Village — ZIP 80104, 80108, 80109

Furnace Replacement near Castle Rock

Furnace Replacement in Castle Rock: common questions

How much does furnace replacement cost in Castle Rock?

Our published range is $3,500 – $8,500 installed. Every Hytek job is quoted flat-rate and approved before work begins, so the price you agree to is the price you pay. Replacements get free in-home estimates; see the full HVAC cost guide for the other services.

Do I need a permit for HVAC work in Castle Rock?

Repairs generally do not. Replacing or installing a furnace, AC, heat pump or water heater does. Permits for Castle Rock addresses go through Town of Castle Rock Building Division. Contractors must register with the Town before doing any work, backed by an ICC-comparable license from a testing municipality; unregistered contractors cannot pull permits. We pull the permit and schedule the inspection.

What HVAC rebates are available in Castle Rock in 2026?

For heat pumps: no Xcel electric rebate, because CORE Electric offers thermostat credits rather than a heat pump rebate; the $1,500 Power Ahead Colorado rebate (pre-approval required); Colorado’s $1,000 air-source heat pump credit, at least a third of which the installer must pass to you as a line-item discount. Black Hills gas customers get $260–$375 on a new 90%+ furnace. Xcel’s gas furnace rebates ended Jan. 1, 2026, and the federal 25C credit does not apply to 2026 installs.

How long do furnaces last in Castle Rock?

Typically 15–20 years here. With a median home built in 2007, many Castle Rock houses are on their second or third furnace. Age alone is not a reason to replace; a cracked heat exchanger, repeated repairs over about $1,000, or a unit under 80% AFUE is.

Who provides gas and electricity in Castle Rock?

Electric: CORE Electric Cooperative. Gas: Black Hills Energy. That matters because rebates, operating costs and who you call about a gas leak all depend on the utility.

Does Hytek serve my part of Castle Rock?

Yes. We serve all of Castle Rock (ZIP 80104, 80108, 80109), including The Meadows, Crystal Valley Ranch, Castlewood Ranch, Terrain, Plum Creek. Call (303) 627-3395 or request service online.

Local data: U.S. Census Bureau (2025 population estimates; ACS 2020–2024 housing age), NOAA 1991–2020 climate normals, and city, county and utility program pages, checked September 2026. Rebates change; we confirm eligibility on your address when we quote.

Castle Rock, CO

Need furnace replacement in Castle Rock?

Flat-rate pricing, approved before work starts. Family-owned in Centennial since 2004.

Call (303) 627-3395
Or schedule online →

$100 furnace tune-up & safety checkup in Castle Rock

Before the first cold snap: our 20-point furnace checkup covers the heat exchanger, gas pressure, carbon monoxide output, igniter, flame sensor and filter, with a written report. Flat-rate, 60 to 90 minutes.

Book a furnace tune-upCall (303) 627-3395

More furnace help in Castle Rock: furnace repair in Castle Rock · furnace maintenance in Castle Rock · all furnace repair services.

$88 Furnace
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