Furnace Repair in Castle Rock

Manufacturers require furnace input to drop about 4 percent per 1,000 feet once a unit is installed above 2,000 feet, and they specify a different pressure switch above 4,000 feet. Here that comes to roughly a 25 percent derate from the nameplate. When a replacement furnace from a big-box store or an out-of-area installer was never converted, it overfires, which can overheat the heat exchanger, trip high limits, and produce carbon monoxide. Checking that setup is part of every furnace call we run in town.

We test for carbon monoxide and run a combustion safety check before anything else. Then we pull fault codes, measure gas pressure and temperature rise, check flame quality and the flame sensor signal, and inspect the venting, filter, blower and condensate system. You get the diagnosis and a flat-rate repair price up front, the diagnostic is free if you approve the repair, and there are no overtime charges for nights or weekends.

Our trucks are stocked with the parts that fail most on Trane, Lennox, Carrier, Goodman, Bryant and Rheem furnaces, which covers most of what is installed across Douglas County.

For homes inside town limits, permits and inspections run through the Town of Castle Rock Building Division, which takes applications, payments and inspection requests on its eTRAKiT portal. Many addresses with a Castle Rock mailing address are actually unincorporated county land, and those go to the Douglas County Building Division. We check which jurisdiction your parcel is in before pulling a permit.

Natural gas in most of town comes from Black Hills Energy. Its 2026 Colorado residential program offers rebates on furnaces rated at least 90 percent AFUE and on qualifying smart thermostats, for equipment installed between January 1 and December 31, 2026, with applications due January 31, 2027. We itemize the make, model and serial number on the invoice the way the application requires.

As a rule of thumb, we recommend repair when the heat exchanger is sound and the furnace is under about 15 years old, and we discuss replacement when a 1990s unit needs a board or inducer for the second time, or when the heat exchanger shows cracks.