Boulder HVAC ServicesBoulder HVAC ServicesFurnace replacement in Boulder generally runs $4,000–$9,500 installed, with most homes near $5,500–$7,500. Guardian HVAC handles sizing, removal, and permitting for the homeowner. Boulder's altitude affects combustion tuning, so proper local sizing matters.
| Furnace type / size | Typical installed cost range |
|---|---|
| 80% AFUE, 60,000–80,000 BTU (small home) | $4,000–$5,800 |
| 80% AFUE, 90,000–120,000 BTU (larger home) | $5,000–$6,800 |
| 95%+ AFUE high-efficiency, 60,000–80,000 BTU | $6,000–$8,000 |
| 95%+ AFUE high-efficiency, 90,000–120,000 BTU | $7,000–$9,500 |
| Add: new PVC venting / gas line update | $500–$1,800 |
| Add: ductwork modification | $800–$2,500 |
Boulder furnace replacement cost ranges by type and size
The two biggest cost factors in a furnace replacement are heating capacity and efficiency rating. Standard 80% AFUE furnaces cost less upfront and run $4,000–$6,800 installed in most Boulder homes. High-efficiency 95%+ AFUE condensing furnaces cost $6,000–$9,500 installed but use less gas. Larger homes need higher BTU output, which raises equipment cost. Proper load sizing prevents an oversized unit that short-cycles and wastes fuel.
A furnace replacement quote covers more than the equipment. Old-unit removal, new thermostat wiring, and gas line connection are standard parts of the job. Switching from an 80% to a 95%+ furnace usually requires new PVC sidewall venting, adding $500–$1,800. Boulder requires a mechanical permit for furnace replacement, and the contractor typically handles that filing. These items explain why total installed cost sits well above the equipment sticker price alone.
Homes with undersized or leaky ducts may need modification during a furnace replacement, adding $800–$2,500. Older Boulder homes sometimes need updated returns to match a new furnace's airflow. Electrical upgrades for a variable-speed blower or a new condensate pump can add cost. A free on-site visit confirms whether these are needed. The minimum service charge is $150, and exact figures depend on what the installer finds at the home.
Boulder's elevation near 5,400 feet reduces air density, so gas furnaces are commonly derated and combustion is tuned for altitude — a step that separates a correct local install from a flatland spec. Older housing stock in Mapleton Hill, Whittier, and University Hill often has original chimney-vented furnaces, and converting to a high-efficiency condensing unit means adding PVC sidewall venting and a condensate drain, which raises cost. Boulder County requires a mechanical permit and inspection for furnace replacement. Xcel Energy rebates for qualifying high-efficiency gas furnaces can offset part of the cost — amounts vary by program year, so confirm current rebate levels before buying. Newer builds in Gunbarrel and Wonderland Hill typically have compatible venting already in place.
Most standard furnace replacements are completed in one day. Jobs involving new venting, ductwork changes, or a fuel-type switch may take a second day.
Replacing both together is often cost-effective because labor and system matching overlap, but it is not required if the AC is newer and working well.
Furnace size is set by a Manual J load calculation, not square footage alone. Most Boulder single-family homes fall between 60,000 and 120,000 BTU.
A 95%+ AFUE furnace costs more upfront but lowers gas use through cold Front Range winters and may qualify for Xcel rebates, making it worthwhile for many homeowners.
Yes. Boulder County requires a mechanical permit and inspection for furnace replacement, which a licensed installer typically files on the homeowner's behalf.