HVAC System Replacement Cost in Great Falls, Montana
Full HVAC system replacement in Great Falls runs about $15,600 for a typical job. Basic installs start near $9,500. High-efficiency equipment with duct or electrical work can reach $20,600.
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Great Falls Weather and HVAC Load
Great Falls logs 6,942 heating degree days and 421 cooling degree days in a normal year, based on the closest NOAA weather station. Heating is the bigger job here, and furnaces and heat pumps in Great Falls put in far more hours than the air conditioner. Count on roughly 143 nights below 32°F and 25 afternoons past 90°F in a typical year. Snowfall averages about 66 inches. For a 2,000 sq ft house, this climate points to a heating load somewhere near 70,000 BTU/h. Treat that as a starting number. A Manual J calculation will move it up or down based on insulation and windows.
| Heating degree days / year | 6,942 |
|---|---|
| Cooling degree days / year | 421 |
| Nights at or below 32°F | 143 |
| Days above 90°F | 25 |
| Average low / high | 35.1°F / 59°F |
Great Falls Housing Stock
Census figures put the median build year in Great Falls at 1965, so a typical house here has about 61 years on it. A lot of these homes are on their second or third system by now. The ductwork is usually original, and leaky joints are common. Great Falls has roughly 18,000 owner-occupied homes, or 68.4% of households. The median home value is $237,400, and median household income is $63,934. We use both figures to adjust labor and pricing for this page.
NOAA storm reports for Cascade County show 12 hail days and 22 days with damaging thunderstorm winds over the six years from 2020 to 2025. The largest hail reported was 3 inches across. Hail flattens the thin aluminum fins on condenser coils and cuts airflow. After a big storm, take a look at the outdoor unit; homeowners insurance often covers the damage. In Great Falls, 20% of residents are 65 or older. For older adults, a house with no heat in January or no AC during a heat wave is a medical risk. Mention it when you call, since many companies put those calls first.
When Replacement Makes Sense
- Some rooms are uncomfortable, and the energy bills are high
- An old R-22 AC paired with an aging furnace
- Both the heating and cooling equipment are 15 years old or more
What Moves the Price
- Efficiency ratings: SEER2, AFUE and HSPF2
- Permits and electrical work
- Duct repair or replacement
- Thermostat and zoning upgrades
- Furnace plus AC, or heat pump plus air handler
- Equipment sized to the house and climate
For Great Falls we raised the national figures about 12%, based on local income, home values and climate-based equipment sizing. Get at least three written quotes; real bids can land outside this range.
What the Quote Should Cover
- Startup, testing and warranty registration
- A load calculation and system design
- New, matched heating and cooling equipment
- Removing the old equipment
- Duct connections and sealing
Montana Permits, Efficiency Rules and Rebates
Montana falls in the DOE's North region. New split central air conditioners must meet at least 13.4 SEER2, and heat pumps sold anywhere in the U.S. need 14.3 SEER2 and 7.5 HSPF2. Equipment replacements in Great Falls generally need a mechanical permit, and a reputable contractor will pull it for you. Ask for their Montana license or registration number and a certificate of insurance with the quote. The federal 25C tax credit ended for equipment installed after December 31, 2025, so incentives now come mostly from utilities and state programs. Check your electric and gas utility's rebate page before you pick equipment.
Before You Hire
- Replacing both pieces at once usually costs less than two separate jobs a few years apart.
- Make every bidder quote the same efficiency ratings, or the prices won't compare.
- Ask for a duct leakage test. Leaky ducts can lose 20 to 30% of what the system puts out.
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HVAC System Replacement Questions from Great Falls Homeowners
How much is full HVAC system replacement in Great Falls?
Plan on $9,500 to $20,600, with most jobs near $15,600. Equipment efficiency, house size and the condition of the ducts and wiring decide where your quote falls.
When is the best time to schedule full HVAC system replacement in Great Falls?
Between late spring and early fall. Great Falls averages 143 freezing nights a year, and heating calls spike from November through February.
How often should an HVAC system be replaced?
Most systems get replaced every 15 to 20 years. AC units and heat pumps usually wear out before gas furnaces do.
Can I replace only the AC and keep my furnace?
Yes, as long as the indoor coil and blower work with the new AC. A mismatched system loses efficiency and can void the warranty.
HVAC System Replacement Near Great Falls
Sources: U.S. Census Bureau ACS 5-year estimates 2019-2023 and 2024 population estimates; NOAA NCEI U.S. Climate Normals 1991-2020, station Great Falls 16st; NOAA Storm Events Database 2020-2025, Cascade County. Prices are our estimates, not contractor quotes. Updated 2026.