HVAC System Replacement Cost in San Marcos, Texas
Our 2026 estimate for full HVAC system replacement in San Marcos, TX is $8,800 to $19,200. That puts San Marcos 4% above the national average, mainly because of lower local labor costs and the larger cooling equipment local summers call for.
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San Marcos Weather and HVAC Load
NOAA's 1991-2020 climate normals put San Marcos at 1,620 heating degree days and 2,973 cooling degree days per year. Cooling carries most of the load, which is why compressors and condenser fan motors wear out faster here than in northern cities. A normal year brings 20 nights at or below freezing and 117 days over 90°F. For a 2,000 sq ft house, this climate points to a heating load somewhere near 35,000 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 | 1,620 |
|---|---|
| Cooling degree days / year | 2,973 |
| Nights at or below 32°F | 20 |
| Days above 90°F | 117 |
| Average low / high | 57.2°F / 80.1°F |
San Marcos Housing Stock
Census figures put the median build year in San Marcos at 1998, so a typical house here has about 28 years on it. Plenty of houses from this period still run original 1990s or early-2000s equipment, which is past its expected service life. About 8,400 households here own their home, 30.5% of the occupied total. The median home value is $269,700, and median household income is $51,030. We use both figures to adjust labor and pricing for this page.
Between 2020 and 2025, NOAA's Storm Events Database logged 15 hail days and 13 days with damaging thunderstorm winds in Hays County. 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.
When Replacement Makes Sense
- An old R-22 AC paired with an aging furnace
- Some rooms are uncomfortable, and the energy bills are high
- Both units keep needing repairs
What Moves the Price
- Thermostat and zoning upgrades
- Efficiency ratings: SEER2, AFUE and HSPF2
- Equipment sized to the house and climate
- Furnace plus AC, or heat pump plus air handler
- Duct repair or replacement
- Permits and electrical work
We raised the national figures about 4% for San Marcos using local income, home values and the equipment size this climate needs. Real bids can still come in outside the range, so collect three written quotes.
What the Quote Should Cover
- Duct connections and sealing
- Startup, testing and warranty registration
- New, matched heating and cooling equipment
- Removing the old equipment
- A load calculation and system design
Texas Permits, Efficiency Rules and Rebates
Texas is in the DOE's Southeast region, where new split central air conditioners need at least 14.3 SEER2 (13.8 SEER2 for systems of 45,000 BTU/h and up). Expect the contractor to pull a mechanical permit for a replacement job in San Marcos. If a bidder suggests skipping it, move on. Also ask for a Texas license or registration number and proof of insurance. 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.
- Ask for a duct leakage test. Leaky ducts can lose 20 to 30% of what the system puts out.
- Get one quote for a heat pump system and one for a furnace plus AC.
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HVAC System Replacement Questions from San Marcos Homeowners
How much is full HVAC system replacement in San Marcos?
Plan on $8,800 to $19,200, with most jobs near $14,500. 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 San Marcos?
Between late fall and early spring. With 117 days over 90°F, San Marcos contractors are booked solid all summer, and off-season jobs are easier to schedule and negotiate.
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.
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.
HVAC System Replacement Near San Marcos
- Kyle $10,200 to $22,300
- New Braunfels $10,000 to $21,700
- Cedar Park $12,000 to $26,000
- Harlingen $8,800 to $19,200
- Missouri City $10,400 to $22,600
- North Richland Hills $10,100 to $22,000
- Flower Mound $13,000 to $28,400
- Rowlett $10,600 to $23,000
Sources: U.S. Census Bureau ACS 5-year estimates 2019-2023 and 2024 population estimates; NOAA NCEI U.S. Climate Normals 1991-2020, station San Marcos; NOAA Storm Events Database 2020-2025, Hays County. Prices are our estimates, not contractor quotes. Updated 2026.