Worked example: 2,000 sq ft, AC + furnace changeout
Sizing gives 4 tons. At $1,900/ton standard efficiency, the AC side is $7,600; the furnace adds $3,500, landing at $11,100 with sound existing ducts. That's the national mid-market: real quotes from $9,500 to $13,500 are all normal depending on brand (same compressor, different badge — most brands are made by a handful of OEMs). A heat pump doing the same job prices ~$13,600 but nets ~$11,600 after the federal credit.
- • Oversizing is the most common expensive mistake: a 5-ton unit on a 4-ton house short-cycles, never dehumidifies, and dies early.
- • The install quality matters more than the brand — refrigerant charge and airflow setup determine real-world efficiency.
- • Get the AHRI-matched system certificate: mismatched coil and condenser void efficiency ratings and some warranties.
Repair vs replace: the $5,000 rule
Multiply the system's age by the repair cost. Over $5,000, replace — a $600 repair on a 14-year-old AC (=$8,400) is throwing money at a compressor that's statistically near end of life. Under $5,000, repair. R-410A refrigerant phase-down has made refrigerant-related repairs on pre-2023 systems notably more expensive, tilting more decisions toward replacement.
FAQ
How much does a new HVAC system cost in 2026?
A full AC + gas furnace replacement runs $8,000–$12,000 for an average home; heat pump systems $9,000–$15,000 before the federal tax credit of up to $2,000. AC-only changeouts run $4,000–$8,000.
What size AC do I need for 2,000 square feet?
The rule of thumb is 4 tons (1 ton per 500 sq ft), but insulation, window area, ceiling height, and climate zone shift it — a Manual J load calculation is the only correct answer.
How long does an HVAC system last?
AC and heat pumps: 12–17 years. Gas furnaces: 15–20. Maintenance is the single biggest lifespan variable — dirty coils and low refrigerant kill compressors early.
Is a heat pump cheaper to run than a furnace?
In moderate climates, yes — modern heat pumps deliver 2–3× the heat per unit of electricity. In severe cold climates, dual-fuel (heat pump + furnace backup) is the sweet spot.
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