Estimate AC, furnace, heat-pump, mini-split, combo, or boiler replacement by tonnage, efficiency tier, duct replacement %, line-set length, and zone count. 2026 data; not a contractor bid.
| Item | Quantity | Estimated range |
|---|
Got an HVAC quote? Compare it to the planning range.
What this is: a planning-range HVAC calculator informed by Carrier / Trane / Lennox / Mitsubishi / Daikin / Rheem manufacturer pricing, HomeGuide, HomeAdvisor, Homewyse, and licensed cost-estimating references.
Sizing: equipment material scales with tonnage / 3 (3-ton reference) and an efficiency-tier multiplier (basic 1.00, mid 1.25, high 1.65). Mini-splits scale with zone count rather than tonnage. Refrigerant line-set scales per LF; ducts scale per percent replaced.
Labor is modeled from per-unit installed rates with a crew-rate sanity check ($80-$140/crew-hr loaded billing rate), informed by BLS OEWS 49-9021 (HVAC Mechanics).
Section 25C credit: applied to qualifying high-efficiency heat pumps, central AC, and furnaces placed in service on or before December 31, 2025. Projects placed in service in 2026 generally do not qualify under current IRS guidance (One Big Beautiful Bill Act, July 2025). Verify on IRS Form 5695 before relying on it; state and utility rebates may still apply.
Last updated: May 2026. Full methodology →
| Configuration | Range | Timeline |
|---|---|---|
| 3-ton AC + furnace combo (mid, existing ducts) | $5,500-$11,500 | 1-2 days |
| 3-ton AC only replacement | $3,500-$8,000 | 1 day |
| Furnace-only replacement (80k BTU) | $3,500-$7,500 | 1 day |
| 4-ton high-efficiency heat pump | $9,000-$18,000 | 1-2 days |
| 3-zone ductless mini-split | $9,000-$16,000 | 2-3 days |
| Add-on: 100% duct replacement | +$3,000-$8,000 | +1-2 days |
| Add-on: 200A panel upgrade | +$1,500-$3,500 | +1 day |
Tonnage — cooling capacity, where 1 ton = 12,000 BTU/hr — is the first driver of cost. The planning rule of thumb is 1 ton per 600 sq ft in mild climates and 1 ton per 400–500 sq ft in hot or humid ones:
| Home size | Mild climate | Hot / humid climate |
|---|---|---|
| 1,000 – 1,200 sq ft | 2 ton | 2.5 – 3 ton |
| 1,500 – 1,800 sq ft | 2.5 – 3 ton | 3.5 – 4 ton |
| 2,000 – 2,400 sq ft | 3.5 – 4 ton | 4.5 – 5 ton |
| 2,500 – 3,000 sq ft | 4 – 5 ton | 5+ ton / two systems |
The rule of thumb is for budgeting only. Insulation, windows, ceiling height, and duct condition swing the real load — which is why a proper Manual J load calculation should anchor any quote. An oversized system short-cycles, dehumidifies poorly, and wears out early; it is the most common and most expensive sizing mistake.
The configuration table above shows the trade: a mid-tier 3-ton AC + gas furnace combo runs $5,500–$11,500 installed, while a 4-ton high-efficiency heat pump runs $9,000–$18,000. The heat pump replaces both machines — it heats and cools with one outdoor unit — and modern cold-climate models hold capacity well below freezing, which made them viable far north of their old territory.
The operating-cost math hinges on local utility prices: where electricity is cheap relative to natural gas, heat pumps win clearly; where gas is cheap, a high-AFUE furnace can still be the lower-bill choice for heating-dominated climates. Note that the federal 25C credit that subsidized high-efficiency heat pumps applied to equipment placed in service on or before December 31, 2025 — 2026 installs generally do not qualify, though state and utility rebate programs (Mass Save, NYSERDA, TECH Clean California) continue independently.
A practical middle path when a working furnace is staying: pair a heat-pump-capable condenser with the existing furnace as a dual-fuel system, letting the heat pump carry mild weather and the furnace take the coldest hours.
Equipment gets the brochure, but duct condition decides whether you feel the upgrade. Leaky, crushed, or undersized ducts waste a meaningful share of every conditioned air dollar and starve far rooms regardless of how efficient the new unit is. Full duct replacement adds $3,000–$8,000 and one to two days (per the configuration table above); sealing and re-balancing an intact system costs far less.
Before signing a replacement quote, ask for a static-pressure reading and a duct-leakage estimate. A contractor who tests is bidding your house; one who doesn't is bidding a brochure.
3-ton AC + furnace combo (mid efficiency, existing ducts): $5,500-$11,500 installed. 4-ton high-efficiency heat pump: $9,000-$18,000+ (the federal Section 25C credit applied only to systems placed in service on or before December 31, 2025). 3-zone ductless mini-split: $9,000-$16,000. Tonnage, SEER2/AFUE/HSPF efficiency tier, and duct replacement % drive the spread.
Rule of thumb: 1 ton per 600 sf in mild climates, 1 ton per 400-500 sf in hot/humid climates. A 1500-1800 sf home typically needs 3 tons. Manual J load calculation is the proper way — your contractor should run one for any new install.
High-efficiency heat pumps and central AC units qualified for the federal Section 25C Energy Efficient Home Improvement credit for property placed in service on or before December 31, 2025. Projects placed in service in 2026 generally do not qualify under current IRS guidance — verify on IRS Form 5695 before relying on it. State and utility rebates (Mass Save, NYSERDA, TECH Clean California) may still apply — check program-specific equipment lists.
Basic: 14-15 SEER2 / 80 AFUE / 8 HSPF. Mid: 16-17 / 90 / 9. High: 18+ / 95+ / 10+ — the Section 25C credit applied through December 31, 2025; 2026 installs generally do not qualify.
Federal Section 25C applied to qualifying systems placed in service on or before December 31, 2025; projects placed in service in 2026 generally do not qualify under current IRS guidance. Verify on IRS Form 5695. State and utility rebates may still apply.
Refrigerant work requires EPA Section 608 cert. Only DIY-realistic option is mini-split kits with pre-charged line-sets. Everything else is pro work.
A 2,000 sq ft home typically needs 3.5-4 tons of capacity. Plan on the upper half of the 3-ton combo range - roughly $7,000-$11,500 for a mid-tier AC + furnace with existing ducts - or $9,000-$18,000 for a 4-ton high-efficiency heat pump. Duct replacement, if needed, adds $3,000-$8,000.
If both are past about 10 years, usually yes: the blower in the furnace drives the AC airflow, matched coils and air handlers perform as rated, you pay one mobilization instead of two, and a single-system warranty avoids finger-pointing between vintages. Replacing only the failed half of an old pair often costs more over the following five years.
Planning figures: gas furnaces 15-20 years, central AC 12-15, heat pumps 10-15 (they run year-round), mini-splits 15-20. Coastal salt air and poor maintenance shorten everything; annual service and clean filters stretch it.
