HVAC gets quoted as one number — "$9,000 for the system" — more than almost any other trade, and that number hides more variation than it reveals. A furnace swap, a heat pump conversion, and a ductless retrofit are three different jobs with three different cost drivers. Here's what's actually in the price.
Pricing by system
- Central AC replacement (condenser + coil, existing ductwork reused) — $4,500–$8,500 installed for a 2.5–4 ton system. The most common single-system swap, and the cheapest of the full-replacement categories since the furnace and ducts stay untouched.
- Gas furnace replacement — $3,800–$7,500 installed, depending on AFUE rating (80% standard-efficiency vs. 95–98% high-efficiency condensing) and BTU size. High-efficiency units need a condensate drain and often a new PVC intake/exhaust run, which adds labor even before the unit cost.
- Combo furnace + AC replacement (same footprint, same ductwork) — $8,500–$15,000. Priced as one job rather than two because the coil and furnace are matched and installed together — quoting them separately usually undercounts shared labor.
- Air-source heat pump replacement (heating + cooling in one system) — $7,000–$16,000, with the range driven almost entirely by SEER2/HSPF2 tier. Cold-climate heat pumps rated to perform below 5°F sit at the top of that range.
- Ductless mini-split, single zone — $3,500–$6,500 installed. Multi-zone systems run $9,000–$18,000+ for 3–4 indoor heads on one outdoor condenser — common in additions, converted attics, or homes without existing ductwork.
- Ductwork replacement or major modification — $40–$65 per linear foot, or $6,000–$14,000 for a whole-house redo. Usually its own line item, not bundled into equipment pricing, since the scope depends entirely on what's already there.
For a typical single-family home doing a straight furnace-and-AC swap with usable existing ductwork, that lands around $9,000–$13,000 — the number most homeowners are actually comparing when they call three contractors.
What drives the price within a category
Tonnage and load calculation. Equipment gets sized by a Manual J load calculation — square footage, insulation, window count and orientation, climate zone. A contractor who quotes off the old unit's size without running the numbers is guessing, and an oversized system short-cycles (poor dehumidification, uneven temps) while an undersized one runs constantly and still can't keep up on the hottest or coldest days. This is a five-minute calculation that belongs in the estimate, not an assumption.
SEER2/HSPF2 efficiency tier. Since the 2023 testing standard change, efficiency ratings run a few points lower than the old SEER numbers for the same physical equipment — worth explaining to a client comparing a new quote against an old one and wondering why the "SEER 16" system now shows as SEER2 15.2. Every tier up in efficiency adds equipment cost that pays back through lower utility bills over years, not months — a legitimate upsell conversation, not padding, as long as the payback math is shown rather than asserted.
Refrigerant transition. The industry moved from R-410A to the lower-GWP R-454B (an A2L, mildly flammable refrigerant) starting with 2025-model equipment. New systems use new refrigerant, new line-set requirements in some cases, and technician handling procedures that didn't exist two years ago. If a job is replacing only the condenser and reusing an old R-410A line set and coil, flag it explicitly — mismatched refrigerant across old and new components is a callback waiting to happen, and full line-set replacement adds $500–$1,500 depending on run length and accessibility.
Ductwork condition. Undersized returns, leaky joints, or ducts sized for a different-tonnage system than what's being installed will bottleneck a brand-new unit's performance. A contractor who inspects the ducts before quoting, rather than after installing, is the one who doesn't end up eating a return trip. Duct sealing alone runs $500–$2,000; resizing or replacing runs is priced under the ductwork category above.
Electrical requirements. Heat pumps and some high-efficiency furnaces need a dedicated circuit, and older panels sometimes don't have room for it — a $150–$400 whip and disconnect on an easy job, or a panel subpanel/upgrade conversation on a harder one (see panel upgrade pricing separately if that's in play).
The line items people miss
- Manual J load calculation — sometimes bundled into the estimate, sometimes billed separately ($100–$300). Either way, confirm it happened; it's the basis for every sizing decision after it.
- Permits and inspection — nearly universal for HVAC replacement, $100–$500 depending on jurisdiction, and required before a utility or inspector will sign off on gas or high-voltage connections.
- Old equipment removal and EPA-compliant refrigerant recovery — refrigerant can't legally be vented; recovery and disposal of the old unit is a real cost, not a freebie, typically $150–$400.
- Condensate drain/pump — required on high-efficiency furnaces and most AC coils; easy to leave off a quick verbal quote and then charge as an add-on.
- Startup and commissioning — refrigerant charge verification, airflow measurement, thermostat setup. Skipping this is how a system runs at 80% of rated efficiency for its entire life without anyone noticing.
- Thermostat and zoning — a smart thermostat is often assumed included by the client and assumed extra by the contractor; state it either way rather than letting the assumption surface as a dispute at final walkthrough.
DIY vs. hire
This isn't a DIY category for the core equipment. Refrigerant handling requires EPA Section 608 certification by federal law, gas furnace work involves combustion and carbon monoxide risk, and heat pump/AC circuits are high-voltage. The DIY-adjacent decision that does come up is a straight like-for-like thermostat swap or filter/maintenance work — real, but it doesn't touch the replacement scope priced above.
Structuring the estimate
An HVAC estimate holds together in four pieces: equipment (furnace, condenser, coil, or heat pump unit, priced by tonnage and efficiency tier), labor (removal, install, electrical and gas connections, priced as a job rather than itemized hours since crews work as a unit), ductwork (kept as its own line whenever sealing, resizing, or replacement is in scope, since it's the part most likely to be skipped in a lowball quote), and a miscellaneous section for permits, load calc, refrigerant recovery, and commissioning — the items that don't disappear just because they're easy to forget.
JobPencil's builder supports this structure directly — materials and labor broken out, a miscellaneous section for permits and commissioning, and margins applied transparently across the whole estimate. Build an HVAC estimate free, no account required until you save it.