HVAC system installation is estimated from a Manual J load calculation that determines the required BTU/ton capacity. Equipment, refrigerant line sets, electrical, ductwork, and permit are all priced separately.
Simplified Load Estimate (rule of thumb only)
Tons = Conditioned sq ft ÷ 500 (mild climate) to ÷ 400 (hot/humid climate). Always confirm with Manual J.
Example
2,000 sq ft in hot-humid climate: 2,000 ÷ 400 = 5 tons. Manual J may yield 3.5 tons — always run the calculation.
Waste factor: 10% on refrigerant line set; 15% on ductwork
Never size HVAC equipment by square footage alone — an oversized unit short-cycles (poor humidity control, premature failure) and an undersized unit runs constantly (high bills, wears out fast). Manual J factors in insulation, window area, orientation, infiltration, and internal heat gains. Use software (ACCA Manual J, Wrightsoft, or equivalent). This is non-negotiable on new installs.
Match the calculated BTU capacity with equipment. Price the condenser, air handler, and coil separately — they may come from different suppliers. Equipment markup: 25–35% over cost. A 3-ton 16 SEER2 split system: $2,200–$3,500 at markup depending on brand and efficiency tier.
Measure the distance from condenser to air handler (line set length). Standard copper line sets: 3/8 suction + 5/8 liquid for 3-ton, 3/8 + 3/4 for 4–5 ton. Price at cost + 20%. Pre-charged line sets are faster to install but more expensive. Long runs (over 50 ft) may require additional refrigerant.
Existing ductwork: inspect for leaks, size, and condition. Poorly sealed ducts waste 20–30% of conditioned air. Duct sealing: $800–$2,500. Full duct replacement: $3,000–$8,000 for a typical home. New construction ductwork: $1,500–$4,000 depending on home size and complexity. Never bundle ductwork into the equipment price.
Disconnect: $125–$200 installed. Electrical whip from disconnect to condenser: $75–$150. Control wiring (thermostat wire): $0.50–$1.00/LF. Permit: $150–$450. Utility interconnection (if applicable): coordinate in advance.
Run Manual J before every equipment selection — not after
Sizing first, then selecting equipment is the only defensible approach. An oversized unit installed without Manual J documentation is an unreported liability if the homeowner later experiences comfort or humidity issues.
Inspect ductwork on every replacement job
50% of replacement jobs have ductwork with significant leakage. Duct sealing adds $800–$2,500 to a job but often reduces energy bills by 20–30%. Present it as an option — most homeowners accept it when shown the numbers.
Offer a one-year service agreement with every installation
A $150–$250 first-year service agreement covers two tune-ups and provides a reason to return. Clients on annual service agreements have 3× the lifetime revenue of one-time installation customers.
A 3-ton, 16 SEER2 split system installed in an existing home runs $5,500–$9,500 in 2026, including equipment, line set, electrical, permit, and one-year service agreement. Variable-speed units (higher efficiency) add $1,500–$3,000. The range is driven by ductwork condition, accessibility, and market.
New construction ductwork is estimated by the ton of equipment plus linear footage of main trunk and branch runs. A 2,000 sq ft home with a 3-ton system typically has 150–250 LF of duct. Rule of thumb: $500–$800 per ton for basic sheet metal ductwork in new construction. Flex duct is $100–$200 per ton cheaper but performs worse.
Variable-speed/inverter-driven systems maintain precise temperature and humidity control, operate more quietly, and use 20–40% less energy than single-stage systems. They cost $1,500–$3,000 more than standard equipment. Recommend them when: the client prioritizes comfort and efficiency, the home has high cooling loads, or ductwork is oversized for a single-stage unit.
Best practice says yes — always. Many homeowners have existing systems that were oversized from the original install, and simply replacing with the same tonnage perpetuates the problem. A Manual J takes 30–60 minutes and costs nothing if you use software. It protects you from a callback when the client complains the new system doesn't dehumidify.
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