Load calculations, equipment sizing, and refrigerant pricing. Choose a project type below for a complete step-by-step guide with formulas, waste factors, productivity benchmarks, and pro tips.
HVAC pricing centers on system-level flat rates for replacements and new installs (per ton of cooling capacity, per BTU for heating) plus per-fixture work for ductwork, vents, and mini-split heads. Equipment sizing is non-negotiable: Manual J load calculation is the residential standard, and oversizing is more common — and more damaging — than undersizing. An oversized AC short-cycles, doesn't dehumidify, and wears out faster; the customer thinks they got more capacity but actually got worse comfort. A properly sized 3-ton system costs less than a 4-ton one and performs better. Ductwork is its own pricing layer: per linear foot of trunk and per branch, with returns and supply pricing differently because returns are larger and harder to route. Modifying existing duct is usually more expensive than new duct because of demolition and re-tying. Refrigerant cost is a 2026 sensitivity — R-410A is being phased down, R-454B is the current standard for new equipment, and pricing on either has been volatile. Always quote refrigerant by weight at current market plus a margin, not at last year's rate. Service work uses flat-rate books that pre-price common repairs. Permits and inspections are 1–3 hours of non-billable time per job. The trade is distinct from electricians (who handle the circuit feeding the unit but not the refrigerant lines) and plumbers (who don't touch refrigerant, full stop — that requires EPA 608 certification).
Manual J load calc is the right answer. Rule-of-thumb sizing by sq ft is fast but routinely oversizes by 20–40%, hurting performance and pricing.
New trunk and branches in a clean attic is fast. Modifying existing duct in finished spaces with returns scattered everywhere is the expensive case.
R-454B is the new standard; R-410A is phasing out. Price refrigerant by weight at current market — not at last year's rate.
Charging refrigerant requires EPA 608 certification. If only one tech on the truck has it, that constrains scheduling and cost.
1 ton per 600 sq ft is a starting point, not an answer. Run Manual J or a software equivalent. Oversizing causes comfort and warranty issues.
Cutting in new returns through finished ceilings is hours of work plus drywall patching by another trade. Price modifications honestly.
Most jurisdictions require an HVAC permit for equipment changes. Pulling, scheduling, and meeting inspection is paid labor — quote it.