Sources and independence
We prefer current US government data, standards organizations, manufacturer pricing guides, and consumer project datasets that explain where their numbers came from. A single national average is never treated as a contractor price. We compare multiple references and disclose when they measure different project scopes.
Sources do not pay for inclusion. The site currently has no affiliate relationships, contractor lead forms, sponsored rankings, or manufacturer placements.
Current replacement-cost model
Model 2026.09-v2 builds low, central, and high totals from separate project components:
- Choose a system-specific equipment baseline and a discrete capacity price class.
- Apply the selected efficiency package to equipment only.
- Adjust installation labor using state HVAC wage data and the selected access condition.
- Add standard materials, removal, permit, project scope, ductwork, and selected extras as visible components.
Each component has its own uncertainty. Equipment uses a different band from labor, permits, ductwork, and conversions. The calculator adds the component lows, central values, and highs separately. Every output is rounded to the nearest $50 because more precision would imply knowledge the model does not have.
State labor adjustment
The location adjustment uses the May 2025 median wage for heating, air conditioning, and refrigeration mechanics and installers, occupation 49-9021, divided by the national median of $61,010. The factor changes installation labor only. It does not multiply equipment, materials, ducts, or the full project.
BLS occupational wages are not contractor billing rates. They provide a consistent state index for relative labor costs. Contractor overhead, demand, insurance, travel, and local permitting can still move a quote beyond the calculated range.
Why floor area is not an equipment size
If the user knows the current tonnage or furnace input rating, the model uses it only as a price class. Otherwise, conditioned floor area maps to a broad, discrete class. Nearby floor-area values inside the same class produce the same equipment estimate. ENERGY STAR recommends that contractors use the home's actual construction and a Manual J load calculation rather than a square-foot rule of thumb. The result never claims to recommend tonnage or BTU capacity.
Homes with more than 4,000 square feet per central system fall outside the supported model. The calculator asks for the number of systems instead of pretending that one unit scales indefinitely. Ductless systems use indoor-zone count as their primary price input.
Confidence rating
Confidence describes how much project-specific information the model received. Selecting a state and supplying known equipment capacity improves it. Unknown capacity, conversions, full duct replacement, difficult access, and unusually large service areas reduce it. Confidence does not measure contractor quality or guarantee that the range contains every local quote.
What the model cannot inspect
A browser cannot inspect duct leakage, electrical capacity, refrigerant piping, combustion venting, equipment access, code compliance, hazardous materials, or the quality of the existing installation. Those conditions can change the real price substantially. The result is not a bid, appraisal, engineering calculation, or equipment specification.
Testing and review
Calculation code is separate from interface code. Automated tests check input limits, component totals, capacity steps, state labor isolation, efficiency adjustments, multi-zone pricing, quote comparison, and benchmark guardrails for common standard systems. We review cost references at least twice a year and sooner when equipment rules or the market change.
Corrections
When a source changes or an assumption proves stale, we update the calculation module, add or change a regression test, update the visible review date, and record the change in version control. To report a source or calculation problem, open a public correction issue. Do not include private information in an issue.
Guide publishing policy
Editorial guides answer a different question from calculator pages. They explain project scope, efficiency, equipment choices, or sizing and then link readers to the relevant model or technical source. We do not create near-duplicate city pages, publish generated claims without review, or use a keyword-density target. Start with the HVAC planning guide library.