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Calculator Methodology

How the HVAC Load Estimate Planner estimate works

Use this to challenge tonnage-by-square-foot and identify whether the problem is load, ducts, zoning, or comfort distribution.

This estimate is for planning. Actual results may change based on local pricing, contracts, title practice, lender disclosures, insurance documents, inspection findings, hidden conditions, timing, and professional review.

Use the calculator Build decision packet

Inputs used

Defaults are planning placeholders, not recommendations.

Conditioned square feet
Default: 2200 sq ft
Typical ceiling height
Default: 8 ft
Climate pressure
Default: hot-humid
Insulation and air sealing
Default: average
Window and glass load
Default: average
Sun exposure
Default: average
Duct and return-air condition
Default: unknown
Bad ducts can make the old tonnage look wrong even when the real problem is airflow.
Current equipment size, if known
Default: 4 tons
Rooms with comfort complaints
Default: 2
Likely project path
Default: central

What is included

  • The visible inputs listed on the calculator page.
  • The assumptions shown below the calculator.
  • A planning estimate based on the calculator family, not a binding quote, contract, appraisal, insurance settlement, title statement, or lender disclosure.
  • Input: Conditioned square feet.
  • Input: Typical ceiling height.
  • Input: Climate pressure.
  • Input: Insulation and air sealing.
  • Input: Window and glass load.
  • Input: Sun exposure.
  • Input: Duct and return-air condition.
  • Input: Current equipment size, if known.
  • Input: Rooms with comfort complaints.
  • Input: Likely project path.

What is excluded

  • Final contractor pricing, local permit interpretation, lender underwriting, title-company settlement, insurance claim approval, tax advice, legal advice, or property-specific professional judgment.
  • Every local custom, contract term, hidden condition, inspection finding, market shift, and timing issue.
  • Guaranteed savings, resale value, coverage, approval, or final cash due.
  • Full Manual J design, in-person HVAC diagnosis, roof inspection, structural inspection, code inspection, or contractor warranty review.

What can make the estimate too low

  • Hidden damage, access difficulty, permit/code requirements, disposal, electrical, gas, duct, decking, flashing, ventilation, or warranty scope is not included.
  • The quote is a low base price with change orders likely.
  • Emergency timing reduces quote leverage.

What can make the estimate too high

  • A narrower repair, partial replacement, roof-over, owner-supplied material path, rebate, or scope trim is safe and documented.
  • Access is easier, hidden conditions are absent, or the project is bundled efficiently.
  • A second quote proves the first quote included unnecessary scope.

Assumptions

  • Uses rough capacity pressure, not Manual J design.
  • A contractor should still perform a proper load calculation before equipment is selected.
  • Comfort complaints can be duct, return-air, solar-gain, humidity, or zoning problems rather than tonnage problems.

When to verify before acting

  • Before signing a contractor quote, purchase contract, listing agreement, loan document, title document, insurance claim document, or association document.
  • When a result depends on local custom, contract language, code, warranty, hidden conditions, eligibility, or professional judgment.
  • When the result changes whether you repair, replace, sell, buy, claim, finance, or walk away.