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Calculator Methodology

How the HVAC Diagnosis Live Matrix estimate works

A dead AC, heater problem, weak heat, or furnace lockout is not automatically a system replacement. Start with what the homeowner saw, then make the quote show evidence.

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.

What you see at home
Default: cooling-dead
Thermostat call
Default: calls-cool
Indoor blower behavior
Default: runs
Outdoor unit behavior, if cooling or heat pump
Default: hums-no-fan
Gas furnace pattern
Default: na
Electric heat / sequencer pattern
Default: na
Breaker status
Default: not-tripped
Drain float switch / water safety
Default: unknown
A clogged condensate drain can shut the system off before anything expensive is broken.
Technician quoted a control board
Default: false
Board replacement can be real, but it should not be the first guess before power, thermostat, safeties, sensors, relays, and wiring are checked.
Flame sensor already cleaned/tested
Default: false
Thermostat was recently replaced or reprogrammed
Default: false
Filter is dirty or airflow seems weak
Default: false
Capacitor age
Default: 5 yrs
System age
Default: 12 yrs
What the contractor is saying
Default: no-quote

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: What you see at home.
  • Input: Thermostat call.
  • Input: Indoor blower behavior.
  • Input: Outdoor unit behavior, if cooling or heat pump.
  • Input: Gas furnace pattern.
  • Input: Electric heat / sequencer pattern.
  • Input: Breaker status.
  • Input: Drain float switch / water safety.
  • Input: Technician quoted a control board.
  • Input: Flame sensor already cleaned/tested.
  • Input: Thermostat was recently replaced or reprogrammed.
  • Input: Filter is dirty or airflow seems weak.

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

  • Use symptoms, recent history, and what the technician said. You do not need to know the failed part.
  • Do not open electrical cabinets unless qualified. Capacitors can hold dangerous charge.
  • Gas smell, carbon monoxide alarm, flame rollout, cracked heat exchanger, burning smell, melted wiring, or repeated breaker trips are stop conditions. Shut the system down and call qualified help.
  • This is a homeowner pushback checklist, not a live electrical diagnostic procedure.
  • Identify the heat type first: gas furnace, electric furnace or air handler heat strips, heat pump with auxiliary heat, boiler, or another setup.
  • A breaker that trips immediately, burning smell, melted wire, or shorted compressor needs a qualified technician.

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.